[llvm] e92d63b - Revert "[LoopFlatten] Move it to a LoopPassManager"

[David Green via llvm-commits]

Author: David Green
Date: 2022-01-10T11:03:49Z
New Revision: e92d63b467e13227408f9726fbd66d07cc58811c

URL: https://github.com/llvm/llvm-project/commit/e92d63b467e13227408f9726fbd66d07cc58811c
DIFF: https://github.com/llvm/llvm-project/commit/e92d63b467e13227408f9726fbd66d07cc58811c.diff

LOG: Revert "[LoopFlatten] Move it to a LoopPassManager"

This commit caused performance regressions due to differences in the
expected code during loop flattening. Reverting it until the fix is
ready, which hopefully wont take too long.

This reverts commit 86825fc2fb363b807569327880c05e4b0b5393ec.

Added: 
    

Modified: 
    llvm/lib/Passes/PassBuilderPipelines.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 79c42b886fbbe..a6a36ff254029 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -311,8 +311,6 @@ PassBuilder::buildO1FunctionSimplificationPipeline(OptimizationLevel Level,
 
   if (EnableLoopInterchange)
     LPM2.addPass(LoopInterchangePass());
-  if (EnableLoopFlatten)
-    LPM2.addPass(LoopFlattenPass());
 
   // Do not enable unrolling in PreLinkThinLTO phase during sample PGO
   // because it changes IR to makes profile annotation in back compile
@@ -337,6 +335,8 @@ PassBuilder::buildO1FunctionSimplificationPipeline(OptimizationLevel Level,
                                               /*UseBlockFrequencyInfo=*/true));
   FPM.addPass(SimplifyCFGPass());
   FPM.addPass(InstCombinePass());
+  if (EnableLoopFlatten)
+    FPM.addPass(createFunctionToLoopPassAdaptor(LoopFlattenPass()));
   // The loop passes in LPM2 (LoopFullUnrollPass) do not preserve MemorySSA.
   // *All* loop passes must preserve it, in order to be able to use it.
   FPM.addPass(createFunctionToLoopPassAdaptor(std::move(LPM2),
@@ -485,8 +485,6 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
 
   if (EnableLoopInterchange)
     LPM2.addPass(LoopInterchangePass());
-  if (EnableLoopFlatten)
-    LPM2.addPass(LoopFlattenPass());
 
   // Do not enable unrolling in PreLinkThinLTO phase during sample PGO
   // because it changes IR to makes profile annotation in back compile
@@ -511,6 +509,8 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
                                               /*UseBlockFrequencyInfo=*/true));
   FPM.addPass(SimplifyCFGPass());
   FPM.addPass(InstCombinePass());
+  if (EnableLoopFlatten)
+    FPM.addPass(createFunctionToLoopPassAdaptor(LoopFlattenPass()));
   // The loop passes in LPM2 (LoopIdiomRecognizePass, IndVarSimplifyPass,
   // LoopDeletionPass and LoopFullUnrollPass) do not preserve MemorySSA.
   // *All* loop passes must preserve it, in order to be able to use it.
@@ -1623,6 +1623,9 @@ PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
   MainFPM.addPass(DSEPass());
   MainFPM.addPass(MergedLoadStoreMotionPass());
 
+  // More loops are countable; try to optimize them.
+  if (EnableLoopFlatten && Level.getSpeedupLevel() > 1)
+    MainFPM.addPass(createFunctionToLoopPassAdaptor(LoopFlattenPass()));
 
   if (EnableConstraintElimination)
     MainFPM.addPass(ConstraintEliminationPass());
@@ -1630,8 +1633,6 @@ PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
   LoopPassManager LPM;
   LPM.addPass(IndVarSimplifyPass());
   LPM.addPass(LoopDeletionPass());
-  if (EnableLoopFlatten && Level.getSpeedupLevel() > 1)
-    LPM.addPass(LoopFlattenPass());
   // FIXME: Add loop interchange.
 
   // Unroll small loops and perform peeling.