Index: lib/CodeGen/CodeGenPrepare.cpp =================================================================== --- lib/CodeGen/CodeGenPrepare.cpp +++ lib/CodeGen/CodeGenPrepare.cpp @@ -2362,6 +2362,8 @@ /// Keep track of the original uses (pair Instruction, Index). SmallVector OriginalUses; + /// Keep track of the debug users. + SmallVector DbgValues; using use_iterator = SmallVectorImpl::iterator; @@ -2375,6 +2377,10 @@ Instruction *UserI = cast(U.getUser()); OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo())); } + // Record the debug uses separately. They are not in the instruction's + // use list, but they are replaced by RAUW. + findDbgValues(DbgValues, Inst); + // Now, we can replace the uses. Inst->replaceAllUsesWith(New); } @@ -2387,6 +2393,12 @@ UseIt != EndIt; ++UseIt) { UseIt->Inst->setOperand(UseIt->Idx, Inst); } + // Reinstate the original debug uses. + for (auto *DVI: DbgValues) { + LLVMContext &Ctx = Inst->getType()->getContext(); + auto *MV = MetadataAsValue::get(Ctx, ValueAsMetadata::get(Inst)); + DVI->setOperand(0, MV); + } } }; Index: test/DebugInfo/Generic/codegenprep-value.ll =================================================================== --- /dev/null +++ test/DebugInfo/Generic/codegenprep-value.ll @@ -0,0 +1,75 @@ +; RUN: opt -codegenprepare -S %s | FileCheck %s +; +; Generated from the following source with: +; clang -O2 -g -S -emit-llvm -mllvm -stop-after=indirectbr-expand test.cpp +; +; extern void use(int); +; extern int foo(long long); +; +; void test(int p) +; { +; int i = p + 4; +; (void)foo(i); // sign extension of i +; if (p) +; return; +; use(i); // use of original i +; } +; +; PR39845: Check that CodeGenPrepare does not drop the reference to a local when it is +; sign-extended and used later. +; +; CHECK: define{{.*}}test +; CHECK: call{{.*}}dbg.value(metadata i32 %p +; CHECK: call{{.*}}dbg.value(metadata i32 %add +; +define dso_local void @_Z4testi(i32 %p) local_unnamed_addr !dbg !7 { +entry: + call void @llvm.dbg.value(metadata i32 %p, metadata !12, metadata !DIExpression()), !dbg !14 + %add = add nsw i32 %p, 4, !dbg !15 + call void @llvm.dbg.value(metadata i32 %add, metadata !13, metadata !DIExpression()), !dbg !16 + %conv = sext i32 %add to i64, !dbg !17 + %call = tail call i32 @_Z3foox(i64 %conv), !dbg !18 + %tobool = icmp eq i32 %p, 0, !dbg !19 + br i1 %tobool, label %if.end, label %cleanup, !dbg !21 + +if.end: + tail call void @_Z3usei(i32 %add), !dbg !22 + br label %cleanup, !dbg !23 + +cleanup: + ret void, !dbg !23 +} + +declare dso_local i32 @_Z3foox(i64) local_unnamed_addr +declare dso_local void @_Z3usei(i32) local_unnamed_addr + +declare void @llvm.dbg.value(metadata, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!3, !4, !5} +!llvm.ident = !{!6} + +!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 (trunk 348209)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None) +!1 = !DIFile(filename: "test.cpp", directory: "/home/test/src") +!2 = !{} +!3 = !{i32 2, !"Dwarf Version", i32 4} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!5 = !{i32 1, !"wchar_size", i32 4} +!6 = !{!"clang version 8.0.0 (trunk 348209)"} +!7 = distinct !DISubprogram(name: "test", linkageName: "_Z4testi", scope: !1, file: !1, line: 4, type: !8, scopeLine: 5, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11) +!8 = !DISubroutineType(types: !9) +!9 = !{null, !10} +!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!11 = !{!12, !13} +!12 = !DILocalVariable(name: "p", arg: 1, scope: !7, file: !1, line: 4, type: !10) +!13 = !DILocalVariable(name: "i", scope: !7, file: !1, line: 6, type: !10) +!14 = !DILocation(line: 4, column: 15, scope: !7) +!15 = !DILocation(line: 6, column: 13, scope: !7) +!16 = !DILocation(line: 6, column: 7, scope: !7) +!17 = !DILocation(line: 7, column: 13, scope: !7) +!18 = !DILocation(line: 7, column: 9, scope: !7) +!19 = !DILocation(line: 8, column: 7, scope: !20) +!20 = distinct !DILexicalBlock(scope: !7, file: !1, line: 8, column: 7) +!21 = !DILocation(line: 8, column: 7, scope: !7) +!22 = !DILocation(line: 10, column: 3, scope: !7) +!23 = !DILocation(line: 11, column: 1, scope: !7)