[llvm] a833fa7 - [RISCV] Move Machine Copy Propagation Pass before Branch relaxation pass (#97261)

[via llvm-commits]

Author: Yunzezhu94
Date: 2024-07-02T09:58:00+08:00
New Revision: a833fa7d3ef0ca993e7e788b45349c3246e2995e

URL: https://github.com/llvm/llvm-project/commit/a833fa7d3ef0ca993e7e788b45349c3246e2995e
DIFF: https://github.com/llvm/llvm-project/commit/a833fa7d3ef0ca993e7e788b45349c3246e2995e.diff

LOG: [RISCV] Move Machine Copy Propagation Pass before Branch relaxation pass (#97261)

Machine Copy Propagation Pass may enlarge branch relaxation distance by
breaking generation of compressed insts. This commit moves Machine Copy
Propagation Pass before Branch relaxation pass so the results of Branch
relaxation pass won't be affected by Machine Copy Propagation Pass.

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
    llvm/test/CodeGen/RISCV/O3-pipeline.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index 35d0b3408d09f..f76aef742290c 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -497,9 +497,6 @@ void RISCVPassConfig::addPreSched2() {
 }
 
 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)
@@ -508,6 +505,8 @@ void RISCVPassConfig::addPreEmitPass() {
   if (TM->getOptLevel() >= CodeGenOptLevel::Default &&
       EnableRISCVCopyPropagation)
     addPass(createMachineCopyPropagationPass(true));
+  addPass(&BranchRelaxationPassID);
+  addPass(createRISCVMakeCompressibleOptPass());
 }
 
 void RISCVPassConfig::addPreEmitPass2() {

diff  --git a/llvm/test/CodeGen/RISCV/O3-pipeline.ll b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
index 1eee62e883cf6..3611d92826235 100644
--- a/llvm/test/CodeGen/RISCV/O3-pipeline.ll
+++ b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
@@ -182,9 +182,9 @@
 ; CHECK-NEXT:       Insert fentry calls
 ; CHECK-NEXT:       Insert XRay ops
 ; CHECK-NEXT:       Implement the 'patchable-function' attribute
+; CHECK-NEXT:       Machine Copy Propagation Pass
 ; CHECK-NEXT:       Branch relaxation pass
 ; CHECK-NEXT:       RISC-V 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