Enable InsertFreeze flag of JumpThreading when used in LTO

[aqjune]

Summary

This patch enables inserting freeze when JumpThreading converts a select to
a conditional branch when it is run in LTO.

[aqjune]

D84940 has landed; if this patch looks good, I'll merge this patch too.

[nikic]

LGTM. Hopefully this will go away soon...

llvm/lib/Passes/PassBuilder.cpp

1511

Please use the full name...

[Jim]

Hi,
This flag is enabled in LTO. I met a failure on my test program.
It shows

Unsupported instruction encountered
llvm/lib/Analysis/CFLGraph.h:260!

It looks like that CFLGraph is unable to support FreezeInst.
Could you give me some suggesion to fix it?
Thanks

[aqjune]

In D85534#2636321, @Jim wrote:

Hi,
This flag is enabled in LTO. I met a failure on my test program.
It shows

Unsupported instruction encountered
llvm/lib/Analysis/CFLGraph.h:260!

It looks like that CFLGraph is unable to support FreezeInst.
Could you give me some suggesion to fix it?
Thanks

Hi,
I'll look into this and make a patch today.

llvm/lib/Passes/PassBuilder.cpp

PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level, bool DebugLogging,
   // FIXME: Add ArgumentPromotion pass after once it's ported.
   MPM.addPass(GlobalDCEPass());
 
   FunctionPassManager FPM(DebugLogging);
   // The IPO Passes may leave cruft around. Clean up after them.
   FPM.addPass(InstCombinePass());
   invokePeepholeEPCallbacks(FPM, Level);
 
-  FPM.addPass(JumpThreadingPass());
+  FPM.addPass(JumpThreadingPass(/*InsertFreezeWhenUnfoldingSelect*/ true));
 
   // Do a post inline PGO instrumentation and use pass. This is a context
   // sensitive PGO pass.
   if (PGOOpt) {
     if (PGOOpt->CSAction == PGOOptions::CSIRInstr)
       addPGOInstrPasses(MPM, DebugLogging, Level, /* RunProfileGen */ true,
                         /* IsCS */ true, PGOOpt->CSProfileGenFile,
                         PGOOpt->ProfileRemappingFile);
#if 0
   MainFPM.add(AlignmentFromAssumptionsPass());
 #endif
 
   // FIXME: Conditionally run LoadCombine here, after it's ported
   // (in case we still have this pass, given its questionable usefulness).
 
   MainFPM.addPass(InstCombinePass());
   invokePeepholeEPCallbacks(MainFPM, Level);
-  MainFPM.addPass(JumpThreadingPass());
+  MainFPM.addPass(JumpThreadingPass(/*InsertFreezeWhenUnfoldingSelect*/ true));
   MPM.addPass(createModuleToFunctionPassAdaptor(std::move(MainFPM)));
 
   // Create a function that performs CFI checks for cross-DSO calls with
   // targets in the current module.
   MPM.addPass(CrossDSOCFIPass());
 
   // Lower type metadata and the type.test intrinsic. This pass supports
   // clang's control flow integrity mechanisms (-fsanitize=cfi*) and needs

llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
 
   // If we didn't decide to inline a function, check to see if we can
   // transform it to pass arguments by value instead of by reference.
   PM.add(createArgumentPromotionPass());
 
   // The IPO passes may leave cruft around.  Clean up after them.
   PM.add(createInstructionCombiningPass());
   addExtensionsToPM(EP_Peephole, PM);
-  PM.add(createJumpThreadingPass());
+  PM.add(createJumpThreadingPass(/*FreezeSelectCond*/ true));
 
   // Break up allocas
   PM.add(createSROAPass());
 
   // LTO provides additional opportunities for tailcall elimination due to
   // link-time inlining, and visibility of nocapture attribute.
   if (OptLevel > 1)
     PM.add(createTailCallEliminationPass());
void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
   // After vectorization, assume intrinsics may tell us more about pointer
   // alignments.
   PM.add(createAlignmentFromAssumptionsPass());
 
   // Cleanup and simplify the code after the scalar optimizations.
   PM.add(createInstructionCombiningPass());
   addExtensionsToPM(EP_Peephole, PM);
 
-  PM.add(createJumpThreadingPass());
+  PM.add(createJumpThreadingPass(/*FreezeSelectCond*/ true));
 }
 
 void PassManagerBuilder::addLateLTOOptimizationPasses(
     legacy::PassManagerBase &PM) {
   // See comment in the new PM for justification of scheduling splitting at
   // this stage (\ref buildLTODefaultPipeline).
   if (EnableHotColdSplit)
     PM.add(createHotColdSplittingPass());