Revert "[flang] Run algebraic simplification optimization pass."

This reverts commit 4fbd1d6.

flang/include/flang/Optimizer/Transforms/Passes.h

@@ -39,7 +39,6 @@ std::unique_ptr<mlir::Pass>
 createMemoryAllocationPass(bool dynOnHeap, std::size_t maxStackSize);
 std::unique_ptr<mlir::Pass> createAnnotateConstantOperandsPass();
 std::unique_ptr<mlir::Pass> createSimplifyRegionLitePass();
-std::unique_ptr<mlir::Pass> createAlgebraicSimplificationPass();
 
 // declarative passes
 #define GEN_PASS_REGISTRATION

flang/include/flang/Optimizer/Transforms/Passes.td

@@ -196,17 +196,4 @@ def SimplifyRegionLite : Pass<"simplify-region-lite", "mlir::ModuleOp"> {
   let constructor = "::fir::createSimplifyRegionLitePass()";
 }
 
-def AlgebraicSimplification : Pass<"flang-algebraic-simplification"> {
-  let summary = "";
-  let description = [{
-    Run algebraic simplifications for Math/Complex/etc. dialect operations.
-    This is a flang specific pass, because we may want to "tune"
-    the rewrite patterns specifically for Fortran (e.g. increase
-    the limit for constant exponent value that defines the cases
-    when pow(x, constant) is transformed into a set of multiplications, etc.).
-  }];
-  let dependentDialects = [ "mlir::math::MathDialect" ];
-  let constructor = "::fir::createAlgebraicSimplificationPass()";
-}
-
 #endif // FLANG_OPTIMIZER_TRANSFORMS_PASSES

flang/include/flang/Tools/CLOptions.inc

@@ -15,7 +15,6 @@
 #include "mlir/Transforms/Passes.h"
 #include "flang/Optimizer/CodeGen/CodeGen.h"
 #include "flang/Optimizer/Transforms/Passes.h"
-#include "llvm/Passes/OptimizationLevel.h"
 #include "llvm/Support/CommandLine.h"
 
 #define DisableOption(DOName, DOOption, DODescription) \
@@ -51,10 +50,6 @@ static llvm::cl::opt<bool> ignoreMissingTypeDescriptors(
     llvm::cl::init(false), llvm::cl::Hidden);
 
 namespace {
-/// Default optimization level used to create Flang pass pipeline is O0.
-const static llvm::OptimizationLevel &defaultOptLevel{
-    llvm::OptimizationLevel::O0};
-
 /// Optimizer Passes
 DisableOption(CfgConversion, "cfg-conversion", "disable FIR to CFG pass");
 DisableOption(FirAvc, "avc", "array value copy analysis and transformation");
@@ -155,8 +150,7 @@ inline void addExternalNameConversionPass(mlir::PassManager &pm) {
 /// incremental conversion of FIR.
 ///
 /// \param pm - MLIR pass manager that will hold the pipeline definition
-inline void createDefaultFIROptimizerPassPipeline(
-    mlir::PassManager &pm, llvm::OptimizationLevel optLevel = defaultOptLevel) {
+inline void createDefaultFIROptimizerPassPipeline(mlir::PassManager &pm) {
   // simplify the IR
   mlir::GreedyRewriteConfig config;
   config.enableRegionSimplification = false;
@@ -165,9 +159,6 @@ inline void createDefaultFIROptimizerPassPipeline(
   pm.addNestedPass<mlir::func::FuncOp>(fir::createCharacterConversionPass());
   pm.addPass(mlir::createCanonicalizerPass(config));
   pm.addPass(fir::createSimplifyRegionLitePass());
-  // Algebraic simplifications may increase code size.
-  if (optLevel.isOptimizingForSpeed())
-    pm.addPass(fir::createAlgebraicSimplificationPass());
   pm.addPass(mlir::createCSEPass());
   fir::addMemoryAllocationOpt(pm);
 
@@ -200,12 +191,9 @@ inline void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm) {
 /// Create a pass pipeline for lowering from MLIR to LLVM IR
 ///
 /// \param pm - MLIR pass manager that will hold the pipeline definition
-/// \param optLevel - optimization level used for creating FIR optimization
-///   passes pipeline
-inline void createMLIRToLLVMPassPipeline(
-    mlir::PassManager &pm, llvm::OptimizationLevel optLevel = defaultOptLevel) {
+inline void createMLIRToLLVMPassPipeline(mlir::PassManager &pm) {
   // Add default optimizer pass pipeline.
-  fir::createDefaultFIROptimizerPassPipeline(pm, optLevel);
+  fir::createDefaultFIROptimizerPassPipeline(pm);
 
   // Add codegen pass pipeline.
   fir::createDefaultFIRCodeGenPassPipeline(pm);

flang/lib/Frontend/FrontendActions.cpp

@@ -479,29 +479,11 @@ CodeGenAction::~CodeGenAction() = default;
 
 #include "flang/Tools/CLOptions.inc"
 
-static llvm::OptimizationLevel
-mapToLevel(const Fortran::frontend::CodeGenOptions &opts) {
-  switch (opts.OptimizationLevel) {
-  default:
-    llvm_unreachable("Invalid optimization level!");
-  case 0:
-    return llvm::OptimizationLevel::O0;
-  case 1:
-    return llvm::OptimizationLevel::O1;
-  case 2:
-    return llvm::OptimizationLevel::O2;
-  case 3:
-    return llvm::OptimizationLevel::O3;
-  }
-}
-
 // Lower the previously generated MLIR module into an LLVM IR module
 void CodeGenAction::generateLLVMIR() {
   assert(mlirModule && "The MLIR module has not been generated yet.");
 
