Index: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp =================================================================== --- llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -3211,6 +3211,9 @@ // Check to see if we can DCE the instruction. if (isInstructionTriviallyDead(I, &TLI)) { LLVM_DEBUG(dbgs() << "IC: DCE: " << *I << '\n'); + + if (!salvageDebugInfo(*I)) + replaceDbgUsesWithUndef(I); eraseInstFromFunction(*I); ++NumDeadInst; MadeIRChange = true; Index: llvm/test/Transforms/InstCombine/cast-mul-select.ll =================================================================== --- llvm/test/Transforms/InstCombine/cast-mul-select.ll +++ llvm/test/Transforms/InstCombine/cast-mul-select.ll @@ -13,6 +13,8 @@ ; we preserve the debug information in the resulting ; instruction. ; DBGINFO-LABEL: @mul( +; DBGINFO-NEXT: call void @llvm.dbg.value(metadata i8 undef +; DBGINFO-NEXT: call void @llvm.dbg.value(metadata i8 undef ; DBGINFO-NEXT: [[C:%.*]] = mul i32 {{.*}} ; DBGINFO-NEXT: [[D:%.*]] = and i32 {{.*}} ; DBGINFO-NEXT: call void @llvm.dbg.value(metadata i32 [[C]] Index: llvm/test/Transforms/InstCombine/debuginfo-dce.ll =================================================================== --- llvm/test/Transforms/InstCombine/debuginfo-dce.ll +++ llvm/test/Transforms/InstCombine/debuginfo-dce.ll @@ -34,7 +34,7 @@ call void @llvm.dbg.value(metadata %struct.entry* %1, metadata !18, metadata !20), !dbg !19 ; CHECK: define void @salvage_load ; CHECK-NEXT: entry: -; CHECK-NOT: dbg.value +; CHECK-NEXT: dbg.value store %struct.entry* %1, %struct.entry** %im_not_dead, align 8 ret void, !dbg !21 } Index: llvm/test/Transforms/InstCombine/pr43893.ll =================================================================== --- /dev/null +++ llvm/test/Transforms/InstCombine/pr43893.ll @@ -0,0 +1,58 @@ +; RUN: opt -instcombine -S -o - %s | FileCheck %s + +@a = common dso_local global i8 0, align 1, !dbg !0 +@b = common dso_local global i8 0, align 1, !dbg !6 + +; Function Attrs: noinline nounwind uwtable +define dso_local i32 @main() #0 !dbg !13 { +entry: + %0 = load i8, i8* @a, align 1, !dbg !17 + %dec = add i8 %0, -1, !dbg !17 + store i8 %dec, i8* @a, align 1, !dbg !17 +;CHECK: call void @llvm.dbg.value(metadata i32 undef +;CHECK: call void @llvm.dbg.value(metadata i32 -8 +;CHECK call void @llvm.dbg.value(metadata i32 undef + %conv = sext i8 %dec to i32, !dbg !17 + call void @llvm.dbg.value(metadata i32 %conv, metadata !18, metadata !DIExpression()), !dbg !19 + call void @llvm.dbg.value(metadata i32 -8, metadata !20, metadata !DIExpression()), !dbg !19 + call void @llvm.dbg.value(metadata i32 %conv, metadata !20, metadata !DIExpression()), !dbg !19 + store i8 0, i8* @b, align 1, !dbg !21 + %cmp = icmp sgt i32 %conv, 0, !dbg !22 + %conv1 = zext i1 %cmp to i32, !dbg !22 + ret i32 0, !dbg !23 +} + +; Function Attrs: nounwind readnone speculatable willreturn +declare void @llvm.dbg.value(metadata, metadata, metadata) #1 + +attributes #0 = { noinline nounwind uwtable } +attributes #1 = { nounwind readnone speculatable willreturn } + +!llvm.dbg.cu = !{!2} +!llvm.module.flags = !{!9, !10, !11} +!llvm.ident = !{!12} + +!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression()) +!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 1, type: !8, isLocal: false, isDefinition: true) +!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None) +!3 = !DIFile(filename: "test", directory: "n") +!4 = !{} +!5 = !{!0, !6} +!6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression()) +!7 = distinct !DIGlobalVariable(name: "b", scope: !2, file: !3, line: 1, type: !8, isLocal: false, isDefinition: true) +!8 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char) +!9 = !{i32 2, !"Dwarf Version", i32 4} +!10 = !{i32 2, !"Debug Info Version", i32 3} +!11 = !{i32 1, !"wchar_size", i32 4} +!12 = !{!"clang version 10.0.0"} +!13 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 2, type: !14, scopeLine: 2, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !4) +!14 = !DISubroutineType(types: !15) +!15 = !{!16} +!16 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!17 = !DILocation(line: 4, column: 11, scope: !13) +!18 = !DILocalVariable(name: "c", scope: !13, file: !3, line: 4, type: !16) +!19 = !DILocation(line: 0, scope: !13) +!20 = !DILocalVariable(name: "l_1240", scope: !13, file: !3, line: 6, type: !16) +!21 = !DILocation(line: 10, column: 10, scope: !13) +!22 = !DILocation(line: 10, column: 5, scope: !13) +!23 = !DILocation(line: 12, column: 1, scope: !13) Index: llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll =================================================================== --- llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll +++ llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll @@ -8,10 +8,11 @@ define i32* @test1(i32 %P) !dbg !6 { ; CHECK-LABEL: @test1( -; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[P:%.*]] to i64, !dbg !12 -; CHECK-NEXT: [[A:%.*]] = alloca i32, i64 [[TMP1]], align 4, !dbg !12 -; CHECK-NEXT: call void @llvm.dbg.value(metadata i32* [[A]], metadata !11, metadata !DIExpression()), !dbg !12 -; CHECK-NEXT: ret i32* [[A]], !dbg !13 +; CHECK-NEXT: call void @llvm.dbg.value(metadata i8* undef, metadata !9, metadata !DIExpression()), !dbg !12 +; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[P:%.*]] to i64, !dbg !13 +; CHECK-NEXT: [[A:%.*]] = alloca i32, i64 [[TMP1]], align 4, !dbg !13 +; CHECK-NEXT: call void @llvm.dbg.value(metadata i32* [[A]], metadata !11, metadata !DIExpression()), !dbg !13 +; CHECK-NEXT: ret i32* [[A]], !dbg !14 ; %tmp = call i8* @llvm.stacksave(), !dbg !12 call void @llvm.dbg.value(metadata i8* %tmp, metadata !9, metadata !DIExpression()), !dbg !12