[Flang] Call the CSE pass in the pass pipeline

[kiranchandramohan]

Summary

During the upstreaming process, it was decided to move contents
of the FIR CSE pass to the MLIR pass. Most of the FIR CSE changes
that are used are already moved to the MLIR pass. This patch calls
the MLIR CSE pass in places where the FIR CSE pass is called in the
pass pipeline.

Note: This is part of upstreaming from the fir-dev branch of
https://github.com/flang-compiler/f18-llvm-project.

Co-authored-by: Eric Schweitz <[e-mail]>
Co-authored-by: Valentin Clement <[e-mail]>
Co-authored-by: Andrzej Warzynski <[e-mail]>

[clementval]

LGTM

[awarzynski]

Thanks Kiran! I'm a bit surprised that basic-program.fir doesn't require updating 🤔 . Can you take a look?

[kiranchandramohan]

In D128365#3604072, @awarzynski wrote:

Thanks Kiran! I'm a bit surprised that basic-program.fir doesn't require updating 🤔 . Can you take a look?

This is because they are not strict checks like test_errors.py or the implicit-check-not option for FileCheck. Currently, it checks only for the presence of what is in the check line. I think we cannot make it stricter since mlir-pass-statistics dumps out some statistics in between.

[awarzynski]

In D128365#3604109, @kiranchandramohan wrote:

This is because they are not strict checks like test_errors.py or the implicit-check-not option for FileCheck. Currently, it checks only for the presence of what is in the check line. I think we cannot make it stricter since mlir-pass-statistics dumps out some statistics in between.

Ah, ok, but the output in that file will also change and it would be good to update it too.

[kiranchandramohan]

Update basic-program.fir test to address review comments.

[kiranchandramohan]

In D128365#3604111, @awarzynski wrote:

In D128365#3604109, @kiranchandramohan wrote:

This is because they are not strict checks like test_errors.py or the implicit-check-not option for FileCheck. Currently, it checks only for the presence of what is in the check line. I think we cannot make it stricter since mlir-pass-statistics dumps out some statistics in between.

Ah, ok, but the output in that file will also change and it would be good to update it too.

Done.

[awarzynski]

Thanks!

flang/include/flang/Tools/CLOptions.inc

 /// 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
 inline void createDefaultFIROptimizerPassPipeline(mlir::PassManager &pm) {
   // simplify the IR
   mlir::GreedyRewriteConfig config;
   config.enableRegionSimplification = false;
+  pm.addPass(mlir::createCSEPass());
   fir::addAVC(pm);
   pm.addNestedPass<mlir::func::FuncOp>(fir::createCharacterConversionPass());
   pm.addPass(mlir::createCanonicalizerPass(config));
   pm.addPass(fir::createSimplifyRegionLitePass());
+  pm.addPass(mlir::createCSEPass());
   fir::addMemoryAllocationOpt(pm);
 
   // The default inliner pass adds the canonicalizer pass with the default
   // configuration. Create the inliner pass with tco config.
   llvm::StringMap<mlir::OpPassManager> pipelines;
   pm.addPass(
       mlir::createInlinerPass(pipelines, defaultFlangInlinerOptPipeline));
   pm.addPass(mlir::createCSEPass());
 
   // convert control flow to CFG form
   fir::addCfgConversionPass(pm);
   pm.addPass(mlir::createConvertSCFToCFPass());
 
   pm.addPass(mlir::createCanonicalizerPass(config));
   pm.addPass(fir::createSimplifyRegionLitePass());
+  pm.addPass(mlir::createCSEPass());
 }
 
 #if !defined(FLANG_EXCLUDE_CODEGEN)
 inline void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm) {
   fir::addBoxedProcedurePass(pm);
   pm.addNestedPass<mlir::func::FuncOp>(fir::createAbstractResultOptPass());
   fir::addCodeGenRewritePass(pm);
   fir::addTargetRewritePass(pm);

flang/test/Driver/mlir-pass-pipeline.f90

 ! Test the MLIR pass pipeline
 
 ! RUN: %flang_fc1 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o - 2>&1 | FileCheck %s
 end program
 
 ! CHECK: Pass statistics report
 
+! CHECK: CSE
 ! CHECK-LABEL: 'func.func' Pipeline
 ! CHECK: ArrayValueCopy
 ! CHECK: CharacterConversion
 ! CHECK: Canonicalizer
 ! CHECK: SimplifyRegionLite
+! CHECK: CSE
 
 ! CHECK-LABEL: 'func.func' Pipeline
 ! CHECK: MemoryAllocationOpt
 ! CHECK: Inliner
 ! CHECK: CSE
 
 ! CHECK-LABEL: 'func.func' Pipeline
 ! CHECK: CFGConversion
 ! CHECK: SCFToControlFlow
 ! CHECK: Canonicalizer
 ! CHECK: SimplifyRegionLite
+! CHECK: CSE
 ! CHECK: BoxedProcedurePass
 
 ! CHECK-LABEL: 'func.func' Pipeline
 ! CHECK: AbstractResultOpt
 ! CHECK: CodeGenRewrite
 ! CHECK: TargetRewrite
 ! CHECK: ExternalNameConversion
 ! CHECK: FIRToLLVMLowering
 ! CHECK-NOT: LLVMIRLoweringPass

flang/test/Fir/basic-program.fir

 // RUN: tco %s | FileCheck %s
 // RUN: tco %s --mlir-pass-statistics --mlir-pass-statistics-display=pipeline 2>&1 | FileCheck %s --check-prefix=PASSES
 
 // Check that tco is working with a basic test.
 // Also check the passes in the default pipeline.
 
 func.func @_QQmain() {
   return
 }
 
 // CHECK: ; ModuleID = 'FIRModule'
 // CHECK-LABEL: define void @_QQmain()
 // CHECK:       ret void
 
 // PASSES: Pass statistics report
 
+// PASSES: CSE
 // PASSES-LABEL: 'func.func' Pipeline
 // PASSES: ArrayValueCopy
 // PASSES: CharacterConversion
 // PASSES: Canonicalizer
 // PASSES: SimplifyRegionLite
+// PASSES: CSE
 
 // PASSES-LABEL: 'func.func' Pipeline
 // PASSES: MemoryAllocationOpt
 // PASSES: Inliner
 // PASSES: CSE
 
 // PASSES-LABEL: 'func.func' Pipeline
 // PASSES: CFGConversion
 // PASSES: SCFToControlFlow
 // PASSES: Canonicalizer
 // PASSES: SimplifyRegionLite
+// PASSES: CSE
 // PASSES: BoxedProcedurePass
 
 // PASSES-LABEL: 'func.func' Pipeline
 // PASSES: AbstractResultOpt
 // PASSES: CodeGenRewrite
 // PASSES: TargetRewrite
 // PASSES: FIRToLLVMLowering
 // PASSES: LLVMIRLoweringPass