[PATCH] [CodeGen] Insert TargetLibraryInfoWrapperPass before anything else.

[• koriakin]

Summary

Currently, TargetLibraryInfoWrapperPass is inserted by PMBuilder.
However, some passes are inserted manually before the PMBuilder
ones - if any of them happens to use TargetLibraryInfoWrapperPass,
it'll get a default-constructed one, with an unknown target triple.
This happens to InstrProfiling in D21736, breaking it.

[asl]

Hrm? Why I'm set to review this?

[dnovillo]

LGTM

[mehdi_amini]

Missing test.

[mehdi_amini]

lib/CodeGen/BackendUtil.cpp

459

It is not super clean to duplicated this code.
Also the minimum is to document why it is done.

[• koriakin]

In D21737#468861, @mehdi_amini wrote:

Missing test.

This is tested by D21741 (along with D21736).

[• koriakin]

Added a comment explaining the reason.

[mehdi_amini]

lib/CodeGen/BackendUtil.cpp

422

This seems unnecessary?

[• koriakin]

lib/CodeGen/BackendUtil.cpp

422

This ensures FPM passes get the right TLI as well - since I'm removing the PMBuilder.LIbraryInfo assignment, they would otherwise get the default-constructed ones. Or should I keep the assignment instead, and only special-case MPM?

[mehdi_amini]

LGTM. Thanks!

lib/CodeGen/BackendUtil.cpp

422

Oh right, I was looking at the existing code and I missed that you were removing the LibraryInfo initialization.

lib/CodeGen/BackendUtil.cpp

 
   PassManagerBuilderWrapper PMBuilder(CodeGenOpts, LangOpts);
 
-  // Figure out TargetLibraryInfo.
+  // Figure out TargetLibraryInfo.  This needs to be added to MPM and FPM
+  // manually (and not via PMBuilder), since some passes (eg. InstrProfiling)
+  // are inserted before PMBuilder ones - they'd get the default-constructed
+  // TLI with an unknown target otherwise.
   Triple TargetTriple(TheModule->getTargetTriple());
-  PMBuilder.LibraryInfo = createTLII(TargetTriple, CodeGenOpts);
+  std::unique_ptr<TargetLibraryInfoImpl> TLII(
+      createTLII(TargetTriple, CodeGenOpts));
 
   switch (Inlining) {
   case CodeGenOptions::NoInlining:

   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
+  MPM.add(new TargetLibraryInfoWrapperPass(*TLII));
+
   // Add target-specific passes that need to run as early as possible.
   if (TM)
     PMBuilder.addExtension(

   }
 
   // Set up the per-function pass manager.
+  FPM.add(new TargetLibraryInfoWrapperPass(*TLII));
   if (CodeGenOpts.VerifyModule)
     FPM.add(createVerifierPass());