[flang] Add preserveDeclare option to cg-rewrite pass.

abidh · abidh · commit 2c566dd3790c · 2024-05-07T12:21:05.000+01:00
When this option is true, DeclareOp is converted to XDeclareOp and this OP is used later for debug info generation. When it is false, DeclareOp is removed.
diff --git a/flang/include/flang/Optimizer/CodeGen/CGPasses.td b/flang/include/flang/Optimizer/CodeGen/CGPasses.td
@@ -47,6 +47,10 @@ def CodeGenRewrite : Pass<"cg-rewrite", "mlir::ModuleOp"> {
   let dependentDialects = [
     "fir::FIROpsDialect", "fir::FIRCodeGenDialect"
   ];
+  let options = [
+    Option<"preserveDeclare", "preserve-declare", "bool", /*default=*/"false",
+           "Preserve DeclareOp during pre codegen re-write.">
+  ];
   let statistics = [
     Statistic<"numDCE", "num-dce'd", "Number of operations eliminated">
   ];
diff --git a/flang/include/flang/Optimizer/CodeGen/CodeGen.h b/flang/include/flang/Optimizer/CodeGen/CodeGen.h
@@ -30,7 +30,8 @@ struct NameUniquer;
 
 /// Prerequiste pass for code gen. Perform intermediate rewrites to perform
 /// the code gen (to LLVM-IR dialect) conversion.
-std::unique_ptr<mlir::Pass> createFirCodeGenRewritePass();
+std::unique_ptr<mlir::Pass> createFirCodeGenRewritePass(
+    CodeGenRewriteOptions Options = CodeGenRewriteOptions{});
 
 /// FirTargetRewritePass options.
 struct TargetRewriteOptions {
@@ -88,7 +89,8 @@ void populateFIRToLLVMConversionPatterns(fir::LLVMTypeConverter &converter,
                                          fir::FIRToLLVMPassOptions &options);
 
 /// Populate the pattern set with the PreCGRewrite patterns.
-void populatePreCGRewritePatterns(mlir::RewritePatternSet &patterns);
+void populatePreCGRewritePatterns(mlir::RewritePatternSet &patterns,
+                                  bool preserveDeclare);
 
 // declarative passes
 #define GEN_PASS_REGISTRATION
diff --git a/flang/include/flang/Tools/CLOptions.inc b/flang/include/flang/Tools/CLOptions.inc
@@ -169,9 +169,11 @@ inline void addMemoryAllocationOpt(mlir::PassManager &pm) {
 }
 
 #if !defined(FLANG_EXCLUDE_CODEGEN)
-inline void addCodeGenRewritePass(mlir::PassManager &pm) {
-  addPassConditionally(
-      pm, disableCodeGenRewrite, fir::createFirCodeGenRewritePass);
+inline void addCodeGenRewritePass(mlir::PassManager &pm, bool preserveDeclare) {
+  fir::CodeGenRewriteOptions options;
+  options.preserveDeclare = preserveDeclare;
+  addPassConditionally(pm, disableCodeGenRewrite,
+      [&]() { return fir::createFirCodeGenRewritePass(options); });
 }
 
 inline void addTargetRewritePass(mlir::PassManager &pm) {
@@ -337,7 +339,8 @@ inline void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
     MLIRToLLVMPassPipelineConfig config, llvm::StringRef inputFilename = {}) {
   fir::addBoxedProcedurePass(pm);
   addNestedPassToAllTopLevelOperations(pm, fir::createAbstractResultOpt);
-  fir::addCodeGenRewritePass(pm);
+  fir::addCodeGenRewritePass(
+      pm, (config.DebugInfo != llvm::codegenoptions::NoDebugInfo));
   fir::addTargetRewritePass(pm);
   fir::addExternalNameConversionPass(pm, config.Underscoring);
   fir::createDebugPasses(pm, config.DebugInfo, config.OptLevel, inputFilename);
diff --git a/flang/lib/Optimizer/CodeGen/PreCGRewrite.cpp b/flang/lib/Optimizer/CodeGen/PreCGRewrite.cpp
@@ -270,12 +270,20 @@ class ArrayCoorConversion : public mlir::OpRewritePattern<fir::ArrayCoorOp> {
 };
 
