[ORC] Add generic initializer/deinitializer support.

[lhames]

Summary

Background:

Initializers and deinitializers may be used to implement static constructor
and destructor support, runtime registration (e.g. ObjC) and other tasks
that would typically be performed when a dylib/shared-object is loaded or
unloaded.

Until now, MCJIT and ORC have provided limited support for static constructors
and destructors by scanning the llvm.global_ctors and llvm.global_dtors
variables. This approach suffers from two main drawbacks: It requires LLVM IR to
enable initializer discovery (objects loaded directly or from a compile cache
will not have their initializers run), and not all initializers are described by
llvm.global_ctors (e.g. ObjC registration is described by special sections
instead).

This patch introduces several interdependent changes to ORCv2 to enable full
support for initializers and deinitializers:

(1) The MaterializationUnit and MaterializationResponsibility classes are
extended to describe an optional "initializer" symbol for the module (see the
getInitializerSymbol method on each class). The presence or absence of this
symbol indicates whether the module contains any initializers or
deinitializers. The initializer symbol otherwise behaves like any other:
searching for it triggers materialization.

(2) A new Platform interface is introduced in llvm/ExecutionEngine/Orc/Core.h
which provides the following callback interface:

• Error setupJITDylib(JITDylib &JD): Can be used to install standard symbols in JITDylibs upon creation. E.g. __dso_handle.
• Error notifyAdding(JITDylib &JD, const MaterializationUnit &MU): Generally used to record initializer symbols.
• Error notifyRemoving(JITDylib &JD, VModuleKey K): Used to notify a platform that a module is being removed.
• void notifyReady(JITDylib &JD, SymbolNameVector Symbols): Called to notify a platform that some symbols are ready but have not yet been initialized.
  
  Platform implementations can use these callbacks to track outstanding

initializers and implement a platform-specific approach for executing them. For
example, the MachOPlatform installs plugins in the JIT linker and uses them to
scan both the __mod_inits section (for C++ static constructors) and ObjC
metadata sections, then register and run initializers according to JITDylib
link order (i.e. in the same order that they would have been run if the modules
had been linked into corresponding dylibs on the command line).

(3) An initialized state for symbols. The initialized state comes after the
existing states (NeverSearched, Materializing, Resolved, Emitted, Ready) and
can be used to prevent symbol queries from returning until the searched-for
symbol has been initialized.

This patch updates LLJIT to use this scheme for execution of static initializers
and deinitializers. Two LLJIT::PlatformSupport classes are implemented: A
GenericIR platform and a MachO platform. The GenericIR platform implements a
modified version of the previous llvm.global-ctor scraping scheme to provide
support for Windows and Linux. LLJIT's MachO platform support uses the
MachOPlatform class to provide MachO specific initialization (currently just
static initializers scraped from the __mod_inits section, but will include
ObjC support in the near future).

[sgraenitz]

Hi Lang, I had a look at the first half of your changes. So far it looks really great!
A few mini notes inline and a larger one that's semi-related. I will continue with the second half and run this by the ThinLtoJIT example asap.

llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp

152

Is GV promotion here related to the initializers change? Is it always necessary or can we skip it in the whole module partitioning case?

165

This is an ObjC special case right? Can we have a comment for it?

llvm/lib/ExecutionEngine/Orc/Core.cpp

1137

Unintended newline I guess.

1924

The typical ErrorList vs. reportError() case as discussed in D72176. Isn't it a similar situation as with the OnComplete handler in ReExportsMaterializationUnit::materialize()? That one reports the incoming error.

While looking at this, should it be the handler's responsibility at all to think about incoming errors? Is there a deeper reason for this? Otherwise, couldn't the NotifyComplete callback bring a Optional<SymbolMap> instead of an Expected<SymbolMap>? IIUC AsynchronousSymbolQuery has two distinct code paths for success vs. error already: handleComplete() and handleFailed(). The latter could call NotifyComplete(None) and handle the error independently. However, it's not directly connected to this review.

llvm/lib/ExecutionEngine/Orc/LLJIT.cpp

37

Typo: tha -> that
This is how far I got.

[sgraenitz]

As expected this doesn't affect my code much so far. Only the symbol promotion changes in CompileOnDemandLayer (see inline comment). What do you think?

llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp

167

ThinLtoJIT's lookups in the global index are based on name and flags of a symbol and now uses the promoted ones. Probably, I can work around this, but I wonder if promotion and renaming is at all necessary for the whole module partitioning case. Shouldn't translation units stay intact then and linkage be fine as it is?

llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp

91–92

LLVM_DEBUG([...])

[lhames]

• [ORC] Enable initializer support Objective C runtime registration.

[lhames]

Thanks very much for the review Stefan!

I'll apply your suggestions and update the patch shortly.

The part of this patch that I think still needs the most thought is the new state: Initialized.

Initially I thought I would want this to prevent symbols from being looked up (in the default case) until they were initialized. In practice though I'm not sure it's needed: dlsym interposes for JIT'd code can't use it: You're allowed to dlsym a symbol in initializers (i.e. before the initializer for that symbol is complete), and for clients they can just wait until their initialization call returns before looking up any symbols that depend on initialization and then they're safe.

So the question, since the code already been written, is: Can we think of any use for gating on initializers having run, or should we rip this part back out for now to simplify the patch? The benefit to removing it would be to eliminate some new APIs (e.g. Platform::notifySymbolsReady) and reduce some session locking since the platform won't need to re-lock the session to move the symbols to the initialized state.

Let me know if you have any thoughts on this. I probably shouldn't hold the patch up too much longer either way though: we can fix this in-tree after this lands easily enough.

llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp

152

I think it would be possible to skip it in the whole module case -- I will give that a try.

165

It's not ObjC specific, but I think it is hardcoding something that it shouldn't be:

The \01 bit comes from https://llvm.org/docs/LangRef.html#identifier : Symbols with that prefix should not be mangled. This is fine.

The 'L' that follows is meant to capture the assembler private prefix, but we should probably do that with DL.getPrivatePrefix rather than hardcoding it.

This issue is orthogonal to this patch so I'll fix it on trunk.

llvm/lib/ExecutionEngine/Orc/Core.cpp

1137

Fixed. Thanks!

1924

The typical ErrorList vs. reportError() case as discussed in D72176. Isn't it a similar situation as with the OnComplete handler in ReExportsMaterializationUnit::materialize()? That one reports the incoming error.

Yep. This was just laziness on my part while getting the prototype up and running. This should probably just log the errors and return a new "couldn't find some initializer symbols" error.

While looking at this, should it be the handler's responsibility at all to think about incoming errors? Is there a deeper reason for this? Otherwise, couldn't the NotifyComplete callback bring a Optional<SymbolMap> instead of an Expected<SymbolMap>?

I considered using Optional rather than Expected when I was designing the lookup API, but in the end decided that it was better to force clients to explicitly acknowledge a failure result: In some of my prototypes that used Optional I ran into issues when I accidentally continued past a failure result.

llvm/lib/ExecutionEngine/Orc/LLJIT.cpp

37

Fixed. :)

[sgraenitz]

Will initializer symbols be looked up and run again when calling initialize() a second time on a JITDylib? More specifically, is it possible for a client to break this process down and initialize specific (or simply all uninitialized) MaterializationUnits? Otherwise, wouldn't it mean modules cannot be added (and initialized) to a JITDylib after initializiation (without re-init)?

lli orc-lazy             can we also do this?

add all modules          add some modules <--
run all initializers     run their initializers <--
lookup                   lookup
materialize              materialize
execute                  execute, 
call-through             call-through
lookup                   lookup
materialize              add more modules <--
execute                  run their initializers <--
...                      materialize
                         execute

Can we think of any use for gating on initializers having run, or should we rip this part back out for now to simplify the patch?

Not sure if this is related?

llvm/tools/lli/lli.cpp

927

If we called this again, would it re-initialize everything?

[lhames]

In D74300#1878463, @sgraenitz wrote:

Will initializer symbols be looked up and run again when calling initialize() a second time on a JITDylib? More specifically, is it possible for a client to break this process down and initialize specific (or simply all uninitialized) MaterializationUnits? Otherwise, wouldn't it mean modules cannot be added (and initialized) to a JITDylib after initializiation (without re-init)?

lli orc-lazy             can we also do this?

add all modules          add some modules <--
run all initializers     run their initializers <--
lookup                   lookup
materialize              materialize
execute                  execute, 
call-through             call-through
lookup                   lookup
materialize              add more modules <--
execute                  run their initializers <--
...                      materialize
                         execute

Whether the initializers would be re-run is up to the platform.

The platform gets two key pieces of information from ORC: setupJITDylib -- called when new dylibs are created, and notifyAdding -- called when modules are added to the JITDylib. Generally, Platform implementations will need to keep a list of initializers to be run and how this list is managed will determine the answer to your question. Here are some example schemes:

(1) Prohibit any use of initializers

This can be achieved by returning an error from Platform::notifyAdding override. The platform wouldn't provide an initialization API, because it could never do anything useful.

(2) Allow support for exactly one round of initialization (this is your example above)

This can be achieved by maintaining a set of already-initialized JITDylibs in the Platform instance. In the notifyAdding method, if the JITDylib is already in the initialized set then we return an error, e.g.:

if (MU.getInitializerSymbol() != nullptr && AlreadyInitialized.count(&JD))
  make_error<StringError>("dylib " + JD.getName() + " has already been initialized. No new initializers can be added");

This is a sensible mode for a platform that's trying to emulate the execution environment of a normal statically compiled program. Arguably you could go even further and prohibit any new modules from being added after initialization, but this can be tricky: You'd need carve-outs for things like CompileOnDemandLayer's lazily compiled function/partition modules.

(3) On initialization, run newly added initializers only

This may be interesting to REPLs that want to allow new code (including initializers) to be added over time. In this case the Platform would maintain a list of not-yet-executed initializers. This would be appended to each time a new module is added via notifyAdding, and cleared when initializers are run. In this case a call to initialize is a no-op if no new initializers have been added since the last call.

(4) Re-run all initializers every time

I'm not sure who would want such a mode, but it's interesting to discuss as a prelude to something that is useful.

In this mode there would just be a list of initializers to run. New modules that contain initializers would append to this list, but it would never be cleared. Calling initialize (however it's defined for the platform) would run through the whole list each time, essentially resetting it to a state as if it had just been loaded, except that already compiled code would remain present in memory.

I don't think this is useful as a primary mode, but some variant of this might be useful as an addition to mode (2) if clients want to make dlclosing/re-dlopening a dylib relatively efficient by keeping the linked data and text in memory after dlclose is called. In that case you would modify (2) and replace the already-initialized set with a map from JITDylibs to their initializer list. Repeat dlopen operations would be no-ops, but a dlclose would transfer the already-run initializers back to a pending state so that they could be run again on the next dlopen.

Can we think of any use for gating on initializers having run, or should we rip this part back out for now to simplify the patch?

Not sure if this is related?

I don't think so. The initialized state gives JIT clients a way to do something that you can't do in static code, which is issue a lookup that's guaranteed not to return until the static initializers for the target have run.

I think I'm going to take this back out for now: We can always add it back in later, but there's no sense adding an experimental feature with no use case to an already complicated patch.

[lhames]

• [ORC] Remove extraneous whitespace
• [ORC] Fix typo in comment
• [ORC] Address Stefan's feedback, plus remove the 'initialized' state and associated transitions.

[sgraenitz]

Whether the initializers would be re-run is up to the platform.

Great!

I think I'm going to take this back out for now: We can always add it back in later, but there's no sense adding an experimental feature with no use case to an already complicated patch.

Agree, so from my side this is ready once the on-demand layer skips promotion for globals in the whole module case.

[lhames]

• [ORC][examples] Fix examples
• [ORC] Don't add initializer symbols for llvm.global_ctors decls.
• [ORC] Replace init symbols in MaterializationResponsibility::replace.
• [ORC] Don't promote globals for whole-module partitions in CompileOnDemandLayer.

[lhames]

I've updated CompileOnDemandLayer. Tomorrow I will clang-format everything and land the patch when I have time to watch the bots for fallout.

Thanks very much for the feedback Stefan!

[lhames]

Follow-up commits to fix build failures on the bots:

9df65ca19e5a4f5e49d036b190d814ca8a1784a0 -- [ORC] Qualify nullptr_t.
63d0932c358012bcfc1a87f78a5f05bafc2dc86d -- [ORC] Fix a missing move.
f5efa08247c7b5dded4e6854c49c9f49b96398f2 -- [JITLink] Fix testcase for main JITDylib rename in 85fb997659b.

[dyung]

I think there is still at least one bot failure due to this change:

http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/62923

7.710 [49/74/85] Building CXX object examples/ThinLtoJIT/CMakeFiles/ThinLtoJIT.dir/ThinLtoJIT.cpp.o
FAILED: examples/ThinLtoJIT/CMakeFiles/ThinLtoJIT.dir/ThinLtoJIT.cpp.o 
/usr/bin/clang++  -DBUILD_EXAMPLES -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Iexamples/ThinLtoJIT -I/home/buildslave/ps4-buildslave4/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm-project/llvm/examples/ThinLtoJIT -Iinclude -I/home/buildslave/ps4-buildslave4/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm-project/llvm/include -std=c++11 -Wdocumentation -Wno-documentation-deprecated-sync -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fdiagnostics-color -ffunction-sections -fdata-sections -O3     -fno-exceptions -fno-rtti -UNDEBUG -std=c++14 -MD -MT examples/ThinLtoJIT/CMakeFiles/ThinLtoJIT.dir/ThinLtoJIT.cpp.o -MF examples/ThinLtoJIT/CMakeFiles/ThinLtoJIT.dir/ThinLtoJIT.cpp.o.d -o examples/ThinLtoJIT/CMakeFiles/ThinLtoJIT.dir/ThinLtoJIT.cpp.o -c /home/buildslave/ps4-buildslave4/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm-project/llvm/examples/ThinLtoJIT/ThinLtoJIT.cpp
/home/buildslave/ps4-buildslave4/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm-project/llvm/examples/ThinLtoJIT/ThinLtoJIT.cpp:161:12: error: taking the address of a temporary object of type 'Expected<llvm::orc::JITDylib &>' [-Waddress-of-temporary]
  MainJD = &ES.createJITDylib("main");
           ^~~~~~~~~~~~~~~~~~~~~~~~~~
/home/buildslave/ps4-buildslave4/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm-project/llvm/examples/ThinLtoJIT/ThinLtoJIT.cpp:161:12: error: assigning to 'llvm::orc::JITDylib *' from incompatible type 'Expected<llvm::orc::JITDylib &> *'
  MainJD = &ES.createJITDylib("main");
           ^~~~~~~~~~~~~~~~~~~~~~~~~~
2 errors generated.

Can you take a look?

[ftynse]

This also broke MLIR's usage of ORC (https://github.com/llvm/llvm-project/blob/master/mlir/lib/ExecutionEngine/ExecutionEngine.cpp, error https://buildkite.com/mlir/mlir-core/builds/2874#f5df5065-4124-4abe-8783-d9c2c1649e73/348-522). In particular, it can no longer resolve the symbols available in the parent process, such as malloc.

[thakis]

llvm/lib/ExecutionEngine/Orc/Core.cpp

1898

This broke building with clang and gcc 5.3 --gcc-toolchain:

/b/s/w/ir/cache/builder/src/third_party/llvm-bootstrap-install/bin/clang++  -DGTEST_HAS_RTTI=0 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/ExecutionEngine/Orc -I/b/s/w/ir/cache/builder/src/third_party/llvm/llvm/lib/ExecutionEngine/Orc -I/usr/include/libxml2 -Iinclude -I/b/s/w/ir/cache/builder/src/third_party/llvm/llvm/include --gcc-toolchain=/b/s/w/ir/cache/builder/src/third_party/llvm-build-tools/gcc530trusty -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fdiagnostics-color -ffunction-sections -fdata-sections -fprofile-generate="/b/s/w/ir/cache/builder/src/third_party/llvm-instrumented/profiles" -O3 -DNDEBUG    -fno-exceptions -fno-unwind-tables -fno-asynchronous-unwind-tables -fno-rtti -std=c++14 -MD -MT lib/ExecutionEngine/Orc/CMakeFiles/LLVMOrcJIT.dir/Core.cpp.o -MF lib/ExecutionEngine/Orc/CMakeFiles/LLVMOrcJIT.dir/Core.cpp.o.d -o lib/ExecutionEngine/Orc/CMakeFiles/LLVMOrcJIT.dir/Core.cpp.o -c /b/s/w/ir/cache/builder/src/third_party/llvm/llvm/lib/ExecutionEngine/Orc/Core.cpp


