[lld][thinlto] Include -mllvm options in the thinlto cache key

[mtrofin]

Summary

They may modify thinlto optimization.

This patch only extends support for -mllvm. There is another way to pass llvm flags, -plugin-opt, but its processing is different and will be provided in a subsequent patch.

[MaskRay]

lld/ELF/Driver.cpp

1352

emplace_back or push_back

lld/test/ELF/lto/cache.ll

53

Use ;; for non-RUN-non-CHECK comments.

54

In the top of the file and other places in test/ELF, we prefer rm -rf %t.cache && mkdir %t.cache in one line

llvm/include/llvm/LTO/Config.h

52

Move before PassPlugins for an alphabetical order among vector<string> variables.

[aeubanks]

are you planning on doing this for all the lld backends?

[mtrofin]

feedback

lld/test/ELF/lto/cache.ll

54

ack - let me fix the other occurrence here then, too.

[mtrofin]

In D134013#3795876, @aeubanks wrote:

are you planning on doing this for all the lld backends?

Not sure - I'm looking for guidance as to how to approach that.

[MaskRay]

LGTM. I think fixing just ELF is fine, but will be great if you fix COFF/MachO/WebAssembly as well as follow-up patches.
I'd recommend some options more general and more common than -mllvm -enable-ml-inliner=default -mllvm -max-devirt-iterations=1, but using them is fine, too.

lld/ELF/LTO.cpp

82

const auto => StringRef

[MaskRay]

lld/test/ELF/lto/cache.ll

65

Perhaps change on test to use -plugin-opt=-max-... for some variance.

[mtrofin]

also using -plugin-opt

[mtrofin]

In D134013#3796393, @MaskRay wrote:

LGTM. I think fixing just ELF is fine, but will be great if you fix COFF/MachO/WebAssembly as well as follow-up patches.

ack

I'd recommend some options more general and more common than -mllvm -enable-ml-inliner=default -mllvm -max-devirt-iterations=1, but using them is fine, too.

[mtrofin]

lld/test/ELF/lto/cache.ll

65

huh, so it turns out -plugin-opt= is handled in a different way. Do we want to make the feature "force" --plugin-opt equivalence to -mllvm, or we're happy to treat them differently, and just validate that "it also works with --plugin-opt"?

[mtrofin]

-plugin-opt isn't actually supported, needs explicit support

lld/ELF/Config.h

struct Configuration {
   llvm::SmallVector<llvm::StringRef, 0> filterList;
   llvm::SmallVector<llvm::StringRef, 0> passPlugins;
   llvm::SmallVector<llvm::StringRef, 0> searchPaths;
   llvm::SmallVector<llvm::StringRef, 0> symbolOrderingFile;
   llvm::SmallVector<llvm::StringRef, 0> thinLTOModulesToCompile;
   llvm::SmallVector<llvm::StringRef, 0> undefined;
   llvm::SmallVector<SymbolVersion, 0> dynamicList;
   llvm::SmallVector<uint8_t, 0> buildIdVector;
+  llvm::SmallVector<llvm::StringRef, 0> mllvmOpts;
   llvm::MapVector<std::pair<const InputSectionBase *, const InputSectionBase *>,
                   uint64_t>
       callGraphProfile;
   bool allowMultipleDefinition;
   bool androidPackDynRelocs = false;
   bool armHasBlx = false;
   bool armHasMovtMovw = false;
   bool armJ1J2BranchEncoding = false;

lld/ELF/Driver.cpp

static void readConfigs(opt::InputArgList &args) {
   for (opt::Arg *arg : args.filtered(OPT_plugin_opt_eq))
     if (!StringRef(arg->getValue()).endswith("lto-wrapper"))
       error(arg->getSpelling() + ": unknown plugin option '" + arg->getValue() +
             "'");
 
   config->passPlugins = args::getStrings(args, OPT_load_pass_plugins);
 
   // Parse -mllvm options.
-  for (auto *arg : args.filtered(OPT_mllvm))
+  for (auto *arg : args.filtered(OPT_mllvm)) {
     parseClangOption(arg->getValue(), arg->getSpelling());
+    config->mllvmOpts.emplace_back(arg->getValue());
+  }
 
   // --threads= takes a positive integer and provides the default value for
   // --thinlto-jobs=.
   if (auto *arg = args.getLastArg(OPT_threads)) {
     StringRef v(arg->getValue());
     unsigned threads = 0;
     if (!llvm::to_integer(v, threads, 0) || threads == 0)
       error(arg->getSpelling() + ": expected a positive integer, but got '" +

lld/ELF/LTO.cpp

 
 static lto::Config createConfig() {
   lto::Config c;
 
   // LLD supports the new relocations and address-significance tables.
   c.Options = initTargetOptionsFromCodeGenFlags();
   c.Options.RelaxELFRelocations = true;
   c.Options.EmitAddrsig = true;
+  for (StringRef C : config->mllvmOpts)
+    c.MllvmArgs.emplace_back(C.str());
 