 class DeclareOpConversion : public mlir::OpRewritePattern<fir::DeclareOp> {
+  bool preserveDeclare;
+
 public:
   using OpRewritePattern::OpRewritePattern;
+  DeclareOpConversion(mlir::MLIRContext *ctx, bool preserveDecl)
+      : OpRewritePattern(ctx), preserveDeclare(preserveDecl) {}
 
   mlir::LogicalResult
   matchAndRewrite(fir::DeclareOp declareOp,
                   mlir::PatternRewriter &rewriter) const override {
+    if (!preserveDeclare) {
+      rewriter.replaceOp(declareOp, declareOp.getMemref());
+      return mlir::success();
+    }
     auto loc = declareOp.getLoc();
     llvm::SmallVector<mlir::Value> shapeOpers;
     llvm::SmallVector<mlir::Value> shiftOpers;
@@ -319,6 +327,7 @@ class DummyScopeOpConversion
 
 class CodeGenRewrite : public fir::impl::CodeGenRewriteBase<CodeGenRewrite> {
 public:
+  CodeGenRewrite(fir::CodeGenRewriteOptions opts) : Base(opts) {}
   void runOnOperation() override final {
     mlir::ModuleOp mod = getOperation();
 
@@ -336,7 +345,7 @@ class CodeGenRewrite : public fir::impl::CodeGenRewriteBase<CodeGenRewrite> {
                    mlir::cast<fir::BaseBoxType>(embox.getType()).getEleTy()));
     });
     mlir::RewritePatternSet patterns(&context);
-    fir::populatePreCGRewritePatterns(patterns);
+    fir::populatePreCGRewritePatterns(patterns, preserveDeclare);
     if (mlir::failed(
             mlir::applyPartialConversion(mod, target, std::move(patterns)))) {
       mlir::emitError(mlir::UnknownLoc::get(&context),
@@ -352,12 +361,14 @@ class CodeGenRewrite : public fir::impl::CodeGenRewriteBase<CodeGenRewrite> {
 
 } // namespace
 
-std::unique_ptr<mlir::Pass> fir::createFirCodeGenRewritePass() {
-  return std::make_unique<CodeGenRewrite>();
+std::unique_ptr<mlir::Pass>
+fir::createFirCodeGenRewritePass(fir::CodeGenRewriteOptions Options) {
+  return std::make_unique<CodeGenRewrite>(Options);
 }
 
-void fir::populatePreCGRewritePatterns(mlir::RewritePatternSet &patterns) {
+void fir::populatePreCGRewritePatterns(mlir::RewritePatternSet &patterns,
+                                       bool preserveDeclare) {
   patterns.insert<EmboxConversion, ArrayCoorConversion, ReboxConversion,
-                  DeclareOpConversion, DummyScopeOpConversion>(
-      patterns.getContext());
+                  DummyScopeOpConversion>(patterns.getContext());
+  patterns.add<DeclareOpConversion>(patterns.getContext(), preserveDeclare);
 }
diff --git a/flang/test/Fir/declare-codegen.fir b/flang/test/Fir/declare-codegen.fir
@@ -1,5 +1,7 @@
 // Test rewrite of fir.declare. The result is replaced by the memref operand.
-// RUN: fir-opt --cg-rewrite %s -o - | FileCheck %s
+// RUN: fir-opt --cg-rewrite="preserve-declare=true" %s -o - | FileCheck %s --check-prefixes DECL
+// RUN: fir-opt --cg-rewrite="preserve-declare=false" %s -o - | FileCheck %s --check-prefixes NODECL
+// RUN: fir-opt --cg-rewrite %s -o - | FileCheck %s --check-prefixes NODECL
 
 
 func.func @test(%arg0: !fir.ref<!fir.array<12x23xi32>>) {
@@ -15,9 +17,13 @@ func.func @test(%arg0: !fir.ref<!fir.array<12x23xi32>>) {
 func.func private @bar(%arg0: !fir.ref<!fir.array<12x23xi32>>)
 
