[PATCH] D146191: [MachineOutliner][MCP][RISCV] Don't run MCP on outlined functions

[Wang Pengcheng via Phabricator via llvm-commits]

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We add a field `IsOutlined` to indicate whether a MachineFunction
is outlined and set it true for outlined functions in MachineOutliner.

For outlined functions, its live-outs are not complete so we don't
run MCP on them.

This is a fix for D146037 <https://reviews.llvm.org/D146037>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D146191

Files:
  llvm/include/llvm/CodeGen/MachineFunction.h
  llvm/lib/CodeGen/MachineCopyPropagation.cpp
  llvm/lib/CodeGen/MachineOutliner.cpp
  llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
  llvm/test/CodeGen/RISCV/O3-pipeline.ll


Index: llvm/test/CodeGen/RISCV/O3-pipeline.ll
===================================================================
--- llvm/test/CodeGen/RISCV/O3-pipeline.ll
+++ llvm/test/CodeGen/RISCV/O3-pipeline.ll
@@ -166,7 +166,6 @@
 ; CHECK-NEXT:       Implement the 'patchable-function' attribute
 ; CHECK-NEXT:       Branch relaxation pass
 ; CHECK-NEXT:       RISCV Make Compressible
-; CHECK-NEXT:       Machine Copy Propagation Pass
 ; CHECK-NEXT:       Contiguously Lay Out Funclets
 ; CHECK-NEXT:       StackMap Liveness Analysis
 ; CHECK-NEXT:       Live DEBUG_VALUE analysis
@@ -177,6 +176,7 @@
 ; CHECK-NEXT:       Machine Optimization Remark Emitter
 ; CHECK-NEXT:       Stack Frame Layout Analysis
 ; CHECK-NEXT:       RISCV pseudo instruction expansion pass
+; CHECK-NEXT:       Machine Copy Propagation Pass
 ; CHECK-NEXT:       RISCV atomic pseudo instruction expansion pass
 ; CHECK-NEXT:       Lazy Machine Block Frequency Analysis
 ; CHECK-NEXT:       Machine Optimization Remark Emitter
Index: llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -337,19 +337,16 @@
 void RISCVPassConfig::addPreEmitPass() {
   addPass(&BranchRelaxationPassID);
   addPass(createRISCVMakeCompressibleOptPass());
-
-  // TODO: It would potentially be better to schedule copy propagation after
-  // expanding pseudos (in addPreEmitPass2). However, performing copy
-  // propagation after the machine outliner (which runs after addPreEmitPass)
-  // currently leads to incorrect code-gen, where copies to registers within
-  // outlined functions are removed erroneously.
-  if (TM->getOptLevel() >= CodeGenOpt::Default && EnableRISCVCopyPropagation)
-    addPass(createMachineCopyPropagationPass(true));
 }
 
 void RISCVPassConfig::addPreEmitPass2() {
   addPass(createRISCVExpandPseudoPass());
 
+  // Do the copy propagation after expanding pseudos because we may produce some
+  // MVs when expanding.
+  if (TM->getOptLevel() >= CodeGenOpt::Default && EnableRISCVCopyPropagation)
+    addPass(createMachineCopyPropagationPass(true));
+
   // Schedule the expansion of AMOs at the last possible moment, avoiding the
   // possibility for other passes to break the requirements for forward
   // progress in the LR/SC block.
Index: llvm/lib/CodeGen/MachineOutliner.cpp
===================================================================
--- llvm/lib/CodeGen/MachineOutliner.cpp
+++ llvm/lib/CodeGen/MachineOutliner.cpp
@@ -720,6 +720,7 @@
 
   MachineModuleInfo &MMI = getAnalysis<MachineModuleInfoWrapperPass>().getMMI();
   MachineFunction &MF = MMI.getOrCreateMachineFunction(*F);
+  MF.setIsOutlined(true);
   MachineBasicBlock &MBB = *MF.CreateMachineBasicBlock();
 
   // Insert the new function into the module.
Index: llvm/lib/CodeGen/MachineCopyPropagation.cpp
===================================================================
--- llvm/lib/CodeGen/MachineCopyPropagation.cpp
+++ llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -1388,6 +1388,9 @@
   if (skipFunction(MF.getFunction()))
     return false;
 
+  if (MF.isOutlined())
+    return false;
+
   bool isSpillageCopyElimEnabled = false;
   switch (EnableSpillageCopyElimination) {
   case cl::BOU_UNSET:
Index: llvm/include/llvm/CodeGen/MachineFunction.h
===================================================================
--- llvm/include/llvm/CodeGen/MachineFunction.h
+++ llvm/include/llvm/CodeGen/MachineFunction.h
@@ -374,6 +374,7 @@
   bool HasEHCatchret = false;
   bool HasEHScopes = false;
   bool HasEHFunclets = false;
+  bool IsOutlined = false;
 
   /// BBID to assign to the next basic block of this function.
   unsigned NextBBID = 0;
@@ -1116,6 +1117,9 @@
   bool hasEHFunclets() const { return HasEHFunclets; }
   void setHasEHFunclets(bool V) { HasEHFunclets = V; }
 
+  bool isOutlined() const { return IsOutlined; }
+  void setIsOutlined(bool V) { IsOutlined = V; }
+
   /// Find or create an LandingPadInfo for the specified MachineBasicBlock.
   LandingPadInfo &getOrCreateLandingPadInfo(MachineBasicBlock *LandingPad);
 


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