[flang-commits] [flang] 76f971b - [flang][nfc] Split out the pre- and post-cfg FIR pipelines (#218778)

[via flang-commits]

Author: Ivan R. Ivanov
Date: 2026-08-26T00:45:56+02:00
New Revision: 76f971b1ebb5f1c95bf250e649afafc88d7d9226

URL: https://github.com/llvm/llvm-project/commit/76f971b1ebb5f1c95bf250e649afafc88d7d9226
DIFF: https://github.com/llvm/llvm-project/commit/76f971b1ebb5f1c95bf250e649afafc88d7d9226.diff

LOG: [flang][nfc] Split out the pre- and post-cfg FIR pipelines (#218778)

Split the FIR optimization pipeline in its pre- and post-cfg parts and
expose the builders so that alternative downstream pipelines can build
around them.

Added: 
    

Modified: 
    flang/include/flang/Optimizer/Passes/Pipelines.h
    flang/lib/Optimizer/Passes/Pipelines.cpp

Removed: 
    


################################################################################
diff  --git a/flang/include/flang/Optimizer/Passes/Pipelines.h b/flang/include/flang/Optimizer/Passes/Pipelines.h
index c50d41844941e..726607613260a 100644
--- a/flang/include/flang/Optimizer/Passes/Pipelines.h
+++ b/flang/include/flang/Optimizer/Passes/Pipelines.h
@@ -136,6 +136,16 @@ void registerDefaultInlinerPass(MLIRToLLVMPassPipelineConfig &config);
 /// e.g. --mlir-print-ir-before=<pass> and similar.
 void registerFlangPipelinePasses();
 
+/// Create a pass pipeline for default FIR optimizations that run before CFG
+/// conversion.
+void createDefaultFIRPreCFGOptimizerPassPipeline(
+    mlir::PassManager &pm, MLIRToLLVMPassPipelineConfig &pc);
+
+/// Create a pass pipeline for default FIR optimizations that run after CFG
+/// conversion.
+void createDefaultFIRPostCFGOptimizerPassPipeline(
+    mlir::PassManager &pm, MLIRToLLVMPassPipelineConfig &pc);
+
 /// Create a pass pipeline for running default optimization passes for
 /// incremental conversion of FIR.
 ///

diff  --git a/flang/lib/Optimizer/Passes/Pipelines.cpp b/flang/lib/Optimizer/Passes/Pipelines.cpp
index 232b27a148ab2..4c5fd32cf342b 100644
--- a/flang/lib/Optimizer/Passes/Pipelines.cpp
+++ b/flang/lib/Optimizer/Passes/Pipelines.cpp
@@ -173,15 +173,8 @@ void registerDefaultInlinerPass(MLIRToLLVMPassPipelineConfig &config) {
       });
 }
 
-/// Create a pass pipeline for running default optimization passes for
-/// incremental conversion of FIR.
-///
-/// \param pm - MLIR pass manager that will hold the pipeline definition
-void createDefaultFIROptimizerPassPipeline(mlir::PassManager &pm,
-                                           MLIRToLLVMPassPipelineConfig &pc) {
-  // Early Optimizer EP Callback
-  pc.invokeFIROptEarlyEPCallbacks(pm, pc.OptLevel);
-
+void createDefaultFIRPreCFGOptimizerPassPipeline(
+    mlir::PassManager &pm, MLIRToLLVMPassPipelineConfig &pc) {
   // simplify the IR
   mlir::GreedyRewriteConfig config;
   config.setRegionSimplificationLevel(
@@ -245,8 +238,14 @@ void createDefaultFIROptimizerPassPipeline(mlir::PassManager &pm,
 
   addNestedPassToAllTopLevelOperations<PassConstructor>(
       pm, fir::createStackReclaim);
-  // convert control flow to CFG form
-  fir::addCfgConversionPass(pm, pc);
+}
+
+void createDefaultFIRPostCFGOptimizerPassPipeline(
+    mlir::PassManager &pm, MLIRToLLVMPassPipelineConfig &pc) {
+  mlir::GreedyRewriteConfig config;
+  config.setRegionSimplificationLevel(
+      mlir::GreedySimplifyRegionLevel::Disabled);
+
   pm.addPass(mlir::createSCFToControlFlowPass());
 
   pm.addPass(mlir::createCanonicalizerPass(config));
@@ -257,8 +256,18 @@ void createDefaultFIROptimizerPassPipeline(mlir::PassManager &pm,
 
   if (pc.OptLevel != llvm::OptimizationLevel::O0)
     pm.addPass(fir::createSetRuntimeCallAttributes());
+}
 
-  // Last Optimizer EP Callback
+/// Create a pass pipeline for running default optimization passes for
+/// incremental conversion of FIR.
+///
+/// \param pm - MLIR pass manager that will hold the pipeline definition
+void createDefaultFIROptimizerPassPipeline(mlir::PassManager &pm,
+                                           MLIRToLLVMPassPipelineConfig &pc) {
+  pc.invokeFIROptEarlyEPCallbacks(pm, pc.OptLevel);
+  createDefaultFIRPreCFGOptimizerPassPipeline(pm, pc);
+  fir::addCfgConversionPass(pm, pc);
+  createDefaultFIRPostCFGOptimizerPassPipeline(pm, pc);
   pc.invokeFIROptLastEPCallbacks(pm, pc.OptLevel);
 }