[flang] always run PolymorphicOpConversion sequentially (#90721)

It was pointed out in post commit review of
https://github.com/llvm/llvm-project/pull/90597 that the pass should
never have been run in parallel over all functions (and now other top
level operations) in the first place. The mutex used in the pass was
ineffective at preventing races since each instance of the pass would
have a different mutex.

7 files changed, 15 insertions, 51 deletions

diff --git a/flang/include/flang/Optimizer/Transforms/Passes.td b/flang/include/flang/Optimizer/Transforms/Passes.td
index dcb7037e2991..1eaaa32a508a 100644
--- a/flang/include/flang/Optimizer/Transforms/Passes.td
+++ b/flang/include/flang/Optimizer/Transforms/Passes.td
@@ -298,7 +298,7 @@ def AlgebraicSimplification : Pass<"flang-algebraic-simplification"> {
   let constructor = "::fir::createAlgebraicSimplificationPass()";
 }
 
-def PolymorphicOpConversion : Pass<"fir-polymorphic-op"> {
+def PolymorphicOpConversion : Pass<"fir-polymorphic-op", "mlir::ModuleOp"> {
   let summary =
     "Simplify operations on polymorphic types";
   let description = [{
diff --git a/flang/include/flang/Tools/CLOptions.inc b/flang/include/flang/Tools/CLOptions.inc
index bd60c66b61ad..d85436489870 100644
--- a/flang/include/flang/Tools/CLOptions.inc
+++ b/flang/include/flang/Tools/CLOptions.inc
@@ -271,7 +271,7 @@ inline void createDefaultFIROptimizerPassPipeline(
   pm.addPass(mlir::createCSEPass());
 
   // Polymorphic types
-  addNestedPassToAllTopLevelOperations(pm, fir::createPolymorphicOpConversion);
+  pm.addPass(fir::createPolymorphicOpConversion());
 
   if (pc.AliasAnalysis && !disableFirAliasTags && !useOldAliasTags)
     pm.addPass(fir::createAliasTagsPass());
diff --git a/flang/lib/Optimizer/Transforms/PolymorphicOpConversion.cpp b/flang/lib/Optimizer/Transforms/PolymorphicOpConversion.cpp
index 0f5c43882ee3..76c12d2de5c4 100644
--- a/flang/lib/Optimizer/Transforms/PolymorphicOpConversion.cpp
+++ b/flang/lib/Optimizer/Transforms/PolymorphicOpConversion.cpp
@@ -29,7 +29,6 @@
 #include "mlir/Transforms/DialectConversion.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/Support/CommandLine.h"
-#include <mutex>
 
 namespace fir {
 #define GEN_PASS_DEF_POLYMORPHICOPCONVERSION
@@ -48,9 +47,8 @@ class SelectTypeConv : public OpConversionPattern<fir::SelectTypeOp> {
 public:
   using OpConversionPattern<fir::SelectTypeOp>::OpConversionPattern;
 
-  SelectTypeConv(mlir::MLIRContext *ctx, std::mutex *moduleMutex)
-      : mlir::OpConversionPattern<fir::SelectTypeOp>(ctx),
-        moduleMutex(moduleMutex) {}
+  SelectTypeConv(mlir::MLIRContext *ctx)
+      : mlir::OpConversionPattern<fir::SelectTypeOp>(ctx) {}
 
   mlir::LogicalResult
   matchAndRewrite(fir::SelectTypeOp selectType, OpAdaptor adaptor,
@@ -72,9 +70,6 @@ private:
 
   llvm::SmallSet<llvm::StringRef, 4> collectAncestors(fir::TypeInfoOp dt,
                                                       mlir::ModuleOp mod) const;
-
-  // Mutex used to guard insertion of mlir::func::FuncOp in the module.
-  std::mutex *moduleMutex;
 };
 
