[NewPM] Add support for new-PM plugins to clang

[melver]

Summary

This adds support for new-PM plugin loading to clang. The option
-fpass-plugin= may be used to specify a dynamic shared object file
that adheres to the PassPlugin API.

Tested: created simple plugin that registers an EP callback; with optimization level > 0, the pass is run as expected.

[philip.pfaffe]

This generally looks sane. What will happen on windows though? Will it silently fail?

clang/include/clang/Basic/CodeGenOptions.h

292 ↗

(On Diff #182603)

This should be SmallVector.

[melver]

• Use SmallVector in CodeGenOptions.h

[melver]

Thanks!

In D56935#1366756, @philip.pfaffe wrote:

This generally looks sane. What will happen on windows though? Will it silently fail?

AFAIK PassPlugin::Load uses sys::DynamicLibrary::getPermanentLibrary, which uses DynamicLibrary::HandleSet::AddLibrary which works for Windows as well. (The story is similar to legacy -fplugin=).

clang/include/clang/Basic/CodeGenOptions.h

292 ↗

(On Diff #182603)

Not sure if this is better. getAllArgValues returns a vector<string>, which is why I think the above members are also vector<string>. And std::vector cannot be assigned to SmallVector, which required an extra line in CompilerInvocation.cpp.

Let me know what you think.

[melver]

This generally looks sane. What will happen on windows though? Will it silently fa

AFAIK PassPlugin::Load uses sys::DynamicLibrary::getPermanentLibrary, which uses DynamicLibrary::HandleSet::AddLibrary which works for Windows as well. (The story is similar to legacy -fplugin=).

s/AddLibrary/DLOpen/ -- DLOpen and others in DynamicLibrary:: are wrappers around platform-specific code. On Windows the implementation is in: llvm/lib/Support/Windows/DynamicLibrary.inc

[philip.pfaffe]

I'm not sure what the current state of plugins on windows is. They were broken and disabled last time I worked on this, but that might've changed in the meantime! Worth checking.

clang/include/clang/Basic/CodeGenOptions.h

292 ↗

(On Diff #182603)

You're right, SmallVector doesn't actually help here. Sorry!

[melver]

• Revert use of SmallVector

[melver]

Thanks!

In D56935#1367545, @philip.pfaffe wrote:

I'm not sure what the current state of plugins on windows is. They were broken and disabled last time I worked on this, but that might've changed in the meantime! Worth checking.

Right, though I feel this is related to DynamicLibrary, and orthogonal to this patch. I don't have access to a Windows machine right now, but I can try to check if you feel it's urgent to land this. What do you think?

[philip.pfaffe]

It would be good to check, since the bots won't! Otherwise this looks good.

[melver]

• Improve error reporting. While testing on Windows, noticed that Clang wants the error to be checked otherwise crashed quite verbosely.

[melver]

In D56935#1370861, @philip.pfaffe wrote:

It would be good to check, since the bots won't! Otherwise this looks good.

Thanks!

I attempted to test on Windows, but noticed that for a shared library CMake already reports "Loadable modules not supported on this platform", and couldn't create a real plugin. In any case, I attempted to load an arbitrary DLL to see if errors are reported correctly and subsequently improved that. If a library can't be loaded, it will not fail silently now.

If you're happy with this version, I would need you to land this for me (I do not have commit access). Many thanks!

[melver]

Gentle ping. Need someone to land this on my behalf, as I do not have commit access. Many thanks!

[philip.pfaffe]

Landed it for you in r352972. Thanks!

[melver]

In D56935#1382156, @philip.pfaffe wrote:

Landed it for you in r352972. Thanks!

Great, thanks!

include/clang/Basic/CodeGenOptions.h

public:
   /// registers.
   std::string PreferVectorWidth;
 
   /// Set of XRay instrumentation kinds to emit.
   XRayInstrSet XRayInstrumentationBundle;
 
   std::vector<std::string> DefaultFunctionAttrs;
 
+  /// List of dynamic shared object files to be loaded as pass plugins.
+  std::vector<std::string> PassPlugins;
+
 public:
   // Define accessors/mutators for code generation options of enumeration type.
 #define CODEGENOPT(Name, Bits, Default)
 #define ENUM_CODEGENOPT(Name, Type, Bits, Default) \
   Type get##Name() const { return static_cast<Type>(Name); } \
   void set##Name(Type Value) { Name = static_cast<unsigned>(Value); }
 #include "clang/Basic/CodeGenOptions.def"
 

