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[flang] Lowering support for -gdwarf-N flag. #159137

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merged 2 commits into from
Sep 17, 2025
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[flang] Lowering support for -gdwarf-N flag. #159137

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bff7664
[flang] Lowering support for -gdwarf-N flag.
abidh Sep 15, 2025
65bfa4b
Handle review comments.
abidh Sep 17, 2025
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4 changes: 2 additions & 2 deletions flang/include/flang/Optimizer/Passes/Pipelines.h
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Original file line number Diff line number Diff line change
Expand Up @@ -102,7 +102,7 @@ void addCompilerGeneratedNamesConversionPass(mlir::PassManager &pm);
void addDebugInfoPass(mlir::PassManager &pm,
llvm::codegenoptions::DebugInfoKind debugLevel,
llvm::OptimizationLevel optLevel,
llvm::StringRef inputFilename);
llvm::StringRef inputFilename, int32_t dwarfVersion);

void addFIRToLLVMPass(mlir::PassManager &pm,
const MLIRToLLVMPassPipelineConfig &config);
Expand Down Expand Up @@ -158,7 +158,7 @@ void createOpenMPFIRPassPipeline(mlir::PassManager &pm,
void createDebugPasses(mlir::PassManager &pm,
llvm::codegenoptions::DebugInfoKind debugLevel,
llvm::OptimizationLevel OptLevel,
llvm::StringRef inputFilename);
llvm::StringRef inputFilename, int32_t dwarfVersion);
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Could you please give dwarfVersion a default value in the declaration?

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Can you kindly describe what problem do you see because the version have a default value both in pass declaration and in opts.


void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
MLIRToLLVMPassPipelineConfig config,
Expand Down
4 changes: 4 additions & 0 deletions flang/include/flang/Optimizer/Transforms/Passes.td
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Expand Up @@ -242,6 +242,10 @@ def AddDebugInfo : Pass<"add-debug-info", "mlir::ModuleOp"> {
"std::string",
/*default=*/"std::string{}",
"name of the input source file">,
Option<"dwarfVersion", "dwarf-version",
"int32_t",
/*default=*/"0",
"dwarf version">,
];
}

Expand Down
2 changes: 2 additions & 0 deletions flang/include/flang/Tools/CrossToolHelpers.h
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Expand Up @@ -108,6 +108,7 @@ struct MLIRToLLVMPassPipelineConfig : public FlangEPCallBacks {
InstrumentFunctionEntry = "__cyg_profile_func_enter";
InstrumentFunctionExit = "__cyg_profile_func_exit";
}
DwarfVersion = opts.DwarfVersion;
}

llvm::OptimizationLevel OptLevel; ///< optimisation level
Expand Down Expand Up @@ -143,6 +144,7 @@ struct MLIRToLLVMPassPipelineConfig : public FlangEPCallBacks {
Fortran::frontend::CodeGenOptions::ComplexRangeKind ComplexRange =
Fortran::frontend::CodeGenOptions::ComplexRangeKind::
CX_Full; ///< Method for calculating complex number division
int32_t DwarfVersion = 0; ///< Version of DWARF debug info to generate
};