/b/s/w/ir/cache/builder/src/third_party/llvm/llvm/lib/ExecutionEngine/Orc/Core.cpp:1898:8: error: no type named 'condition_variable' in namespace 'std'
  std::condition_variable CV;
  ~~~~~^

For some reason, stage 1 (gcc 5.3) is happy, but stage 2 isn't.

Maybe it just needs an #include <condition_variable> up top?

[thakis]

llvm/lib/ExecutionEngine/Orc/Core.cpp

1898

Ah no, good news, it seems to not build with just regular gcc 5.3 either: https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8887928236979492592/+/steps/gclient_runhooks/0/stdout

[hans]

Maybe it just needs an #include <condition_variable> up top?

Yes, that seems to do it. Added in 1f984c83a41bb68b8af4998a7f68876d52bff872

[lhames]

In D74300#1884678, @hans wrote:

Maybe it just needs an #include <condition_variable> up top?

Yes, that seems to do it. Added in 1f984c83a41bb68b8af4998a7f68876d52bff872

Thanks very much Hans!

@thakis, @ftnyse, @dyung — Sorry for the fallout. I’ve got a fix for the ThinLtoJIT example building now, and I’ll look in to the symbol resolution issue next.

[lhames]

@ftynse, @mehdi_amini, @rriddle — This patch changed the way that LLJIT’s DataLayout member is initialized, but I’m still not sure exactly how it’s affecting your use case.

What happens if you explicitly set the LLJIT instance’s data layout by adding a ‘setDataLayout’ call to your LLJITBuilder? E.g.

auto jit =
    cantFail(llvm::orc::LLJITBuilder()
                 .setDataLayout(dataLayout)
                 .setCompileFunctionCreator(compileFunctionCreator)
                 .setObjectLinkingLayerCreator(objectLinkingLayerCreator)
                 .create());

[ftynse]

@lhames still failing with the same error. The use case should be similar to that of lli. Are we missing search order specification maybe?

[lhames]

The ThinLtoJIT example should be fixed by 70d8fec7c94.

@lhames still failing with the same error. The use case should be similar to that of lli. Are we missing search order specification maybe?

@ftynse -- Ok, the DataLayout change didn't break it. That's comforting on some level. I'll have a bit more of a read of the MLIR ExecutionEngine code and see what I can spot. Does this only reproduce on Linux?

[lhames]

Oops -- The ThinLtoJIT example should be fixed by 6de21c556d1, rather.

@ftynse I'll be on discord if you want to chat about this in real time. Side note: I noticed you're getting an assertion after the error:

/var/lib/buildkite-agent/builds/buildkite-6d6d45d7dd-4njcg-1/mlir/mlir-core/llvm/include/llvm/ExecutionEngine/Orc/SymbolStringPool.h:149: llvm::orc::SymbolStringPool::~SymbolStringPool(): Assertion `Pool.empty() && "Dangling references at pool destruction time"' failed.

That indicates that you're holding SymbolStringPtrs allocated by LLJIT after the JIT is torn down, but I can't see where they'd be held. If you can arrange for the LLJIT instance to outlive these strings it will eliminate this assertion.

[rriddle]

In D74300#1885049, @lhames wrote:

Oops -- The ThinLtoJIT example should be fixed by 6de21c556d1, rather.

@ftynse I'll be on discord if you want to chat about this in real time. Side note: I noticed you're getting an assertion after the error:

I just pinged on discord :)

/var/lib/buildkite-agent/builds/buildkite-6d6d45d7dd-4njcg-1/mlir/mlir-core/llvm/include/llvm/ExecutionEngine/Orc/SymbolStringPool.h:149: llvm::orc::SymbolStringPool::~SymbolStringPool(): Assertion `Pool.empty() && "Dangling references at pool destruction time"' failed.

That indicates that you're holding SymbolStringPtrs allocated by LLJIT after the JIT is torn down, but I can't see where they'd be held. If you can arrange for the LLJIT instance to outlive these strings it will eliminate this assertion.

Yeah, the string pool errors are orthogonal, but very unfortunate. Those really need to be fixed.

[ftynse]

In D74300#1885092, @rriddle wrote:

In D74300#1885049, @lhames wrote:

Oops -- The ThinLtoJIT example should be fixed by 6de21c556d1, rather.

@ftynse I'll be on discord if you want to chat about this in real time. Side note: I noticed you're getting an assertion after the error:

I just pinged on discord :)

Thanks for picking this up! :) I'm in a different time zone so it may be tricky for me to be more reactive.

/var/lib/buildkite-agent/builds/buildkite-6d6d45d7dd-4njcg-1/mlir/mlir-core/llvm/include/llvm/ExecutionEngine/Orc/SymbolStringPool.h:149: llvm::orc::SymbolStringPool::~SymbolStringPool(): Assertion `Pool.empty() && "Dangling references at pool destruction time"' failed.

That indicates that you're holding SymbolStringPtrs allocated by LLJIT after the JIT is torn down, but I can't see where they'd be held. If you can arrange for the LLJIT instance to outlive these strings it will eliminate this assertion.

Yeah, the string pool errors are orthogonal, but very unfortunate. Those really need to be fixed.

Indeed, I remember seeing this quite a while ago, but it only manifests in the situations where the executor is going to abort anyway, so we did not spend too much time trying to fix it.

llvm/examples/Kaleidoscope/BuildingAJIT/Chapter1/KaleidoscopeJIT.h

 public:
   KaleidoscopeJIT(JITTargetMachineBuilder JTMB, DataLayout DL)
       : ObjectLayer(ES,
                     []() { return std::make_unique<SectionMemoryManager>(); }),
         CompileLayer(ES, ObjectLayer,
                      std::make_unique<ConcurrentIRCompiler>(std::move(JTMB))),
         DL(std::move(DL)), Mangle(ES, this->DL),
         Ctx(std::make_unique<LLVMContext>()),
-        MainJD(ES.createJITDylib("<main>")) {
+        MainJD(ES.createBareJITDylib("<main>")) {
     MainJD.addGenerator(
         cantFail(DynamicLibrarySearchGenerator::GetForCurrentProcess(
             DL.getGlobalPrefix())));
   }
 
   static Expected<std::unique_ptr<KaleidoscopeJIT>> Create() {
     auto JTMB = JITTargetMachineBuilder::detectHost();
 

llvm/examples/Kaleidoscope/BuildingAJIT/Chapter2/KaleidoscopeJIT.h

 public:
   KaleidoscopeJIT(JITTargetMachineBuilder JTMB, DataLayout DL)
       : ObjectLayer(ES,
                     []() { return std::make_unique<SectionMemoryManager>(); }),
         CompileLayer(ES, ObjectLayer,
                      std::make_unique<ConcurrentIRCompiler>(std::move(JTMB))),
         OptimizeLayer(ES, CompileLayer, optimizeModule), DL(std::move(DL)),
         Mangle(ES, this->DL), Ctx(std::make_unique<LLVMContext>()),
-        MainJD(ES.createJITDylib("<main>")) {
+        MainJD(ES.createBareJITDylib("<main>")) {
     MainJD.addGenerator(
         cantFail(DynamicLibrarySearchGenerator::GetForCurrentProcess(
             DL.getGlobalPrefix())));
   }
 
   const DataLayout &getDataLayout() const { return DL; }
 
   LLVMContext &getContext() { return *Ctx.getContext(); }

llvm/include/llvm/ExecutionEngine/JITLink/JITLink.h

void setLinkage(Linkage L) {
     this->L = static_cast<uint8_t>(L);
   }
 
   /// Get the visibility for this Symbol.
   Scope getScope() const { return static_cast<Scope>(S); }
 
   /// Set the visibility for this Symbol.
   void setScope(Scope S) {
+    assert((!Name.empty() || S == Scope::Local) &&
+           "Can not set anonymous symbol to non-local scope");
     assert((S == Scope::Default || Base->isDefined() || Base->isAbsolute()) &&
            "Invalid visibility for symbol type");
     this->S = static_cast<uint8_t>(S);
   }
 
 private:
   void makeExternal(Addressable &A) {
     assert(!A.isDefined() && "Attempting to make external with defined block");

llvm/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h

CompileOnDemandLayer(ExecutionSession &ES, IRLayer &BaseLayer,
                         LazyCallThroughManager &LCTMgr,
                         IndirectStubsManagerBuilder BuildIndirectStubsManager);
 
   /// Sets the partition function.
   void setPartitionFunction(PartitionFunction Partition);
 
   /// Sets the ImplSymbolMap
   void setImplMap(ImplSymbolMap *Imp);
+
   /// Emits the given module. This should not be called by clients: it will be
   /// called by the JIT when a definition added via the add method is requested.
   void emit(MaterializationResponsibility R, ThreadSafeModule TSM) override;
 
 private:
   struct PerDylibResources {
   public:
     PerDylibResources(JITDylib &ImplD,

llvm/include/llvm/ExecutionEngine/Orc/CompileUtils.h

 class Module;
 class ObjectCache;
 class TargetMachine;
 
 namespace orc {
 
 class JITTargetMachineBuilder;
 
-IRMaterializationUnit::ManglingOptions
+IRSymbolMapper::ManglingOptions
 irManglingOptionsFromTargetOptions(const TargetOptions &Opts);
 
 /// Simple compile functor: Takes a single IR module and returns an ObjectFile.
 /// This compiler supports a single compilation thread and LLVMContext only.
 /// For multithreaded compilation, use ConcurrentIRCompiler below.
 class SimpleCompiler : public IRCompileLayer::IRCompiler {
 public:
   using CompileResult = std::unique_ptr<MemoryBuffer>;
 
   /// Construct a simple compile functor with the given target.
   SimpleCompiler(TargetMachine &TM, ObjectCache *ObjCache = nullptr)
       : IRCompiler(irManglingOptionsFromTargetOptions(TM.Options)), TM(TM),
         ObjCache(ObjCache) {}
 
   /// Set an ObjectCache to query before compiling.
   void setObjectCache(ObjectCache *NewCache) { ObjCache = NewCache; }
 
   /// Compile a Module to an ObjectFile.
   Expected<CompileResult> operator()(Module &M) override;
 
 private:
-  IRMaterializationUnit::ManglingOptions
+  IRSymbolMapper::ManglingOptions
   manglingOptionsForTargetMachine(const TargetMachine &TM);
 
   CompileResult tryToLoadFromObjectCache(const Module &M);
   void notifyObjectCompiled(const Module &M, const MemoryBuffer &ObjBuffer);
 
   TargetMachine &TM;
   ObjectCache *ObjCache = nullptr;
 };

llvm/include/llvm/ExecutionEngine/Orc/Core.h

 //===------ Core.h -- Core ORC APIs (Layer, JITDylib, etc.) -----*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Contains core ORC APIs.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_EXECUTIONENGINE_ORC_CORE_H
 #define LLVM_EXECUTIONENGINE_ORC_CORE_H
 
 #include "llvm/ADT/BitmaskEnum.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/FunctionExtras.h"
 #include "llvm/ExecutionEngine/JITSymbol.h"
 #include "llvm/ExecutionEngine/Orc/SymbolStringPool.h"
 #include "llvm/ExecutionEngine/OrcV1Deprecation.h"
-#include "llvm/IR/Module.h"
 #include "llvm/Support/Debug.h"
 
 #include <memory>
 #include <vector>
 
 #define DEBUG_TYPE "orc"
 
 namespace llvm {
public:
   VModuleKey getVModuleKey() const { return K; }
 
   /// Returns the symbol flags map for this responsibility instance.
   /// Note: The returned flags may have transient flags (Lazy, Materializing)
   /// set. These should be stripped with JITSymbolFlags::stripTransientFlags
   /// before using.
   const SymbolFlagsMap &getSymbols() const { return SymbolFlags; }
 
+  /// Returns the initialization pseudo-symbol, if any. This symbol will also
+  /// be present in the SymbolFlagsMap for this MaterializationResponsibility
+  /// object.
+  const SymbolStringPtr &getInitializerSymbol() const { return InitSymbol; }
+
   /// Returns the names of any symbols covered by this
   /// MaterializationResponsibility object that have queries pending. This
   /// information can be used to return responsibility for unrequested symbols
   /// back to the JITDylib via the delegate method.
   SymbolNameSet getRequestedSymbols() const;
 
   /// Notifies the target JITDylib that the given symbols have been resolved.
   /// This will update the given symbols' addresses in the JITDylib, and notify
public:
 
   /// Add dependencies that apply to all symbols covered by this instance.
   void addDependenciesForAll(const SymbolDependenceMap &Dependencies);
 
 private:
   /// Create a MaterializationResponsibility for the given JITDylib and
   ///        initial symbols.
   MaterializationResponsibility(JITDylib &JD, SymbolFlagsMap SymbolFlags,
-                                VModuleKey K);
+                                SymbolStringPtr InitSymbol, VModuleKey K)
+      : JD(JD), SymbolFlags(std::move(SymbolFlags)),
+        InitSymbol(std::move(InitSymbol)), K(std::move(K)) {
+    assert(!this->SymbolFlags.empty() && "Materializing nothing?");
+  }
 
   JITDylib &JD;
   SymbolFlagsMap SymbolFlags;
+  SymbolStringPtr InitSymbol;
   VModuleKey K;
 };
 
 /// A MaterializationUnit represents a set of symbol definitions that can
 ///        be materialized as a group, or individually discarded (when
 ///        overriding definitions are encountered).
 ///
 /// MaterializationUnits are used when providing lazy definitions of symbols to
 /// JITDylibs. The JITDylib will call materialize when the address of a symbol
 /// is requested via the lookup method. The JITDylib will call discard if a
 /// stronger definition is added or already present.
 class MaterializationUnit {
 public:
-  MaterializationUnit(SymbolFlagsMap InitalSymbolFlags, VModuleKey K)
-      : SymbolFlags(std::move(InitalSymbolFlags)), K(std::move(K)) {}
+  MaterializationUnit(SymbolFlagsMap InitalSymbolFlags,
+                      SymbolStringPtr InitSymbol, VModuleKey K)
+      : SymbolFlags(std::move(InitalSymbolFlags)),
+        InitSymbol(std::move(InitSymbol)), K(std::move(K)) {
+    assert((!this->InitSymbol || this->SymbolFlags.count(this->InitSymbol)) &&
+           "If set, InitSymbol should appear in InitialSymbolFlags map");
+  }
 
   virtual ~MaterializationUnit() {}
 
   /// Return the name of this materialization unit. Useful for debugging
   /// output.
   virtual StringRef getName() const = 0;
 
   /// Return the set of symbols that this source provides.
   const SymbolFlagsMap &getSymbols() const { return SymbolFlags; }
 
+  /// Returns the initialization symbol for this MaterializationUnit (if any).
+  const SymbolStringPtr &getInitializerSymbol() const { return InitSymbol; }
+
   /// Called by materialization dispatchers (see
   /// ExecutionSession::DispatchMaterializationFunction) to trigger
   /// materialization of this MaterializationUnit.
   void doMaterialize(JITDylib &JD) {
-    materialize(MaterializationResponsibility(JD, std::move(SymbolFlags),
-                                              std::move(K)));
+    materialize(MaterializationResponsibility(
+        JD, std::move(SymbolFlags), std::move(InitSymbol), std::move(K)));
   }
 
   /// Called by JITDylibs to notify MaterializationUnits that the given symbol
   /// has been overridden.
   void doDiscard(const JITDylib &JD, const SymbolStringPtr &Name) {
     SymbolFlags.erase(Name);
     discard(JD, std::move(Name));
   }
 
 protected:
   SymbolFlagsMap SymbolFlags;
+  SymbolStringPtr InitSymbol;
   VModuleKey K;
 
 private:
   virtual void anchor();
 
   /// Implementations of this method should materialize all symbols
   ///        in the materialzation unit, except for those that have been
   ///        previously discarded.

 
 /// Build a SymbolAliasMap for the common case where you want to re-export
 /// symbols from another JITDylib with the same linkage/flags.
 Expected<SymbolAliasMap>
 buildSimpleReexportsAAliasMap(JITDylib &SourceJD, const SymbolNameSet &Symbols);
 
 /// Represents the state that a symbol has reached during materialization.
 enum class SymbolState : uint8_t {
-  Invalid,       /// No symbol should be in this state.
-  NeverSearched, /// Added to the symbol table, never queried.
-  Materializing, /// Queried, materialization begun.
-  Resolved,      /// Assigned address, still materializing.
-  Emitted,       /// Emitted to memory, but waiting on transitive dependencies.
-  Ready = 0x3f   /// Ready and safe for clients to access.
+  Invalid,           /// No symbol should be in this state.
+  NeverSearched,     /// Added to the symbol table, never queried.
+  Materializing,     /// Queried, materialization begun.
+  Resolved,          /// Assigned address, still materializing.
+  Emitted,           /// Emitted to memory, but waiting on transitive deps.
+  Ready             /// Symbol and transitive dependencies emitted.
 };
 
 /// A symbol query that returns results via a callback when results are
 ///        ready.
 ///
 /// makes a callback when all symbols are available.
 class AsynchronousSymbolQuery {
   friend class ExecutionSession;

 ///
 /// Represents a virtual shared object. Instances can not be copied or moved, so
 /// their addresses may be used as keys for resource management.
 /// JITDylib state changes must be made via an ExecutionSession to guarantee
 /// that they are synchronized with respect to other JITDylib operations.
 class JITDylib {
   friend class AsynchronousSymbolQuery;
   friend class ExecutionSession;
+  friend class Platform;
   friend class MaterializationResponsibility;
 public:
   /// Definition generators can be attached to JITDylibs to generate new
   /// definitions for otherwise unresolved symbols during lookup.
   class DefinitionGenerator {
   public:
     virtual ~DefinitionGenerator();
 
private:
   std::string JITDylibName;
   SymbolTable Symbols;
   UnmaterializedInfosMap UnmaterializedInfos;
   MaterializingInfosMap MaterializingInfos;
   std::vector<std::unique_ptr<DefinitionGenerator>> DefGenerators;
   JITDylibSearchOrder SearchOrder;
 };
 
+/// Platforms set up standard symbols and mediate interactions between dynamic
+/// initializers (e.g. C++ static constructors) and ExecutionSession state.
+/// Note that Platforms do not automatically run initializers: clients are still
+/// responsible for doing this.
+class Platform {
+public:
+  virtual ~Platform();
+
+  /// This method will be called outside the session lock each time a JITDylib
+  /// is created (unless it is created with EmptyJITDylib set) to allow the
+  /// Platform to install any JITDylib specific standard symbols (e.g
+  /// __dso_handle).
+  virtual Error setupJITDylib(JITDylib &JD) = 0;
+
+  /// This method will be called under the ExecutionSession lock each time a
+  /// MaterializationUnit is added to a JITDylib.
+  virtual Error notifyAdding(JITDylib &JD, const MaterializationUnit &MU) = 0;
+
+  /// This method will be called under the ExecutionSession lock when a
+  /// VModuleKey is removed.
+  virtual Error notifyRemoving(JITDylib &JD, VModuleKey K) = 0;
+
+  /// A utility function for looking up initializer symbols. Performs a blocking
+  /// lookup for the given symbols in each of the given JITDylibs.
+  static Expected<DenseMap<JITDylib *, SymbolMap>>
+  lookupInitSymbols(ExecutionSession &ES,
+                    const DenseMap<JITDylib *, SymbolLookupSet> &InitSyms);
+
+};
+
 /// An ExecutionSession represents a running JIT program.
 class ExecutionSession {
   // FIXME: Remove this when we remove the old ORC layers.
   friend class JITDylib;
 
 public:
   /// For reporting errors.
   using ErrorReporter = std::function<void(Error)>;
 
   /// For dispatching MaterializationUnit::materialize calls.
   using DispatchMaterializationFunction = std::function<void(
       JITDylib &JD, std::unique_ptr<MaterializationUnit> MU)>;
 
   /// Construct an ExecutionSession.
   ///
   /// SymbolStringPools may be shared between ExecutionSessions.
   ExecutionSession(std::shared_ptr<SymbolStringPool> SSP = nullptr);
 
   /// Add a symbol name to the SymbolStringPool and return a pointer to it.
   SymbolStringPtr intern(StringRef SymName) { return SSP->intern(SymName); }
 
   /// Returns a shared_ptr to the SymbolStringPool for this ExecutionSession.
   std::shared_ptr<SymbolStringPool> getSymbolStringPool() const { return SSP; }
 
+  /// Set the Platform for this ExecutionSession.
+  void setPlatform(std::unique_ptr<Platform> P) { this->P = std::move(P); }
+
+  /// Get the Platform for this session.
+  /// Will return null if no Platform has been set for this ExecutionSession.
+  Platform *getPlatform() { return P.get(); }
+
   /// Run the given lambda with the session mutex locked.
   template <typename Func> decltype(auto) runSessionLocked(Func &&F) {
     std::lock_guard<std::recursive_mutex> Lock(SessionMutex);
     return F();
   }
 
   /// Return a pointer to the "name" JITDylib.
   /// Ownership of JITDylib remains within Execution Session
   JITDylib *getJITDylibByName(StringRef Name);
 
+  /// Add a new bare JITDylib to this ExecutionSession.
+  ///
+  /// The JITDylib Name is required to be unique. Clients should verify that
+  /// names are not being re-used (E.g. by calling getJITDylibByName) if names
+  /// are based on user input.
+  ///
+  /// This call does not install any library code or symbols into the newly
+  /// created JITDylib. The client is responsible for all configuration.
+  JITDylib &createBareJITDylib(std::string Name);
+
   /// Add a new JITDylib to this ExecutionSession.
   ///
   /// The JITDylib Name is required to be unique. Clients should verify that
   /// names are not being re-used (e.g. by calling getJITDylibByName) if names
   /// are based on user input.
-  JITDylib &createJITDylib(std::string Name);
+  ///
+  /// If a Platform is attached then Platform::setupJITDylib will be called to
+  /// install standard platform symbols (e.g. standard library interposes).
+  /// If no Platform is attached this call is equivalent to createBareJITDylib.
+  Expected<JITDylib &> createJITDylib(std::string Name);
 
   /// Allocate a module key for a new module to add to the JIT.
   VModuleKey allocateVModule() {
     return runSessionLocked([this]() { return ++LastKey; });
   }
 
   /// Return a module key to the ExecutionSession so that it can be
   ///        re-used. This should only be done once all resources associated
public:
 
   /// Blocking version of lookup above. Returns the resolved symbol map.
   /// If WaitUntilReady is true (the default), will not return until all
   /// requested symbols are ready (or an error occurs). If WaitUntilReady is
   /// false, will return as soon as all requested symbols are resolved,
   /// or an error occurs. If WaitUntilReady is false and an error occurs
   /// after resolution, the function will return a success value, but the
   /// error will be reported via reportErrors.
-  Expected<SymbolMap> lookup(const JITDylibSearchOrder &SearchOrder,
-                             const SymbolLookupSet &Symbols,
-                             LookupKind K = LookupKind::Static,
-                             SymbolState RequiredState = SymbolState::Ready,
-                             RegisterDependenciesFunction RegisterDependencies =
-                                 NoDependenciesToRegister);
+  Expected<SymbolMap>
+  lookup(const JITDylibSearchOrder &SearchOrder, const SymbolLookupSet &Symbols,
 
   /// Convenience version of blocking lookup.
   /// Searches each of the JITDylibs in the search order in turn for the given
   /// symbol.
-  Expected<JITEvaluatedSymbol> lookup(const JITDylibSearchOrder &SearchOrder,
-                                      SymbolStringPtr Symbol);
+  Expected<JITEvaluatedSymbol>
+  lookup(const JITDylibSearchOrder &SearchOrder, SymbolStringPtr Symbol,
+         SymbolState RequiredState = SymbolState::Ready);
 
   /// Convenience version of blocking lookup.
   /// Searches each of the JITDylibs in the search order in turn for the given
   /// symbol. The search will not find non-exported symbols.
-  Expected<JITEvaluatedSymbol> lookup(ArrayRef<JITDylib *> SearchOrder,
-                                      SymbolStringPtr Symbol);
+  Expected<JITEvaluatedSymbol>
+  lookup(ArrayRef<JITDylib *> SearchOrder, SymbolStringPtr Symbol,
+         SymbolState RequiredState = SymbolState::Ready);
 
   /// Convenience version of blocking lookup.
   /// Searches each of the JITDylibs in the search order in turn for the given
   /// symbol. The search will not find non-exported symbols.
-  Expected<JITEvaluatedSymbol> lookup(ArrayRef<JITDylib *> SearchOrder,
-                                      StringRef Symbol);
+  Expected<JITEvaluatedSymbol>
+  lookup(ArrayRef<JITDylib *> SearchOrder, StringRef Symbol,
+         SymbolState RequiredState = SymbolState::Ready);
 
   /// Materialize the given unit.
   void dispatchMaterialization(JITDylib &JD,
                                std::unique_ptr<MaterializationUnit> MU) {
     LLVM_DEBUG({
       runSessionLocked([&]() {
         dbgs() << "Dispatching " << *MU << " for " << JD.getName() << "\n";
       });
materializeOnCurrentThread(JITDylib &JD,
                              std::unique_ptr<MaterializationUnit> MU) {
     MU->doMaterialize(JD);
   }
 
   void runOutstandingMUs();
 
   mutable std::recursive_mutex SessionMutex;
   std::shared_ptr<SymbolStringPool> SSP;
+  std::unique_ptr<Platform> P;
   VModuleKey LastKey = 0;
   ErrorReporter ReportError = logErrorsToStdErr;
   DispatchMaterializationFunction DispatchMaterialization =
       materializeOnCurrentThread;
 
   std::vector<std::unique_ptr<JITDylib>> JDs;
 
   // FIXME: Remove this (and runOutstandingMUs) once the linking layer works

 
 template <typename MaterializationUnitType>
 Error JITDylib::define(std::unique_ptr<MaterializationUnitType> &&MU) {
   assert(MU && "Can not define with a null MU");
   return ES.runSessionLocked([&, this]() -> Error {
     if (auto Err = defineImpl(*MU))
       return Err;
 
+    if (auto *P = ES.getPlatform()) {
+      if (auto Err = P->notifyAdding(*this, *MU))
+        return Err;
+    }
+
     /// defineImpl succeeded.
     auto UMI = std::make_shared<UnmaterializedInfo>(std::move(MU));
     for (auto &KV : UMI->MU->getSymbols())
       UnmaterializedInfos[KV.first] = UMI;
 
     return Error::success();
   });
 }
 
 template <typename MaterializationUnitType>
 Error JITDylib::define(std::unique_ptr<MaterializationUnitType> &MU) {
   assert(MU && "Can not define with a null MU");
 
   return ES.runSessionLocked([&, this]() -> Error {
     if (auto Err = defineImpl(*MU))
       return Err;
 
+    if (auto *P = ES.getPlatform()) {
+      if (auto Err = P->notifyAdding(*this, *MU))
+        return Err;
+    }
+
     /// defineImpl succeeded.
     auto UMI = std::make_shared<UnmaterializedInfo>(std::move(MU));
     for (auto &KV : UMI->MU->getSymbols())
       UnmaterializedInfos[KV.first] = UMI;
 
     return Error::success();
   });
 }
Error tryToGenerate(LookupKind K, JITDylib &JD,
                       const SymbolLookupSet &LookupSet) override;
 
 private:
   JITDylib &SourceJD;
   JITDylibLookupFlags SourceJDLookupFlags;
   SymbolPredicate Allow;
 };
 
-/// Mangles symbol names then uniques them in the context of an
-/// ExecutionSession.
-class MangleAndInterner {
-public:
-  MangleAndInterner(ExecutionSession &ES, const DataLayout &DL);
-  SymbolStringPtr operator()(StringRef Name);
-
-private:
-  ExecutionSession &ES;
-  const DataLayout &DL;
-};
-
 } // End namespace orc