include/clang/Driver/Options.td

 def fno_plt : Flag<["-"], "fno-plt">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Do not use the PLT to make function calls">;
 def fropi : Flag<["-"], "fropi">, Group<f_Group>;
 def fno_ropi : Flag<["-"], "fno-ropi">, Group<f_Group>;
 def frwpi : Flag<["-"], "frwpi">, Group<f_Group>;
 def fno_rwpi : Flag<["-"], "fno-rwpi">, Group<f_Group>;
 def fplugin_EQ : Joined<["-"], "fplugin=">, Group<f_Group>, Flags<[DriverOption]>, MetaVarName<"<dsopath>">,
   HelpText<"Load the named plugin (dynamic shared object)">;
+def fpass_plugin_EQ : Joined<["-"], "fpass-plugin=">,
+  Group<f_Group>, Flags<[CC1Option]>, MetaVarName<"<dsopath>">,
+  HelpText<"Load pass plugin from a dynamic shared object file (only with new pass manager).">;
 def fpreserve_as_comments : Flag<["-"], "fpreserve-as-comments">, Group<f_Group>;
 def fno_preserve_as_comments : Flag<["-"], "fno-preserve-as-comments">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Do not preserve comments in inline assembly">;
 def fprofile_arcs : Flag<["-"], "fprofile-arcs">, Group<f_Group>;
 def fno_profile_arcs : Flag<["-"], "fno-profile-arcs">, Group<f_Group>;
 def framework : Separate<["-"], "framework">, Flags<[LinkerInput]>;
 def frandom_seed_EQ : Joined<["-"], "frandom-seed=">, Group<clang_ignored_f_Group>;
 def freg_struct_return : Flag<["-"], "freg-struct-return">, Group<f_Group>, Flags<[CC1Option]>,

lib/CodeGen/BackendUtil.cpp

 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/ModuleSummaryIndex.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/LTO/LTOBackend.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Passes/PassBuilder.h"
+#include "llvm/Passes/PassPlugin.h"
 #include "llvm/Support/BuryPointer.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
PGOOpt = PGOOptions("", "", CodeGenOpts.SampleProfileFile,
                         CodeGenOpts.ProfileRemappingFile, false,
                         CodeGenOpts.DebugInfoForProfiling);
   else if (CodeGenOpts.DebugInfoForProfiling)
     // -fdebug-info-for-profiling
     PGOOpt = PGOOptions("", "", "", "", false, true);
 
   PassBuilder PB(TM.get(), PGOOpt);
 
+  // Attempt to load pass plugins and register their callbacks with PB.
+  for (auto &PluginFN : CodeGenOpts.PassPlugins) {
+    auto PassPlugin = PassPlugin::Load(PluginFN);
+    if (PassPlugin) {
+      PassPlugin->registerPassBuilderCallbacks(PB);
+    } else {
+      Diags.Report(diag::err_fe_unable_to_load_plugin)
+          << PluginFN << toString(PassPlugin.takeError());
+    }
+  }
+
   LoopAnalysisManager LAM(CodeGenOpts.DebugPassManager);
   FunctionAnalysisManager FAM(CodeGenOpts.DebugPassManager);
   CGSCCAnalysisManager CGAM(CodeGenOpts.DebugPassManager);
   ModuleAnalysisManager MAM(CodeGenOpts.DebugPassManager);
 
   // Register the AA manager first so that our version is the one used.
   FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });
 

lib/Driver/ToolChains/Clang.cpp

 
   // Turn -fplugin=name.so into -load name.so
   for (const Arg *A : Args.filtered(options::OPT_fplugin_EQ)) {
     CmdArgs.push_back("-load");
     CmdArgs.push_back(A->getValue());
     A->claim();
   }
 
+  // Forward -fpass-plugin=name.so to -cc1.
+  for (const Arg *A : Args.filtered(options::OPT_fpass_plugin_EQ)) {
+    CmdArgs.push_back(
+        Args.MakeArgString(Twine("-fpass-plugin=") + A->getValue()));
+    A->claim();
+  }
+
   // Setup statistics file output.
   SmallString<128> StatsFile = getStatsFileName(Args, Output, Input, D);
   if (!StatsFile.empty())
     CmdArgs.push_back(Args.MakeArgString(Twine("-stats-file=") + StatsFile));
 
   // Forward -Xclang arguments to -cc1, and -mllvm arguments to the LLVM option
   // parser.
   // -finclude-default-header flag is for preprocessor,

lib/Frontend/CompilerInvocation.cpp

static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.BranchTargetEnforcement = Args.hasArg(OPT_mbranch_target_enforce);
 
   Opts.KeepStaticConsts = Args.hasArg(OPT_fkeep_static_consts);
 
   Opts.SpeculativeLoadHardening = Args.hasArg(OPT_mspeculative_load_hardening);
 
   Opts.DefaultFunctionAttrs = Args.getAllArgValues(OPT_default_function_attr);
 
+  Opts.PassPlugins = Args.getAllArgValues(OPT_fpass_plugin_EQ);
+
   return Success;
 }
 
 static void ParseDependencyOutputArgs(DependencyOutputOptions &Opts,
                                       ArgList &Args) {
   Opts.OutputFile = Args.getLastArgValue(OPT_dependency_file);
   Opts.Targets = Args.getAllArgValues(OPT_MT);
   Opts.IncludeSystemHeaders = Args.hasArg(OPT_sys_header_deps);