[PATCH] D108073: [PassBuilder] Don't use MemorySSA for standalone LoopRotate passes

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added a reviewer: asbirlea.
Herald added subscribers: george.burgess.iv, hiraditya.
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Two standalone LoopRotate passes scheduled using createFunctionToLoopPassAdaptor() currently enable MemorySSA. However, while LoopRotate can preserve MemorySSA, it does not use it, so requiring MemorySSA is unnecessary.

Weirdly, I'm not seeing any significant compile-time change from this patch, so I'm wondering if I'm misunderstanding something here...


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D108073

Files:
  llvm/lib/Passes/PassBuilder.cpp


Index: llvm/lib/Passes/PassBuilder.cpp
===================================================================
--- llvm/lib/Passes/PassBuilder.cpp
+++ llvm/lib/Passes/PassBuilder.cpp
@@ -923,7 +923,7 @@
   FunctionPassManager FPM;
   // Disable header duplication in loop rotation at -Oz.
   FPM.addPass(createFunctionToLoopPassAdaptor(
-      LoopRotatePass(Level != OptimizationLevel::Oz), EnableMSSALoopDependency,
+      LoopRotatePass(Level != OptimizationLevel::Oz), /*UseMemorySSA=*/false,
       /*UseBlockFrequencyInfo=*/false));
   MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
 
@@ -1399,8 +1399,7 @@
   // Disable header duplication at -Oz.
   OptimizePM.addPass(createFunctionToLoopPassAdaptor(
       LoopRotatePass(Level != OptimizationLevel::Oz, LTOPreLink),
-      EnableMSSALoopDependency,
-      /*UseBlockFrequencyInfo=*/false));
+      /*UseMemorySSA=*/false, /*UseBlockFrequencyInfo=*/false));
 
   // Distribute loops to allow partial vectorization.  I.e. isolate dependences
   // into separate loop that would otherwise inhibit vectorization.  This is


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