 } // End namespace llvm
 
 #undef DEBUG_TYPE // "orc"
 
 #endif // LLVM_EXECUTIONENGINE_ORC_CORE_H

llvm/include/llvm/ExecutionEngine/Orc/ExecutionUtils.h

 
 #ifndef LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
 #define LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
 
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/ExecutionEngine/JITSymbol.h"
 #include "llvm/ExecutionEngine/Orc/Core.h"
+#include "llvm/ExecutionEngine/Orc/Mangling.h"
 #include "llvm/ExecutionEngine/Orc/OrcError.h"
 #include "llvm/ExecutionEngine/RuntimeDyld.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Support/DynamicLibrary.h"
 #include <algorithm>
 #include <cstdint>
 #include <string>
 #include <utility>

 /// Create an iterator range over the entries of the llvm.global_ctors
 ///        array.
 iterator_range<CtorDtorIterator> getConstructors(const Module &M);
 
 /// Create an iterator range over the entries of the llvm.global_ctors
 ///        array.
 iterator_range<CtorDtorIterator> getDestructors(const Module &M);
 
+/// This iterator provides a convenient way to iterate over GlobalValues that
+/// have initialization effects.
+class StaticInitGVIterator {
+public:
+
+  StaticInitGVIterator() = default;
+
+  StaticInitGVIterator(Module &M)
+      : I(M.global_values().begin()), E(M.global_values().end()),
+        ObjFmt(Triple(M.getTargetTriple()).getObjectFormat()) {
+    if (I != E) {
+      if (!isStaticInitGlobal(*I))
+        moveToNextStaticInitGlobal();
+    } else
+      I = E = Module::global_value_iterator();
+  }
+
+  bool operator==(const StaticInitGVIterator &O) const { return I == O.I; }
+  bool operator!=(const StaticInitGVIterator &O) const { return I != O.I; }
+
+  StaticInitGVIterator &operator++() {
+    assert(I != E && "Increment past end of range");
+    moveToNextStaticInitGlobal();
+    return *this;
+  }
+
+  GlobalValue &operator*() { return *I; }
+
+private:
+
+  bool isStaticInitGlobal(GlobalValue &GV);
+  void moveToNextStaticInitGlobal() {
+    ++I;
+    while (I != E && !isStaticInitGlobal(*I))
+      ++I;
+    if (I == E)
+      I = E = Module::global_value_iterator();
+  }
+
+  Module::global_value_iterator I, E;
+  Triple::ObjectFormatType ObjFmt;
+};
+
+/// Create an iterator range over the GlobalValues that contribute to static
+/// initialization.
+inline iterator_range<StaticInitGVIterator> getStaticInitGVs(Module &M) {
+  return make_range(StaticInitGVIterator(M), StaticInitGVIterator());
+}
+
 /// Convenience class for recording constructor/destructor names for
 ///        later execution.
 template <typename JITLayerT>
 class LegacyCtorDtorRunner {
 public:
   /// Construct a CtorDtorRunner for the given range using the given
   ///        name mangling function.
   LLVM_ATTRIBUTE_DEPRECATED(
LegacyLocalCXXRuntimeOverrides::LegacyLocalCXXRuntimeOverrides(
   addOverride(Mangle("__cxa_atexit"), toTargetAddress(&CXAAtExitOverride));
 }
 
 class LocalCXXRuntimeOverrides : public LocalCXXRuntimeOverridesBase {
 public:
   Error enable(JITDylib &JD, MangleAndInterner &Mangler);
 };
 
+/// An interface for Itanium __cxa_atexit interposer implementations.
+class ItaniumCXAAtExitSupport {
+public:
+  struct AtExitRecord {
+    void (*F)(void *);
+    void *Ctx;
+  };
+
+  void registerAtExit(void (*F)(void *), void *Ctx, void *DSOHandle);
+  void runAtExits(void *DSOHandle);
+
+private:
+  std::mutex AtExitsMutex;
+  DenseMap<void *, std::vector<AtExitRecord>> AtExitRecords;
+};
+
 /// A utility class to expose symbols found via dlsym to the JIT.
 ///
 /// If an instance of this class is attached to a JITDylib as a fallback
 /// definition generator, then any symbol found in the given DynamicLibrary that
 /// passes the 'Allow' predicate will be added to the JITDylib.
 class DynamicLibrarySearchGenerator : public JITDylib::DefinitionGenerator {
 public:
   using SymbolPredicate = std::function<bool(const SymbolStringPtr &)>;

llvm/include/llvm/ExecutionEngine/Orc/IRCompileLayer.h

 class Module;
 
 namespace orc {
 
 class IRCompileLayer : public IRLayer {
 public:
   class IRCompiler {
   public:
-    IRCompiler(IRMaterializationUnit::ManglingOptions MO) : MO(std::move(MO)) {}
+    IRCompiler(IRSymbolMapper::ManglingOptions MO) : MO(std::move(MO)) {}
     virtual ~IRCompiler();
-    const IRMaterializationUnit::ManglingOptions &getManglingOptions() const {
+    const IRSymbolMapper::ManglingOptions &getManglingOptions() const {
       return MO;
     }
     virtual Expected<std::unique_ptr<MemoryBuffer>> operator()(Module &M) = 0;
 
   protected:
-    IRMaterializationUnit::ManglingOptions &manglingOptions() { return MO; }
+    IRSymbolMapper::ManglingOptions &manglingOptions() { return MO; }
 
   private:
-    IRMaterializationUnit::ManglingOptions MO;
+    IRSymbolMapper::ManglingOptions MO;
   };
 
   using NotifyCompiledFunction =
       std::function<void(VModuleKey K, ThreadSafeModule TSM)>;
 
   IRCompileLayer(ExecutionSession &ES, ObjectLayer &BaseLayer,
                  std::unique_ptr<IRCompiler> Compile);
 
   IRCompiler &getCompiler() { return *Compile; }
 
   void setNotifyCompiled(NotifyCompiledFunction NotifyCompiled);
 
   void emit(MaterializationResponsibility R, ThreadSafeModule TSM) override;
 
 private:
   mutable std::mutex IRLayerMutex;
   ObjectLayer &BaseLayer;
   std::unique_ptr<IRCompiler> Compile;
-  const IRMaterializationUnit::ManglingOptions *ManglingOpts;
+  const IRSymbolMapper::ManglingOptions *ManglingOpts;
   NotifyCompiledFunction NotifyCompiled = NotifyCompiledFunction();
 };
 
 /// Eager IR compiling layer.
 ///
 ///   This layer immediately compiles each IR module added via addModule to an
 /// object file and adds this module file to the layer below, which must
 /// implement the object layer concept.

llvm/include/llvm/ExecutionEngine/Orc/IRTransformLayer.h

 namespace orc {
 
 /// A layer that applies a transform to emitted modules.
 /// The transform function is responsible for locking the ThreadSafeContext
 /// before operating on the module.
 class IRTransformLayer : public IRLayer {
 public:
   using TransformFunction = std::function<Expected<ThreadSafeModule>(
-      ThreadSafeModule, const MaterializationResponsibility &R)>;
+      ThreadSafeModule, MaterializationResponsibility &R)>;
 
   IRTransformLayer(ExecutionSession &ES, IRLayer &BaseLayer,
                    TransformFunction Transform = identityTransform);
 
   void setTransform(TransformFunction Transform) {
     this->Transform = std::move(Transform);
   }
 
   void emit(MaterializationResponsibility R, ThreadSafeModule TSM) override;
 
-  static ThreadSafeModule
-  identityTransform(ThreadSafeModule TSM,
-                    const MaterializationResponsibility &R) {
+  static ThreadSafeModule identityTransform(ThreadSafeModule TSM,
+                                            MaterializationResponsibility &R) {
     return TSM;
   }
 
 private:
   IRLayer &BaseLayer;
   TransformFunction Transform;
 };
 

llvm/include/llvm/ExecutionEngine/Orc/IndirectionUtils.h

public:
   JITTargetAddress executeCompileCallback(JITTargetAddress TrampolineAddr);
 
 protected:
   /// Construct a JITCompileCallbackManager.
   JITCompileCallbackManager(std::unique_ptr<TrampolinePool> TP,
                             ExecutionSession &ES,
                             JITTargetAddress ErrorHandlerAddress)
       : TP(std::move(TP)), ES(ES),
-        CallbacksJD(ES.createJITDylib("<Callbacks>")),
+        CallbacksJD(ES.createBareJITDylib("<Callbacks>")),
         ErrorHandlerAddress(ErrorHandlerAddress) {}
 
   void setTrampolinePool(std::unique_ptr<TrampolinePool> TP) {
     this->TP = std::move(TP);
   }
 
 private:
   std::mutex CCMgrMutex;

llvm/include/llvm/ExecutionEngine/Orc/LLJIT.h

 class LLLazyJITBuilderState;
 
 /// A pre-fabricated ORC JIT stack that can serve as an alternative to MCJIT.
 ///
 /// Create instances using LLJITBuilder.
 class LLJIT {
   template <typename, typename, typename> friend class LLJITBuilderSetters;
 
+  friend void setUpGenericLLVMIRPlatform(LLJIT &J);
+
+public:
+  /// Initializer support for LLJIT.
+  class PlatformSupport {
   public:
+    virtual ~PlatformSupport();
+
+    virtual Error initialize(JITDylib &JD) = 0;
+
+    virtual Error deinitialize(JITDylib &JD) = 0;
+
+  protected:
+    static void setInitTransform(LLJIT &J,
+                                 IRTransformLayer::TransformFunction T);
+  };
+
   static Expected<std::unique_ptr<LLJIT>> Create(LLJITBuilderState &S);
 
   /// Destruct this instance. If a multi-threaded instance, waits for all
   /// compile threads to complete.
   ~LLJIT();
 
   /// Returns the ExecutionSession for this instance.
   ExecutionSession &getExecutionSession() { return *ES; }
 
   /// Returns a reference to the triple for this instance.
   const Triple &getTargetTriple() const { return TT; }
 
   /// Returns a reference to the DataLayout for this instance.
   const DataLayout &getDataLayout() const { return DL; }
 
   /// Returns a reference to the JITDylib representing the JIT'd main program.
-  JITDylib &getMainJITDylib() { return Main; }
+  JITDylib &getMainJITDylib() { return *Main; }
 
   /// Returns the JITDylib with the given name, or nullptr if no JITDylib with
   /// that name exists.
   JITDylib *getJITDylibByName(StringRef Name) {
     return ES->getJITDylibByName(Name);
   }
 
   /// Create a new JITDylib with the given name and return a reference to it.
   ///
   /// JITDylib names must be unique. If the given name is derived from user
   /// input or elsewhere in the environment then the client should check
   /// (e.g. by calling getJITDylibByName) that the given name is not already in
   /// use.
-  JITDylib &createJITDylib(std::string Name) {
+  Expected<JITDylib &> createJITDylib(std::string Name) {
     return ES->createJITDylib(std::move(Name));
   }
 
   /// Convenience method for defining an absolute symbol.
   Error defineAbsolute(StringRef Name, JITEvaluatedSymbol Address);
 
   /// Adds an IR module to the given JITDylib.
   Error addIRModule(JITDylib &JD, ThreadSafeModule TSM);
 
   /// Adds an IR module to the Main JITDylib.
   Error addIRModule(ThreadSafeModule TSM) {
-    return addIRModule(Main, std::move(TSM));
+    return addIRModule(*Main, std::move(TSM));
   }
 
   /// Adds an object file to the given JITDylib.
   Error addObjectFile(JITDylib &JD, std::unique_ptr<MemoryBuffer> Obj);
 
   /// Adds an object file to the given JITDylib.
   Error addObjectFile(std::unique_ptr<MemoryBuffer> Obj) {
-    return addObjectFile(Main, std::move(Obj));
+    return addObjectFile(*Main, std::move(Obj));
   }
 
   /// Look up a symbol in JITDylib JD by the symbol's linker-mangled name (to
   /// look up symbols based on their IR name use the lookup function instead).
   Expected<JITEvaluatedSymbol> lookupLinkerMangled(JITDylib &JD,
                                                    StringRef Name);
 
   /// Look up a symbol in the main JITDylib by the symbol's linker-mangled name
   /// (to look up symbols based on their IR name use the lookup function
   /// instead).
   Expected<JITEvaluatedSymbol> lookupLinkerMangled(StringRef Name) {
-    return lookupLinkerMangled(Main, Name);
+    return lookupLinkerMangled(*Main, Name);
   }
 
   /// Look up a symbol in JITDylib JD based on its IR symbol name.
   Expected<JITEvaluatedSymbol> lookup(JITDylib &JD, StringRef UnmangledName) {
     return lookupLinkerMangled(JD, mangle(UnmangledName));
   }
 
   /// Look up a symbol in the main JITDylib based on its IR symbol name.
   Expected<JITEvaluatedSymbol> lookup(StringRef UnmangledName) {
-    return lookup(Main, UnmangledName);
+    return lookup(*Main, UnmangledName);
+  }
+
+  /// Set the PlatformSupport instance.
+  void setPlatformSupport(std::unique_ptr<PlatformSupport> PS) {
+    this->PS = std::move(PS);
   }
 
-  /// Runs all not-yet-run static constructors.
-  Error runConstructors() { return CtorRunner.run(); }
+  /// Get the PlatformSupport instance.
+  PlatformSupport *getPlatformSupport() { return PS.get(); }
 
-  /// Runs all not-yet-run static destructors.
-  Error runDestructors() { return DtorRunner.run(); }
+  /// Run the initializers for the given JITDylib.
+  Error initialize(JITDylib &JD) {
+    assert(PS && "PlatformSupport must be set to run initializers.");
+    return PS->initialize(JD);
+  }
+
+  /// Run the deinitializers for the given JITDylib.
+  Error deinitialize(JITDylib &JD) {
+    assert(PS && "PlatformSupport must be set to run initializers.");
+    return PS->deinitialize(JD);
+  }
 
   /// Returns a reference to the ObjLinkingLayer
   ObjectLayer &getObjLinkingLayer() { return *ObjLinkingLayer; }
 
   /// Returns a reference to the object transform layer.
   ObjectTransformLayer &getObjTransformLayer() { return ObjTransformLayer; }
 
   /// Returns a reference to the IR transform layer.
   IRTransformLayer &getIRTransformLayer() { return *TransformLayer; }
 
+  /// Returns a reference to the IR compile layer.
+  IRCompileLayer &getIRCompileLayer() { return *CompileLayer; }
+
 protected:
   static std::unique_ptr<ObjectLayer>
   createObjectLinkingLayer(LLJITBuilderState &S, ExecutionSession &ES);
 
   static Expected<std::unique_ptr<IRCompileLayer::IRCompiler>>
   createCompileFunction(LLJITBuilderState &S, JITTargetMachineBuilder JTMB);
 
   /// Create an LLJIT instance with a single compile thread.
   LLJIT(LLJITBuilderState &S, Error &Err);
 
   std::string mangle(StringRef UnmangledName);
 
   Error applyDataLayout(Module &M);
 
   void recordCtorDtors(Module &M);
 
   std::unique_ptr<ExecutionSession> ES;
-  JITDylib &Main;
+  std::unique_ptr<PlatformSupport> PS;
+
+  JITDylib *Main = nullptr;
 
   DataLayout DL;
   Triple TT;
   std::unique_ptr<ThreadPool> CompileThreads;
 
   std::unique_ptr<ObjectLayer> ObjLinkingLayer;
   ObjectTransformLayer ObjTransformLayer;
   std::unique_ptr<IRCompileLayer> CompileLayer;
   std::unique_ptr<IRTransformLayer> TransformLayer;
-
-  CtorDtorRunner CtorRunner, DtorRunner;
+  std::unique_ptr<IRTransformLayer> InitHelperTransformLayer;
 };
 
 /// An extended version of LLJIT that supports lazy function-at-a-time
 /// compilation of LLVM IR.
 class LLLazyJIT : public LLJIT {
   template <typename, typename, typename> friend class LLJITBuilderSetters;
 
 public:
 
   /// Sets the partition function.
   void
   setPartitionFunction(CompileOnDemandLayer::PartitionFunction Partition) {
     CODLayer->setPartitionFunction(std::move(Partition));
   }
 
   /// Add a module to be lazily compiled to JITDylib JD.
   Error addLazyIRModule(JITDylib &JD, ThreadSafeModule M);
 
   /// Add a module to be lazily compiled to the main JITDylib.
   Error addLazyIRModule(ThreadSafeModule M) {
-    return addLazyIRModule(Main, std::move(M));
+    return addLazyIRModule(*Main, std::move(M));
   }
 
 private:
 
   // Create a single-threaded LLLazyJIT instance.
   LLLazyJIT(LLLazyJITBuilderState &S, Error &Err);
 
   std::unique_ptr<LazyCallThroughManager> LCTMgr;
   std::unique_ptr<CompileOnDemandLayer> CODLayer;
 };
 
 class LLJITBuilderState {
 public:
   using ObjectLinkingLayerCreator = std::function<std::unique_ptr<ObjectLayer>(
       ExecutionSession &, const Triple &TT)>;
 
   using CompileFunctionCreator =
       std::function<Expected<std::unique_ptr<IRCompileLayer::IRCompiler>>(
           JITTargetMachineBuilder JTMB)>;
 
+  using PlatformSetupFunction = std::function<Error(LLJIT &J)>;
+
   std::unique_ptr<ExecutionSession> ES;
   Optional<JITTargetMachineBuilder> JTMB;
+  Optional<DataLayout> DL;
   ObjectLinkingLayerCreator CreateObjectLinkingLayer;
   CompileFunctionCreator CreateCompileFunction;
+  PlatformSetupFunction SetUpPlatform;
   unsigned NumCompileThreads = 0;
 
   /// Called prior to JIT class construcion to fix up defaults.
   Error prepareForConstruction();
 };
 
 template <typename JITType, typename SetterImpl, typename State>
 class LLJITBuilderSetters {
 public:
   /// Set the JITTargetMachineBuilder for this instance.
   ///
   /// If this method is not called, JITTargetMachineBuilder::detectHost will be
   /// used to construct a default target machine builder for the host platform.
   SetterImpl &setJITTargetMachineBuilder(JITTargetMachineBuilder JTMB) {
     impl().JTMB = std::move(JTMB);
     return impl();
   }
 
   /// Return a reference to the JITTargetMachineBuilder.
   ///
   Optional<JITTargetMachineBuilder> &getJITTargetMachineBuilder() {
     return impl().JTMB;
   }
 
+  /// Set a DataLayout for this instance. If no data layout is specified then
+  /// the target's default data layout will be used.
+  SetterImpl &setDataLayout(Optional<DataLayout> DL) {
+    impl().DL = std::move(DL);
+    return impl();
+  }
+
   /// Set an ObjectLinkingLayer creation function.
   ///
   /// If this method is not called, a default creation function will be used
   /// that will construct an RTDyldObjectLinkingLayer.
   SetterImpl &setObjectLinkingLayerCreator(
       LLJITBuilderState::ObjectLinkingLayerCreator CreateObjectLinkingLayer) {
     impl().CreateObjectLinkingLayer = std::move(CreateObjectLinkingLayer);
     return impl();
   }
 
   /// Set a CompileFunctionCreator.
   ///
   /// If this method is not called, a default creation function wil be used
   /// that will construct a basic IR compile function that is compatible with
   /// the selected number of threads (SimpleCompiler for '0' compile threads,
   /// ConcurrentIRCompiler otherwise).
   SetterImpl &setCompileFunctionCreator(
       LLJITBuilderState::CompileFunctionCreator CreateCompileFunction) {
     impl().CreateCompileFunction = std::move(CreateCompileFunction);
     return impl();
   }
 
+  /// Set up an PlatformSetupFunction.
+  ///
+  /// If this method is not called then setUpGenericLLVMIRPlatform
+  /// will be used to configure the JIT's platform support.
+  SetterImpl &
+  setPlatformSetUp(LLJITBuilderState::PlatformSetupFunction SetUpPlatform) {
+    impl().SetUpPlatform = std::move(SetUpPlatform);
+    return impl();
+  }
+
   /// Set the number of compile threads to use.
   ///
   /// If set to zero, compilation will be performed on the execution thread when
   /// JITing in-process. If set to any other number N, a thread pool of N
   /// threads will be created for compilation.
   ///
   /// If this method is not called, behavior will be as if it were called with
   /// a zero argument.

 };
 
 /// Constructs LLLazyJIT instances.
 class LLLazyJITBuilder
     : public LLLazyJITBuilderState,
       public LLLazyJITBuilderSetters<LLLazyJIT, LLLazyJITBuilder,
                                      LLLazyJITBuilderState> {};
 
+/// Configure the LLJIT instance to scrape modules for llvm.global_ctors and
+/// llvm.global_dtors variables and (if present) build initialization and
+/// deinitialization functions. Platform specific initialization configurations
+/// should be preferred where available.
+void setUpGenericLLVMIRPlatform(LLJIT &J);
+
+/// Configure the LLJIT instance to use MachOPlatform support.
+///
+/// Warning: MachOPlatform *requires* that LLJIT be configured to use
+/// ObjectLinkingLayer (default on platforms supported by JITLink). If
+/// MachOPlatform is used with RTDyldObjectLinkingLayer it will result in
+/// undefined behavior).
+///
+/// MachOPlatform installs an ObjectLinkingLayer plugin to scrape initializers
+/// from the __mod_inits section. It also provides interposes for the dlfcn
+/// functions (dlopen, dlclose, dlsym, dlerror) that work for JITDylibs as
+/// well as regular libraries (JITDylibs will be preferenced, so make sure
+/// your JITDylib names do not shadow any real library paths).
+Error setUpMachOPlatform(LLJIT &J);
+
 } // End namespace orc
 } // End namespace llvm
 
 #endif // LLVM_EXECUTIONENGINE_ORC_LLJIT_H

llvm/include/llvm/ExecutionEngine/Orc/Layer.h

 //===---------------- Layer.h -- Layer interfaces --------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Layer interfaces.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_EXECUTIONENGINE_ORC_LAYER_H
 #define LLVM_EXECUTIONENGINE_ORC_LAYER_H
 
 #include "llvm/ExecutionEngine/Orc/Core.h"
+#include "llvm/ExecutionEngine/Orc/Mangling.h"
 #include "llvm/ExecutionEngine/Orc/ThreadSafeModule.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/MemoryBuffer.h"
 
 namespace llvm {
 namespace orc {
 
 /// IRMaterializationUnit is a convenient base class for MaterializationUnits
 /// wrapping LLVM IR. Represents materialization responsibility for all symbols
 /// in the given module. If symbols are overridden by other definitions, then
 /// their linkage is changed to available-externally.
 class IRMaterializationUnit : public MaterializationUnit {
 public:
-  struct ManglingOptions {
-    bool EmulatedTLS = false;
-  };
-
   using SymbolNameToDefinitionMap = std::map<SymbolStringPtr, GlobalValue *>;
 
   /// Create an IRMaterializationLayer. Scans the module to build the
   /// SymbolFlags and SymbolToDefinition maps.
-  IRMaterializationUnit(ExecutionSession &ES, const ManglingOptions &MO,
+  IRMaterializationUnit(ExecutionSession &ES,
+                        const IRSymbolMapper::ManglingOptions &MO,
                         ThreadSafeModule TSM, VModuleKey K);
 
   /// Create an IRMaterializationLayer from a module, and pre-existing
   /// SymbolFlags and SymbolToDefinition maps. The maps must provide
   /// entries for each definition in M.
   /// This constructor is useful for delegating work from one
   /// IRMaterializationUnit to another.
   IRMaterializationUnit(ThreadSafeModule TSM, VModuleKey K,
-                        SymbolFlagsMap SymbolFlags,
+                        SymbolFlagsMap SymbolFlags, SymbolStringPtr InitSymbol,
                         SymbolNameToDefinitionMap SymbolToDefinition);
 
   /// Return the ModuleIdentifier as the name for this MaterializationUnit.
   StringRef getName() const override;
 
+  /// Return a reference to the contained ThreadSafeModule.
   const ThreadSafeModule &getModule() const { return TSM; }
 
 protected:
   ThreadSafeModule TSM;
   SymbolNameToDefinitionMap SymbolToDefinition;
 
 private:
+  static SymbolStringPtr getInitSymbol(ExecutionSession &ES,
+                                       const ThreadSafeModule &TSM);
+
   void discard(const JITDylib &JD, const SymbolStringPtr &Name) override;
 };
 
 /// Interface for layers that accept LLVM IR.
 class IRLayer {
 public:
-  IRLayer(ExecutionSession &ES,
-          const IRMaterializationUnit::ManglingOptions *&MO)
+  IRLayer(ExecutionSession &ES, const IRSymbolMapper::ManglingOptions *&MO)
       : ES(ES), MO(MO) {}
 
   virtual ~IRLayer();
 
   /// Returns the ExecutionSession for this layer.
   ExecutionSession &getExecutionSession() { return ES; }
 
   /// Get the mangling options for this layer.
-  const IRMaterializationUnit::ManglingOptions *&getManglingOptions() const {
+  const IRSymbolMapper::ManglingOptions *&getManglingOptions() const {
     return MO;
   }
 
   /// Sets the CloneToNewContextOnEmit flag (false by default).
   ///
   /// When set, IR modules added to this layer will be cloned on to a new
   /// context before emit is called. This can be used by clients who want
   /// to load all IR using one LLVMContext (to save memory via type and
virtual Error add(JITDylib &JD, ThreadSafeModule TSM,
                     VModuleKey K = VModuleKey());
 
   /// Emit should materialize the given IR.
   virtual void emit(MaterializationResponsibility R, ThreadSafeModule TSM) = 0;
 
 private:
   bool CloneToNewContextOnEmit = false;
   ExecutionSession &ES;
-  const IRMaterializationUnit::ManglingOptions *&MO;
+  const IRSymbolMapper::ManglingOptions *&MO;
 };
 
 /// MaterializationUnit that materializes modules by calling the 'emit' method
 /// on the given IRLayer.
 class BasicIRLayerMaterializationUnit : public IRMaterializationUnit {
 public:
-  BasicIRLayerMaterializationUnit(IRLayer &L, const ManglingOptions &MO,
+  BasicIRLayerMaterializationUnit(IRLayer &L,
+                                  const IRSymbolMapper::ManglingOptions &MO,
                                   ThreadSafeModule TSM, VModuleKey K);
 
 private:
 
   void materialize(MaterializationResponsibility R) override;
 
   IRLayer &L;
   VModuleKey K;

 /// instance) by calling 'emit' on the given ObjectLayer.
 class BasicObjectLayerMaterializationUnit : public MaterializationUnit {
 public:
   static Expected<std::unique_ptr<BasicObjectLayerMaterializationUnit>>
   Create(ObjectLayer &L, VModuleKey K, std::unique_ptr<MemoryBuffer> O);
 
   BasicObjectLayerMaterializationUnit(ObjectLayer &L, VModuleKey K,
                                       std::unique_ptr<MemoryBuffer> O,
-                                      SymbolFlagsMap SymbolFlags);
+                                      SymbolFlagsMap SymbolFlags,
+                                      SymbolStringPtr InitSymbol);
 
   /// Return the buffer's identifier as the name for this MaterializationUnit.
   StringRef getName() const override;
 
 private:
 
   void materialize(MaterializationResponsibility R) override;
   void discard(const JITDylib &JD, const SymbolStringPtr &Name) override;
 
   ObjectLayer &L;
   std::unique_ptr<MemoryBuffer> O;
 };
 
-/// Returns a SymbolFlagsMap for the object file represented by the given
-/// buffer, or an error if the buffer does not contain a valid object file.
-// FIXME: Maybe move to Core.h?
-Expected<SymbolFlagsMap> getObjectSymbolFlags(ExecutionSession &ES,
-                                              MemoryBufferRef ObjBuffer);
-
 } // End namespace orc
 } // End namespace llvm
 
 #endif // LLVM_EXECUTIONENGINE_ORC_LAYER_H

llvm/include/llvm/ExecutionEngine/Orc/MachOPlatform.h

+//===-- MachOPlatform.h - Utilities for executing MachO in Orc --*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Utilities for executing JIT'd MachO in Orc.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_ORC_MACHOPLATFORM_H
+#define LLVM_EXECUTIONENGINE_ORC_MACHOPLATFORM_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ExecutionEngine/Orc/Core.h"
+#include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
+#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
+
+#include <future>
+#include <thread>
+#include <vector>
+
+namespace llvm {
+namespace orc {
+
+/// Enable registration of JIT'd ObjC classes and selectors.
+Error enableObjCRegistration(const char *PathToLibObjC);
+bool objCRegistrationEnabled();
+
+class MachOJITDylibInitializers {
+public:
+  struct SectionExtent {
+    SectionExtent() = default;
+    SectionExtent(JITTargetAddress Address, uint64_t NumPtrs)
+        : Address(Address), NumPtrs(NumPtrs) {}
+    JITTargetAddress Address = 0;
+    uint64_t NumPtrs = 0;
+  };
+
