[llvm] [VPlan] Use BlockFrequencyInfo in getPredBlockCostDivisor (PR #158690)

[Luke Lau via llvm-commits]

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@@ -10265,9 +10272,7 @@ PreservedAnalyses LoopVectorizePass::run(Function &F,
 
   auto &MAMProxy = AM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
   PSI = MAMProxy.getCachedResult<ProfileSummaryAnalysis>(*F.getParent());
-  BFI = nullptr;
-  if (PSI && PSI->hasProfileSummary())
-    BFI = &AM.getResult<BlockFrequencyAnalysis>(F);
+  BFI = &AM.getResult<BlockFrequencyAnalysis>(F);
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lukel97 wrote:

Looks there's like's a significant compile time increase on -O2 & -O3: https://llvm-compile-time-tracker.com/compare.php?from=f15b756b56d0653181f062901916806bc5eba280&to=fb50e0f89db09b13cb9c4ac2c69dda8c92169eee&stat=instructions%3Au

I'm pretty sure this is from LoopVectorizer now requesting BranchProbabilityInfo and BlockFrequencyInfo, not because we're invalidating it since we already previously invalidated all CFG analyses.

I'm going to see if we can only request BranchProbabilityInfo on demand, e.g. when we know vectorization is legal.

https://github.com/llvm/llvm-project/pull/158690