   CompilerInstance &ci = this->getInstance();
-  auto opts = ci.getInvocation().getCodeGenOpts();
-  llvm::OptimizationLevel level = mapToLevel(opts);
 
   fir::support::loadDialects(*mlirCtx);
   fir::support::registerLLVMTranslation(*mlirCtx);
@@ -513,7 +495,7 @@ void CodeGenAction::generateLLVMIR() {
   pm.enableVerifier(/*verifyPasses=*/true);
 
   // Create the pass pipeline
-  fir::createMLIRToLLVMPassPipeline(pm, level);
+  fir::createMLIRToLLVMPassPipeline(pm);
   mlir::applyPassManagerCLOptions(pm);
 
   // run the pass manager
@@ -648,6 +630,22 @@ static void generateMachineCodeOrAssemblyImpl(clang::DiagnosticsEngine &diags,
   codeGenPasses.run(llvmModule);
 }
 
+static llvm::OptimizationLevel
+mapToLevel(const Fortran::frontend::CodeGenOptions &opts) {
+  switch (opts.OptimizationLevel) {
+  default:
+    llvm_unreachable("Invalid optimization level!");
+  case 0:
+    return llvm::OptimizationLevel::O0;
+  case 1:
+    return llvm::OptimizationLevel::O1;
+  case 2:
+    return llvm::OptimizationLevel::O2;
+  case 3:
+    return llvm::OptimizationLevel::O3;
+  }
+}
+
 void CodeGenAction::runOptimizationPipeline(llvm::raw_pwrite_stream &os) {
   auto opts = getInstance().getInvocation().getCodeGenOpts();
   llvm::OptimizationLevel level = mapToLevel(opts);

flang/lib/Optimizer/Transforms/CMakeLists.txt

@@ -10,7 +10,6 @@ add_flang_library(FIRTransforms
   MemRefDataFlowOpt.cpp
   RewriteLoop.cpp
   SimplifyRegionLite.cpp
-  AlgebraicSimplification.cpp
 
   DEPENDS
   FIRBuilder
@@ -24,7 +23,6 @@ add_flang_library(FIRTransforms
   MLIRAffineUtils
   MLIRFuncDialect
   MLIRLLVMDialect
-  MLIRMathTransforms
   MLIROpenACCDialect
   MLIROpenMPDialect
   FIRSupport

flang/lib/Optimizer/Transforms/PassDetail.h

@@ -12,7 +12,6 @@
 #include "mlir/Dialect/Affine/IR/AffineOps.h"
 #include "mlir/Dialect/Func/IR/FuncOps.h"
 #include "mlir/Dialect/LLVMIR/LLVMDialect.h"
-#include "mlir/Dialect/Math/IR/Math.h"
 #include "mlir/Dialect/OpenACC/OpenACC.h"
 #include "mlir/Dialect/OpenMP/OpenMPDialect.h"
 #include "mlir/Pass/Pass.h"

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

@@ -1,58 +1,35 @@
 ! Test the MLIR pass pipeline
 
-! RUN: %flang_fc1 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline -o /dev/null %s 2>&1 | FileCheck --check-prefixes=ALL %s
-! -O0 is the default:
-! RUN: %flang_fc1 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -O0 -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL %s
-! RUN: %flang_fc1 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -O2 -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL,O2 %s
+! RUN: %flang_fc1 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o - 2>&1 | FileCheck %s
 end program
 
-! ALL: Pass statistics report
-
-! ALL: Fortran::lower::VerifierPass
-! ALL-NEXT: CSE
-! Ideally, we need an output with only the pass names, but
-! there is currently no way to get that, so in order to
-! guarantee that the passes are in the expected order
-! (i.e. use -NEXT) we have to check the statistics output as well.
-! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
-! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
-
-! ALL-NEXT: 'func.func' Pipeline
-! ALL-NEXT:   ArrayValueCopy
-! ALL-NEXT:   CharacterConversion
-
-! ALL-NEXT: Canonicalizer
-! ALL-NEXT: SimplifyRegionLite
-!  O2-NEXT: AlgebraicSimplification
-! ALL-NEXT: CSE
-! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
-! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
-
-! ALL-NEXT: 'func.func' Pipeline
-! ALL-NEXT:   MemoryAllocationOpt
-
-! ALL-NEXT: Inliner
-! ALL-NEXT: CSE
-! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
-! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
-
-! ALL-NEXT: 'func.func' Pipeline
-! ALL-NEXT:   CFGConversion
-
-! ALL-NEXT: SCFToControlFlow
-! ALL-NEXT: Canonicalizer
-! ALL-NEXT: SimplifyRegionLite
-! ALL-NEXT: CSE
-! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
-! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
-! ALL-NEXT: BoxedProcedurePass
-
-! ALL-NEXT: 'func.func' Pipeline
-! ALL-NEXT:   AbstractResultOpt
-
-! ALL-NEXT: CodeGenRewrite
-! ALL-NEXT:   (S) 0 num-dce'd - Number of operations eliminated
-! ALL-NEXT: TargetRewrite
-! ALL-NEXT: ExternalNameConversion
-! ALL-NEXT: FIRToLLVMLowering
-! ALL-NOT: LLVMIRLoweringPass
+! 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