[llvm] 5678c93 - [CodeGen][NPM] Do not implicitly flush pipeline when switching to CGSCC (#173315)

[via llvm-commits]

Author: Aiden Grossman
Date: 2025-12-22T16:33:57-08:00
New Revision: 5678c939e8fd578efd38732f6d46bb57d8d7d04b

URL: https://github.com/llvm/llvm-project/commit/5678c939e8fd578efd38732f6d46bb57d8d7d04b
DIFF: https://github.com/llvm/llvm-project/commit/5678c939e8fd578efd38732f6d46bb57d8d7d04b.diff

LOG: [CodeGen][NPM] Do not implicitly flush pipeline when switching to CGSCC (#173315)

Added: 
    

Modified: 
    llvm/include/llvm/Passes/CodeGenPassBuilder.h
    llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/Passes/CodeGenPassBuilder.h b/llvm/include/llvm/Passes/CodeGenPassBuilder.h
index d0246f8006dd6..2cdf5262fabde 100644
--- a/llvm/include/llvm/Passes/CodeGenPassBuilder.h
+++ b/llvm/include/llvm/Passes/CodeGenPassBuilder.h
@@ -277,12 +277,17 @@ template <typename DerivedT, typename TargetMachineT> class CodeGenPassBuilder {
 
   void requireCGSCCOrder(PassManagerWrapper &PMW) const {
     assert(!AddInCGSCCOrder);
-    flushFPMsToMPM(PMW);
+    assert(PMW.FPM.isEmpty() && PMW.MFPM.isEmpty() &&
+           "Requiring CGSCC ordering requires flushing the current function "
+           "pipelines to the MPM.");
     AddInCGSCCOrder = true;
   }
+
   void stopAddingInCGSCCOrder(PassManagerWrapper &PMW) const {
     assert(AddInCGSCCOrder);
-    flushFPMsToMPM(PMW);
+    assert(PMW.FPM.isEmpty() && PMW.MFPM.isEmpty() &&
+           "Stopping CGSCC ordering requires flushing the current function "
+           "pipelines to the MPM.");
     AddInCGSCCOrder = false;
   }
 

diff  --git a/llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp b/llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
index c24962dccdd65..309e92a2ee88e 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
@@ -2206,6 +2206,7 @@ void AMDGPUCodeGenPassBuilder::addCodeGenPrepare(
   // many cases.
   flushFPMsToMPM(PMW);
   addModulePass(AMDGPULowerBufferFatPointersPass(TM), PMW);
+  flushFPMsToMPM(PMW);
   requireCGSCCOrder(PMW);
 
   addModulePass(AMDGPULowerIntrinsicsPass(TM), PMW);