   // Always emit a section per function/datum with LTO.
   c.Options.FunctionSections = true;
   c.Options.DataSections = true;
 
   // Check if basic block sections must be used.
   // Allowed values for --lto-basic-block-sections are "all", "labels",
   // "<file name specifying basic block ids>", or none.  This is the equivalent

lld/test/ELF/lto/cache.ll

 ; RUN: ld.lld --thinlto-cache-dir=%t.cache --thinlto-cache-policy prune_after=0s:cache_size=0%:cache_size_files=0:prune_interval=0s -o %t3 %t2.o %t.o
 ; RUN: ls %t.cache | count 4
 
 ; Delete everything except for the timestamp, "foo" and one cache file.
 ; RUN: ld.lld --thinlto-cache-dir=%t.cache --thinlto-cache-policy prune_after=0s:cache_size=0%:cache_size_files=1:prune_interval=0s -o %t3 %t2.o %t.o
 ; RUN: ls %t.cache | count 3
 
 ; Check that we remove the least recently used file first.
-; RUN: rm -fr %t.cache
-; RUN: mkdir %t.cache
+; RUN: rm -fr %t.cache && mkdir %t.cache
 ; RUN: echo xyz > %t.cache/llvmcache-old
 ; RUN: touch -t 198002011200 %t.cache/llvmcache-old
 ; RUN: echo xyz > %t.cache/llvmcache-newer
 ; RUN: touch -t 198002021200 %t.cache/llvmcache-newer
 ; RUN: ld.lld --thinlto-cache-dir=%t.cache --thinlto-cache-policy prune_after=0s:cache_size=0%:cache_size_files=3:prune_interval=0s -o %t3 %t2.o %t.o
 ; RUN: ls %t.cache | FileCheck %s
 
 ; CHECK-NOT: llvmcache-old
 ; CHECK: llvmcache-newer
 ; CHECK-NOT: llvmcache-old
 
+;; Check that mllvm options participate in the cache key
+; RUN: rm -rf %t.cache && mkdir %t.cache
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o
+; RUN: ls %t.cache | count 3
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default
+; RUN: ls %t.cache | count 5
+
+;; Adding another option resuls in 2 more cache entries
+; RUN: rm -rf %t.cache && mkdir %t.cache
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o
+; RUN: ls %t.cache | count 3
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default
+; RUN: ls %t.cache | count 5
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default -mllvm -max-devirt-iterations=1
+; RUN: ls %t.cache | count 7
+
+;; Changing order may matter - e.g. if overriding -mllvm options - so we get 2 more entries
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -max-devirt-iterations=1 -mllvm -enable-ml-inliner=default
+; RUN: ls %t.cache | count 9
+
+;; Going back to a pre-cached order doesn't create more entries.
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default -mllvm -max-devirt-iterations=1
+; RUN: ls %t.cache | count 9
+
+;; Different flag values matter
+; RUN: rm -rf %t.cache && mkdir %t.cache
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default -mllvm -max-devirt-iterations=2
+; RUN: ls %t.cache | count 3
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default -mllvm -max-devirt-iterations=1
+; RUN: ls %t.cache | count 5
+
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 define void @globalfunc() #0 {
 entry:
   ret void
 }

llvm/include/llvm/LTO/Config.h

enum VisScheme {
     FromPrevailing,
     ELF,
   };
   // Note: when adding fields here, consider whether they need to be added to
   // computeCacheKey in LTO.cpp.
   std::string CPU;
   TargetOptions Options;
   std::vector<std::string> MAttrs;
+  std::vector<std::string> MllvmArgs;
   std::vector<std::string> PassPlugins;
   /// For adding passes that run right before codegen.
   std::function<void(legacy::PassManager &)> PreCodeGenPassesHook;
   Optional<Reloc::Model> RelocModel = Reloc::PIC_;
   Optional<CodeModel::Model> CodeModel = None;
   CodeGenOpt::Level CGOptLevel = CodeGenOpt::Default;
   CodeGenFileType CGFileType = CGFT_ObjectFile;
   unsigned OptLevel = 2;
   bool DisableVerify = false;
 

llvm/lib/LTO/LTO.cpp

#endif
   if (Conf.RelocModel)
     AddUnsigned(*Conf.RelocModel);
   else
     AddUnsigned(-1);
   if (Conf.CodeModel)
     AddUnsigned(*Conf.CodeModel);
   else
     AddUnsigned(-1);
+  for (const auto &S : Conf.MllvmArgs)
+    AddString(S);
   AddUnsigned(Conf.CGOptLevel);
   AddUnsigned(Conf.CGFileType);
   AddUnsigned(Conf.OptLevel);
   AddUnsigned(Conf.Freestanding);
   AddString(Conf.OptPipeline);
   AddString(Conf.AAPipeline);
   AddString(Conf.OverrideTriple);
   AddString(Conf.DefaultTriple);