+  void setObjCImageInfoAddr(JITTargetAddress ObjCImageInfoAddr) {
+    this->ObjCImageInfoAddr = ObjCImageInfoAddr;
+  }
+
+  void addModInitsSection(SectionExtent ModInit) {
+    ModInitSections.push_back(std::move(ModInit));
+  }
+
+  void addObjCSelRefsSection(SectionExtent ObjCSelRefs) {
+    ObjCSelRefsSections.push_back(std::move(ObjCSelRefs));
+  }
+
+  void addObjCClassListSection(SectionExtent ObjCClassList) {
+    ObjCClassListSections.push_back(std::move(ObjCClassList));
+  }
+
+  void runModInits() const;
+  void registerObjCSelectors() const;
+  void registerObjCClasses() const;
+
+  void dump() const;
+
+private:
+
+  using RawPointerSectionList = std::vector<SectionExtent>;
+
+  JITTargetAddress ObjCImageInfoAddr;
+  RawPointerSectionList ModInitSections;
+  RawPointerSectionList ObjCSelRefsSections;
+  RawPointerSectionList ObjCClassListSections;
+};
+
+class MachOJITDylibDeinitializers {};
+
+/// Mediates between MachO initialization and ExecutionSession state.
+class MachOPlatform : public Platform {
+public:
+  using InitializerSequence =
+      std::vector<std::pair<JITDylib *, MachOJITDylibInitializers>>;
+
+  using DeinitializerSequence =
+      std::vector<std::pair<JITDylib *, MachOJITDylibDeinitializers>>;
+
+  MachOPlatform(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
+                std::unique_ptr<MemoryBuffer> StandardSymbolsObject);
+
+  ExecutionSession &getExecutionSession() const { return ES; }
+
+  Error setupJITDylib(JITDylib &JD) override;
+  Error notifyAdding(JITDylib &JD, const MaterializationUnit &MU) override;
+  Error notifyRemoving(JITDylib &JD, VModuleKey K) override;
+
+  Expected<InitializerSequence> getInitializerSequence(JITDylib &JD);
+
+  Expected<DeinitializerSequence> getDeinitializerSequence(JITDylib &JD);
+
+private:
+  // This ObjectLinkingLayer plugin scans JITLink graphs for __mod_init_func,
+  // __objc_classlist and __sel_ref sections and records their extents so that
+  // they can be run in the target process.
+  class InitScraperPlugin : public ObjectLinkingLayer::Plugin {
+  public:
+    InitScraperPlugin(MachOPlatform &MP) : MP(MP) {}
+
+    void modifyPassConfig(MaterializationResponsibility &MR, const Triple &TT,
+                          jitlink::PassConfiguration &Config) override;
+
+    LocalDependenciesMap
+    getSyntheticSymbolLocalDependencies(
+        MaterializationResponsibility &MR) override;
+
+  private:
+
+    using InitSymbolDepMap =
+      DenseMap<MaterializationResponsibility*, JITLinkSymbolVector>;
+
+    void preserveInitSectionIfPresent(JITLinkSymbolVector &Syms,
+                                      jitlink::LinkGraph &G,
+                                      StringRef SectionName);
+
+    Error processObjCImageInfo(jitlink::LinkGraph &G,
+                               MaterializationResponsibility &MR);
+
+    std::mutex InitScraperMutex;
+    MachOPlatform &MP;
+    DenseMap<JITDylib*, std::pair<uint32_t, uint32_t>> ObjCImageInfos;
+    InitSymbolDepMap InitSymbolDeps;
+  };
+
+  static std::vector<JITDylib *> getDFSLinkOrder(JITDylib &JD);
+
+  void registerInitInfo(JITDylib &JD,
+                        JITTargetAddress ObjCImageInfoAddr,
+                        MachOJITDylibInitializers::SectionExtent ModInits,
+                        MachOJITDylibInitializers::SectionExtent ObjCSelRefs,
+                        MachOJITDylibInitializers::SectionExtent ObjCClassList);
+
+  std::mutex PlatformMutex;
+  ExecutionSession &ES;
+  ObjectLinkingLayer &ObjLinkingLayer;
+  std::unique_ptr<MemoryBuffer> StandardSymbolsObject;
+
+  DenseMap<JITDylib *, SymbolLookupSet> RegisteredInitSymbols;
+  DenseMap<JITDylib *, MachOJITDylibInitializers> InitSeqs;
+};
+
+} // end namespace orc
+} // end namespace llvm
+
+#endif // LLVM_EXECUTIONENGINE_ORC_MACHOPLATFORM_H

llvm/include/llvm/ExecutionEngine/Orc/Mangling.h

+//===------ Mangling.h -- Name Mangling Utilities for ORC -------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Name mangling utilities for ORC.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_ORC_MANGLING_H
+#define LLVM_EXECUTIONENGINE_ORC_MANGLING_H
+
+#include "llvm/ExecutionEngine/Orc/Core.h"
+#include "llvm/ExecutionEngine/Orc/ThreadSafeModule.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+namespace llvm {
+namespace orc {
+
+/// Mangles symbol names then uniques them in the context of an
+/// ExecutionSession.
+class MangleAndInterner {
+public:
+  MangleAndInterner(ExecutionSession &ES, const DataLayout &DL);
+  SymbolStringPtr operator()(StringRef Name);
+
+private:
+  ExecutionSession &ES;
+  const DataLayout &DL;
+};
+
+/// Maps IR global values to their linker symbol names / flags.
+///
+/// This utility can be used when adding new IR globals in the JIT.
+class IRSymbolMapper {
+public:
+  struct ManglingOptions {
+    bool EmulatedTLS = false;
+  };
+
+  using SymbolNameToDefinitionMap = std::map<SymbolStringPtr, GlobalValue *>;
+
+  /// Add mangled symbols for the given GlobalValues to SymbolFlags.
+  /// If a SymbolToDefinitionMap pointer is supplied then it will be populated
+  /// with Name-to-GlobalValue* mappings. Note that this mapping is not
+  /// necessarily one-to-one: thread-local GlobalValues, for example, may
+  /// produce more than one symbol, in which case the map will contain duplicate
+  /// values.
+  static void add(ExecutionSession &ES, const ManglingOptions &MO,
+                  ArrayRef<GlobalValue *> GVs, SymbolFlagsMap &SymbolFlags,
+                  SymbolNameToDefinitionMap *SymbolToDefinition = nullptr);
+};
+
+/// Returns a SymbolFlagsMap for the object file represented by the given
+/// buffer, or an error if the buffer does not contain a valid object file.
+Expected<std::pair<SymbolFlagsMap, SymbolStringPtr>>
+getObjectSymbolInfo(ExecutionSession &ES, MemoryBufferRef ObjBuffer);
+
+} // End namespace orc
+} // End namespace llvm
+
+#endif // LLVM_EXECUTIONENGINE_ORC_MANGLING_H

llvm/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h

 #include <string>
 #include <utility>
 #include <vector>
 
 namespace llvm {
 
 namespace jitlink {
 class EHFrameRegistrar;
+class Symbol;
 } // namespace jitlink
 
 namespace object {
 class ObjectFile;
 } // namespace object
 
 namespace orc {
 
 class ObjectLinkingLayerJITLinkContext;
 
 /// An ObjectLayer implementation built on JITLink.
 ///
 /// Clients can use this class to add relocatable object files to an
 /// ExecutionSession, and it typically serves as the base layer (underneath
 /// a compiling layer like IRCompileLayer) for the rest of the JIT.
 class ObjectLinkingLayer : public ObjectLayer {
   friend class ObjectLinkingLayerJITLinkContext;
 
 public:
   /// Plugin instances can be added to the ObjectLinkingLayer to receive
   /// callbacks when code is loaded or emitted, and when JITLink is being
   /// configured.
   class Plugin {
   public:
+
+    using JITLinkSymbolVector = std::vector<const jitlink::Symbol*>;
+    using LocalDependenciesMap =
+      DenseMap<SymbolStringPtr, JITLinkSymbolVector>;
+
     virtual ~Plugin();
     virtual void modifyPassConfig(MaterializationResponsibility &MR,
                                   const Triple &TT,
                                   jitlink::PassConfiguration &Config) {}
+
     virtual void notifyLoaded(MaterializationResponsibility &MR) {}
     virtual Error notifyEmitted(MaterializationResponsibility &MR) {
       return Error::success();
     }
     virtual Error notifyRemovingModule(VModuleKey K) {
       return Error::success();
     }
     virtual Error notifyRemovingAllModules() { return Error::success(); }
+
+    /// Return any dependencies that synthetic symbols (e.g. init symbols)
+    /// have on locally scoped jitlink::Symbols. This is used by the
+    /// ObjectLinkingLayer to update the dependencies for the synthetic
+    /// symbols.
+    virtual LocalDependenciesMap
+    getSyntheticSymbolLocalDependencies(MaterializationResponsibility &MR) {
+      return LocalDependenciesMap();
+    }
   };
 
   using ReturnObjectBufferFunction =
       std::function<void(std::unique_ptr<MemoryBuffer>)>;
 
   /// Construct an ObjectLinkingLayer with the given NotifyLoaded,
   /// and NotifyEmitted functors.
   ObjectLinkingLayer(ExecutionSession &ES,

llvm/include/llvm/ExecutionEngine/Orc/SymbolStringPool.h

 
 /// Pointer to a pooled string representing a symbol name.
 class SymbolStringPtr {
   friend class SymbolStringPool;
   friend struct DenseMapInfo<SymbolStringPtr>;
 
 public:
   SymbolStringPtr() = default;
+  SymbolStringPtr(nullptr_t) {}
   SymbolStringPtr(const SymbolStringPtr &Other)
     : S(Other.S) {
     if (isRealPoolEntry(S))
       ++S->getValue();
   }
 
   SymbolStringPtr& operator=(const SymbolStringPtr &Other) {
     if (isRealPoolEntry(S))
SymbolStringPtr& operator=(SymbolStringPtr &&Other) {
     return *this;
   }
 
   ~SymbolStringPtr() {
     if (isRealPoolEntry(S))
       --S->getValue();
   }
 
+  explicit operator bool() const { return S; }
+
   StringRef operator*() const { return S->first(); }
 
   friend bool operator==(const SymbolStringPtr &LHS,
                          const SymbolStringPtr &RHS) {
     return LHS.S == RHS.S;
   }
 
   friend bool operator!=(const SymbolStringPtr &LHS,

llvm/lib/ExecutionEngine/Orc/CMakeLists.txt

 add_llvm_component_library(LLVMOrcJIT
   CompileOnDemandLayer.cpp
   CompileUtils.cpp
   Core.cpp
   DebugUtils.cpp
   ExecutionUtils.cpp
   IndirectionUtils.cpp
   IRCompileLayer.cpp
   IRTransformLayer.cpp
   JITTargetMachineBuilder.cpp
   LazyReexports.cpp
   Legacy.cpp
   Layer.cpp
   LLJIT.cpp
+  MachOPlatform.cpp
+  Mangling.cpp
   NullResolver.cpp
   ObjectLinkingLayer.cpp
   ObjectTransformLayer.cpp
   OrcABISupport.cpp
   OrcCBindings.cpp
   OrcMCJITReplacement.cpp
   RTDyldObjectLinkingLayer.cpp
   ThreadSafeModule.cpp

llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp

 //===----- CompileOnDemandLayer.cpp - Lazily emit IR on first call --------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h"
+#include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
 #include "llvm/IR/Mangler.h"
 #include "llvm/IR/Module.h"
 
 using namespace llvm;
 using namespace llvm::orc;
 
 static ThreadSafeModule extractSubModule(ThreadSafeModule &TSM,
                                          StringRef Suffix,

 }
 
 namespace llvm {
 namespace orc {
 
 class PartitioningIRMaterializationUnit : public IRMaterializationUnit {
 public:
   PartitioningIRMaterializationUnit(ExecutionSession &ES,
-                                    const ManglingOptions &MO,
+                                    const IRSymbolMapper::ManglingOptions &MO,
                                     ThreadSafeModule TSM, VModuleKey K,
                                     CompileOnDemandLayer &Parent)
       : IRMaterializationUnit(ES, MO, std::move(TSM), std::move(K)),
         Parent(Parent) {}
 
   PartitioningIRMaterializationUnit(
-      ThreadSafeModule TSM, SymbolFlagsMap SymbolFlags,
-      SymbolNameToDefinitionMap SymbolToDefinition,
+      ThreadSafeModule TSM, VModuleKey K, SymbolFlagsMap SymbolFlags,
+      SymbolStringPtr InitSymbol, SymbolNameToDefinitionMap SymbolToDefinition,
       CompileOnDemandLayer &Parent)
       : IRMaterializationUnit(std::move(TSM), std::move(K),
-                              std::move(SymbolFlags),
+                              std::move(SymbolFlags), std::move(InitSymbol),
                               std::move(SymbolToDefinition)),
         Parent(Parent) {}
 
 private:
   void materialize(MaterializationResponsibility R) override {
     Parent.emitPartition(std::move(R), std::move(TSM),
                          std::move(SymbolToDefinition));
   }
void CompileOnDemandLayer::emit(MaterializationResponsibility R,
 
   for (auto &KV : R.getSymbols()) {
     auto &Name = KV.first;
     auto &Flags = KV.second;
     if (Flags.isCallable())
       Callables[Name] = SymbolAliasMapEntry(Name, Flags);
     else
       NonCallables[Name] = SymbolAliasMapEntry(Name, Flags);
   }
 
   // Create a partitioning materialization unit and lodge it with the
   // implementation dylib.
   if (auto Err = PDR.getImplDylib().define(
           std::make_unique<PartitioningIRMaterializationUnit>(
               ES, *getManglingOptions(), std::move(TSM), R.getVModuleKey(),
               *this))) {
     ES.reportError(std::move(Err));
     R.failMaterialization();
     return;
   }
 
   R.replace(reexports(PDR.getImplDylib(), std::move(NonCallables),
                       JITDylibLookupFlags::MatchAllSymbols));
   R.replace(lazyReexports(LCTMgr, PDR.getISManager(), PDR.getImplDylib(),
                           std::move(Callables), AliaseeImpls));
 }
 
 CompileOnDemandLayer::PerDylibResources &
 CompileOnDemandLayer::getPerDylibResources(JITDylib &TargetD) {
   auto I = DylibResources.find(&TargetD);
   if (I == DylibResources.end()) {
     auto &ImplD =
-        getExecutionSession().createJITDylib(TargetD.getName() + ".impl");
+        getExecutionSession().createBareJITDylib(TargetD.getName() + ".impl");
+    JITDylibSearchOrder NewSearchOrder;
     TargetD.withSearchOrderDo(
         [&](const JITDylibSearchOrder &TargetSearchOrder) {
-          auto NewSearchOrder = TargetSearchOrder;
-          assert(
-              !NewSearchOrder.empty() &&
-              NewSearchOrder.front().first == &TargetD &&
-              NewSearchOrder.front().second ==
-                  JITDylibLookupFlags::MatchAllSymbols &&
-              "TargetD must be at the front of its own search order and match "
-              "non-exported symbol");
-          NewSearchOrder.insert(std::next(NewSearchOrder.begin()),
-                                {&ImplD, JITDylibLookupFlags::MatchAllSymbols});
-          ImplD.setSearchOrder(std::move(NewSearchOrder), false);
-        });
+          NewSearchOrder = TargetSearchOrder;
+        });
+
+        !NewSearchOrder.empty() && NewSearchOrder.front().first == &TargetD &&
+        NewSearchOrder.front().second == JITDylibLookupFlags::MatchAllSymbols &&
+    ImplD.setSearchOrder(NewSearchOrder, false);
+    TargetD.setSearchOrder(std::move(NewSearchOrder), false);
+
     PerDylibResources PDR(ImplD, BuildIndirectStubsManager());
     I = DylibResources.insert(std::make_pair(&TargetD, std::move(PDR))).first;
   }
 
   return I->second;
 }
 
 void CompileOnDemandLayer::cleanUpModule(Module &M) {
void CompileOnDemandLayer::emitPartition(
   // FIXME: Need a 'notify lazy-extracting/emitting' callback to tie the
   //        extracted module key, extracted module, and source module key
   //        together. This could be used, for example, to provide a specific
   //        memory manager instance to the linking layer.
 
   auto &ES = getExecutionSession();
   GlobalValueSet RequestedGVs;
   for (auto &Name : R.getRequestedSymbols()) {
+    if (Name == R.getInitializerSymbol())
+      TSM.withModuleDo([&](Module &M) {
+          for (auto &GV : getStaticInitGVs(M))
+            RequestedGVs.insert(&GV);
+        });
+    else {
       assert(Defs.count(Name) && "No definition for symbol");
       RequestedGVs.insert(Defs[Name]);
     }
+  }
 
   /// Perform partitioning with the context lock held, since the partition
   /// function is allowed to access the globals to compute the partition.
   auto GVsToExtract =
       TSM.withModuleDo([&](Module &M) { return Partition(RequestedGVs); });
 
   // Take a 'None' partition to mean the whole module (as opposed to an empty
   // partition, which means "materialize nothing"). Emit the whole module
   // unmodified to the base layer.
   if (GVsToExtract == None) {
     Defs.clear();
     BaseLayer.emit(std::move(R), std::move(TSM));
     return;
   }
 
   // If the partition is empty, return the whole module to the symbol table.
   if (GVsToExtract->empty()) {
     R.replace(std::make_unique<PartitioningIRMaterializationUnit>(
-        std::move(TSM), R.getSymbols(), std::move(Defs), *this));
+        std::move(TSM), R.getVModuleKey(), R.getSymbols(),
+        R.getInitializerSymbol(), std::move(Defs), *this));
     return;
   }
 
   // Ok -- we actually need to partition the symbols. Promote the symbol
   // linkages/names, expand the partition to include any required symbols
   // (i.e. symbols that can't be separated from our partition), and
   // then extract the partition.
   //

llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp

 #include "llvm/Support/SmallVectorMemoryBuffer.h"
 #include "llvm/Target/TargetMachine.h"
 
 #include <algorithm>
 
 namespace llvm {
 namespace orc {
 
-IRMaterializationUnit::ManglingOptions
+IRSymbolMapper::ManglingOptions
 irManglingOptionsFromTargetOptions(const TargetOptions &Opts) {
-  IRMaterializationUnit::ManglingOptions MO;
+  IRSymbolMapper::ManglingOptions MO;
 
   MO.EmulatedTLS = Opts.EmulatedTLS;
 
   return MO;
 }
 
 /// Compile a Module to an ObjectFile.
 Expected<SimpleCompiler::CompileResult> SimpleCompiler::operator()(Module &M) {

llvm/lib/ExecutionEngine/Orc/Core.cpp

 //===--- Core.cpp - Core ORC APIs (MaterializationUnit, JITDylib, etc.) ---===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/Orc/Core.h"
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/ExecutionEngine/Orc/OrcError.h"
-#include "llvm/IR/Mangler.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Format.h"
 
 #if LLVM_ENABLE_THREADS
 #include <future>
 #endif
 

 void AsynchronousSymbolQuery::detach() {
   ResolvedSymbols.clear();
   OutstandingSymbolsCount = 0;
   for (auto &KV : QueryRegistrations)
     KV.first->detachQueryHelper(*this, KV.second);
   QueryRegistrations.clear();
 }
 
-MaterializationResponsibility::MaterializationResponsibility(
-    JITDylib &JD, SymbolFlagsMap SymbolFlags, VModuleKey K)
-    : JD(JD), SymbolFlags(std::move(SymbolFlags)), K(std::move(K)) {
-  assert(!this->SymbolFlags.empty() && "Materializing nothing?");
-}
-
 MaterializationResponsibility::~MaterializationResponsibility() {
   assert(SymbolFlags.empty() &&
          "All symbols should have been explicitly materialized or failed");
 }
 
 SymbolNameSet MaterializationResponsibility::getRequestedSymbols() const {
   return JD.getRequestedSymbols(SymbolFlags);
 }
for (auto &KV : SymbolFlags)
     Worklist.push_back(std::make_pair(&JD, KV.first));
   SymbolFlags.clear();
 
   JD.notifyFailed(std::move(Worklist));
 }
 
 void MaterializationResponsibility::replace(
     std::unique_ptr<MaterializationUnit> MU) {
+
   for (auto &KV : MU->getSymbols())
     SymbolFlags.erase(KV.first);
 
+  if (MU->getInitializerSymbol() == InitSymbol)
+    InitSymbol = nullptr;
+
   LLVM_DEBUG(JD.getExecutionSession().runSessionLocked([&]() {
     dbgs() << "In " << JD.getName() << " replacing symbols with " << *MU
            << "\n";
   }););
 
   JD.replace(std::move(MU));
 }
 
 MaterializationResponsibility
 MaterializationResponsibility::delegate(const SymbolNameSet &Symbols,
                                         VModuleKey NewKey) {
 
   if (NewKey == VModuleKey())
     NewKey = K;
 
+  SymbolStringPtr DelegatedInitSymbol;
   SymbolFlagsMap DelegatedFlags;
 
   for (auto &Name : Symbols) {
     auto I = SymbolFlags.find(Name);
     assert(I != SymbolFlags.end() &&
            "Symbol is not tracked by this MaterializationResponsibility "
            "instance");
 
     DelegatedFlags[Name] = std::move(I->second);
+    if (Name == InitSymbol)
+      std::swap(InitSymbol, DelegatedInitSymbol);
+
     SymbolFlags.erase(I);
   }
 
   return MaterializationResponsibility(JD, std::move(DelegatedFlags),
+                                       std::move(DelegatedInitSymbol),
                                        std::move(NewKey));
 }
 
 void MaterializationResponsibility::addDependencies(
     const SymbolStringPtr &Name, const SymbolDependenceMap &Dependencies) {
   assert(SymbolFlags.count(Name) &&
          "Symbol not covered by this MaterializationResponsibility instance");
   JD.addDependencies(Name, Dependencies);
 }
 
 void MaterializationResponsibility::addDependenciesForAll(
     const SymbolDependenceMap &Dependencies) {
   for (auto &KV : SymbolFlags)
     JD.addDependencies(KV.first, Dependencies);
 }
 
 AbsoluteSymbolsMaterializationUnit::AbsoluteSymbolsMaterializationUnit(
     SymbolMap Symbols, VModuleKey K)
-    : MaterializationUnit(extractFlags(Symbols), std::move(K)),
+    : MaterializationUnit(extractFlags(Symbols), nullptr, std::move(K)),
       Symbols(std::move(Symbols)) {}
 
 StringRef AbsoluteSymbolsMaterializationUnit::getName() const {
   return "<Absolute Symbols>";
 }
 
 void AbsoluteSymbolsMaterializationUnit::materialize(
     MaterializationResponsibility R) {
AbsoluteSymbolsMaterializationUnit::extractFlags(const SymbolMap &Symbols) {
   for (const auto &KV : Symbols)
     Flags[KV.first] = KV.second.getFlags();
   return Flags;
 }
 
 ReExportsMaterializationUnit::ReExportsMaterializationUnit(
     JITDylib *SourceJD, JITDylibLookupFlags SourceJDLookupFlags,
     SymbolAliasMap Aliases, VModuleKey K)
-    : MaterializationUnit(extractFlags(Aliases), std::move(K)),
+    : MaterializationUnit(extractFlags(Aliases), nullptr, std::move(K)),
       SourceJD(SourceJD), SourceJDLookupFlags(SourceJDLookupFlags),
       Aliases(std::move(Aliases)) {}
 
 StringRef ReExportsMaterializationUnit::getName() const {
   return "<Reexports>";
 }
 
 void ReExportsMaterializationUnit::materialize(
for (auto &OtherSymbol : KV.second) {
 
       // Check the sym entry for the dependency.
       auto OtherSymI = OtherJITDylib.Symbols.find(OtherSymbol);
 
 #ifndef NDEBUG
       // Assert that this symbol exists and has not reached the ready state
       // already.
       assert(OtherSymI != OtherJITDylib.Symbols.end() &&
-             (OtherSymI->second.getState() != SymbolState::Ready &&
+             (OtherSymI->second.getState() < SymbolState::Ready &&
               "Dependency on emitted/ready symbol"));
 #endif
 
       auto &OtherSymEntry = OtherSymI->second;
 
       // If the dependency is in an error state then note this and continue,
       // we will move this symbol to the error state below.
       if (OtherSymEntry.getFlags().hasError()) {
Error JITDylib::resolve(const SymbolMap &Resolved) {
   }
 
   return Error::success();
 }
 
 Error JITDylib::emit(const SymbolFlagsMap &Emitted) {
   AsynchronousSymbolQuerySet CompletedQueries;
   SymbolNameSet SymbolsInErrorState;
+  DenseMap<JITDylib *, SymbolNameVector> ReadySymbols;
 
   ES.runSessionLocked([&, this]() {
     std::vector<SymbolTable::iterator> Worklist;
 
     // Scan to build worklist, record any symbols in the erorr state.
     for (const auto &KV : Emitted) {
       auto &Name = KV.first;
 
ES.runSessionLocked([&, this]() {
     while (!Worklist.empty()) {
       auto SymI = Worklist.back();
       Worklist.pop_back();
 
       auto &Name = SymI->first;
       auto &SymEntry = SymI->second;
 
       // Move symbol to the emitted state.
       assert(SymEntry.getState() == SymbolState::Resolved &&
              "Emitting from state other than Resolved");
       SymEntry.setState(SymbolState::Emitted);
 
       auto MII = MaterializingInfos.find(Name);
       assert(MII != MaterializingInfos.end() &&
              "Missing MaterializingInfo entry");
       auto &MI = MII->second;
 
       // For each dependant, transfer this node's emitted dependencies to
       // it. If the dependant node is ready (i.e. has no unemitted
       // dependencies) then notify any pending queries.
       for (auto &KV : MI.Dependants) {
         auto &DependantJD = *KV.first;
+        auto &DependantJDReadySymbols = ReadySymbols[&DependantJD];
         for (auto &DependantName : KV.second) {
           auto DependantMII =
               DependantJD.MaterializingInfos.find(DependantName);
           assert(DependantMII != DependantJD.MaterializingInfos.end() &&
                  "Dependant should have MaterializingInfo");
 
           auto &DependantMI = DependantMII->second;
 
while (!Worklist.empty()) {
           if (DependantSymEntry.getState() == SymbolState::Emitted &&
               DependantMI.UnemittedDependencies.empty()) {
             assert(DependantMI.Dependants.empty() &&
                    "Dependants should be empty by now");
 
             // Since this dependant is now ready, we erase its MaterializingInfo
             // and update its materializing state.
             DependantSymEntry.setState(SymbolState::Ready);
+            DependantJDReadySymbols.push_back(DependantName);
 
             for (auto &Q : DependantMI.takeQueriesMeeting(SymbolState::Ready)) {
               Q->notifySymbolMetRequiredState(
                   DependantName, DependantSymI->second.getSymbol());
               if (Q->isComplete())
                 CompletedQueries.insert(Q);
               Q->removeQueryDependence(DependantJD, DependantName);
             }
-
-            DependantJD.MaterializingInfos.erase(DependantMII);
           }
         }
       }
 
+      auto &ThisJDReadySymbols = ReadySymbols[this];
       MI.Dependants.clear();
       if (MI.UnemittedDependencies.empty()) {
         SymI->second.setState(SymbolState::Ready);
+        ThisJDReadySymbols.push_back(Name);
         for (auto &Q : MI.takeQueriesMeeting(SymbolState::Ready)) {
           Q->notifySymbolMetRequiredState(Name, SymI->second.getSymbol());
           if (Q->isComplete())
             CompletedQueries.insert(Q);
           Q->removeQueryDependence(*this, Name);
         }
-        MaterializingInfos.erase(MII);
       }
     }
   });
 
   assert((SymbolsInErrorState.empty() || CompletedQueries.empty()) &&
          "Can't fail symbols and completed queries at the same time");
 
   // If we failed any symbols then return an error.
for (auto &DependencyName : KV.second) {
             &DependantMI.UnemittedDependencies[&DependencyJD];
 
       DependencyMI.Dependants[this].insert(DependantName);
       UnemittedDependenciesOnDependencyJD->insert(DependencyName);
     }
   }
 }
 
+Platform::~Platform() {}
+
+Expected<DenseMap<JITDylib *, SymbolMap>> Platform::lookupInitSymbols(
+    ExecutionSession &ES,
+    const DenseMap<JITDylib *, SymbolLookupSet> &InitSyms) {
+
+  DenseMap<JITDylib *, SymbolMap> CompoundResult;
+  Error CompoundErr = Error::success();
+  std::mutex LookupMutex;
+  std::condition_variable CV;
+  uint64_t Count = InitSyms.size();
+
+  LLVM_DEBUG({
+    dbgs() << "Issuing init-symbol lookup:\n";
+    for (auto &KV : InitSyms)
+      dbgs() << "  " << KV.first->getName() << ": " << KV.second << "\n";
+  });
+
+  for (auto &KV : InitSyms) {
+    auto *JD = KV.first;
+    auto Names = std::move(KV.second);
+    ES.lookup(
+        LookupKind::Static,
+        JITDylibSearchOrder({{JD, JITDylibLookupFlags::MatchAllSymbols}}),
