Index: include/llvm/MC/MCTargetOptions.h =================================================================== --- include/llvm/MC/MCTargetOptions.h +++ include/llvm/MC/MCTargetOptions.h @@ -58,6 +58,9 @@ /// Preserve Comments in Assembly. bool PreserveAsmComments : 1; + /// Emit debug directives only, disable emission of the debug sections. + bool DebugDirectivesOnly : 1; + int DwarfVersion = 0; std::string ABIName; Index: lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp =================================================================== --- lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp +++ lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp @@ -269,6 +269,10 @@ } void DwarfCompileUnit::initStmtList() { + // Do not emit DWARF sections if it is not required. + if (Asm->TM.Options.MCOptions.DebugDirectivesOnly) + return; + // Define start line table label for each Compile Unit. MCSymbol *LineTableStartSym; const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering(); Index: lib/CodeGen/AsmPrinter/DwarfDebug.cpp =================================================================== --- lib/CodeGen/AsmPrinter/DwarfDebug.cpp +++ lib/CodeGen/AsmPrinter/DwarfDebug.cpp @@ -624,6 +624,11 @@ M->debug_compile_units_end()); // Tell MMI whether we have debug info. MMI->setDebugInfoAvailability(NumDebugCUs > 0); + + // Do not emit DWARF sections if it is not required. + if (Asm->TM.Options.MCOptions.DebugDirectivesOnly) + return; + SingleCU = NumDebugCUs == 1; DenseMap> GVMap; @@ -813,6 +818,10 @@ if (!MMI->hasDebugInfo()) return; + // Do not emit DWARF sections if it is not required. + if (Asm->TM.Options.MCOptions.DebugDirectivesOnly) + return; + // Finalize the debug info for the module. finalizeModuleInfo(); Index: lib/MC/MCTargetOptions.cpp =================================================================== --- lib/MC/MCTargetOptions.cpp +++ lib/MC/MCTargetOptions.cpp @@ -18,7 +18,7 @@ MCSaveTempLabels(false), MCUseDwarfDirectory(false), MCIncrementalLinkerCompatible(false), MCPIECopyRelocations(false), ShowMCEncoding(false), ShowMCInst(false), AsmVerbose(false), - PreserveAsmComments(true) {} + PreserveAsmComments(true), DebugDirectivesOnly(false) {} StringRef MCTargetOptions::getABIName() const { return ABIName; Index: test/DebugInfo/Generic/directives-only.ll =================================================================== --- /dev/null +++ test/DebugInfo/Generic/directives-only.ll @@ -0,0 +1,65 @@ +; RUN: llc -filetype=asm -asm-verbose=0 -O0 -debug-directives-only=true < %s | FileCheck %s --check-prefixes=DISABLED,CHECK +; RUN: llc -filetype=asm -asm-verbose=0 -O0 -debug-directives-only=false < %s | FileCheck %s --check-prefixes=ENABLED,CHECK + +; Check that the assembly output properly handles is_stmt changes. And since +; we're testing anyway, check the integrated assembler too. + +; Generated with clang from multiline.c: +; void f1(); +; void f2() { +; f1(); f1(); f1(); +; f1(); f1(); f1(); +; } + + +; CHECK: .file 1 "/tmp/dbginfo{{.*}}multiline.c" +; CHECK: .loc 1 2 0 +; CHECK: .loc 1 3 3 +; CHECK: .loc 1 3 9 +; CHECK: .loc 1 3 15 +; CHECK: .loc 1 4 3 +; CHECK: .loc 1 4 9 +; CHECK: .loc 1 4 15 +; CHECK: .loc 1 5 1 + +; ENABLED: .section .{{debug.*}} +; DISABLED-NOT: .section .{{debug.*}} + +; Function Attrs: nounwind uwtable +define void @f2() #0 !dbg !4 { +entry: + call void (...) @f1(), !dbg !11 + call void (...) @f1(), !dbg !12 + call void (...) @f1(), !dbg !13 + call void (...) @f1(), !dbg !14 + call void (...) @f1(), !dbg !15 + call void (...) @f1(), !dbg !16 + ret void, !dbg !17 +} + +declare void @f1(...) #1 + +attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } +attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!8, !9} +!llvm.ident = !{!10} + +!0 = distinct !DICompileUnit(language: DW_LANG_C99, producer: "clang version 3.6.0 (trunk 225000) (llvm/trunk 224999)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2) +!1 = !DIFile(filename: "multiline.c", directory: "/tmp/dbginfo") +!2 = !{} +!4 = distinct !DISubprogram(name: "f2", line: 2, isLocal: false, isDefinition: true, isOptimized: false, unit: !0, scopeLine: 2, file: !1, scope: !5, type: !6, variables: !2) +!5 = !DIFile(filename: "multiline.c", directory: "/tmp/dbginfo") +!6 = !DISubroutineType(types: !7) +!7 = !{null} +!8 = !{i32 2, !"Dwarf Version", i32 4} +!9 = !{i32 2, !"Debug Info Version", i32 3} +!10 = !{!"clang version 3.6.0 (trunk 225000) (llvm/trunk 224999)"} +!11 = !DILocation(line: 3, column: 3, scope: !4) +!12 = !DILocation(line: 3, column: 9, scope: !4) +!13 = !DILocation(line: 3, column: 15, scope: !4) +!14 = !DILocation(line: 4, column: 3, scope: !4) +!15 = !DILocation(line: 4, column: 9, scope: !4) +!16 = !DILocation(line: 4, column: 15, scope: !4) +!17 = !DILocation(line: 5, column: 1, scope: !4) Index: tools/llc/llc.cpp =================================================================== --- tools/llc/llc.cpp +++ tools/llc/llc.cpp @@ -80,6 +80,11 @@ cl::desc("Preserve Comments in outputted assembly"), cl::init(true)); +static cl::opt DebugDirectivesOnly( + "debug-directives-only", cl::Hidden, + cl::desc("Emit only debug directives, do not emit DWARF sections."), + cl::init(false)); + // Determine optimization level. static cl::opt OptLevel("O", @@ -442,6 +447,7 @@ Options.MCOptions.PreserveAsmComments = PreserveComments; Options.MCOptions.IASSearchPaths = IncludeDirs; Options.MCOptions.SplitDwarfFile = SplitDwarfFile; + Options.MCOptions.DebugDirectivesOnly = DebugDirectivesOnly; std::unique_ptr Target(TheTarget->createTargetMachine( TheTriple.getTriple(), CPUStr, FeaturesStr, Options, getRelocModel(),