[llvm] c141c65 - [NPM][LTO] Do not enable MemorySSA with LoopFullUnrollPass

[David Green via llvm-commits]

Author: David Green
Date: 2021-02-19T08:35:11Z
New Revision: c141c6551be64f220b71786d24e98f6de906e6de

URL: https://github.com/llvm/llvm-project/commit/c141c6551be64f220b71786d24e98f6de906e6de
DIFF: https://github.com/llvm/llvm-project/commit/c141c6551be64f220b71786d24e98f6de906e6de.diff

LOG: [NPM][LTO] Do not enable MemorySSA with LoopFullUnrollPass

As with the standard opt pipeline, we disable the MemorySSA dependency
in the LTO LPM pipeline as not all passes preserve MemorySSA.

Added: 
    

Modified: 
    llvm/lib/Passes/PassBuilder.cpp

Removed: 
    


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diff  --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 1581af9d6aa9..236d54b97bba 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -1764,8 +1764,10 @@ PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
   LPM.addPass(LoopFullUnrollPass(Level.getSpeedupLevel(),
                                  /* OnlyWhenForced= */ !PTO.LoopUnrolling,
                                  PTO.ForgetAllSCEVInLoopUnroll));
+  // The loop passes in LPM (LoopFullUnrollPass) do not preserve MemorySSA.
+  // *All* loop passes must preserve it, in order to be able to use it.
   MainFPM.addPass(createFunctionToLoopPassAdaptor(
-      std::move(LPM), EnableMSSALoopDependency, /*UseBlockFrequencyInfo=*/true,
+      std::move(LPM), /*UseMemorySSA=*/false, /*UseBlockFrequencyInfo=*/true,
       DebugLogging));
 
   MainFPM.addPass(LoopDistributePass());