[CSPGO][CHR] Disable CHR in ThinLTOPostLink mode

[xur]

Summary

Disable CHR in ThinLTOPostLink pipeline. In the previous commit 6327d263f5e2a: [CHR] Add a threshold for the code duplication,
I disabled CHR for CSIRInstr in ThinLTOPostLink. That change creates profile mismatch issues in CSFDO profile use compilation.

Here I disable CHR for ThinLTOPostLink. We have an earlier round of CHR and I don't think we need this round CHR here.

I think the better place for CHR would be in ModuleOptimization pipeline after CSFDO because CHR is an expensive optimization. I will have a follow-up patch for that after some performance test.

[davidxl]

There is a related patch by Arthur: https://reviews.llvm.org/D143424. Can that patch solve the problem?

[xur]

Yes. D143424 is actually what I wanted to do in the following up patch. We need to do some performance test though.

[aeubanks]

is this now obsolete?

[xur]

Yes. This patch is obsolete now.

llvm/lib/Passes/PassBuilderPipelines.cpp

PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
 
   FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions()
                                   .convertSwitchRangeToICmp(true)
                                   .hoistCommonInsts(true)
                                   .sinkCommonInsts(true)));
   FPM.addPass(InstCombinePass());
   invokePeepholeEPCallbacks(FPM, Level);
 
-  // Don't add CHR pass for CSIRInstr build in PostLink as the profile
-  // is still the same as the PreLink compilation.
+  // Don't add CHR pass for ThinLTOPostLink compiliation as the
+  // profile is still the same as the PreLink compilation.
   if (EnableCHR && Level == OptimizationLevel::O3 && PGOOpt &&
       ((PGOOpt->Action == PGOOptions::IRUse &&
-        (Phase != ThinOrFullLTOPhase::ThinLTOPostLink ||
-         PGOOpt->CSAction != PGOOptions::CSIRInstr)) ||
+        Phase != ThinOrFullLTOPhase::ThinLTOPostLink) ||
        PGOOpt->Action == PGOOptions::SampleUse))
     FPM.addPass(ControlHeightReductionPass());
 
   return FPM;
 }
 
 void PassBuilder::addRequiredLTOPreLinkPasses(ModulePassManager &MPM) {
   MPM.addPass(CanonicalizeAliasesPass());