[PATCH] D96694: Use LoopRotate PrepareForLTO stage in NPM

[Sanne Wouda via Phabricator via llvm-commits]

sanwou01 created this revision.
Herald added subscribers: hiraditya, inglorion.
sanwou01 requested review of this revision.
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The PrepareForLTO stage of LoopRotate tries to avoid unrolling loops
with calls that might be inlined later.  See D94232 <https://reviews.llvm.org/D94232> where this was
introduced.

We didn't catch all occurances of the LoopRotatePass in the New Pass
Manager, so the original regression in astar returned with the pass
manager switch.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D96694

Files:
  llvm/lib/Passes/PassBuilder.cpp


Index: llvm/lib/Passes/PassBuilder.cpp
===================================================================
--- llvm/lib/Passes/PassBuilder.cpp
+++ llvm/lib/Passes/PassBuilder.cpp
@@ -516,6 +516,17 @@
   MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
 }
 
+// Helper to check the current compilation phase
+static bool isLTOPreLink(ThinOrFullLTOPhase Phase) {
+  switch (Phase) {
+  case ThinOrFullLTOPhase::ThinLTOPreLink:
+  case ThinOrFullLTOPhase::FullLTOPreLink:
+    return true;
+  default:
+    return false;
+  }
+}
+
 // TODO: Investigate the cost/benefit of tail call elimination on debugging.
 FunctionPassManager
 PassBuilder::buildO1FunctionSimplificationPipeline(OptimizationLevel Level,
@@ -562,7 +573,8 @@
   LPM1.addPass(LoopInstSimplifyPass());
   LPM1.addPass(LoopSimplifyCFGPass());
 
-  LPM1.addPass(LoopRotatePass(/* Disable header duplication */ true));
+  LPM1.addPass(LoopRotatePass(/* Disable header duplication */ true,
+                              isLTOPreLink(Phase)));
   // TODO: Investigate promotion cap for O1.
   LPM1.addPass(LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap));
   LPM1.addPass(SimpleLoopUnswitchPass());
@@ -726,7 +738,8 @@
   LPM1.addPass(LoopSimplifyCFGPass());
 
   // Disable header duplication in loop rotation at -Oz.
-  LPM1.addPass(LoopRotatePass(Level != OptimizationLevel::Oz));
+  LPM1.addPass(
+      LoopRotatePass(Level != OptimizationLevel::Oz, isLTOPreLink(Phase)));
   // TODO: Investigate promotion cap for O1.
   LPM1.addPass(LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap));
   LPM1.addPass(


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