 
-// CHECK-LABEL: func.func @test(
-// CHECK-SAME: %[[arg0:.*]]: !fir.ref<!fir.array<12x23xi32>>) {
-// CHECK: fircg.ext_declare
+// NODECL-LABEL: func.func @test(
+// NODECL-SAME: %[[arg0:.*]]: !fir.ref<!fir.array<12x23xi32>>) {
+// NODECL-NEXT: fir.call @bar(%[[arg0]]) : (!fir.ref<!fir.array<12x23xi32>>) -> ()
+
+// DECL-LABEL: func.func @test(
+// DECL-SAME: %[[arg0:.*]]: !fir.ref<!fir.array<12x23xi32>>) {
+// DECL: fircg.ext_declare
 
 
 func.func @useless_shape_with_duplicate_extent_operand(%arg0: !fir.ref<!fir.array<3x3xf32>>) {
@@ -27,5 +33,8 @@ func.func @useless_shape_with_duplicate_extent_operand(%arg0: !fir.ref<!fir.arra
   return
 }
 
-// CHECK-LABEL: func.func @useless_shape_with_duplicate_extent_operand(
-// CHECK: fircg.ext_declare
+// NODECL-LABEL: func.func @useless_shape_with_duplicate_extent_operand(
+// NODECL-NEXT: return
+
+// DECL-LABEL: func.func @useless_shape_with_duplicate_extent_operand(
+// DECL: fircg.ext_declare
diff --git a/flang/test/Fir/dummy-scope-codegen.fir b/flang/test/Fir/dummy-scope-codegen.fir
@@ -1,9 +1,14 @@
-// RUN: fir-opt --cg-rewrite %s -o - | FileCheck %s
+// RUN: fir-opt --cg-rewrite="preserve-declare=true" %s -o - | FileCheck %s --check-prefixes DECL
+// RUN: fir-opt --cg-rewrite="preserve-declare=false" %s -o - | FileCheck %s --check-prefixes NODECL
+// RUN: fir-opt --cg-rewrite %s -o - | FileCheck %s  --check-prefixes NODECL
 
 func.func @dummy_scope(%arg0: !fir.ref<f32>) {
   %scope = fir.dummy_scope : !fir.dscope
   %0 = fir.declare %arg0 dummy_scope %scope {uniq_name = "x"} : (!fir.ref<f32>, !fir.dscope) -> !fir.ref<f32>
   return
 }
-// CHECK-LABEL: func.func @dummy_scope(
-// CHECK: fircg.ext_declare
+// DECL-LABEL: func.func @dummy_scope(
+// DECL: fircg.ext_declare
+
+// NODECL-LABEL: func.func @dummy_scope(
+// NODECL-NEXT: return
diff --git a/flang/test/Transforms/debug-local-var.f90 b/flang/test/Transforms/debug-local-var.f90
@@ -1,5 +1,5 @@
 ! RUN: %flang_fc1 -emit-fir -debug-info-kind=standalone -mmlir --mlir-print-debuginfo %s -o - | \
-! RUN: fir-opt --cg-rewrite --mlir-print-debuginfo | fir-opt --add-debug-info --mlir-print-debuginfo | FileCheck %s
+! RUN: fir-opt --cg-rewrite="preserve-declare=true" --mlir-print-debuginfo | fir-opt --add-debug-info --mlir-print-debuginfo | FileCheck %s
 
 ! CHECK-DAG: #[[INT8:.*]] = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "integer", sizeInBits = 64, encoding = DW_ATE_signed>
 ! CHECK-DAG: #[[INT4:.*]] = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "integer", sizeInBits = 32, encoding = DW_ATE_signed>