+        std::move(Names), SymbolState::Ready,
+        [&, JD](Expected<SymbolMap> Result) {
+          {
+            std::lock_guard<std::mutex> Lock(LookupMutex);
+            --Count;
+            if (Result) {
+              assert(!CompoundResult.count(JD) &&
+                     "Duplicate JITDylib in lookup?");
+              CompoundResult[JD] = std::move(*Result);
+            } else
+              CompoundErr =
+                  joinErrors(std::move(CompoundErr), Result.takeError());
+          }
+          CV.notify_one();
+        },
+        NoDependenciesToRegister);
+  }
+
+  std::unique_lock<std::mutex> Lock(LookupMutex);
+  CV.wait(Lock, [&] { return Count == 0 || CompoundErr; });
+
+  if (CompoundErr)
+    return std::move(CompoundErr);
+
+  return std::move(CompoundResult);
+}
+
 ExecutionSession::ExecutionSession(std::shared_ptr<SymbolStringPool> SSP)
     : SSP(SSP ? std::move(SSP) : std::make_shared<SymbolStringPool>()) {
 }
 
 JITDylib *ExecutionSession::getJITDylibByName(StringRef Name) {
   return runSessionLocked([&, this]() -> JITDylib * {
     for (auto &JD : JDs)
       if (JD->getName() == Name)
         return JD.get();
     return nullptr;
   });
 }
 
-JITDylib &ExecutionSession::createJITDylib(std::string Name) {
+JITDylib &ExecutionSession::createBareJITDylib(std::string Name) {
   assert(!getJITDylibByName(Name) && "JITDylib with that name already exists");
   return runSessionLocked([&, this]() -> JITDylib & {
     JDs.push_back(
         std::unique_ptr<JITDylib>(new JITDylib(*this, std::move(Name))));
     return *JDs.back();
   });
 }
 
+Expected<JITDylib &> ExecutionSession::createJITDylib(std::string Name) {
+  auto &JD = createBareJITDylib(Name);
+  if (P)
+    if (auto Err = P->setupJITDylib(JD))
+      return std::move(Err);
+  return JD;
+}
+
 void ExecutionSession::legacyFailQuery(AsynchronousSymbolQuery &Q, Error Err) {
   assert(!!Err && "Error should be in failure state");
 
   bool SendErrorToQuery;
   runSessionLocked([&]() {
     Q.detach();
     SendErrorToQuery = Q.canStillFail();
   });
if (ResolutionError)
     return std::move(ResolutionError);
 
   return Result;
 #endif
 }
 
 Expected<JITEvaluatedSymbol>
 ExecutionSession::lookup(const JITDylibSearchOrder &SearchOrder,
-                         SymbolStringPtr Name) {
+                         SymbolStringPtr Name, SymbolState RequiredState) {
   SymbolLookupSet Names({Name});
 
   if (auto ResultMap = lookup(SearchOrder, std::move(Names), LookupKind::Static,
-                              SymbolState::Ready, NoDependenciesToRegister)) {
+                              RequiredState, NoDependenciesToRegister)) {
     assert(ResultMap->size() == 1 && "Unexpected number of results");
     assert(ResultMap->count(Name) && "Missing result for symbol");
     return std::move(ResultMap->begin()->second);
   } else
     return ResultMap.takeError();
 }
 
 Expected<JITEvaluatedSymbol>
-ExecutionSession::lookup(ArrayRef<JITDylib *> SearchOrder,
-                         SymbolStringPtr Name) {
-  return lookup(makeJITDylibSearchOrder(SearchOrder), Name);
+ExecutionSession::lookup(ArrayRef<JITDylib *> SearchOrder, SymbolStringPtr Name,
+                         SymbolState RequiredState) {
+  return lookup(makeJITDylibSearchOrder(SearchOrder), Name, RequiredState);
 }
 
 Expected<JITEvaluatedSymbol>
-ExecutionSession::lookup(ArrayRef<JITDylib *> SearchOrder, StringRef Name) {
-  return lookup(SearchOrder, intern(Name));
+ExecutionSession::lookup(ArrayRef<JITDylib *> SearchOrder, StringRef Name,
+                         SymbolState RequiredState) {
+  return lookup(SearchOrder, intern(Name), RequiredState);
 }
 
 void ExecutionSession::dump(raw_ostream &OS) {
   runSessionLocked([this, &OS]() {
     for (auto &JD : JDs)
       JD->dump(OS);
   });
 }
if (JITDylibAndMU.first) {
       assert(JITDylibAndMU.second && "JITDylib, but no MU?");
       dispatchMaterialization(*JITDylibAndMU.first,
                               std::move(JITDylibAndMU.second));
     } else
       break;
   }
 }
 
-MangleAndInterner::MangleAndInterner(ExecutionSession &ES, const DataLayout &DL)
-    : ES(ES), DL(DL) {}
-
-SymbolStringPtr MangleAndInterner::operator()(StringRef Name) {
-  std::string MangledName;
-  {
-    raw_string_ostream MangledNameStream(MangledName);
-    Mangler::getNameWithPrefix(MangledNameStream, Name, DL);
-  }
-  return ES.intern(MangledName);
-}
-
 } // End namespace orc.
 } // End namespace llvm.

llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp

 }
 
 iterator_range<CtorDtorIterator> getDestructors(const Module &M) {
   const GlobalVariable *DtorsList = M.getNamedGlobal("llvm.global_dtors");
   return make_range(CtorDtorIterator(DtorsList, false),
                     CtorDtorIterator(DtorsList, true));
 }
 
+bool StaticInitGVIterator::isStaticInitGlobal(GlobalValue &GV) {
+  if (GV.isDeclaration())
+    return false;
+
+  if (GV.hasName() &&
+        (GV.getName() == "llvm.global_ctors" ||
+         GV.getName() == "llvm.global_dtors"))
+    return true;
+
+  if (ObjFmt == Triple::MachO) {
+    // FIXME: These section checks are too strict: We should match first and
+    // second word split by comma.
+    if (GV.hasSection() &&
+        (GV.getSection().startswith("__DATA,__objc_classlist") ||
+         GV.getSection().startswith("__DATA,__objc_selrefs")))
+      return true;
+  }
+
+  return false;
+}
+
 void CtorDtorRunner::add(iterator_range<CtorDtorIterator> CtorDtors) {
   if (CtorDtors.empty())
     return;
 
   MangleAndInterner Mangle(
       JD.getExecutionSession(),
       (*CtorDtors.begin()).Func->getParent()->getDataLayout());
 
JITEvaluatedSymbol(toTargetAddress(&DSOHandleOverride),
                        JITSymbolFlags::Exported);
   RuntimeInterposes[Mangle("__cxa_atexit")] =
     JITEvaluatedSymbol(toTargetAddress(&CXAAtExitOverride),
                        JITSymbolFlags::Exported);
 
   return JD.define(absoluteSymbols(std::move(RuntimeInterposes)));
 }
 
+void ItaniumCXAAtExitSupport::registerAtExit(void (*F)(void *), void *Ctx,
+                                             void *DSOHandle) {
+  std::lock_guard<std::mutex> Lock(AtExitsMutex);
+  AtExitRecords[DSOHandle].push_back({F, Ctx});
+}
+
+void ItaniumCXAAtExitSupport::runAtExits(void *DSOHandle) {
+  std::vector<AtExitRecord> AtExitsToRun;
+
+  {
+    std::lock_guard<std::mutex> Lock(AtExitsMutex);
+    auto I = AtExitRecords.find(DSOHandle);
+    if (I != AtExitRecords.end()) {
+      AtExitsToRun = std::move(I->second);
+      AtExitRecords.erase(I);
+    }
+  }
+
+  while (!AtExitsToRun.empty()) {
+    AtExitsToRun.back().F(AtExitsToRun.back().Ctx);
+    AtExitsToRun.pop_back();
+  }
+}
+
 DynamicLibrarySearchGenerator::DynamicLibrarySearchGenerator(
     sys::DynamicLibrary Dylib, char GlobalPrefix, SymbolPredicate Allow)
     : Dylib(std::move(Dylib)), Allow(std::move(Allow)),
       GlobalPrefix(GlobalPrefix) {}
 
 Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
 DynamicLibrarySearchGenerator::Load(const char *FileName, char GlobalPrefix,
                                     SymbolPredicate Allow) {

llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp

 
 class CompileCallbackMaterializationUnit : public orc::MaterializationUnit {
 public:
   using CompileFunction = JITCompileCallbackManager::CompileFunction;
 
   CompileCallbackMaterializationUnit(SymbolStringPtr Name,
                                      CompileFunction Compile, VModuleKey K)
       : MaterializationUnit(SymbolFlagsMap({{Name, JITSymbolFlags::Exported}}),
-                            std::move(K)),
+                            nullptr, std::move(K)),
         Name(std::move(Name)), Compile(std::move(Compile)) {}
 
   StringRef getName() const override { return "<Compile Callbacks>"; }
 
 private:
   void materialize(MaterializationResponsibility R) override {
     SymbolMap Result;
     Result[Name] = JITEvaluatedSymbol(Compile(), JITSymbolFlags::Exported);

llvm/lib/ExecutionEngine/Orc/LLJIT.cpp

 //===--------- LLJIT.cpp - An ORC-based JIT for compiling LLVM IR ---------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
 #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
+#include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
 #include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
 #include "llvm/ExecutionEngine/Orc/OrcError.h"
 #include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Mangler.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/DynamicLibrary.h"
+
+#include <map>
+
+using namespace llvm;
+using namespace llvm::orc;
+
+namespace {
+
+/// Add a reference to the __dso_handle global to the given module.
+/// Returns a reference to the __dso_handle IR decl.
+GlobalVariable *addDSOHandleDecl(Module &M) {
+  auto DSOHandleTy = StructType::create(M.getContext(), "lljit.dso_handle");
+  return new GlobalVariable(M, DSOHandleTy, true, GlobalValue::ExternalLinkage,
+                            nullptr, "__dso_handle");
+}
+
+/// Adds helper function decls and wrapper functions that call the helper with
+/// some additional prefix arguments.
+///
+/// E.g. For wrapper "foo" with type i8(i8, i64), helper "bar", and prefix
+/// args i32 4 and i16 12345, this function will add:
+///
+/// declare i8 @bar(i32, i16, i8, i64)
+///
+/// define i8 @foo(i8, i64) {
+/// entry:
+///   %2 = call i8 @bar(i32 4, i16 12345, i8 %0, i64 %1)
+///   ret i8 %2
+/// }
+///
+Function *addHelperAndWrapper(Module &M, StringRef WrapperName,
+                              FunctionType *WrapperFnType,
+                              GlobalValue::VisibilityTypes WrapperVisibility,
+                              StringRef HelperName,
+                              ArrayRef<Value *> HelperPrefixArgs) {
+  std::vector<Type *> HelperArgTypes;
+  for (auto *Arg : HelperPrefixArgs)
+    HelperArgTypes.push_back(Arg->getType());
+  for (auto *T : WrapperFnType->params())
+    HelperArgTypes.push_back(T);
+  auto *HelperFnType =
+      FunctionType::get(WrapperFnType->getReturnType(), HelperArgTypes, false);
+  auto *HelperFn = Function::Create(HelperFnType, GlobalValue::ExternalLinkage,
+                                    HelperName, M);
+
+  auto *WrapperFn = Function::Create(
+      WrapperFnType, GlobalValue::ExternalLinkage, WrapperName, M);
+  WrapperFn->setVisibility(WrapperVisibility);
+
+  auto *EntryBlock = BasicBlock::Create(M.getContext(), "entry", WrapperFn);
+  IRBuilder<> IB(EntryBlock);
+
+  std::vector<Value *> HelperArgs;
+  for (auto *Arg : HelperPrefixArgs)
+    HelperArgs.push_back(Arg);
+  for (auto &Arg : WrapperFn->args())
+    HelperArgs.push_back(&Arg);
+  auto *HelperResult = IB.CreateCall(HelperFn, HelperArgs);
+  if (HelperFn->getReturnType()->isVoidTy())
+    IB.CreateRetVoid();
+  else
+    IB.CreateRet(HelperResult);
+
+  return WrapperFn;
+}
+
+class GenericLLVMIRPlatformSupport;
+
+/// orc::Platform component of Generic LLVM IR Platform support.
+/// Just forwards calls to the GenericLLVMIRPlatformSupport class below.
+class GenericLLVMIRPlatform : public Platform {
+public:
+  GenericLLVMIRPlatform(GenericLLVMIRPlatformSupport &S) : S(S) {}
+  Error setupJITDylib(JITDylib &JD) override;
+  Error notifyAdding(JITDylib &JD, const MaterializationUnit &MU) override;
+  Error notifyRemoving(JITDylib &JD, VModuleKey K) override {
+    // Noop -- Nothing to do (yet).
+    return Error::success();
+  }
+
+private:
+  GenericLLVMIRPlatformSupport &S;
+};
+
+/// This transform parses llvm.global_ctors to produce a single initialization
+/// function for the module, records the function, then deletes
+/// llvm.global_ctors.
+class GlobalCtorDtorScraper {
+public:
+  GlobalCtorDtorScraper(GenericLLVMIRPlatformSupport &PS) : PS(PS) {}
+  Expected<ThreadSafeModule> operator()(ThreadSafeModule TSM,
+                                        MaterializationResponsibility &R);
+
+private:
+  GenericLLVMIRPlatformSupport &PS;
+};
+
+/// Generic IR Platform Support
+///
+/// Scrapes llvm.global_ctors and llvm.global_dtors and replaces them with
+/// specially named 'init' and 'deinit'. Injects definitions / interposes for
+/// some runtime API, including __cxa_atexit, dlopen, and dlclose.
+class GenericLLVMIRPlatformSupport : public LLJIT::PlatformSupport {
+public:
+  // GenericLLVMIRPlatform &P) : P(P) {
+  GenericLLVMIRPlatformSupport(LLJIT &J) : J(J) {
+
+    getExecutionSession().setPlatform(
+        std::make_unique<GenericLLVMIRPlatform>(*this));
+
+    setInitTransform(J, GlobalCtorDtorScraper(*this));
+
+    MangleAndInterner Mangle(getExecutionSession(), J.getDataLayout());
+    SymbolMap StdInterposes;
+
+    StdInterposes[Mangle("__lljit.platform_support_instance")] =
+        JITEvaluatedSymbol(pointerToJITTargetAddress(this), JITSymbolFlags());
+    StdInterposes[Mangle("__lljit.cxa_atexit_helper")] = JITEvaluatedSymbol(
+        pointerToJITTargetAddress(registerAtExitHelper), JITSymbolFlags());
+    StdInterposes[Mangle("__lljit.run_atexits_helper")] = JITEvaluatedSymbol(
+        pointerToJITTargetAddress(runAtExitsHelper), JITSymbolFlags());
+
+    cantFail(
+        J.getMainJITDylib().define(absoluteSymbols(std::move(StdInterposes))));
+    cantFail(setupJITDylib(J.getMainJITDylib()));
+    cantFail(J.addIRModule(J.getMainJITDylib(), createPlatformRuntimeModule()));
+  }
+
+  ExecutionSession &getExecutionSession() { return J.getExecutionSession(); }
+
+  /// Adds a module that defines the __dso_handle global.
+  Error setupJITDylib(JITDylib &JD) {
+    auto Ctx = std::make_unique<LLVMContext>();
+    auto M = std::make_unique<Module>("__standard_lib", *Ctx);
+    M->setDataLayout(J.getDataLayout());
+
+    auto *Int64Ty = Type::getInt64Ty(*Ctx);
+    auto *DSOHandle = new GlobalVariable(
+        *M, Int64Ty, true, GlobalValue::ExternalLinkage,
+        ConstantInt::get(Int64Ty, reinterpret_cast<uintptr_t>(&JD)),
+        "__dso_handle");
+    DSOHandle->setVisibility(GlobalValue::HiddenVisibility);
+    DSOHandle->setInitializer(
+        ConstantInt::get(Int64Ty, pointerToJITTargetAddress(&JD)));
+    return J.addIRModule(JD, ThreadSafeModule(std::move(M), std::move(Ctx)));
+  }
+
+  Error notifyAdding(JITDylib &JD, const MaterializationUnit &MU) {
+    std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+    if (auto &InitSym = MU.getInitializerSymbol())
+      InitSymbols[&JD].add(InitSym);
+    return Error::success();
+  }
+
+  Error initialize(JITDylib &JD) override {
+    if (auto Initializers = getInitializers(JD)) {
+      for (auto InitFnAddr : *Initializers) {
+        auto *InitFn = jitTargetAddressToFunction<void (*)()>(InitFnAddr);
+        InitFn();
+      }
+    } else
+      return Initializers.takeError();
+    return Error::success();
+  }
+
+  Error deinitialize(JITDylib &JD) override {
+    if (auto Deinitializers = getDeinitializers(JD)) {
+      for (auto DeinitFnAddr : *Deinitializers) {
+        auto *DeinitFn = jitTargetAddressToFunction<void (*)()>(DeinitFnAddr);
+        DeinitFn();
+      }
+    } else
+      return Deinitializers.takeError();
+
+    return Error::success();
+  }
+
+  void registerInitFunc(JITDylib &JD, SymbolStringPtr InitName) {
+    std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+    InitFunctions[&JD].add(InitName);
+  }
+
+private:
+  Expected<std::vector<JITTargetAddress>> getInitializers(JITDylib &JD) {
+    if (auto Err = issueInitLookups(JD))
+      return std::move(Err);
+
+    DenseMap<JITDylib *, SymbolLookupSet> LookupSymbols;
+    std::vector<JITDylib *> DFSLinkOrder;
+
+    {
+      std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+      DFSLinkOrder = getDFSLinkOrder(JD);
+
+      for (auto *NextJD : DFSLinkOrder) {
+        auto IFItr = InitFunctions.find(NextJD);
+        if (IFItr != InitFunctions.end()) {
+          LookupSymbols[NextJD] = std::move(IFItr->second);
+          InitFunctions.erase(IFItr);
+        }
+      }
+    }
+
+    auto &ES = getExecutionSession();
+    auto LookupResult = Platform::lookupInitSymbols(ES, LookupSymbols);
+
+    if (!LookupResult)
+      return LookupResult.takeError();
+
+    std::vector<JITTargetAddress> Initializers;
+    while (!DFSLinkOrder.empty()) {
+      auto &NextJD = *DFSLinkOrder.back();
+      DFSLinkOrder.pop_back();
+      auto InitsItr = LookupResult->find(&NextJD);
+      if (InitsItr == LookupResult->end())
+        continue;
+      for (auto &KV : InitsItr->second)
+        Initializers.push_back(KV.second.getAddress());
+    }
+
+    return Initializers;
+  }
+
+  Expected<std::vector<JITTargetAddress>> getDeinitializers(JITDylib &JD) {
+    auto &ES = getExecutionSession();
+
+    MangleAndInterner Mangle(getExecutionSession(), J.getDataLayout());
+    auto LLJITRunAtExits = Mangle("__lljit_run_atexits");
+
+    DenseMap<JITDylib *, SymbolLookupSet> LookupSymbols;
+    std::vector<JITDylib *> DFSLinkOrder;
+
+    {
+      std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+      DFSLinkOrder = getDFSLinkOrder(JD);
+
+      for (auto *NextJD : DFSLinkOrder) {
+        auto &JDLookupSymbols = LookupSymbols[NextJD];
+        auto DIFItr = DeInitFunctions.find(NextJD);
+        if (DIFItr != DeInitFunctions.end()) {
+          LookupSymbols[NextJD] = std::move(DIFItr->second);
+          DeInitFunctions.erase(DIFItr);
+        }
+        JDLookupSymbols.add(LLJITRunAtExits,
+                            SymbolLookupFlags::WeaklyReferencedSymbol);
+      }
+    }
+
+    auto LookupResult = Platform::lookupInitSymbols(ES, LookupSymbols);
+
+    if (!LookupResult)
+      return LookupResult.takeError();
+
+    std::vector<JITTargetAddress> DeInitializers;
+    for (auto *NextJD : DFSLinkOrder) {
+      auto DeInitsItr = LookupResult->find(NextJD);
+      assert(DeInitsItr != LookupResult->end() &&
+             "Every JD should have at least __lljit_run_atexits");
+
+      auto RunAtExitsItr = DeInitsItr->second.find(LLJITRunAtExits);
+      if (RunAtExitsItr != DeInitsItr->second.end())
+        DeInitializers.push_back(RunAtExitsItr->second.getAddress());
+
+      for (auto &KV : DeInitsItr->second)
+        if (KV.first != LLJITRunAtExits)
+          DeInitializers.push_back(KV.second.getAddress());
+    }
+
+    return DeInitializers;
+  }
+
+  // Returns a DFS traversal order of the JITDylibs reachable (via
+  // links-against edges) from JD, starting with JD itself.
+  static std::vector<JITDylib *> getDFSLinkOrder(JITDylib &JD) {
+    std::vector<JITDylib *> DFSLinkOrder;
+    std::vector<JITDylib *> WorkStack({&JD});
+    DenseSet<JITDylib *> Visited;
+
+    while (!WorkStack.empty()) {
+      auto &NextJD = *WorkStack.back();
+      WorkStack.pop_back();
+      if (Visited.count(&NextJD))
+        continue;
+      Visited.insert(&NextJD);
+      DFSLinkOrder.push_back(&NextJD);
+      NextJD.withSearchOrderDo([&](const JITDylibSearchOrder &SearchOrder) {
+        for (auto &KV : SearchOrder)
+          WorkStack.push_back(KV.first);
+      });
+    }
+
+    return DFSLinkOrder;
+  }
+
+  /// Issue lookups for all init symbols required to initialize JD (and any
+  /// JITDylibs that it depends on).
+  Error issueInitLookups(JITDylib &JD) {
+    DenseMap<JITDylib *, SymbolLookupSet> RequiredInitSymbols;
+
+    {
+      std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+
+      auto DFSLinkOrder = getDFSLinkOrder(JD);
+
+      for (auto *NextJD : DFSLinkOrder) {
+        auto ISItr = InitSymbols.find(NextJD);
+        if (ISItr != InitSymbols.end()) {
+          RequiredInitSymbols[NextJD] = std::move(ISItr->second);
+          InitSymbols.erase(ISItr);
+        }
+      }
+    }
+
+    return Platform::lookupInitSymbols(getExecutionSession(),
+                                       RequiredInitSymbols)
+        .takeError();
+  }
+
+  static void registerAtExitHelper(void *Self, void (*F)(void *), void *Ctx,
+                                   void *DSOHandle) {
+    static_cast<GenericLLVMIRPlatformSupport *>(Self)->AtExitMgr.registerAtExit(
+        F, Ctx, DSOHandle);
+  }
+
+  static void runAtExitsHelper(void *Self, void *DSOHandle) {
+    static_cast<GenericLLVMIRPlatformSupport *>(Self)->AtExitMgr.runAtExits(
+        DSOHandle);
+  }
+
+  // Constructs an LLVM IR module containing platform runtime globals,
+  // functions, and interposes.
+  ThreadSafeModule createPlatformRuntimeModule() {
+    auto Ctx = std::make_unique<LLVMContext>();
+    auto M = std::make_unique<Module>("__standard_lib", *Ctx);
+    M->setDataLayout(J.getDataLayout());
+
+    auto *GenericIRPlatformSupportTy =
+        StructType::create(*Ctx, "lljit.GenericLLJITIRPlatformSupport");
+
+    auto *PlatformInstanceDecl = new GlobalVariable(
+        *M, GenericIRPlatformSupportTy, true, GlobalValue::ExternalLinkage,
+        nullptr, "__lljit.platform_support_instance");
+
+    auto *DSOHandleDecl = addDSOHandleDecl(*M);
+
+    auto *Int8Ty = Type::getInt8Ty(*Ctx);
+    auto *IntTy = Type::getIntNTy(*Ctx, sizeof(int) * CHAR_BIT);
+    auto *VoidTy = Type::getVoidTy(*Ctx);
+    auto *BytePtrTy = PointerType::getUnqual(Int8Ty);
+    auto *AtExitCallbackTy = FunctionType::get(VoidTy, {BytePtrTy}, false);
+    auto *AtExitCallbackPtrTy = PointerType::getUnqual(AtExitCallbackTy);
+
+    addHelperAndWrapper(
+        *M, "__cxa_atexit",
+        FunctionType::get(IntTy, {AtExitCallbackPtrTy, BytePtrTy, BytePtrTy},
+                          false),
+        GlobalValue::HiddenVisibility, "__lljit.cxa_atexit_helper",
+        {PlatformInstanceDecl});
+
+    addHelperAndWrapper(
+        *M, "__lljit_run_atexits", FunctionType::get(VoidTy, {}, false),
+        GlobalValue::HiddenVisibility, "__lljit.run_atexits_helper",
+        {PlatformInstanceDecl, DSOHandleDecl});
+
+    return ThreadSafeModule(std::move(M), std::move(Ctx));
+  }
+
+  std::mutex PlatformSupportMutex;
+  LLJIT &J;
+  DenseMap<JITDylib *, SymbolLookupSet> InitSymbols;
+  DenseMap<JITDylib *, SymbolLookupSet> InitFunctions;
+  DenseMap<JITDylib *, SymbolLookupSet> DeInitFunctions;
+  ItaniumCXAAtExitSupport AtExitMgr;
+};
+
+Error GenericLLVMIRPlatform::setupJITDylib(JITDylib &JD) {
+  return S.setupJITDylib(JD);
+}
+
+Error GenericLLVMIRPlatform::notifyAdding(JITDylib &JD,
+                                          const MaterializationUnit &MU) {
+  return S.notifyAdding(JD, MU);
+}
+
+Expected<ThreadSafeModule>
+GlobalCtorDtorScraper::operator()(ThreadSafeModule TSM,
+                                  MaterializationResponsibility &R) {
+  auto Err = TSM.withModuleDo([&](Module &M) -> Error {
+    auto &Ctx = M.getContext();
+    auto *GlobalCtors = M.getNamedGlobal("llvm.global_ctors");
+
+    // If there's no llvm.global_ctors or it's just a decl then skip.
+    if (!GlobalCtors || GlobalCtors->isDeclaration())
+      return Error::success();
+
+    std::string InitFunctionName;
+    raw_string_ostream(InitFunctionName)
+      << "__orc_init." << M.getModuleIdentifier();
+
+    MangleAndInterner Mangle(PS.getExecutionSession(), M.getDataLayout());
+    auto InternedName = Mangle(InitFunctionName);
+    if (auto Err =
+        R.defineMaterializing({{InternedName, JITSymbolFlags::Callable}}))
+      return Err;
+
+    auto *InitFunc =
+      Function::Create(FunctionType::get(Type::getVoidTy(Ctx), {}, false),
+                       GlobalValue::ExternalLinkage, InitFunctionName, &M);
+    InitFunc->setVisibility(GlobalValue::HiddenVisibility);
+    std::vector<std::pair<Function *, unsigned>> Inits;
+    for (auto E : getConstructors(M))
+      Inits.push_back(std::make_pair(E.Func, E.Priority));
+    llvm::sort(Inits, [](const std::pair<Function *, unsigned> &LHS,
+                         const std::pair<Function *, unsigned> &RHS) {
+                 return LHS.first < RHS.first;
+               });
+    auto *EntryBlock = BasicBlock::Create(Ctx, "entry", InitFunc);
+    IRBuilder<> IB(EntryBlock);
+    for (auto &KV : Inits)
+      IB.CreateCall(KV.first);
+    IB.CreateRetVoid();
+
+    PS.registerInitFunc(R.getTargetJITDylib(), InternedName);
+    GlobalCtors->eraseFromParent();
+    return Error::success();
+  });
+
+  if (Err)
+    return std::move(Err);
+
+  return TSM;
+}
+
+class MachOPlatformSupport : public LLJIT::PlatformSupport {
+public:
+  using DLOpenType = void *(*)(const char *Name, int Mode);
+  using DLCloseType = int (*)(void *Handle);
+  using DLSymType = void *(*)(void *Handle, const char *Name);
+  using DLErrorType = const char *(*)();
+
+  struct DlFcnValues {
+    Optional<void *> RTLDDefault;
+    DLOpenType dlopen = nullptr;
+    DLCloseType dlclose = nullptr;
+    DLSymType dlsym = nullptr;
+    DLErrorType dlerror = nullptr;
+  };
+
+  static Expected<std::unique_ptr<MachOPlatformSupport>>
+  Create(LLJIT &J, JITDylib &PlatformJITDylib) {
+
+    // Make process symbols visible.
+    {
+      std::string ErrMsg;
+      auto Lib = sys::DynamicLibrary::getPermanentLibrary(nullptr, &ErrMsg);
+      if (!Lib.isValid())
+        return make_error<StringError>(std::move(ErrMsg),
+                                       inconvertibleErrorCode());
+    }
+
+    DlFcnValues DlFcn;
+
+    // Add support for RTLDDefault on known platforms.
+#ifdef __APPLE__
+    DlFcn.RTLDDefault = reinterpret_cast<void *>(-2);
+#endif // __APPLE__
+
+    if (auto Err = hookUpFunction(DlFcn.dlopen, "dlopen"))
+      return std::move(Err);
+    if (auto Err = hookUpFunction(DlFcn.dlclose, "dlclose"))
+      return std::move(Err);
+    if (auto Err = hookUpFunction(DlFcn.dlsym, "dlsym"))
+      return std::move(Err);
+    if (auto Err = hookUpFunction(DlFcn.dlerror, "dlerror"))
+      return std::move(Err);
+
+    std::unique_ptr<MachOPlatformSupport> MP(
+        new MachOPlatformSupport(J, PlatformJITDylib, DlFcn));
+    return std::move(MP);
+  }
+
+  Error initialize(JITDylib &JD) override {
+    if (auto InitSeq = MP.getInitializerSequence(JD)) {
+      for (auto &KV : *InitSeq) {
+        KV.second.registerObjCSelectors();
+        KV.second.registerObjCClasses();
+      }
+      for (auto &KV : *InitSeq)
+        KV.second.runModInits();
+    } else
+      return InitSeq.takeError();
+    return Error::success();
+  }
+
+  Error deinitialize(JITDylib &JD) override {
+    auto &ES = J.getExecutionSession();
+    if (auto DeinitSeq = MP.getDeinitializerSequence(JD)) {
+      for (auto &KV : *DeinitSeq) {
+        auto DSOHandleName = ES.intern("___dso_handle");
+
+        // FIXME: Run DeInits here.
+        auto Result = ES.lookup(
+            {{KV.first, JITDylibLookupFlags::MatchAllSymbols}},
+            SymbolLookupSet(DSOHandleName,
+                            SymbolLookupFlags::WeaklyReferencedSymbol));
+        if (!Result)
+          return Result.takeError();
+        if (Result->empty())
+          continue;