struct OffloadModuleOpts {
Expand Down
3 changes: 1 addition & 2 deletions flang/lib/Frontend/CompilerInvocation.cpp
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Expand Up @@ -157,10 +157,9 @@ static bool parseDebugArgs(Fortran::frontend::CodeGenOptions &opts,
clang::DiagnosticsEngine::Warning, "Unsupported debug option: %0");
diags.Report(debugWarning) << arg->getValue();
}
// The default value of 2 here is to match clang.
opts.DwarfVersion =
getLastArgIntValue(args, clang::driver::options::OPT_dwarf_version_EQ,
/*Default=*/2, diags);
/*Default=*/0, diags);
}
return true;
}
Expand Down
10 changes: 6 additions & 4 deletions flang/lib/Optimizer/Passes/Pipelines.cpp
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Expand Up @@ -95,11 +95,12 @@ getEmissionKind(llvm::codegenoptions::DebugInfoKind kind) {
void addDebugInfoPass(mlir::PassManager &pm,
llvm::codegenoptions::DebugInfoKind debugLevel,
llvm::OptimizationLevel optLevel,
llvm::StringRef inputFilename) {
llvm::StringRef inputFilename, int32_t dwarfVersion) {
fir::AddDebugInfoOptions options;
options.debugLevel = getEmissionKind(debugLevel);
options.isOptimized = optLevel != llvm::OptimizationLevel::O0;
options.inputFilename = inputFilename;
options.dwarfVersion = dwarfVersion;
addPassConditionally(pm, disableDebugInfo,
[&]() { return fir::createAddDebugInfoPass(options); });
}
Expand Down Expand Up @@ -333,9 +334,9 @@ void createOpenMPFIRPassPipeline(mlir::PassManager &pm,
void createDebugPasses(mlir::PassManager &pm,
llvm::codegenoptions::DebugInfoKind debugLevel,
llvm::OptimizationLevel OptLevel,
llvm::StringRef inputFilename) {
llvm::StringRef inputFilename, int32_t dwarfVersion) {
if (debugLevel != llvm::codegenoptions::NoDebugInfo)
addDebugInfoPass(pm, debugLevel, OptLevel, inputFilename);
addDebugInfoPass(pm, debugLevel, OptLevel, inputFilename, dwarfVersion);
}

void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
Expand All @@ -352,7 +353,8 @@ void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
fir::addCodeGenRewritePass(
pm, (config.DebugInfo != llvm::codegenoptions::NoDebugInfo));
fir::addExternalNameConversionPass(pm, config.Underscoring);
fir::createDebugPasses(pm, config.DebugInfo, config.OptLevel, inputFilename);
fir::createDebugPasses(pm, config.DebugInfo, config.OptLevel, inputFilename,
config.DwarfVersion);
fir::addTargetRewritePass(pm);
fir::addCompilerGeneratedNamesConversionPass(pm);

Expand Down
14 changes: 13 additions & 1 deletion flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
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Expand Up @@ -649,6 +649,19 @@ void AddDebugInfoPass::runOnOperation() {
signalPassFailure();
return;
}
mlir::OpBuilder builder(context);
if (dwarfVersion > 0) {
mlir::OpBuilder::InsertionGuard guard(builder);
builder.setInsertionPointToEnd(module.getBody());
llvm::SmallVector<mlir::Attribute> moduleFlags;
mlir::IntegerType int32Ty = mlir::IntegerType::get(context, 32);
moduleFlags.push_back(builder.getAttr<mlir::LLVM::ModuleFlagAttr>(
mlir::LLVM::ModFlagBehavior::Max,
mlir::StringAttr::get(context, "Dwarf Version"),
mlir::IntegerAttr::get(int32Ty, dwarfVersion)));
mlir::LLVM::ModuleFlagsOp::create(builder, module.getLoc(),
builder.getArrayAttr(moduleFlags));
}
fir::DebugTypeGenerator typeGen(module, &symbolTable, *dl);
// We need 2 type of file paths here.
// 1. Name of the file as was presented to compiler. This can be absolute
Expand Down Expand Up @@ -686,7 +699,6 @@ void AddDebugInfoPass::runOnOperation() {
module.walk([&](mlir::func::FuncOp funcOp) {
handleFuncOp(funcOp, fileAttr, cuAttr, typeGen, &symbolTable);
});
mlir::OpBuilder builder(context);
// We have processed all function. Attach common block variables to the
// global that represent the storage.
for (auto [global, exprs] : globalToGlobalExprsMap) {
Expand Down
24 changes: 24 additions & 0 deletions flang/test/Integration/debug-dwarf-flags.f90
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@@ -0,0 +1,24 @@
! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone -dwarf-version=5 %s \
! RUN: -o - | FileCheck --check-prefix=CHECK-DWARF5 %s
! RUN: %flang_fc1 -emit-llvm -debug-info-kind=line-tables-only -dwarf-version=5 \
! RUN: %s -o - | FileCheck --check-prefix=CHECK-DWARF5 %s
! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone -dwarf-version=4 %s \
! RUN: -o - | FileCheck --check-prefix=CHECK-DWARF4 %s
! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone -dwarf-version=3 %s \
! RUN: -o - | FileCheck --check-prefix=CHECK-DWARF3 %s
! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone -dwarf-version=2 %s \
! RUN: -o - | FileCheck --check-prefix=CHECK-DWARF2 %s
! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone %s -o -\
! RUN: | FileCheck --check-prefix=CHECK-WITHOUT-VERSION %s
! RUN: %flang_fc1 -emit-llvm -dwarf-version=5 %s -o - \
! RUN: | FileCheck --check-prefix=CHECK-WITHOUT-DEBUG-KIND %s
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It looks like both CHECK-WITHOUT-VERSION and CHECK-WITHOUT-DEBUG-KIND check for the absence of "Dwarf version" in the output. We can probably just use CHECK-WITHOUT-VERSION here to eliminate redundant check prefixes.

