Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h =================================================================== --- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h +++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h @@ -372,6 +372,10 @@ DIExpression *Expr, DebugLoc DbgLoc, unsigned Order, bool IsVariadic); + /// Create a record for a kill location debug intrinsic. + void handleKillDebugValue(DILocalVariable *Var, DIExpression *Expr, + DebugLoc DbgLoc, unsigned Order); + /// Evict any dangling debug information, attempting to salvage it first. void resolveOrClearDbgInfo(); Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp =================================================================== --- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -1383,6 +1383,19 @@ << "\n"); } +void SelectionDAGBuilder::handleKillDebugValue(DILocalVariable *Var, + DIExpression *Expr, + DebugLoc DbgLoc, + unsigned Order) { + Value *Poison = PoisonValue::get(Type::getInt1Ty(*Context)); + DIExpression *NewExpr = DIExpression::get(*Context, std::nullopt); + if (auto Frag = Expr->getFragmentInfo()) + NewExpr = *DIExpression::createFragmentExpression( + NewExpr, Frag->OffsetInBits, Frag->SizeInBits); + handleDebugValue(Poison, Var, NewExpr, DbgLoc, Order, + /*IsVariadic*/ false); +} + bool SelectionDAGBuilder::handleDebugValue(ArrayRef Values, DILocalVariable *Var, DIExpression *Expr, DebugLoc DbgLoc, @@ -6208,11 +6221,14 @@ DILocalVariable *Variable = DI.getVariable(); DIExpression *Expression = DI.getExpression(); dropDanglingDebugInfo(Variable, Expression); - SmallVector Values(DI.getValues()); - if (Values.empty()) + + if (DI.isKillLocation()) { + handleKillDebugValue(Variable, Expression, DI.getDebugLoc(), SDNodeOrder); return; + } - if (llvm::is_contained(Values, nullptr)) + SmallVector Values(DI.getValues()); + if (Values.empty()) return; bool IsVariadic = DI.hasArgList(); Index: llvm/test/DebugInfo/X86/dbg-empty-metadata-lowering.ll =================================================================== --- /dev/null +++ llvm/test/DebugInfo/X86/dbg-empty-metadata-lowering.ll @@ -0,0 +1,49 @@ +; RUN: llc %s -stop-after=finalize-isel -o - | FileCheck %s --implicit-check-not=DBG + +;; Check that dbg.values with empty metadata are treated as kills (i.e. become +;; DBG_VALUE $noreg, ...). + +; CHECK: DBG_VALUE float 5.000000e+00 +; CHECK: @ext +; CHECK: DBG_VALUE $noreg +; CHECK: @ext + +target triple = "x86_64-unknown-linux-gnu" + +; Function Attrs: mustprogress uwtable +define dso_local void @fun() local_unnamed_addr #0 !dbg !9 { +entry: + call void @llvm.dbg.value(metadata float 5.000000e+00, metadata !13, metadata !DIExpression()), !dbg !15 + tail call void @ext(), !dbg !16 + call void @llvm.dbg.value(metadata !{}, metadata !13, metadata !DIExpression()), !dbg !15 + tail call void @ext(), !dbg !16 + ret void, !dbg !17 +} + +declare !dbg !18 void @ext() local_unnamed_addr +declare void @llvm.dbg.value(metadata, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!2, !3, !4, !5, !6, !7} +!llvm.ident = !{!8} + +!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 16.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None) +!1 = !DIFile(filename: "test.cpp", directory: "/") +!2 = !{i32 7, !"Dwarf Version", i32 5} +!3 = !{i32 2, !"Debug Info Version", i32 3} +!4 = !{i32 1, !"wchar_size", i32 4} +!5 = !{i32 8, !"PIC Level", i32 2} +!6 = !{i32 7, !"PIE Level", i32 2} +!7 = !{i32 7, !"uwtable", i32 2} +!8 = !{!"clang version 16.0.0"} +!9 = distinct !DISubprogram(name: "fun", linkageName: "fun", scope: !1, file: !1, line: 2, type: !10, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12) +!10 = !DISubroutineType(types: !11) +!11 = !{null} +!12 = !{!13} +!13 = !DILocalVariable(name: "f", scope: !9, file: !1, line: 3, type: !14) +!14 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float) +!15 = !DILocation(line: 0, scope: !9) +!16 = !DILocation(line: 4, column: 3, scope: !9) +!17 = !DILocation(line: 5, column: 1, scope: !9) +!18 = !DISubprogram(name: "ext", linkageName: "ext", scope: !1, file: !1, line: 1, type: !10, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !19) +!19 = !{}