+        assert(Result->count(DSOHandleName) &&
+               "Result does not contain __dso_handle");
+        auto *DSOHandle = jitTargetAddressToPointer<void *>(
+            Result->begin()->second.getAddress());
+        AtExitMgr.runAtExits(DSOHandle);
+      }
+    } else
+      return DeinitSeq.takeError();
+    return Error::success();
+  }
+
+private:
+  template <typename FunctionPtrTy>
+  static Error hookUpFunction(FunctionPtrTy &Fn, const char *Name) {
+    if (auto *FnAddr = sys::DynamicLibrary::SearchForAddressOfSymbol(Name)) {
+      Fn = reinterpret_cast<FunctionPtrTy>(Fn);
+      return Error::success();
+    }
+
+    return make_error<StringError>((Twine("Can not enable MachO JIT Platform: "
+                                          "missing function: ") +
+                                    Name)
+                                       .str(),
+                                   inconvertibleErrorCode());
+  }
+
+  MachOPlatformSupport(LLJIT &J, JITDylib &PlatformJITDylib, DlFcnValues DlFcn)
+      : J(J), MP(setupPlatform(J)), DlFcn(std::move(DlFcn)) {
+
+    MangleAndInterner Mangle(J.getExecutionSession(), J.getDataLayout());
+    SymbolMap HelperSymbols;
+
+    // platform and atexit helpers.
+    HelperSymbols[Mangle("__lljit.platform_support_instance")] =
+        JITEvaluatedSymbol(pointerToJITTargetAddress(this), JITSymbolFlags());
+    HelperSymbols[Mangle("__lljit.cxa_atexit_helper")] = JITEvaluatedSymbol(
+        pointerToJITTargetAddress(registerAtExitHelper), JITSymbolFlags());
+    HelperSymbols[Mangle("__lljit.run_atexits_helper")] = JITEvaluatedSymbol(
+        pointerToJITTargetAddress(runAtExitsHelper), JITSymbolFlags());
+
+    // dlfcn helpers.
+    HelperSymbols[Mangle("__lljit.dlopen_helper")] = JITEvaluatedSymbol(
+        pointerToJITTargetAddress(dlopenHelper), JITSymbolFlags());
+    HelperSymbols[Mangle("__lljit.dlclose_helper")] = JITEvaluatedSymbol(
+        pointerToJITTargetAddress(dlcloseHelper), JITSymbolFlags());
+    HelperSymbols[Mangle("__lljit.dlsym_helper")] = JITEvaluatedSymbol(
+        pointerToJITTargetAddress(dlsymHelper), JITSymbolFlags());
+    HelperSymbols[Mangle("__lljit.dlerror_helper")] = JITEvaluatedSymbol(
+        pointerToJITTargetAddress(dlerrorHelper), JITSymbolFlags());
+
+    cantFail(
+        PlatformJITDylib.define(absoluteSymbols(std::move(HelperSymbols))));
+    cantFail(MP.setupJITDylib(J.getMainJITDylib()));
+    cantFail(J.addIRModule(PlatformJITDylib, createPlatformRuntimeModule()));
+  }
+
+  static MachOPlatform &setupPlatform(LLJIT &J) {
+    auto Tmp = std::make_unique<MachOPlatform>(
+        J.getExecutionSession(),
+        static_cast<ObjectLinkingLayer &>(J.getObjLinkingLayer()),
+        createStandardSymbolsObject(J));
+    auto &MP = *Tmp;
+    J.getExecutionSession().setPlatform(std::move(Tmp));
+    return MP;
+  }
+
+  static std::unique_ptr<MemoryBuffer> createStandardSymbolsObject(LLJIT &J) {
+    LLVMContext Ctx;
+    Module M("__standard_symbols", Ctx);
+    M.setDataLayout(J.getDataLayout());
+
+    auto *Int64Ty = Type::getInt64Ty(Ctx);
+
+    auto *DSOHandle =
+        new GlobalVariable(M, Int64Ty, true, GlobalValue::ExternalLinkage,
+                           ConstantInt::get(Int64Ty, 0), "__dso_handle");
+    DSOHandle->setVisibility(GlobalValue::HiddenVisibility);
+
+    return cantFail(J.getIRCompileLayer().getCompiler()(M));
+  }
+
+  ThreadSafeModule createPlatformRuntimeModule() {
+    auto Ctx = std::make_unique<LLVMContext>();
+    auto M = std::make_unique<Module>("__standard_lib", *Ctx);
+    M->setDataLayout(J.getDataLayout());
+
+    auto *MachOPlatformSupportTy =
+        StructType::create(*Ctx, "lljit.MachOPlatformSupport");
+
+    auto *PlatformInstanceDecl = new GlobalVariable(
+        *M, MachOPlatformSupportTy, true, GlobalValue::ExternalLinkage, nullptr,
+        "__lljit.platform_support_instance");
+
+    auto *Int8Ty = Type::getInt8Ty(*Ctx);
+    auto *IntTy = Type::getIntNTy(*Ctx, sizeof(int) * CHAR_BIT);
+    auto *VoidTy = Type::getVoidTy(*Ctx);
+    auto *BytePtrTy = PointerType::getUnqual(Int8Ty);
+    auto *AtExitCallbackTy = FunctionType::get(VoidTy, {BytePtrTy}, false);
+    auto *AtExitCallbackPtrTy = PointerType::getUnqual(AtExitCallbackTy);
+
+    addHelperAndWrapper(
+        *M, "__cxa_atexit",
+        FunctionType::get(IntTy, {AtExitCallbackPtrTy, BytePtrTy, BytePtrTy},
+                          false),
+        GlobalValue::DefaultVisibility, "__lljit.cxa_atexit_helper",
+        {PlatformInstanceDecl});
+
+    addHelperAndWrapper(*M, "dlopen",
+                        FunctionType::get(BytePtrTy, {BytePtrTy, IntTy}, false),
+                        GlobalValue::DefaultVisibility, "__lljit.dlopen_helper",
+                        {PlatformInstanceDecl});
+
+    addHelperAndWrapper(*M, "dlclose",
+                        FunctionType::get(IntTy, {BytePtrTy}, false),
+                        GlobalValue::DefaultVisibility,
+                        "__lljit.dlclose_helper", {PlatformInstanceDecl});
+
+    addHelperAndWrapper(
+        *M, "dlsym",
+        FunctionType::get(BytePtrTy, {BytePtrTy, BytePtrTy}, false),
+        GlobalValue::DefaultVisibility, "__lljit.dlsym_helper",
+        {PlatformInstanceDecl});
+
+    addHelperAndWrapper(*M, "dlerror", FunctionType::get(BytePtrTy, {}, false),
+                        GlobalValue::DefaultVisibility,
+                        "__lljit.dlerror_helper", {PlatformInstanceDecl});
+
+    return ThreadSafeModule(std::move(M), std::move(Ctx));
+  }
+
+  static void registerAtExitHelper(void *Self, void (*F)(void *), void *Ctx,
+                                   void *DSOHandle) {
+    static_cast<MachOPlatformSupport *>(Self)->AtExitMgr.registerAtExit(
+        F, Ctx, DSOHandle);
+  }
+
+  static void runAtExitsHelper(void *Self, void *DSOHandle) {
+    static_cast<MachOPlatformSupport *>(Self)->AtExitMgr.runAtExits(DSOHandle);
+  }
+
+  void *jit_dlopen(const char *Path, int Mode) {
+    JITDylib *JDToOpen = nullptr;
+    // FIXME: Do the right thing with Mode flags.
+    {
+      std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+
+      // Clear any existing error messages.
+      dlErrorMsgs.erase(std::this_thread::get_id());
+
+      if (auto *JD = J.getExecutionSession().getJITDylibByName(Path)) {
+        auto I = JDRefCounts.find(JD);
+        if (I != JDRefCounts.end()) {
+          ++I->second;
+          return JD;
+        }
+
+        JDRefCounts[JD] = 1;
+        JDToOpen = JD;
+      }
+    }
+
+    if (JDToOpen) {
+      if (auto Err = initialize(*JDToOpen)) {
+        recordError(std::move(Err));
+        return 0;
+      }
+    }
+
+    // Fall through to dlopen if no JITDylib found for Path.
+    return DlFcn.dlopen(Path, Mode);
+  }
+
+  static void *dlopenHelper(void *Self, const char *Path, int Mode) {
+    return static_cast<MachOPlatformSupport *>(Self)->jit_dlopen(Path, Mode);
+  }
+
+  int jit_dlclose(void *Handle) {
+    JITDylib *JDToClose = nullptr;
+
+    {
+      std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+
+      // Clear any existing error messages.
+      dlErrorMsgs.erase(std::this_thread::get_id());
+
+      auto I = JDRefCounts.find(Handle);
+      if (I != JDRefCounts.end()) {
+        --I->second;
+        if (I->second == 0) {
+          JDRefCounts.erase(I);
+          JDToClose = static_cast<JITDylib *>(Handle);
+        } else
+          return 0;
+      }
+    }
+
+    if (JDToClose) {
+      if (auto Err = deinitialize(*JDToClose)) {
+        recordError(std::move(Err));
+        return -1;
+      }
+      return 0;
+    }
+
+    // Fall through to dlclose if no JITDylib found for Path.
+    return DlFcn.dlclose(Handle);
+  }
+
+  static int dlcloseHelper(void *Self, void *Handle) {
+    return static_cast<MachOPlatformSupport *>(Self)->jit_dlclose(Handle);
+  }
+
+  void *jit_dlsym(void *Handle, const char *Name) {
+    JITDylibSearchOrder JITSymSearchOrder;
+
+    // FIXME: RTLD_NEXT, RTLD_SELF not supported.
+    {
+      std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+
+      // Clear any existing error messages.
+      dlErrorMsgs.erase(std::this_thread::get_id());
+
+      if (JDRefCounts.count(Handle)) {
+        JITSymSearchOrder.push_back(
+            {static_cast<JITDylib *>(Handle),
+             JITDylibLookupFlags::MatchExportedSymbolsOnly});
+      } else if (Handle == DlFcn.RTLDDefault) {
+        for (auto &KV : JDRefCounts)
+          JITSymSearchOrder.push_back(
+              {static_cast<JITDylib *>(KV.first),
+               JITDylibLookupFlags::MatchExportedSymbolsOnly});
+      }
+    }
+
+    if (!JITSymSearchOrder.empty()) {
+      MangleAndInterner Mangle(J.getExecutionSession(), J.getDataLayout());
+      auto MangledName = Mangle(Name);
+      SymbolLookupSet Syms(MangledName,
+                           SymbolLookupFlags::WeaklyReferencedSymbol);
+      if (auto Result = J.getExecutionSession().lookup(JITSymSearchOrder, Syms,
+                                                       LookupKind::DLSym)) {
+        auto I = Result->find(MangledName);
+        if (I != Result->end())
+          return jitTargetAddressToPointer<void *>(I->second.getAddress());
+      } else {
+        recordError(Result.takeError());
+        return 0;
+      }
+    }
+
+    // Fall through to dlsym.
+    return DlFcn.dlsym(Handle, Name);
+  }
+
+  static void *dlsymHelper(void *Self, void *Handle, const char *Name) {
+    return static_cast<MachOPlatformSupport *>(Self)->jit_dlsym(Handle, Name);
+  }
+
+  const char *jit_dlerror() {
+    {
+      std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+      auto I = dlErrorMsgs.find(std::this_thread::get_id());
+      if (I != dlErrorMsgs.end())
+        return I->second->c_str();
+    }
+    return DlFcn.dlerror();
+  }
+
+  static const char *dlerrorHelper(void *Self) {
+    return static_cast<MachOPlatformSupport *>(Self)->jit_dlerror();
+  }
+
+  void recordError(Error Err) {
+    std::lock_guard<std::mutex> Lock(PlatformSupportMutex);
+    dlErrorMsgs[std::this_thread::get_id()] =
+        std::make_unique<std::string>(toString(std::move(Err)));
+  }
+
+  std::mutex PlatformSupportMutex;
+  LLJIT &J;
+  MachOPlatform &MP;
+  DlFcnValues DlFcn;
+  ItaniumCXAAtExitSupport AtExitMgr;
+  DenseMap<void *, unsigned> JDRefCounts;
+  std::map<std::thread::id, std::unique_ptr<std::string>> dlErrorMsgs;
+};
+
+} // end anonymous namespace
 
 namespace llvm {
 namespace orc {
 
+void LLJIT::PlatformSupport::setInitTransform(
+    LLJIT &J, IRTransformLayer::TransformFunction T) {
+  J.InitHelperTransformLayer->setTransform(std::move(T));
+}
+
+LLJIT::PlatformSupport::~PlatformSupport() {}
+
 Error LLJITBuilderState::prepareForConstruction() {
 
   if (!JTMB) {
     if (auto JTMBOrErr = JITTargetMachineBuilder::detectHost())
       JTMB = std::move(*JTMBOrErr);
     else
       return JTMBOrErr.takeError();
   }

 LLJIT::~LLJIT() {
   if (CompileThreads)
     CompileThreads->wait();
 }
 
 Error LLJIT::defineAbsolute(StringRef Name, JITEvaluatedSymbol Sym) {
   auto InternedName = ES->intern(Name);
   SymbolMap Symbols({{InternedName, Sym}});
-  return Main.define(absoluteSymbols(std::move(Symbols)));
+  return Main->define(absoluteSymbols(std::move(Symbols)));
 }
 
 Error LLJIT::addIRModule(JITDylib &JD, ThreadSafeModule TSM) {
   assert(TSM && "Can not add null module");
 
   if (auto Err =
           TSM.withModuleDo([&](Module &M) { return applyDataLayout(M); }))
     return Err;
 
-  return TransformLayer->add(JD, std::move(TSM), ES->allocateVModule());
+  return InitHelperTransformLayer->add(JD, std::move(TSM),
+                                       ES->allocateVModule());
 }
 
 Error LLJIT::addObjectFile(JITDylib &JD, std::unique_ptr<MemoryBuffer> Obj) {
   assert(Obj && "Can not add null object");
 
   return ObjTransformLayer.add(JD, std::move(Obj), ES->allocateVModule());
 }
 
LLJIT::createCompileFunction(LLJITBuilderState &S,
   auto TM = JTMB.createTargetMachine();
   if (!TM)
     return TM.takeError();
 
   return std::make_unique<TMOwningSimpleCompiler>(std::move(*TM));
 }
 
 LLJIT::LLJIT(LLJITBuilderState &S, Error &Err)
-    : ES(S.ES ? std::move(S.ES) : std::make_unique<ExecutionSession>()),
-      Main(this->ES->createJITDylib("<main>")), DL(""),
-      TT(S.JTMB->getTargetTriple()),
+    : ES(S.ES ? std::move(S.ES) : std::make_unique<ExecutionSession>()), Main(),
+      DL(""), TT(S.JTMB->getTargetTriple()),
       ObjLinkingLayer(createObjectLinkingLayer(S, *ES)),
-      ObjTransformLayer(*this->ES, *ObjLinkingLayer), CtorRunner(Main),
-      DtorRunner(Main) {
+      ObjTransformLayer(*this->ES, *ObjLinkingLayer) {
 
   ErrorAsOutParameter _(&Err);
 
-  if (auto DLOrErr = S.JTMB->getDefaultDataLayoutForTarget())
+  if (auto MainOrErr = this->ES->createJITDylib("main"))
+    Main = &*MainOrErr;
+  else {
+    Err = MainOrErr.takeError();
+    return;
+  }
+
+  if (S.DL)
+    DL = std::move(*S.DL);
+  else if (auto DLOrErr = S.JTMB->getDefaultDataLayoutForTarget())
     DL = std::move(*DLOrErr);
   else {
     Err = DLOrErr.takeError();
     return;
   }
 
   {
     auto CompileFunction = createCompileFunction(S, std::move(*S.JTMB));
     if (!CompileFunction) {
       Err = CompileFunction.takeError();
       return;
     }
     CompileLayer = std::make_unique<IRCompileLayer>(
         *ES, ObjTransformLayer, std::move(*CompileFunction));
     TransformLayer = std::make_unique<IRTransformLayer>(*ES, *CompileLayer);
+    InitHelperTransformLayer =
+        std::make_unique<IRTransformLayer>(*ES, *TransformLayer);
   }
 
   if (S.NumCompileThreads > 0) {
-    TransformLayer->setCloneToNewContextOnEmit(true);
+    InitHelperTransformLayer->setCloneToNewContextOnEmit(true);
     CompileThreads =
         std::make_unique<ThreadPool>(hardware_concurrency(S.NumCompileThreads));
     ES->setDispatchMaterialization(
         [this](JITDylib &JD, std::unique_ptr<MaterializationUnit> MU) {
           // FIXME: Switch to move capture once we have c++14.
           auto SharedMU = std::shared_ptr<MaterializationUnit>(std::move(MU));
           auto Work = [SharedMU, &JD]() { SharedMU->doMaterialize(JD); };
           CompileThreads->async(std::move(Work));
         });
   }
+
+  if (S.SetUpPlatform)
+    Err = S.SetUpPlatform(*this);
+  else
+    setUpGenericLLVMIRPlatform(*this);
 }
 
 std::string LLJIT::mangle(StringRef UnmangledName) {
   std::string MangledName;
   {
     raw_string_ostream MangledNameStream(MangledName);
     Mangler::getNameWithPrefix(MangledNameStream, UnmangledName, DL);
   }
   return MangledName;
 }
 
 Error LLJIT::applyDataLayout(Module &M) {
   if (M.getDataLayout().isDefault())
     M.setDataLayout(DL);
 
   if (M.getDataLayout() != DL)
     return make_error<StringError>(
-        "Added modules have incompatible data layouts",
+        "Added modules have incompatible data layouts: " +
+            M.getDataLayout().getStringRepresentation() + " (module) vs " +
+            DL.getStringRepresentation() + " (jit)",
         inconvertibleErrorCode());
 
   return Error::success();
 }
 
-void LLJIT::recordCtorDtors(Module &M) {
-  CtorRunner.add(getConstructors(M));
-  DtorRunner.add(getDestructors(M));
+void setUpGenericLLVMIRPlatform(LLJIT &J) {
+  J.setPlatformSupport(std::make_unique<GenericLLVMIRPlatformSupport>(J));
+}
+
+Error setUpMachOPlatform(LLJIT &J) {
+  auto MP = MachOPlatformSupport::Create(J, J.getMainJITDylib());
+  if (!MP)
+    return MP.takeError();
+  J.setPlatformSupport(std::move(*MP));
+  return Error::success();
 }
 
 Error LLLazyJITBuilderState::prepareForConstruction() {
   if (auto Err = LLJITBuilderState::prepareForConstruction())
     return Err;
   TT = JTMB->getTargetTriple();
   return Error::success();
 }
 
 Error LLLazyJIT::addLazyIRModule(JITDylib &JD, ThreadSafeModule TSM) {
   assert(TSM && "Can not add null module");
 
-  if (auto Err = TSM.withModuleDo([&](Module &M) -> Error {
-        if (auto Err = applyDataLayout(M))
-          return Err;
-
-        recordCtorDtors(M);
-        return Error::success();
-      }))
+  if (auto Err = TSM.withModuleDo(
+          [&](Module &M) -> Error { return applyDataLayout(M); }))
     return Err;
 
   return CODLayer->add(JD, std::move(TSM), ES->allocateVModule());
 }
 
 LLLazyJIT::LLLazyJIT(LLLazyJITBuilderState &S, Error &Err) : LLJIT(S, Err) {
 
   // If LLJIT construction failed then bail out.
Err = make_error<StringError>("Could not construct "
                                   "IndirectStubsManagerBuilder for target " +
                                       S.TT.str(),
                                   inconvertibleErrorCode());
     return;
   }
 
   // Create the COD layer.
   CODLayer = std::make_unique<CompileOnDemandLayer>(
-      *ES, *TransformLayer, *LCTMgr, std::move(ISMBuilder));
+      *ES, *InitHelperTransformLayer, *LCTMgr, std::move(ISMBuilder));
 
   if (S.NumCompileThreads > 0)
     CODLayer->setCloneToNewContextOnEmit(true);
 }
 
 } // End namespace orc.
 } // End namespace llvm.

llvm/lib/ExecutionEngine/Orc/Layer.cpp

 //===-------------------- Layer.cpp - Layer interfaces --------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/Orc/Layer.h"
+
+#include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/Object/MachO.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/Debug.h"
 
 #define DEBUG_TYPE "orc"
 
 namespace llvm {
 namespace orc {
 
 IRLayer::~IRLayer() {}
 
 Error IRLayer::add(JITDylib &JD, ThreadSafeModule TSM, VModuleKey K) {
   return JD.define(std::make_unique<BasicIRLayerMaterializationUnit>(
       *this, *getManglingOptions(), std::move(TSM), std::move(K)));
 }
 
-IRMaterializationUnit::IRMaterializationUnit(ExecutionSession &ES,
-                                             const ManglingOptions &MO,
-                                             ThreadSafeModule TSM, VModuleKey K)
-    : MaterializationUnit(SymbolFlagsMap(), std::move(K)), TSM(std::move(TSM)) {
+IRMaterializationUnit::IRMaterializationUnit(
+    ExecutionSession &ES, const IRSymbolMapper::ManglingOptions &MO,
+    : MaterializationUnit(SymbolFlagsMap(), nullptr, std::move(K)),
+      TSM(std::move(TSM)) {
 
   assert(this->TSM && "Module must not be null");
 
   MangleAndInterner Mangle(ES, this->TSM.getModuleUnlocked()->getDataLayout());
   this->TSM.withModuleDo([&](Module &M) {
+
     for (auto &G : M.global_values()) {
       // Skip globals that don't generate symbols.
+
       if (!G.hasName() || G.isDeclaration() || G.hasLocalLinkage() ||
           G.hasAvailableExternallyLinkage() || G.hasAppendingLinkage())
         continue;
 
       // thread locals generate different symbols depending on whether or not
       // emulated TLS is enabled.
       if (G.isThreadLocal() && MO.EmulatedTLS) {
         auto &GV = cast<GlobalVariable>(G);
for (auto &G : M.global_values()) {
         continue;
       }
 
       // Otherwise we just need a normal linker mangling.
       auto MangledName = Mangle(G.getName());
       SymbolFlags[MangledName] = JITSymbolFlags::fromGlobalValue(G);
       SymbolToDefinition[MangledName] = &G;
     }
+
+    // If we need an init symbol for this module then create one.
+    if (!llvm::empty(getStaticInitGVs(M))) {
+      std::string InitSymbolName;
+      raw_string_ostream(InitSymbolName)
+        << "$." << M.getModuleIdentifier() << ".__inits";
+      InitSymbol = ES.intern(InitSymbolName);
+      SymbolFlags[InitSymbol] = JITSymbolFlags();
+    }
   });
 }
 
 IRMaterializationUnit::IRMaterializationUnit(
     ThreadSafeModule TSM, VModuleKey K, SymbolFlagsMap SymbolFlags,
-    SymbolNameToDefinitionMap SymbolToDefinition)
-    : MaterializationUnit(std::move(SymbolFlags), std::move(K)),
+    SymbolStringPtr InitSymbol, SymbolNameToDefinitionMap SymbolToDefinition)
+    : MaterializationUnit(std::move(SymbolFlags), std::move(InitSymbol),
+                          std::move(K)),
       TSM(std::move(TSM)), SymbolToDefinition(std::move(SymbolToDefinition)) {}
 
 StringRef IRMaterializationUnit::getName() const {
   if (TSM)
     return TSM.withModuleDo(
         [](const Module &M) -> StringRef { return M.getModuleIdentifier(); });
   return "<null module>";
 }
assert(I != SymbolToDefinition.end() &&
          "Symbol not provided by this MU, or previously discarded");
   assert(!I->second->isDeclaration() &&
          "Discard should only apply to definitions");
   I->second->setLinkage(GlobalValue::AvailableExternallyLinkage);
   SymbolToDefinition.erase(I);
 }
 
 BasicIRLayerMaterializationUnit::BasicIRLayerMaterializationUnit(
-    IRLayer &L, const ManglingOptions &MO, ThreadSafeModule TSM, VModuleKey K)
+    IRLayer &L, const IRSymbolMapper::ManglingOptions &MO, ThreadSafeModule TSM,
+    VModuleKey K)
     : IRMaterializationUnit(L.getExecutionSession(), MO, std::move(TSM),
                             std::move(K)),
       L(L), K(std::move(K)) {}
 
 void BasicIRLayerMaterializationUnit::materialize(
     MaterializationResponsibility R) {
 
   // Throw away the SymbolToDefinition map: it's not usable after we hand
Error ObjectLayer::add(JITDylib &JD, std::unique_ptr<MemoryBuffer> O,
   if (!ObjMU)
     return ObjMU.takeError();
   return JD.define(std::move(*ObjMU));
 }
 
 Expected<std::unique_ptr<BasicObjectLayerMaterializationUnit>>
 BasicObjectLayerMaterializationUnit::Create(ObjectLayer &L, VModuleKey K,
                                             std::unique_ptr<MemoryBuffer> O) {
-  auto SymbolFlags =
-      getObjectSymbolFlags(L.getExecutionSession(), O->getMemBufferRef());
+  auto ObjSymInfo =
+      getObjectSymbolInfo(L.getExecutionSession(), O->getMemBufferRef());
 
-  if (!SymbolFlags)
-    return SymbolFlags.takeError();
+  if (!ObjSymInfo)
+    return ObjSymInfo.takeError();
+
+  auto &SymbolFlags = ObjSymInfo->first;
+  auto &InitSymbol = ObjSymInfo->second;
 
   return std::unique_ptr<BasicObjectLayerMaterializationUnit>(
-      new BasicObjectLayerMaterializationUnit(L, K, std::move(O),
-                                              std::move(*SymbolFlags)));
+      new BasicObjectLayerMaterializationUnit(
+          L, K, std::move(O), std::move(SymbolFlags), std::move(InitSymbol)));
 }
 
 BasicObjectLayerMaterializationUnit::BasicObjectLayerMaterializationUnit(
     ObjectLayer &L, VModuleKey K, std::unique_ptr<MemoryBuffer> O,
-    SymbolFlagsMap SymbolFlags)
-    : MaterializationUnit(std::move(SymbolFlags), std::move(K)), L(L),
-      O(std::move(O)) {}
+    SymbolFlagsMap SymbolFlags, SymbolStringPtr InitSymbol)
+    : MaterializationUnit(std::move(SymbolFlags), std::move(InitSymbol),
+                          std::move(K)),
+      L(L), O(std::move(O)) {}
 
 StringRef BasicObjectLayerMaterializationUnit::getName() const {
   if (O)
     return O->getBufferIdentifier();
   return "<null object>";
 }
 
 void BasicObjectLayerMaterializationUnit::materialize(
     MaterializationResponsibility R) {
   L.emit(std::move(R), std::move(O));
 }
 
 void BasicObjectLayerMaterializationUnit::discard(const JITDylib &JD,
                                                   const SymbolStringPtr &Name) {
   // FIXME: Support object file level discard. This could be done by building a
   //        filter to pass to the object layer along with the object itself.
 }
 
-Expected<SymbolFlagsMap> getObjectSymbolFlags(ExecutionSession &ES,
-                                              MemoryBufferRef ObjBuffer) {
-  auto Obj = object::ObjectFile::createObjectFile(ObjBuffer);
-
-  if (!Obj)
-    return Obj.takeError();
-
-  SymbolFlagsMap SymbolFlags;
-  for (auto &Sym : (*Obj)->symbols()) {
-    // Skip symbols not defined in this object file.
-    if (Sym.getFlags() & object::BasicSymbolRef::SF_Undefined)
-      continue;
-
-    // Skip symbols that are not global.
-    if (!(Sym.getFlags() & object::BasicSymbolRef::SF_Global))
-      continue;
-
-    auto Name = Sym.getName();
-    if (!Name)
-      return Name.takeError();
-    auto InternedName = ES.intern(*Name);
-    auto SymFlags = JITSymbolFlags::fromObjectSymbol(Sym);
-    if (!SymFlags)
-      return SymFlags.takeError();
-    SymbolFlags[InternedName] = std::move(*SymFlags);
-  }
-
-  return SymbolFlags;
-}
-
 } // End namespace orc.
 } // End namespace llvm.

llvm/lib/ExecutionEngine/Orc/LazyReexports.cpp

SymbolStringPtr SymbolName;
     if (I == Reexports.end())
       return ErrorHandlerAddr;
     SourceJD = I->second.first;
     SymbolName = I->second.second;
   }
 
   auto LookupResult = ES.lookup(
       makeJITDylibSearchOrder(SourceJD, JITDylibLookupFlags::MatchAllSymbols),
-      SymbolName);
+      SymbolName, SymbolState::Ready);
 
   if (!LookupResult) {
     ES.reportError(LookupResult.takeError());
     return ErrorHandlerAddr;
   }
 
   auto ResolvedAddr = LookupResult->getAddress();
 
else
           ES, ErrorHandlerAddr);
   }
 }
 
 LazyReexportsMaterializationUnit::LazyReexportsMaterializationUnit(
     LazyCallThroughManager &LCTManager, IndirectStubsManager &ISManager,
     JITDylib &SourceJD, SymbolAliasMap CallableAliases, ImplSymbolMap *SrcJDLoc,
     VModuleKey K)
-    : MaterializationUnit(extractFlags(CallableAliases), std::move(K)),
+    : MaterializationUnit(extractFlags(CallableAliases), nullptr, std::move(K)),
       LCTManager(LCTManager), ISManager(ISManager), SourceJD(SourceJD),
-      CallableAliases(std::move(CallableAliases)),
-      AliaseeTable(SrcJDLoc) {}
+      CallableAliases(std::move(CallableAliases)), AliaseeTable(SrcJDLoc) {}
 
 StringRef LazyReexportsMaterializationUnit::getName() const {
   return "<Lazy Reexports>";
 }
 
 void LazyReexportsMaterializationUnit::materialize(
     MaterializationResponsibility R) {
   auto RequestedSymbols = R.getRequestedSymbols();

llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp

+//===------ MachOPlatform.cpp - Utilities for executing MachO in Orc ------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
+
+#include "llvm/BinaryFormat/MachO.h"
+#include "llvm/Support/BinaryByteStream.h"
+
+namespace {
+
+struct objc_class;
+struct objc_image_info;
+struct objc_object;
+struct objc_selector;
+
+using Class = objc_class*;
+using id = objc_object*;
+using SEL = objc_selector*;
+
+using ObjCMsgSendTy = id(*)(id, SEL, ...);
+using ObjCReadClassPairTy = Class (*)(Class, const objc_image_info *);
+using SelRegisterNameTy = SEL (*)(const char *);
+
+enum class ObjCRegistrationAPI {
+  Uninitialized,
+  Unavailable,
+  Initialized
+};
+
+ObjCRegistrationAPI ObjCRegistrationAPIState = ObjCRegistrationAPI::Uninitialized;
+ObjCMsgSendTy objc_msgSend = nullptr;
+ObjCReadClassPairTy objc_readClassPair = nullptr;
+SelRegisterNameTy sel_registerName = nullptr;
+
+} // end anonymous namespace
+
+namespace llvm {
+namespace orc {