Suggested change
! RUN: | FileCheck --check-prefix=CHECK-WITHOUT-DEBUG-KIND %s
! RUN: | FileCheck --check-prefix=CHECK-WITHOUT-VERSION %s

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Done.


program test
end program test

! CHECK-DWARF5: !{i32 7, !"Dwarf Version", i32 5}
! CHECK-DWARF4: !{i32 7, !"Dwarf Version", i32 4}
! CHECK-DWARF3: !{i32 7, !"Dwarf Version", i32 3}
! CHECK-DWARF2: !{i32 7, !"Dwarf Version", i32 2}
! CHECK-WITHOUT-VERSION-NOT: "Dwarf Version"
! CHECK-WITHOUT-DEBUG-KIND-NOT: "Dwarf Version"
22 changes: 22 additions & 0 deletions flang/test/Transforms/debug-dwarf-version.fir
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@@ -0,0 +1,22 @@

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nit: Unnecessary empty line at start of file.

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Removed.

// RUN: fir-opt --add-debug-info="dwarf-version=5" --mlir-print-debuginfo %s \
// RUN: | FileCheck --check-prefix=CHECK-DWARF5 %s
// RUN: fir-opt --add-debug-info="dwarf-version=4" --mlir-print-debuginfo %s \
// RUN: | FileCheck --check-prefix=CHECK-DWARF4 %s
// RUN: fir-opt --add-debug-info="dwarf-version=3" --mlir-print-debuginfo %s \
// RUN: | FileCheck --check-prefix=CHECK-DWARF3 %s
// RUN: fir-opt --add-debug-info="dwarf-version=2" --mlir-print-debuginfo %s \
// RUN: | FileCheck --check-prefix=CHECK-DWARF2 %s
// RUN: fir-opt --add-debug-info= --mlir-print-debuginfo %s \
// RUN: | FileCheck --check-prefix=CHECK-WITHOUT-VERSION %s
// REQUIRES: system-linux

module {
} loc(#loc)
#loc = loc("simple.f90":0:0)

// CHECK-DWARF5: llvm.module_flags [#llvm.mlir.module_flag<max, "Dwarf Version", 5 : i32>]
// CHECK-DWARF4: llvm.module_flags [#llvm.mlir.module_flag<max, "Dwarf Version", 4 : i32>]
// CHECK-DWARF3: llvm.module_flags [#llvm.mlir.module_flag<max, "Dwarf Version", 3 : i32>]
// CHECK-DWARF2: llvm.module_flags [#llvm.mlir.module_flag<max, "Dwarf Version", 2 : i32>]
// CHECK-WITHOUT-VERSION-NOT: llvm.module_flags