commit 0410e9c75c4b25d71c9794f8cb51d60642ea8123
author David Green <david.green@arm.com> Fri Feb 19 08:35:11 2021 +0000
committer Copybara-Service <copybara-worker@google.com> Fri Feb 19 03:52:46 2021 -0800
tree cf9d5cce88ea362b49ea4266a5d5e12c8e7683fa
parent 1dd9d1565f649d9f889350ca752baf2fa6f7aecb

[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.

GitOrigin-RevId: c141c6551be64f220b71786d24e98f6de906e6de

lib/Passes/PassBuilder.cpp

diff --git a/lib/Passes/PassBuilder.cpp b/lib/Passes/PassBuilder.cpp
index 1581af9..236d54b 100644
--- a/lib/Passes/PassBuilder.cpp
+++ b/lib/Passes/PassBuilder.cpp
@@ -1764,8 +1764,10 @@
   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());