+
+template <typename FnTy>
+static Error setUpObjCRegAPIFunc(FnTy &Target, sys::DynamicLibrary &LibObjC,
+                                 const char *Name) {
+  if (void *Addr = LibObjC.getAddressOfSymbol(Name))
+    Target = reinterpret_cast<FnTy>(Addr);
+  else
+    return make_error<StringError>((Twine("Could not find address for ") + Name).str(),
+                                   inconvertibleErrorCode());
+  return Error::success();
+}
+
+Error enableObjCRegistration(const char *PathToLibObjC) {
+  // If we've already tried to initialize then just bail out.
+  if (ObjCRegistrationAPIState != ObjCRegistrationAPI::Uninitialized)
+    return Error::success();
+
+  ObjCRegistrationAPIState = ObjCRegistrationAPI::Unavailable;
+
+  std::string ErrMsg;
+  auto LibObjC =
+    sys::DynamicLibrary::getPermanentLibrary(PathToLibObjC, &ErrMsg);
+
+  if (!LibObjC.isValid())
+    return make_error<StringError>(std::move(ErrMsg),
+                                   inconvertibleErrorCode());
+
+  if (auto Err =
+      setUpObjCRegAPIFunc(objc_msgSend, LibObjC, "objc_msgSend"))
+    return Err;
+  if (auto Err =
+      setUpObjCRegAPIFunc(objc_readClassPair, LibObjC, "objc_readClassPair"))
+    return Err;
+  if (auto Err =
+      setUpObjCRegAPIFunc(sel_registerName, LibObjC, "sel_registerName"))
+    return Err;
+
+  ObjCRegistrationAPIState = ObjCRegistrationAPI::Initialized;
+  return Error::success();
+}
+
+bool objcRegistrationEnabled() {
+  return ObjCRegistrationAPIState == ObjCRegistrationAPI::Initialized;
+}
+
+void MachOJITDylibInitializers::runModInits() const {
+  for (const auto &ModInit : ModInitSections) {
+    for (uint64_t I = 0; I != ModInit.NumPtrs; ++I) {
+      auto *InitializerAddr = jitTargetAddressToPointer<uintptr_t *>(
+          ModInit.Address + (I * sizeof(uintptr_t)));
+      auto *Initializer =
+          jitTargetAddressToFunction<void (*)()>(*InitializerAddr);
+      Initializer();
+    }
+  }
+}
+
+void MachOJITDylibInitializers::registerObjCSelectors() const {
+  assert(objcRegistrationEnabled() && "ObjC registration not enabled.");
+
+  for (const auto &ObjCSelRefs : ObjCSelRefsSections) {
+    for (uint64_t I = 0; I != ObjCSelRefs.NumPtrs; ++I) {
+      auto SelEntryAddr = ObjCSelRefs.Address + (I * sizeof(uintptr_t));
+      const auto *SelName =
+        *jitTargetAddressToPointer<const char **>(SelEntryAddr);
+      dbgs() << "Registering selector " << SelName << "...\n";
+      auto Sel = sel_registerName(SelName);
+      *jitTargetAddressToPointer<SEL*>(SelEntryAddr) = Sel;
+    }
+  }
+}
+
+void MachOJITDylibInitializers::registerObjCClasses() const {
+  assert(objcRegistrationEnabled() && "ObjC registration not enabled.");
+
+  struct ObjCClassCompiled {
+    void *Metaclass;
+    void *Parent;
+    void *Cache1;
+    void *Cache2;
+    void *Data;
+  };
+
+  auto *ImageInfo =
+    jitTargetAddressToPointer<const objc_image_info*>(ObjCImageInfoAddr);
+  auto ClassSelector = sel_registerName("class");
+
+  for (const auto &ObjCClassList : ObjCClassListSections) {
+    for (uint64_t I = 0; I != ObjCClassList.NumPtrs; ++I) {
+      auto ClassPtrAddr = ObjCClassList.Address + (I * sizeof(uintptr_t));
+      auto Cls = *jitTargetAddressToPointer<Class*>(ClassPtrAddr);
+      auto *ClassCompiled =
+        *jitTargetAddressToPointer<ObjCClassCompiled**>(ClassPtrAddr);
+      objc_msgSend(reinterpret_cast<id>(ClassCompiled->Parent), ClassSelector);
+      auto Registered = objc_readClassPair(Cls, ImageInfo);
+      if (Registered != Cls) {
+        dbgs() << "Failed to register class!\n";
+        exit(1);
+      }
+    }
+  }
+}
+
+void MachOJITDylibInitializers::dump() const {
+  for (auto &Extent : ModInitSections)
+    dbgs() << formatv("{0:x16}", Extent.Address) << " -- "
+           << formatv("{0:x16}", Extent.Address + 8 * Extent.NumPtrs) << "\n";
+}
+
+MachOPlatform::MachOPlatform(
+    ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
+    std::unique_ptr<MemoryBuffer> StandardSymbolsObject)
+    : ES(ES), ObjLinkingLayer(ObjLinkingLayer),
+      StandardSymbolsObject(std::move(StandardSymbolsObject)) {
+  ObjLinkingLayer.addPlugin(std::make_unique<InitScraperPlugin>(*this));
+}
+
+Error MachOPlatform::setupJITDylib(JITDylib &JD) {
+  auto ObjBuffer = MemoryBuffer::getMemBuffer(
+      StandardSymbolsObject->getMemBufferRef(), false);
+  return ObjLinkingLayer.add(JD, std::move(ObjBuffer));
+}
+
+Error MachOPlatform::notifyAdding(JITDylib &JD, const MaterializationUnit &MU) {
+  const auto &InitSym = MU.getInitializerSymbol();
+  if (!InitSym)
+    return Error::success();
+
+  std::lock_guard<std::mutex> Lock(PlatformMutex);
+  RegisteredInitSymbols[&JD].add(InitSym);
+  return Error::success();
+}
+
+Error MachOPlatform::notifyRemoving(JITDylib &JD, VModuleKey K) {
+  llvm_unreachable("Not supported yet");
+}
+
+Expected<MachOPlatform::InitializerSequence>
+MachOPlatform::getInitializerSequence(JITDylib &JD) {
+
+  std::vector<JITDylib *> DFSLinkOrder;
+
+  while (true) {
+    // Lock the platform while we search for any initializer symbols to
+    // look up.
+    DenseMap<JITDylib *, SymbolLookupSet> NewInitSymbols;
+    {
+      std::lock_guard<std::mutex> Lock(PlatformMutex);
+      DFSLinkOrder = getDFSLinkOrder(JD);
+
+      for (auto *InitJD : DFSLinkOrder) {
+        auto RISItr = RegisteredInitSymbols.find(InitJD);
+        if (RISItr != RegisteredInitSymbols.end()) {
+          NewInitSymbols[InitJD] = std::move(RISItr->second);
+          RegisteredInitSymbols.erase(RISItr);
+        }
+      }
+    }
+
+    if (NewInitSymbols.empty())
+      break;
+
+    // Outside the lock, issue the lookup.
+    if (auto R = lookupInitSymbols(JD.getExecutionSession(), NewInitSymbols))
+      ; // Nothing to do in the success case.
+    else
+      return R.takeError();
+  }
+
+  // Lock again to collect the initializers.
+  InitializerSequence FullInitSeq;
+  {
+    std::lock_guard<std::mutex> Lock(PlatformMutex);
+    for (auto *InitJD : reverse(DFSLinkOrder)) {
+      auto ISItr = InitSeqs.find(InitJD);
+      if (ISItr != InitSeqs.end()) {
+        FullInitSeq.emplace_back(InitJD, std::move(ISItr->second));
+        InitSeqs.erase(ISItr);
+      }
+    }
+  }
+
+  return FullInitSeq;
+}
+
+Expected<MachOPlatform::DeinitializerSequence>
+MachOPlatform::getDeinitializerSequence(JITDylib &JD) {
+  std::vector<JITDylib *> DFSLinkOrder = getDFSLinkOrder(JD);
+
+  DeinitializerSequence FullDeinitSeq;
+  {
+    std::lock_guard<std::mutex> Lock(PlatformMutex);
+    for (auto *DeinitJD : DFSLinkOrder) {
+      FullDeinitSeq.emplace_back(DeinitJD, MachOJITDylibDeinitializers());
+    }
+  }
+
+  return FullDeinitSeq;
+}
+
+std::vector<JITDylib *> MachOPlatform::getDFSLinkOrder(JITDylib &JD) {
+  std::vector<JITDylib *> Result, WorkStack({&JD});
+  DenseSet<JITDylib *> Visited;
+
+  while (!WorkStack.empty()) {
+    auto *NextJD = WorkStack.back();
+    WorkStack.pop_back();
+    if (Visited.count(NextJD))
+      continue;
+    Visited.insert(NextJD);
+    Result.push_back(NextJD);
+    NextJD->withSearchOrderDo([&](const JITDylibSearchOrder &SO) {
+      for (auto &KV : SO)
+        WorkStack.push_back(KV.first);
+    });
+  }
+
+  return Result;
+}
+
+void MachOPlatform::registerInitInfo(
+                       JITDylib &JD,
+                       JITTargetAddress ObjCImageInfoAddr,
+                       MachOJITDylibInitializers::SectionExtent ModInits,
+                       MachOJITDylibInitializers::SectionExtent ObjCSelRefs,
+                       MachOJITDylibInitializers::SectionExtent ObjCClassList) {
+  std::lock_guard<std::mutex> Lock(PlatformMutex);
+
+  auto &InitSeq = InitSeqs[&JD];
+
+  InitSeq.setObjCImageInfoAddr(ObjCImageInfoAddr);
+
+  if (ModInits.Address)
+    InitSeq.addModInitsSection(std::move(ModInits));
+
+  if (ObjCSelRefs.Address)
+    InitSeq.addObjCSelRefsSection(std::move(ObjCSelRefs));
+
+  if (ObjCClassList.Address)
+    InitSeq.addObjCClassListSection(std::move(ObjCClassList));
+}
+
+
+static Expected<MachOJITDylibInitializers::SectionExtent>
+getSectionExtent(jitlink::LinkGraph &G, StringRef SectionName) {
+  auto *Sec = G.findSectionByName(SectionName);
+  if (!Sec)
+    return MachOJITDylibInitializers::SectionExtent();
+  jitlink::SectionRange R(*Sec);
+  if (R.getSize() % G.getPointerSize() != 0)
+    return make_error<StringError>(SectionName + " section size is not a "
+                                                 "multiple of the pointer size",
+                                   inconvertibleErrorCode());
+  return MachOJITDylibInitializers::SectionExtent(
+      R.getStart(), R.getSize() / G.getPointerSize());
+}
+
+void MachOPlatform::InitScraperPlugin::modifyPassConfig(
+    MaterializationResponsibility &MR, const Triple &TT,
+    jitlink::PassConfiguration &Config) {
+
+  Config.PrePrunePasses.push_back(
+      [this,&MR](jitlink::LinkGraph &G) -> Error {
+
+    JITLinkSymbolVector InitSectionSymbols;
+    preserveInitSectionIfPresent(InitSectionSymbols, G, "__mod_init_func");
+    preserveInitSectionIfPresent(InitSectionSymbols, G, "__objc_selrefs");
+    preserveInitSectionIfPresent(InitSectionSymbols, G, "__objc_classlist");
+
+    if (!InitSymbolDeps.empty()) {
+      std::lock_guard<std::mutex> Lock(InitScraperMutex);
+      InitSymbolDeps[&MR] = std::move(InitSectionSymbols);
+    }
+
+    if (auto Err = processObjCImageInfo(G, MR))
+      return Err;
+
+    return Error::success();
+  });
+
+  Config.PostFixupPasses.push_back(
+      [this, &JD = MR.getTargetJITDylib()](jitlink::LinkGraph &G) -> Error {
+        MachOJITDylibInitializers::SectionExtent ModInits, ObjCSelRefs,
+          ObjCClassList;
+
+        JITTargetAddress ObjCImageInfoAddr = 0;
+        if (auto *ObjCImageInfoSec = G.findSectionByName("__objc_image_info")) {
+          if (auto Addr = jitlink::SectionRange(*ObjCImageInfoSec).getStart()) {
+            ObjCImageInfoAddr = Addr;
+            dbgs() << "Recorded __objc_imageinfo @ " << formatv("{0:x16}", Addr);
+          }
+        }
+
+        // Record __mod_init_func.
+        if (auto ModInitsOrErr = getSectionExtent(G, "__mod_init_func"))
+          ModInits = std::move(*ModInitsOrErr);
+        else
+          return ModInitsOrErr.takeError();
+
+        // Record __objc_selrefs.
+        if (auto ObjCSelRefsOrErr = getSectionExtent(G, "__objc_selrefs"))
+          ObjCSelRefs = std::move(*ObjCSelRefsOrErr);
+        else
+          return ObjCSelRefsOrErr.takeError();
+
+        // Record __objc_classlist.
+        if (auto ObjCClassListOrErr = getSectionExtent(G, "__objc_classlist"))
+          ObjCClassList = std::move(*ObjCClassListOrErr);
+        else
+          return ObjCClassListOrErr.takeError();
+
+        MP.registerInitInfo(JD, ObjCImageInfoAddr, std::move(ModInits),
+                            std::move(ObjCSelRefs), std::move(ObjCClassList));
+
+        return Error::success();
+      });
+}
+
+ObjectLinkingLayer::Plugin::LocalDependenciesMap
+MachOPlatform::InitScraperPlugin::getSyntheticSymbolLocalDependencies(
+    MaterializationResponsibility &MR) {
+  std::lock_guard<std::mutex> Lock(InitScraperMutex);
+  auto I = InitSymbolDeps.find(&MR);
+  if (I != InitSymbolDeps.end()) {
+    LocalDependenciesMap Result;
+    Result[MR.getInitializerSymbol()] = std::move(I->second);
+    InitSymbolDeps.erase(&MR);
+    return Result;
+  }
+  return LocalDependenciesMap();
+}
+
+void MachOPlatform::InitScraperPlugin::preserveInitSectionIfPresent(
+                                                   JITLinkSymbolVector &Symbols,
+                                                   jitlink::LinkGraph &G,
+                                                   StringRef SectionName) {
+  if (auto *Sec = G.findSectionByName(SectionName)) {
+    auto SecBlocks = Sec->blocks();
+    if (!llvm::empty(SecBlocks))
+      Symbols.push_back(
+        &G.addAnonymousSymbol(**SecBlocks.begin(), 0, 0, false, true));
+  }
+}
+
+Error MachOPlatform::InitScraperPlugin::processObjCImageInfo(jitlink::LinkGraph &G,
+                                                             MaterializationResponsibility &MR) {
+
+  // If there's an ObjC imagine info then either
+  //   (1) It's the first __objc_imageinfo we've seen in this JITDylib. In
+  //       this case we name and record it.
+  // OR
+  //   (2) We already have a recorded __objc_imageinfo for this JITDylib,
+  //       in which case we just verify it.
+  auto *ObjCImageInfo = G.findSectionByName("__objc_imageinfo");
+  if (!ObjCImageInfo)
+    return Error::success();
+
+  auto ObjCImageInfoBlocks = ObjCImageInfo->blocks();
+
+  // Check that the section is not empty if present.
+  if (llvm::empty(ObjCImageInfoBlocks))
+    return make_error<StringError>("Empty __objc_imageinfo section in " +
+                                   G.getName(),
+                                   inconvertibleErrorCode());
+
+  // Check that there's only one block in the section.
+  if (std::next(ObjCImageInfoBlocks.begin()) !=  ObjCImageInfoBlocks.end())
+    return make_error<StringError>("Multiple blocks in __objc_imageinfo "
+                                   "section in " + G.getName(),
+                                   inconvertibleErrorCode());
+
+  // Check that the __objc_imageinfo section is unreferenced.
+  // FIXME: We could optimize this check if Symbols had a ref-count.
+  for (auto &Sec : G.sections()) {
+    if (&Sec != ObjCImageInfo)
+      for (auto *B : Sec.blocks())
+        for (auto &E : B->edges())
+          if (E.getTarget().isDefined() &&
+              &E.getTarget().getBlock().getSection() == ObjCImageInfo)
+            return make_error<StringError>("__objc_imageinfo is referenced "
+                                           "within file " + G.getName(),
+                                           inconvertibleErrorCode());
+  }
+
+  auto &ObjCImageInfoBlock = **ObjCImageInfoBlocks.begin();
+  auto *ObjCImageInfoData = ObjCImageInfoBlock.getContent().data();
+  auto Version =
+    support::endian::read32(ObjCImageInfoData, G.getEndianness());
+  auto Flags =
+    support::endian::read32(ObjCImageInfoData + 4, G.getEndianness());
+
+  // Lock the mutex while we verify / update the ObjCImageInfos map.
+  std::lock_guard<std::mutex> Lock(InitScraperMutex);
+
+  auto ObjCImageInfoItr = ObjCImageInfos.find(&MR.getTargetJITDylib());
+  if (ObjCImageInfoItr != ObjCImageInfos.end()) {
+    // We've already registered an __objc_imageinfo section. Verify the
+    // content of this new section matches, then delete it.
+    if (ObjCImageInfoItr->second.first != Version)
+      return make_error<StringError>("ObjC version in " + G.getName() +
+                                     " does not match first registered version",
+                                     inconvertibleErrorCode());
+    if (ObjCImageInfoItr->second.second != Flags)
+      return make_error<StringError>("ObjC flags in " + G.getName() +
+                                     " do not match first registered flags",
+                                     inconvertibleErrorCode());
+
+    // __objc_imageinfo is valid. Delete the block.
+    for (auto *S : ObjCImageInfo->symbols())
+      G.removeDefinedSymbol(*S);
+    G.removeBlock(ObjCImageInfoBlock);
+  } else {
+    // We haven't registered an __objc_imageinfo section yet. Register and
+    // move on. The section should already be marked no-dead-strip.
+    ObjCImageInfos[&MR.getTargetJITDylib()] =
+      std::make_pair(Version, Flags);
+  }
+
+  return Error::success();
+}
+
+} // End namespace orc.
+} // End namespace llvm.

llvm/lib/ExecutionEngine/Orc/Mangling.cpp

+//===----------- Mangling.cpp -- Name Mangling Utilities for ORC ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/Mangling.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Mangler.h"
+#include "llvm/Object/MachO.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "orc"
+
+namespace llvm {
+namespace orc {
+
+MangleAndInterner::MangleAndInterner(ExecutionSession &ES, const DataLayout &DL)
+    : ES(ES), DL(DL) {}
+
+SymbolStringPtr MangleAndInterner::operator()(StringRef Name) {
+  std::string MangledName;
+  {
+    raw_string_ostream MangledNameStream(MangledName);
+    Mangler::getNameWithPrefix(MangledNameStream, Name, DL);
+  }
+  return ES.intern(MangledName);
+}
+
+void IRSymbolMapper::add(ExecutionSession &ES, const ManglingOptions &MO,
+                         ArrayRef<GlobalValue *> GVs,
+                         SymbolFlagsMap &SymbolFlags,
+                         SymbolNameToDefinitionMap *SymbolToDefinition) {
+  if (GVs.empty())
+    return;
+
+  MangleAndInterner Mangle(ES, GVs[0]->getParent()->getDataLayout());
+  for (auto *G : GVs) {
+    assert(G && "GVs cannot contain null elements");
+    if (!G->hasName() || G->isDeclaration() || G->hasLocalLinkage() ||
+        G->hasAvailableExternallyLinkage() || G->hasAppendingLinkage())
+      continue;
+
+    if (G->isThreadLocal() && MO.EmulatedTLS) {
+      auto *GV = cast<GlobalVariable>(G);
+
+      auto Flags = JITSymbolFlags::fromGlobalValue(*GV);
+
+      auto EmuTLSV = Mangle(("__emutls_v." + GV->getName()).str());
+      SymbolFlags[EmuTLSV] = Flags;
+      if (SymbolToDefinition)
+        (*SymbolToDefinition)[EmuTLSV] = GV;
+
+      // If this GV has a non-zero initializer we'll need to emit an
+      // __emutls.t symbol too.
+      if (GV->hasInitializer()) {
+        const auto *InitVal = GV->getInitializer();
+
+        // Skip zero-initializers.
+        if (isa<ConstantAggregateZero>(InitVal))
+          continue;
+        const auto *InitIntValue = dyn_cast<ConstantInt>(InitVal);
+        if (InitIntValue && InitIntValue->isZero())
+          continue;
+
+        auto EmuTLST = Mangle(("__emutls_t." + GV->getName()).str());
+        SymbolFlags[EmuTLST] = Flags;
+        if (SymbolToDefinition)
+          (*SymbolToDefinition)[EmuTLST] = GV;
+      }
+      continue;
+    }
+
+    // Otherwise we just need a normal linker mangling.
+    auto MangledName = Mangle(G->getName());
+    SymbolFlags[MangledName] = JITSymbolFlags::fromGlobalValue(*G);
+    if (SymbolToDefinition)
+      (*SymbolToDefinition)[MangledName] = G;
+  }
+}
+
+Expected<std::pair<SymbolFlagsMap, SymbolStringPtr>>
+getObjectSymbolInfo(ExecutionSession &ES, MemoryBufferRef ObjBuffer) {
+  auto Obj = object::ObjectFile::createObjectFile(ObjBuffer);
+
+  if (!Obj)
+    return Obj.takeError();
+
+  SymbolFlagsMap SymbolFlags;
+  for (auto &Sym : (*Obj)->symbols()) {
+    // Skip symbols not defined in this object file.
+    if (Sym.getFlags() & object::BasicSymbolRef::SF_Undefined)
+      continue;
+
+    // Skip symbols that are not global.
+    if (!(Sym.getFlags() & object::BasicSymbolRef::SF_Global))
+      continue;
+
+    auto Name = Sym.getName();
+    if (!Name)
+      return Name.takeError();
+    auto InternedName = ES.intern(*Name);
+    auto SymFlags = JITSymbolFlags::fromObjectSymbol(Sym);
+    if (!SymFlags)
+      return SymFlags.takeError();
+    SymbolFlags[InternedName] = std::move(*SymFlags);
+  }
+
+  SymbolStringPtr InitSymbol;
+
+  if (auto *MachOObj = dyn_cast<object::MachOObjectFile>(Obj->get())) {
+    for (auto &Sec : MachOObj->sections()) {
+      auto SecType = MachOObj->getSectionType(Sec);
+      if ((SecType & MachO::SECTION_TYPE) == MachO::S_MOD_INIT_FUNC_POINTERS) {
+        std::string InitSymString;
+        raw_string_ostream(InitSymString)
+            << "$." << ObjBuffer.getBufferIdentifier() << ".__inits";
+        InitSymbol = ES.intern(InitSymString);
+        break;
+      }
+    }
+  }
+
+  return std::make_pair(std::move(SymbolFlags), std::move(InitSymbol));
+}
+
+} // End namespace orc.
+} // End namespace llvm.

llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp

for (auto *Sym : G.absolute_symbols())
                  "Duplicate symbol to claim?");
           ExtraSymbolsToClaim[InternedName] = Flags;
         }
       }
 
     if (!ExtraSymbolsToClaim.empty())
       if (auto Err = MR.defineMaterializing(ExtraSymbolsToClaim))
         return notifyFailed(std::move(Err));
+
+    if (const auto &InitSym = MR.getInitializerSymbol())
+      InternedResult[InitSym] = JITEvaluatedSymbol();
+
     if (auto Err = MR.notifyResolved(InternedResult)) {
       Layer.getExecutionSession().reportError(std::move(Err));
       MR.failMaterialization();
       return;
     }
     Layer.notifyLoaded(MR);
   }
 
Error modifyPassConfig(const Triple &TT, PassConfiguration &Config) override {
 
     Config.PostPrunePasses.push_back(
         [this](LinkGraph &G) { return computeNamedSymbolDependencies(G); });
 
     return Error::success();
   }
 
 private:
-  using JITLinkSymbolSet = DenseSet<const Symbol *>;
-  using LocalToNamedDependenciesMap = DenseMap<const Symbol *, JITLinkSymbolSet>;
+
+  struct LocalSymbolNamedDependencies {
+    SymbolNameSet Internal, External;
+  };
+
+  using LocalSymbolNamedDependenciesMap =
+    DenseMap<const Symbol *, LocalSymbolNamedDependencies>;
 
   Error externalizeWeakAndCommonSymbols(LinkGraph &G) {
     auto &ES = Layer.getExecutionSession();
     for (auto *Sym : G.defined_symbols())
       if (Sym->hasName() && Sym->getLinkage() == Linkage::Weak) {
         if (!MR.getSymbols().count(ES.intern(Sym->getName())))
           G.makeExternal(*Sym);
       }
for (auto *Sym : G.defined_symbols())
         Sym->setLive(true);
     return Error::success();
   }
 
   Error computeNamedSymbolDependencies(LinkGraph &G) {
     auto &ES = MR.getTargetJITDylib().getExecutionSession();
     auto LocalDeps = computeLocalDeps(G);
 
+    // Compute dependencies for symbols defined in the JITLink graph.
     for (auto *Sym : G.defined_symbols()) {
 
       // Skip local symbols: we do not track dependencies for these.
       if (Sym->getScope() == Scope::Local)
         continue;
       assert(Sym->hasName() &&
              "Defined non-local jitlink::Symbol should have a name");
 
       SymbolNameSet ExternalSymDeps, InternalSymDeps;
 
       // Find internal and external named symbol dependencies.
       for (auto &E : Sym->getBlock().edges()) {
         auto &TargetSym = E.getTarget();
 
         if (TargetSym.getScope() != Scope::Local) {
           if (TargetSym.isExternal())
             ExternalSymDeps.insert(ES.intern(TargetSym.getName()));
           else if (&TargetSym != Sym)
             InternalSymDeps.insert(ES.intern(TargetSym.getName()));
         } else {
           assert(TargetSym.isDefined() &&
                  "local symbols must be defined");
           auto I = LocalDeps.find(&TargetSym);
-          if (I != LocalDeps.end())
-            for (auto &S : I->second) {
-              assert(S->hasName() &&
-                     "LocalDeps should only contain named values");
-              if (S->isExternal())
-                ExternalSymDeps.insert(ES.intern(S->getName()));
-              else if (S != Sym)
-                InternalSymDeps.insert(ES.intern(S->getName()));
-            }
+          if (I != LocalDeps.end()) {
+            for (auto &S : I->second.External)
+              ExternalSymDeps.insert(S);
+            for (auto &S : I->second.Internal)
+              InternalSymDeps.insert(S);
         }
       }
 
       if (ExternalSymDeps.empty() && InternalSymDeps.empty())
         continue;
 
       auto SymName = ES.intern(Sym->getName());
       if (!ExternalSymDeps.empty())
         ExternalNamedSymbolDeps[SymName] = std::move(ExternalSymDeps);
       if (!InternalSymDeps.empty())
         InternalNamedSymbolDeps[SymName] = std::move(InternalSymDeps);
     }
 
+    for (auto &P : Layer.Plugins) {
+      auto SyntheticLocalDeps =  P->getSyntheticSymbolLocalDependencies(MR);
+      if (SyntheticLocalDeps.empty())
+        continue;
+
+      for (auto &KV : SyntheticLocalDeps) {
+        auto &Name = KV.first;
+        auto &LocalDepsForName = KV.second;
+        for (auto *Local : LocalDepsForName) {
+          assert(Local->getScope() == Scope::Local &&
+                 "Dependence on non-local symbol");
+          auto LocalNamedDepsItr = LocalDeps.find(Local);
+          if (LocalNamedDepsItr == LocalDeps.end())
+            continue;
+          for (auto &S : LocalNamedDepsItr->second.Internal)
+            InternalNamedSymbolDeps[Name].insert(S);
+          for (auto &S : LocalNamedDepsItr->second.External)
+            ExternalNamedSymbolDeps[Name].insert(S);
+        }
+      }
+    }
+
     return Error::success();
   }
 
-  LocalToNamedDependenciesMap computeLocalDeps(LinkGraph &G) {
-    LocalToNamedDependenciesMap DepMap;
+  LocalSymbolNamedDependenciesMap computeLocalDeps(LinkGraph &G) {
+    DenseMap<jitlink::Symbol*, DenseSet<jitlink::Symbol*>> DepMap;
 
     // For all local symbols:
     // (1) Add their named dependencies.
     // (2) Add them to the worklist for further iteration if they have any
     //     depend on any other local symbols.
     struct WorklistEntry {
       WorklistEntry(Symbol *Sym, DenseSet<Symbol *> LocalDeps)
           : Sym(Sym), LocalDeps(std::move(LocalDeps)) {}
do {
           auto I = DepMap.find(TargetSym);
           if (I != DepMap.end())
             for (const auto &S : I->second)
               Changed |= NamedDeps.insert(S).second;
         }
       }
     } while (Changed);
 
-    return DepMap;
+    // Intern the results to produce a mapping of jitlink::Symbol* to internal
+    // and external symbol names.
+    auto &ES = Layer.getExecutionSession();
+    LocalSymbolNamedDependenciesMap Result;
+    for (auto &KV : DepMap) {
+      auto *Local = KV.first;
+      assert(Local->getScope() == Scope::Local &&
+             "DepMap keys should all be local symbols");
+      auto &LocalNamedDeps = Result[Local];
+      for (auto *Named : KV.second) {
+        assert(Named->getScope() != Scope::Local &&
+               "DepMap values should all be non-local symbol sets");
+        if (Named->isExternal())
+          LocalNamedDeps.External.insert(ES.intern(Named->getName()));
+        else
+          LocalNamedDeps.Internal.insert(ES.intern(Named->getName()));
+      }
+    }
+
+    return Result;
   }
 
   void registerDependencies(const SymbolDependenceMap &QueryDeps) {
     for (auto &NamedDepsEntry : ExternalNamedSymbolDeps) {
       auto &Name = NamedDepsEntry.first;
       auto &NameDeps = NamedDepsEntry.second;
       SymbolDependenceMap SymbolDeps;
 

llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp

RTDyldObjectLinkingLayer::~RTDyldObjectLinkingLayer() {
   std::lock_guard<std::mutex> Lock(RTDyldLayerMutex);
   for (auto &MemMgr : MemMgrs)
     MemMgr->deregisterEHFrames();
 }
 
 void RTDyldObjectLinkingLayer::emit(MaterializationResponsibility R,
                                     std::unique_ptr<MemoryBuffer> O) {