 /// Lower `fir.dispatch` operation. A virtual call to a method in a dispatch
@@ -223,21 +218,18 @@ class PolymorphicOpConversion
     : public fir::impl::PolymorphicOpConversionBase<PolymorphicOpConversion> {
 public:
   mlir::LogicalResult initialize(mlir::MLIRContext *ctx) override {
-    moduleMutex = new std::mutex();
     return mlir::success();
   }
 
   void runOnOperation() override {
     auto *context = &getContext();
-    auto mod = mlir::dyn_cast_or_null<mlir::ModuleOp>(getOperation());
-    if (!mod)
-      mod = getOperation()->getParentOfType<ModuleOp>();
+    mlir::ModuleOp mod = getOperation();
     mlir::RewritePatternSet patterns(context);
 
     BindingTables bindingTables;
     buildBindingTables(bindingTables, mod);
 
-    patterns.insert<SelectTypeConv>(context, moduleMutex);
+    patterns.insert<SelectTypeConv>(context);
     patterns.insert<DispatchOpConv>(context, bindingTables);
     mlir::ConversionTarget target(*context);
     target.addLegalDialect<mlir::affine::AffineDialect,
@@ -255,9 +247,6 @@ public:
       signalPassFailure();
     }
   }
-
-private:
-  std::mutex *moduleMutex;
 };
 } // namespace
 
@@ -410,7 +399,6 @@ mlir::LogicalResult SelectTypeConv::genTypeLadderStep(
     {
       // Since conversion is done in parallel for each fir.select_type
       // operation, the runtime function insertion must be threadsafe.
-      std::lock_guard<std::mutex> lock(*moduleMutex);
       callee =
           fir::createFuncOp(rewriter.getUnknownLoc(), mod, fctName,
                             rewriter.getFunctionType({descNoneTy, typeDescTy},
diff --git a/flang/test/Driver/bbc-mlir-pass-pipeline.f90 b/flang/test/Driver/bbc-mlir-pass-pipeline.f90
index 07b68bfe03b3..2cc25b3c473f 100644
--- a/flang/test/Driver/bbc-mlir-pass-pipeline.f90
+++ b/flang/test/Driver/bbc-mlir-pass-pipeline.f90
@@ -45,18 +45,16 @@ end program
 ! CHECK-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
 ! CHECK-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
+! CHECK-NEXT: PolymorphicOpConversion
+
 ! CHECK-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'omp.declare_reduction', 'omp.private']
 ! CHECK-NEXT: 'fir.global' Pipeline
-! CHECK-NEXT:   PolymorphicOpConversion
 ! CHECK-NEXT:   CFGConversion
 ! CHECK-NEXT: 'func.func' Pipeline
-! CHECK-NEXT:   PolymorphicOpConversion
 ! CHECK-NEXT:   CFGConversion
 ! CHECK-NEXT: 'omp.declare_reduction' Pipeline
-! CHECK-NEXT:   PolymorphicOpConversion
 ! CHECK-NEXT:   CFGConversion
 ! CHECK-NEXT: 'omp.private' Pipeline
-! CHECK-NEXT:   PolymorphicOpConversion
 ! CHECK-NEXT:   CFGConversion
 
