Index: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp =================================================================== --- llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp +++ llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp @@ -143,7 +143,7 @@ ++NumFastOther; // Try to preserve debug information attached to the dead instruction. - salvageDebugInfo(*DeadInst); + salvageDebugInfoOrMarkUndef(*DeadInst); // This instruction is dead, zap it, in stages. Start by removing it from // MemDep, which needs to know the operands and needs it to be in the Index: llvm/test/DebugInfo/X86/dead-store-elimination-marks-undef.ll =================================================================== --- /dev/null +++ llvm/test/DebugInfo/X86/dead-store-elimination-marks-undef.ll @@ -0,0 +1,35 @@ +; RUN: opt -mtriple=x86_64-- -S --dse %s -o - | FileCheck %s +; Ensure that we can mark a value as undefined when performing dead +; store elimination. +; Bugzilla #45080 + +@b = common dso_local local_unnamed_addr global i32 0, align 1 + +define dso_local i32 @main() local_unnamed_addr !dbg !7 { + %1 = alloca i32, align 4 + %2 = load i32, i32* @b, align 1, !dbg !13 + ; CHECK: call void @llvm.dbg.value(metadata i32 undef + call void @llvm.dbg.value(metadata i32 %2, metadata !12, metadata !DIExpression()), !dbg !13 + store i32 %2, i32* %1, align 4, !dbg !13 + ret i32 0, !dbg !13 +} + +declare void @llvm.dbg.value(metadata, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!3, !4} +!llvm.ident = !{!6} + +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !2, nameTableKind: None) +!1 = !DIFile(filename: "dead-store-elimination-marks-undef.ll", directory: "/temp/bz45080") +!2 = !{} +!3 = !{i32 2, !"Dwarf Version", i32 4} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!6 = !{!"clang version 10.0.0"} +!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 3, type: !8, scopeLine: 3, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11) +!8 = !DISubroutineType(types: !9) +!9 = !{!10} +!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!11 = !{!12} +!12 = !DILocalVariable(name: "l_2864", scope: !7, file: !1, line: 4, type: !10) +!13 = !DILocation(line: 5, column: 12, scope: !7)