   assert(O && "Object must not be null");
-
+  dbgs() << "Emitting via RTDyldObjectLinkingLayer:\n"
+         << R.getSymbols() << "\n";
   // This method launches an asynchronous link step that will fulfill our
   // materialization responsibility. We need to switch R to be heap
   // allocated before that happens so it can live as long as the asynchronous
   // link needs it to (i.e. it must be able to outlive this method).
   auto SharedR = std::make_shared<MaterializationResponsibility>(std::move(R));
 
   auto &ES = getExecutionSession();
 
if (!ExtraSymbolsToClaim.empty()) {
 
     // If we claimed responsibility for any weak symbols but were rejected then
     // we need to remove them from the resolved set.
     for (auto &KV : ExtraSymbolsToClaim)
       if (KV.second.isWeak() && !R.getSymbols().count(KV.first))
         Symbols.erase(KV.first);
   }
 
+  if (const auto &InitSym = R.getInitializerSymbol())
+    Symbols[InitSym] = JITEvaluatedSymbol();
+
   if (auto Err = R.notifyResolved(Symbols)) {
     R.failMaterialization();
     return Err;
   }
 
   if (NotifyLoaded)
     NotifyLoaded(K, Obj, *LoadedObjInfo);
 

llvm/tools/lli/lli.cpp

 #include "llvm/CodeGen/CommandFlags.inc"
 #include "llvm/CodeGen/LinkAllCodegenComponents.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/ExecutionEngine/GenericValue.h"
 #include "llvm/ExecutionEngine/Interpreter.h"
 #include "llvm/ExecutionEngine/JITEventListener.h"
 #include "llvm/ExecutionEngine/MCJIT.h"
 #include "llvm/ExecutionEngine/ObjectCache.h"
+#include "llvm/ExecutionEngine/Orc/DebugUtils.h"
 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
 #include "llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h"
 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
+#include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
 #include "llvm/ExecutionEngine/Orc/OrcRemoteTargetClient.h"
 #include "llvm/ExecutionEngine/OrcMCJITReplacement.h"
 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Verifier.h"
GenerateSoftFloatCalls("soft-float",
     cl::desc("Generate software floating point library calls"),
     cl::init(false));
 
   cl::opt<bool> NoProcessSymbols(
       "no-process-syms",
       cl::desc("Do not resolve lli process symbols in JIT'd code"),
       cl::init(false));
 
+  enum class LLJITPlatform { DetectHost, GenericIR, MachO };
+
+  cl::opt<LLJITPlatform>
+      Platform("lljit-platform", cl::desc("Platform to use with LLJIT"),
+               cl::init(LLJITPlatform::DetectHost),
+               cl::values(clEnumValN(LLJITPlatform::DetectHost, "DetectHost",
+                                     "Select based on JIT target triple"),
+                          clEnumValN(LLJITPlatform::GenericIR, "GenericIR",
+                                     "Use LLJITGenericIRPlatform"),
+                          clEnumValN(LLJITPlatform::MachO, "MachO",
+                                     "Use LLJITMachOPlatform")),
+               cl::Hidden);
+
   enum class DumpKind {
     NoDump,
     DumpFuncsToStdOut,
     DumpModsToStdOut,
     DumpModsToDisk
   };
 
   cl::opt<DumpKind> OrcDumpKind(
int runOrcLazyJIT(const char *ProgName) {
 
   // Parse the main module.
   orc::ThreadSafeContext TSCtx(std::make_unique<LLVMContext>());
   SMDiagnostic Err;
   auto MainModule = parseIRFile(InputFile, Err, *TSCtx.getContext());
   if (!MainModule)
     reportError(Err, ProgName);
 
-  const auto &TT = MainModule->getTargetTriple();
+  Triple TT(MainModule->getTargetTriple());
   orc::LLLazyJITBuilder Builder;
 
   Builder.setJITTargetMachineBuilder(
-      TT.empty() ? ExitOnErr(orc::JITTargetMachineBuilder::detectHost())
-                 : orc::JITTargetMachineBuilder(Triple(TT)));
+      MainModule->getTargetTriple().empty()
+          ? ExitOnErr(orc::JITTargetMachineBuilder::detectHost())
+          : orc::JITTargetMachineBuilder(TT));
 
   if (!MArch.empty())
     Builder.getJITTargetMachineBuilder()->getTargetTriple().setArchName(MArch);
 
+  if (!MainModule->getDataLayout().isDefault())
+    Builder.setDataLayout(MainModule->getDataLayout());
+
   Builder.getJITTargetMachineBuilder()
       ->setCPU(getCPUStr())
       .addFeatures(getFeatureList())
       .setRelocationModel(RelocModel.getNumOccurrences()
                               ? Optional<Reloc::Model>(RelocModel)
                               : None)
       .setCodeModel(CMModel.getNumOccurrences()
                         ? Optional<CodeModel::Model>(CMModel)
                         : None);
 
   Builder.setLazyCompileFailureAddr(
       pointerToJITTargetAddress(exitOnLazyCallThroughFailure));
   Builder.setNumCompileThreads(LazyJITCompileThreads);
 
+  // Set up LLJIT platform.
+  {
+    LLJITPlatform P = Platform;
+    if (P == LLJITPlatform::DetectHost) {
+      if (TT.isOSBinFormatMachO())
+        P = LLJITPlatform::MachO;
+      else
+        P = LLJITPlatform::GenericIR;
+    }
+
+    switch (P) {
+    case LLJITPlatform::GenericIR:
+      // Nothing to do: LLJITBuilder will use this by default.
+      break;
+    case LLJITPlatform::MachO:
+      Builder.setPlatformSetUp(orc::setUpMachOPlatform);
+      ExitOnErr(orc::enableObjCRegistration("libobjc.dylib"));
+      break;
+    default:
+      llvm_unreachable("Unrecognized platform value");
+    }
+  }
+
   auto J = ExitOnErr(Builder.create());
 
   if (PerModuleLazy)
     J->setPartitionFunction(orc::CompileOnDemandLayer::compileWholeModule);
 
   auto Dump = createDebugDumper();
 
   J->getIRTransformLayer().setTransform(
int runOrcLazyJIT(const char *ProgName) {
   if (!NoProcessSymbols)
     J->getMainJITDylib().addGenerator(
         ExitOnErr(orc::DynamicLibrarySearchGenerator::GetForCurrentProcess(
             J->getDataLayout().getGlobalPrefix(),
             [MainName = Mangle("main")](const orc::SymbolStringPtr &Name) {
               return Name != MainName;
             })));
 
-  orc::LocalCXXRuntimeOverrides CXXRuntimeOverrides;
-  ExitOnErr(CXXRuntimeOverrides.enable(J->getMainJITDylib(), Mangle));
-
   // Add the main module.
   ExitOnErr(
       J->addLazyIRModule(orc::ThreadSafeModule(std::move(MainModule), TSCtx)));
 
   // Create JITDylibs and add any extra modules.
   {
     // Create JITDylibs, keep a map from argument index to dylib. We will use
     // -extra-module argument indexes to determine what dylib to use for each
     // -extra-module.
     std::map<unsigned, orc::JITDylib *> IdxToDylib;
     IdxToDylib[0] = &J->getMainJITDylib();
     for (auto JDItr = JITDylibs.begin(), JDEnd = JITDylibs.end();
          JDItr != JDEnd; ++JDItr) {
       orc::JITDylib *JD = J->getJITDylibByName(*JDItr);
-      if (!JD)
-        JD = &J->createJITDylib(*JDItr);
+      if (!JD) {
+        JD = &ExitOnErr(J->createJITDylib(*JDItr));
+        J->getMainJITDylib().addToSearchOrder(*JD);
+        JD->addToSearchOrder(J->getMainJITDylib());
+      }
       IdxToDylib[JITDylibs.getPosition(JDItr - JITDylibs.begin())] = JD;
     }
 
     for (auto EMItr = ExtraModules.begin(), EMEnd = ExtraModules.end();
          EMItr != EMEnd; ++EMItr) {
       auto M = parseIRFile(*EMItr, Err, *TSCtx.getContext());
       if (!M)
         reportError(Err, ProgName);
int runOrcLazyJIT(const char *ProgName) {
 
   // Add the objects.
   for (auto &ObjPath : ExtraObjects) {
     auto Obj = ExitOnErr(errorOrToExpected(MemoryBuffer::getFile(ObjPath)));
     ExitOnErr(J->addObjectFile(std::move(Obj)));
   }
 
   // Run any static constructors.
-  ExitOnErr(J->runConstructors());
+  ExitOnErr(J->initialize(J->getMainJITDylib()));
 
   // Run any -thread-entry points.
   std::vector<std::thread> AltEntryThreads;
   for (auto &ThreadEntryPoint : ThreadEntryPoints) {
     auto EntryPointSym = ExitOnErr(J->lookup(ThreadEntryPoint));
     typedef void (*EntryPointPtr)();
     auto EntryPoint =
       reinterpret_cast<EntryPointPtr>(static_cast<uintptr_t>(EntryPointSym.getAddress()));
     AltEntryThreads.push_back(std::thread([EntryPoint]() { EntryPoint(); }));
   }
 
   // Run main.
   auto MainSym = ExitOnErr(J->lookup("main"));
 
   typedef int (*MainFnPtr)(int, char *[]);
   auto Result = orc::runAsMain(
       jitTargetAddressToFunction<MainFnPtr>(MainSym.getAddress()), InputArgv,
       StringRef(InputFile));
 
   // Wait for -entry-point threads.
   for (auto &AltEntryThread : AltEntryThreads)
     AltEntryThread.join();
 
   // Run destructors.
-  ExitOnErr(J->runDestructors());
-  CXXRuntimeOverrides.runDestructors();
+  ExitOnErr(J->deinitialize(J->getMainJITDylib()));
 
   return Result;
 }
 
 void disallowOrcOptions() {
   // Make sure nobody used an orc-lazy specific option accidentally.
 
   if (LazyJITCompileThreads != 0) {

llvm/tools/llvm-jitlink/llvm-jitlink.h

 #include "llvm/Support/raw_ostream.h"
 
 #include <vector>
 
 namespace llvm {
 
 struct Session {
   orc::ExecutionSession ES;
-  orc::JITDylib &MainJD;
+  orc::JITDylib *MainJD;
   orc::ObjectLinkingLayer ObjLayer;
   std::vector<orc::JITDylib *> JDSearchOrder;
   Triple TT;
 
   Session(Triple TT);
+  static Expected<std::unique_ptr<Session>> Create(Triple TT);
   void dumpSessionInfo(raw_ostream &OS);
   void modifyPassConfig(const Triple &FTT,
                         jitlink::PassConfiguration &PassConfig);
 
   using MemoryRegionInfo = RuntimeDyldChecker::MemoryRegionInfo;
 
   struct FileInfo {
     StringMap<MemoryRegionInfo> SectionInfos;
struct Session {
   bool isSymbolRegistered(StringRef Name);
   Expected<MemoryRegionInfo &> findSymbolInfo(StringRef SymbolName,
                                               Twine ErrorMsgStem);
 
   SymbolInfoMap SymbolInfos;
   FileInfoMap FileInfos;
   uint64_t SizeBeforePruning = 0;
   uint64_t SizeAfterFixups = 0;
+
+private:
+  Session(Triple TT, Error &Err);
 };
 
 Error registerMachOStubsAndGOT(Session &S, jitlink::LinkGraph &G);
 
 } // end namespace llvm
 
 #endif // LLVM_TOOLS_LLVM_JITLINK_LLVM_JITLINK_H

llvm/tools/llvm-jitlink/llvm-jitlink.cpp

 static std::unique_ptr<jitlink::JITLinkMemoryManager> createMemoryManager() {
   if (!SlabAllocateSizeString.empty()) {
     auto SlabSize = ExitOnErr(getSlabAllocSize(SlabAllocateSizeString));
     return ExitOnErr(JITLinkSlabAllocator::Create(SlabSize));
   }
   return std::make_unique<jitlink::InProcessMemoryManager>();
 }
 
-Session::Session(Triple TT)
-    : MainJD(ES.createJITDylib("<main>")), ObjLayer(ES, createMemoryManager()),
-      TT(std::move(TT)) {
+Expected<std::unique_ptr<Session>> Session::Create(Triple TT) {
+  Error Err = Error::success();
+  std::unique_ptr<Session> S(new Session(std::move(TT), Err));
+  if (Err)
+    return std::move(Err);
+  return std::move(S);
+}
+
+// FIXME: Move to createJITDylib if/when we start using Platform support in
+// llvm-jitlink.
+Session::Session(Triple TT, Error &Err)
+    : ObjLayer(ES, createMemoryManager()), TT(std::move(TT)) {
 
   /// Local ObjectLinkingLayer::Plugin class to forward modifyPassConfig to the
   /// Session.
   class JITLinkSessionPlugin : public ObjectLinkingLayer::Plugin {
   public:
     JITLinkSessionPlugin(Session &S) : S(S) {}
     void modifyPassConfig(MaterializationResponsibility &MR, const Triple &TT,
                           PassConfiguration &PassConfig) {
       S.modifyPassConfig(TT, PassConfig);
     }
 
   private:
     Session &S;
   };
 
+  ErrorAsOutParameter _(&Err);
+
+  if (auto MainJDOrErr = ES.createJITDylib("main"))
+    MainJD = &*MainJDOrErr;
+  else {
+    Err = MainJDOrErr.takeError();
+    return;
+  }
+
   if (!NoExec && !TT.isOSWindows())
     ObjLayer.addPlugin(std::make_unique<EHFrameRegistrationPlugin>(
         InProcessEHFrameRegistrar::getInstance()));
 
   ObjLayer.addPlugin(std::make_unique<JITLinkSessionPlugin>(*this));
 }
 
 void Session::dumpSessionInfo(raw_ostream &OS) {
Error loadProcessSymbols(Session &S) {
   if (sys::DynamicLibrary::LoadLibraryPermanently(nullptr, &ErrMsg))
     return make_error<StringError>(std::move(ErrMsg), inconvertibleErrorCode());
 
   char GlobalPrefix = S.TT.getObjectFormat() == Triple::MachO ? '_' : '\0';
   auto InternedEntryPointName = S.ES.intern(EntryPointName);
   auto FilterMainEntryPoint = [InternedEntryPointName](SymbolStringPtr Name) {
     return Name != InternedEntryPointName;
   };
-  S.MainJD.addGenerator(
+  S.MainJD->addGenerator(
       ExitOnErr(orc::DynamicLibrarySearchGenerator::GetForCurrentProcess(
           GlobalPrefix, FilterMainEntryPoint)));
 
   return Error::success();
 }
 
 Error loadDylibs() {
   // FIXME: This should all be handled inside DynamicLibrary.

 Error loadObjects(Session &S) {
 
   std::map<unsigned, JITDylib *> IdxToJLD;
 
   // First, set up JITDylibs.
   LLVM_DEBUG(dbgs() << "Creating JITDylibs...\n");
   {
     // Create a "main" JITLinkDylib.
-    IdxToJLD[0] = &S.MainJD;
-    S.JDSearchOrder.push_back(&S.MainJD);
-    LLVM_DEBUG(dbgs() << "  0: " << S.MainJD.getName() << "\n");
+    IdxToJLD[0] = S.MainJD;
+    S.JDSearchOrder.push_back(S.MainJD);
+    LLVM_DEBUG(dbgs() << "  0: " << S.MainJD->getName() << "\n");
 
     // Add any extra JITLinkDylibs from the command line.
     std::string JDNamePrefix("lib");
     for (auto JLDItr = JITLinkDylibs.begin(), JLDEnd = JITLinkDylibs.end();
          JLDItr != JLDEnd; ++JLDItr) {
-      auto &JD = S.ES.createJITDylib(JDNamePrefix + *JLDItr);
+      auto JD = S.ES.createJITDylib(JDNamePrefix + *JLDItr);
+      if (!JD)
+        return JD.takeError();
       unsigned JDIdx =
           JITLinkDylibs.getPosition(JLDItr - JITLinkDylibs.begin());
-      IdxToJLD[JDIdx] = &JD;
-      S.JDSearchOrder.push_back(&JD);
-      LLVM_DEBUG(dbgs() << "  " << JDIdx << ": " << JD.getName() << "\n");
+      IdxToJLD[JDIdx] = &*JD;
+      S.JDSearchOrder.push_back(&*JD);
+      LLVM_DEBUG(dbgs() << "  " << JDIdx << ": " << JD->getName() << "\n");
     }
 
     // Set every dylib to link against every other, in command line order.
     for (auto *JD : S.JDSearchOrder) {
       auto LookupFlags = JITDylibLookupFlags::MatchExportedSymbolsOnly;
       JITDylibSearchOrder O;
       for (auto *JD2 : S.JDSearchOrder) {
         if (JD2 == JD)
int main(int argc, char *argv[]) {
 
   cl::ParseCommandLineOptions(argc, argv, "llvm jitlink tool");
   ExitOnErr.setBanner(std::string(argv[0]) + ": ");
 
   /// If timers are enabled, create a JITLinkTimers instance.
   std::unique_ptr<JITLinkTimers> Timers =
       ShowTimes ? std::make_unique<JITLinkTimers>() : nullptr;
 
-  Session S(getFirstFileTriple());
+  auto S = ExitOnErr(Session::Create(getFirstFileTriple()));
 
-  ExitOnErr(sanitizeArguments(S));
+  ExitOnErr(sanitizeArguments(*S));
 
   if (!NoProcessSymbols)
-    ExitOnErr(loadProcessSymbols(S));
+    ExitOnErr(loadProcessSymbols(*S));
   ExitOnErr(loadDylibs());
 
 
   {
     TimeRegion TR(Timers ? &Timers->LoadObjectsTimer : nullptr);
-    ExitOnErr(loadObjects(S));
+    ExitOnErr(loadObjects(*S));
   }
 
   JITEvaluatedSymbol EntryPoint = 0;
   {
     TimeRegion TR(Timers ? &Timers->LinkTimer : nullptr);
-    EntryPoint = ExitOnErr(getMainEntryPoint(S));
+    EntryPoint = ExitOnErr(getMainEntryPoint(*S));
   }
 
   if (ShowAddrs)
-    S.dumpSessionInfo(outs());
+    S->dumpSessionInfo(outs());
 
-  ExitOnErr(runChecks(S));
+  ExitOnErr(runChecks(*S));
 
-  dumpSessionStats(S);
+  dumpSessionStats(*S);
 
   if (NoExec)
     return 0;
 
   int Result = 0;
   {
     using MainTy = int (*)(int, char *[]);
     auto EntryFn = jitTargetAddressToFunction<MainTy>(EntryPoint.getAddress());
     TimeRegion TR(Timers ? &Timers->RunTimer : nullptr);
     Result = runAsMain(EntryFn, InputArgv, StringRef(InputFiles.front()));
   }
 
   return Result;
 }

llvm/unittests/ExecutionEngine/Orc/CoreAPIsTest.cpp

TEST_F(CoreAPIsStandardTest, RemoveSymbolsTest) {
   bool BarMaterializerDestructed = false;
   cantFail(JD.define(std::make_unique<SimpleMaterializationUnit>(
       SymbolFlagsMap({{Bar, BarSym.getFlags()}}),
       [this](MaterializationResponsibility R) {
         ADD_FAILURE() << "Unexpected materialization of \"Bar\"";
         cantFail(R.notifyResolved({{Bar, BarSym}}));
         cantFail(R.notifyEmitted());
       },
+      nullptr,
       [&](const JITDylib &JD, const SymbolStringPtr &Name) {
         EXPECT_EQ(Name, Bar) << "Expected \"Bar\" to be discarded";
         if (Name == Bar)
           BarDiscarded = true;
       },
       [&]() { BarMaterializerDestructed = true; })));
 
   // Baz will be in the materializing state initially, then
   // materialized for the final removal attempt.
   Optional<MaterializationResponsibility> BazR;
   cantFail(JD.define(std::make_unique<SimpleMaterializationUnit>(
       SymbolFlagsMap({{Baz, BazSym.getFlags()}}),
       [&](MaterializationResponsibility R) { BazR.emplace(std::move(R)); },
+      nullptr,
       [](const JITDylib &JD, const SymbolStringPtr &Name) {
         ADD_FAILURE() << "\"Baz\" discarded unexpectedly";
       })));
 
   bool OnCompletionRun = false;
   ES.lookup(
       LookupKind::Static, makeJITDylibSearchOrder(&JD),
       SymbolLookupSet({Foo, Baz}), SymbolState::Ready,
TEST_F(CoreAPIsStandardTest, RemoveSymbolsTest) {
   EXPECT_TRUE(BarMaterializerDestructed)
       << "\"Bar\"'s materializer should have been destructed";
   EXPECT_TRUE(OnCompletionRun) << "OnCompletion should have been run";
 }
 
 TEST_F(CoreAPIsStandardTest, ChainedJITDylibLookup) {
   cantFail(JD.define(absoluteSymbols({{Foo, FooSym}})));
 
-  auto &JD2 = ES.createJITDylib("JD2");
+  auto &JD2 = ES.createBareJITDylib("JD2");
 
   bool OnCompletionRun = false;
 
   auto Q = std::make_shared<AsynchronousSymbolQuery>(
       SymbolLookupSet({Foo}), SymbolState::Ready,
       [&](Expected<SymbolMap> Result) {
         cantFail(std::move(Result));
         OnCompletionRun = true;
       });
 
   cantFail(JD2.legacyLookup(Q, cantFail(JD.legacyLookup(Q, {Foo}))));
 
   EXPECT_TRUE(OnCompletionRun) << "OnCompletion was not run for empty query";
 }
 
 TEST_F(CoreAPIsStandardTest, LookupWithHiddenSymbols) {
   auto BarHiddenFlags = BarSym.getFlags() & ~JITSymbolFlags::Exported;
   auto BarHiddenSym = JITEvaluatedSymbol(BarSym.getAddress(), BarHiddenFlags);
 
   cantFail(JD.define(absoluteSymbols({{Foo, FooSym}, {Bar, BarHiddenSym}})));
 
-  auto &JD2 = ES.createJITDylib("JD2");
+  auto &JD2 = ES.createBareJITDylib("JD2");
   cantFail(JD2.define(absoluteSymbols({{Bar, QuxSym}})));
 
   /// Try a blocking lookup.
   auto Result = cantFail(ES.lookup(makeJITDylibSearchOrder({&JD, &JD2}),
                                    SymbolLookupSet({Foo, Bar})));
 
   EXPECT_EQ(Result.size(), 2U) << "Unexpected number of results";
   EXPECT_EQ(Result.count(Foo), 1U) << "Missing result for \"Foo\"";
EXPECT_EQ((*Result)[Baz].getAddress(), FooSym.getAddress())
       << "\"Baz\"'s address should match \"Foo\"'s";
 }
 
 TEST_F(CoreAPIsStandardTest, TestBasicReExports) {
   // Test that the basic use case of re-exporting a single symbol from another
   // JITDylib works.
   cantFail(JD.define(absoluteSymbols({{Foo, FooSym}})));
 
-  auto &JD2 = ES.createJITDylib("JD2");
+  auto &JD2 = ES.createBareJITDylib("JD2");
 
   cantFail(JD2.define(reexports(JD, {{Bar, {Foo, BarSym.getFlags()}}})));
 
   auto Result = cantFail(ES.lookup(makeJITDylibSearchOrder(&JD2), Bar));
   EXPECT_EQ(Result.getAddress(), FooSym.getAddress())
       << "Re-export Bar for symbol Foo should match FooSym's address";
 }
 
 TEST_F(CoreAPIsStandardTest, TestThatReExportsDontUnnecessarilyMaterialize) {
   // Test that re-exports do not materialize symbols that have not been queried
   // for.
   cantFail(JD.define(absoluteSymbols({{Foo, FooSym}})));
 
   bool BarMaterialized = false;
   auto BarMU = std::make_unique<SimpleMaterializationUnit>(
       SymbolFlagsMap({{Bar, BarSym.getFlags()}}),
       [&](MaterializationResponsibility R) {
         BarMaterialized = true;
         cantFail(R.notifyResolved({{Bar, BarSym}}));
         cantFail(R.notifyEmitted());
       });
 
   cantFail(JD.define(BarMU));
 
-  auto &JD2 = ES.createJITDylib("JD2");
+  auto &JD2 = ES.createBareJITDylib("JD2");
 
   cantFail(JD2.define(reexports(
       JD, {{Baz, {Foo, BazSym.getFlags()}}, {Qux, {Bar, QuxSym.getFlags()}}})));
 
   auto Result = cantFail(ES.lookup(makeJITDylibSearchOrder(&JD2), Baz));
   EXPECT_EQ(Result.getAddress(), FooSym.getAddress())
       << "Re-export Baz for symbol Foo should match FooSym's address";
 
   EXPECT_FALSE(BarMaterialized) << "Bar should not have been materialized";
 }
 
 TEST_F(CoreAPIsStandardTest, TestReexportsGenerator) {
   // Test that a re-exports generator can dynamically generate reexports.
 
-  auto &JD2 = ES.createJITDylib("JD2");
+  auto &JD2 = ES.createBareJITDylib("JD2");
   cantFail(JD2.define(absoluteSymbols({{Foo, FooSym}, {Bar, BarSym}})));
 
   auto Filter = [this](SymbolStringPtr Name) { return Name != Bar; };
 
   JD.addGenerator(std::make_unique<ReexportsGenerator>(
       JD2, JITDylibLookupFlags::MatchExportedSymbolsOnly, Filter));
 
   auto Flags = cantFail(JD.lookupFlags(
TEST_F(CoreAPIsStandardTest, DropMaterializerWhenEmpty) {
   JITSymbolFlags WeakExported(JITSymbolFlags::Exported);
   WeakExported |= JITSymbolFlags::Weak;
 
   auto MU = std::make_unique<SimpleMaterializationUnit>(
       SymbolFlagsMap({{Foo, WeakExported}, {Bar, WeakExported}}),
       [](MaterializationResponsibility R) {
         llvm_unreachable("Unexpected call to materialize");
       },
+      nullptr,
       [&](const JITDylib &JD, SymbolStringPtr Name) {
         EXPECT_TRUE(Name == Foo || Name == Bar)
             << "Discard of unexpected symbol?";
       },
       [&]() { DestructorRun = true; });
 
   cantFail(JD.define(MU));
 
TEST_F(CoreAPIsStandardTest, AddAndMaterializeLazySymbol) {
   auto MU = std::make_unique<SimpleMaterializationUnit>(
       SymbolFlagsMap({{Foo, JITSymbolFlags::Exported}, {Bar, WeakExported}}),
       [&](MaterializationResponsibility R) {
         assert(BarDiscarded && "Bar should have been discarded by this point");
         cantFail(R.notifyResolved(SymbolMap({{Foo, FooSym}})));
         cantFail(R.notifyEmitted());
         FooMaterialized = true;
       },
+      nullptr,
       [&](const JITDylib &JD, SymbolStringPtr Name) {
         EXPECT_EQ(Name, Bar) << "Expected Name to be Bar";
         BarDiscarded = true;
       });
 
   cantFail(JD.define(MU));
   cantFail(JD.define(absoluteSymbols({{Bar, BarSym}})));
 
TEST_F(CoreAPIsStandardTest, TestBasicWeakSymbolMaterialization) {
 
   bool DuplicateBarDiscarded = false;
   auto MU2 = std::make_unique<SimpleMaterializationUnit>(
       SymbolFlagsMap({{Bar, BarSym.getFlags()}}),
       [&](MaterializationResponsibility R) {
         ADD_FAILURE() << "Attempt to materialize Bar from the wrong unit";
         R.failMaterialization();
       },
+      nullptr,
       [&](const JITDylib &JD, SymbolStringPtr Name) {
         EXPECT_EQ(Name, Bar) << "Expected \"Bar\" to be discarded";
         DuplicateBarDiscarded = true;
       });
 
   cantFail(JD.define(MU1));
   cantFail(JD.define(MU2));
 

llvm/unittests/ExecutionEngine/Orc/OrcTestCommon.h

 // (4) FooSym, BarSym, BazSym, QuxSym -- JITEvaluatedSymbols with FooAddr,
 //     BarAddr, BazAddr, and QuxAddr respectively. All with default strong,
 //     linkage and non-hidden visibility.
 // (5) V -- A JITDylib associated with ES.
 class CoreAPIsBasedStandardTest : public testing::Test {
 protected:
   std::shared_ptr<SymbolStringPool> SSP = std::make_shared<SymbolStringPool>();
   ExecutionSession ES{SSP};
-  JITDylib &JD = ES.createJITDylib("JD");
+  JITDylib &JD = ES.createBareJITDylib("JD");
   SymbolStringPtr Foo = ES.intern("foo");
   SymbolStringPtr Bar = ES.intern("bar");
   SymbolStringPtr Baz = ES.intern("baz");
   SymbolStringPtr Qux = ES.intern("qux");
   static const JITTargetAddress FooAddr = 1U;
   static const JITTargetAddress BarAddr = 2U;
   static const JITTargetAddress BazAddr = 3U;
   static const JITTargetAddress QuxAddr = 4U;
public:
   using MaterializeFunction =
       std::function<void(orc::MaterializationResponsibility)>;
   using DiscardFunction =
       std::function<void(const orc::JITDylib &, orc::SymbolStringPtr)>;
   using DestructorFunction = std::function<void()>;
 
   SimpleMaterializationUnit(
       orc::SymbolFlagsMap SymbolFlags, MaterializeFunction Materialize,
+      orc::SymbolStringPtr InitSym = nullptr,
       DiscardFunction Discard = DiscardFunction(),
       DestructorFunction Destructor = DestructorFunction())
-      : MaterializationUnit(std::move(SymbolFlags), orc::VModuleKey()),
+      : MaterializationUnit(std::move(SymbolFlags), std::move(InitSym),
+                            orc::VModuleKey()),
         Materialize(std::move(Materialize)), Discard(std::move(Discard)),
         Destructor(std::move(Destructor)) {}
 
   ~SimpleMaterializationUnit() override {
     if (Destructor)
       Destructor();
   }
 

llvm/unittests/ExecutionEngine/Orc/RTDyldObjectLinkingLayerTest.cpp

static bool testSetProcessAllSections(std::unique_ptr<MemoryBuffer> Obj,
 
   private:
     bool &DebugSeen;
   };
 
   bool DebugSectionSeen = false;
 
   ExecutionSession ES;
-  auto &JD = ES.createJITDylib("main");
+  auto &JD = ES.createBareJITDylib("main");
   auto Foo = ES.intern("foo");
 
   RTDyldObjectLinkingLayer ObjLayer(ES, [&DebugSectionSeen]() {
     return std::make_unique<MemoryManagerWrapper>(DebugSectionSeen);
   });
 
   auto OnResolveDoNothing = [](Expected<SymbolMap> R) {
     cantFail(std::move(R));
ThreadSafeModule M;
     IRBuilder<> B2(BarEntry);
     B2.CreateRetVoid();
 
     M = ThreadSafeModule(MB.takeModule(), std::move(TSCtx));
   }
 
   // Create a simple stack and set the override flags option.
   ExecutionSession ES;
-  auto &JD = ES.createJITDylib("main");
+  auto &JD = ES.createBareJITDylib("main");
   auto Foo = ES.intern("foo");
   RTDyldObjectLinkingLayer ObjLayer(
       ES, []() { return std::make_unique<SectionMemoryManager>(); });
   IRCompileLayer CompileLayer(ES, ObjLayer,
                               std::make_unique<FunkySimpleCompiler>(*TM));
 
   ObjLayer.setOverrideObjectFlagsWithResponsibilityFlags(true);
 
ThreadSafeModule M;
     IRBuilder<> B(FooEntry);
     B.CreateRetVoid();
 
     M = ThreadSafeModule(MB.takeModule(), std::move(TSCtx));
   }
 
   // Create a simple stack and set the override flags option.
   ExecutionSession ES;
-  auto &JD = ES.createJITDylib("main");
+  auto &JD = ES.createBareJITDylib("main");
   auto Foo = ES.intern("foo");
   RTDyldObjectLinkingLayer ObjLayer(
       ES, []() { return std::make_unique<SectionMemoryManager>(); });
   IRCompileLayer CompileLayer(ES, ObjLayer,
                               std::make_unique<FunkySimpleCompiler>(*TM));
 
   ObjLayer.setAutoClaimResponsibilityForObjectSymbols(true);