 ! CHECK-NEXT: SCFToControlFlow
diff --git a/flang/test/Driver/mlir-debug-pass-pipeline.f90 b/flang/test/Driver/mlir-debug-pass-pipeline.f90
index cad7415a3b52..a9980e3c932c 100644
--- a/flang/test/Driver/mlir-debug-pass-pipeline.f90
+++ b/flang/test/Driver/mlir-debug-pass-pipeline.f90
@@ -65,18 +65,16 @@ end program
 ! 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: PolymorphicOpConversion
+
 ! ALL-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'omp.declare_reduction', 'omp.private']
 ! ALL-NEXT:   'fir.global' Pipeline
-! ALL-NEXT:     PolymorphicOpConversion
 ! ALL-NEXT:     CFGConversion
 ! ALL-NEXT:   'func.func' Pipeline
-! ALL-NEXT:     PolymorphicOpConversion
 ! ALL-NEXT:     CFGConversion
 ! ALL-NEXT:   'omp.declare_reduction' Pipeline
-! ALL-NEXT:     PolymorphicOpConversion
 ! ALL-NEXT:     CFGConversion
 ! ALL-NEXT:   'omp.private' Pipeline
-! ALL-NEXT:     PolymorphicOpConversion
 ! ALL-NEXT:     CFGConversion
 ! ALL-NEXT: SCFToControlFlow
 ! ALL-NEXT: Canonicalizer
diff --git a/flang/test/Driver/mlir-pass-pipeline.f90 b/flang/test/Driver/mlir-pass-pipeline.f90
index 7f63f946c2fb..4ebac7c3fb65 100644
--- a/flang/test/Driver/mlir-pass-pipeline.f90
+++ b/flang/test/Driver/mlir-pass-pipeline.f90
@@ -1,8 +1,8 @@
 ! 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,NOTO2 %s
+! 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,NOTO2 %s
+! 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
 
 ! REQUIRES: asserts
@@ -56,28 +56,17 @@ end program
 ! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
 ! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
-! O2-NEXT:  Pipeline Collection : ['fir.global', 'func.func', 'omp.declare_reduction', 'omp.private']
-! O2-NEXT:    'fir.global' Pipeline
-! O2-NEXT:      PolymorphicOpConversion
-! O2-NEXT:    'func.func' Pipeline
-! O2-NEXT:      PolymorphicOpConversion
-! O2-NEXT:    'omp.declare_reduction' Pipeline
-! O2-NEXT:      PolymorphicOpConversion
-! O2-NEXT:    'omp.private' Pipeline
-! O2-NEXT:      PolymorphicOpConversion
+! ALL-NEXT: PolymorphicOpConversion
 ! O2-NEXT:  AddAliasTags
+
 ! ALL-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'omp.declare_reduction', 'omp.private']
 ! ALL-NEXT:    'fir.global' Pipeline
-! NOTO2-NEXT:      PolymorphicOpConversion
 ! ALL-NEXT:      CFGConversion
 ! ALL-NEXT:    'func.func' Pipeline
-! NOTO2-NEXT:      PolymorphicOpConversion
 ! ALL-NEXT:      CFGConversion
 ! ALL-NEXT:   'omp.declare_reduction' Pipeline
-! NOTO2-NEXT:      PolymorphicOpConversion
 ! ALL-NEXT:      CFGConversion
 ! ALL-NEXT:   'omp.private' Pipeline
-! NOTO2-NEXT:    PolymorphicOpConversion
 ! ALL-NEXT:      CFGConversion
 
 ! ALL-NEXT: SCFToControlFlow
diff --git a/flang/test/Fir/basic-program.fir b/flang/test/Fir/basic-program.fir
index 67a9c56ed9ac..02fb84ed8c87 100644
--- a/flang/test/Fir/basic-program.fir
+++ b/flang/test/Fir/basic-program.fir
@@ -62,16 +62,7 @@ func.func @_QQmain() {
 // PASSES-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
 // PASSES-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
-// PASSES-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'omp.declare_reduction', 'omp.private']
-// PASSES-NEXT: 'fir.global' Pipeline
-// PASSES-NEXT:   PolymorphicOpConversion
-// PASSES-NEXT: 'func.func' Pipeline
-// PASSES-NEXT:   PolymorphicOpConversion
-// PASSES-NEXT: 'omp.declare_reduction' Pipeline
-// PASSES-NEXT:   PolymorphicOpConversion
-// PASSES-NEXT: 'omp.private' Pipeline
-// PASSES-NEXT:   PolymorphicOpConversion
-
+// PASSES-NEXT: PolymorphicOpConversion
 // PASSES-NEXT: AddAliasTags
 
 // PASSES-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'omp.declare_reduction', 'omp.private']