Index: llvm/trunk/lib/Transforms/IPO/DeadArgumentElimination.cpp =================================================================== --- llvm/trunk/lib/Transforms/IPO/DeadArgumentElimination.cpp +++ llvm/trunk/lib/Transforms/IPO/DeadArgumentElimination.cpp @@ -24,7 +24,6 @@ #include "llvm/IR/Attributes.h" #include "llvm/IR/BasicBlock.h" #include "llvm/IR/CallSite.h" -#include "llvm/IR/Constant.h" #include "llvm/IR/Constants.h" #include "llvm/IR/DerivedTypes.h" #include "llvm/IR/Function.h" @@ -954,16 +953,16 @@ ArgAttrVec.clear(); Instruction *New = NewCS.getInstruction(); - if (!Call->use_empty()) { + if (!Call->use_empty() || Call->isUsedByMetadata()) { if (New->getType() == Call->getType()) { // Return type not changed? Just replace users then. Call->replaceAllUsesWith(New); New->takeName(Call); } else if (New->getType()->isVoidTy()) { - // Our return value has uses, but they will get removed later on. - // Replace by null for now. + // If the return value is dead, replace any uses of it with undef + // (any non-debug value uses will get removed later on). if (!Call->getType()->isX86_MMXTy()) - Call->replaceAllUsesWith(Constant::getNullValue(Call->getType())); + Call->replaceAllUsesWith(UndefValue::get(Call->getType())); } else { assert((RetTy->isStructTy() || RetTy->isArrayTy()) && "Return type changed, but not into a void. The old return type" @@ -1023,10 +1022,10 @@ I2->takeName(&*I); ++I2; } else { - // If this argument is dead, replace any uses of it with null constants - // (these are guaranteed to become unused later on). + // If this argument is dead, replace any uses of it with undef + // (any non-debug value uses will get removed later on). if (!I->getType()->isX86_MMXTy()) - I->replaceAllUsesWith(Constant::getNullValue(I->getType())); + I->replaceAllUsesWith(UndefValue::get(I->getType())); } // If we change the return value of the function we must rewrite any return Index: llvm/trunk/test/Transforms/DeadArgElim/dbginfo-update-dbgval-local.ll =================================================================== --- llvm/trunk/test/Transforms/DeadArgElim/dbginfo-update-dbgval-local.ll +++ llvm/trunk/test/Transforms/DeadArgElim/dbginfo-update-dbgval-local.ll @@ -0,0 +1,67 @@ +; RUN: opt -deadargelim -S < %s | FileCheck %s + +; Verify that the dbg.value intrinsics that use the dead argument and return +; value are marked as undef to indicate that the values are optimized out. + +; Reproducer for PR23260. + +; CHECK-LABEL: define internal void @bar() +; CHECK: call void @llvm.dbg.value(metadata i32 undef, metadata ![[LOCAL1:[0-9]+]] +; CHECK: call void @sink() + +; Function Attrs: alwaysinline nounwind uwtable +define internal i32 @bar(i32 %deadarg) #1 !dbg !10 { +entry: + call void @llvm.dbg.value(metadata i32 %deadarg, metadata !15, metadata !DIExpression()), !dbg !17 + call void @sink(), !dbg !17 + ret i32 123, !dbg !17 +} + +; CHECK-LABEL: define void @foo() +; CHECK: call void @bar() +; CHECK: call void @llvm.dbg.value(metadata i32 undef, metadata ![[LOCAL2:[0-9]+]] +; CHECK: call void @bar() + +; Function Attrs: nounwind uwtable +define void @foo() #0 !dbg !6 { +entry: + %deadret = call i32 @bar(i32 0), !dbg !9 + call void @llvm.dbg.value(metadata i32 %deadret, metadata !16, metadata !DIExpression()), !dbg !9 + call i32 @bar(i32 1), !dbg !9 + ret void, !dbg !9 +} + +declare void @sink() local_unnamed_addr + +; Function Attrs: nounwind readnone speculatable +declare void @llvm.dbg.value(metadata, metadata, metadata) #2 + +attributes #0 = { nounwind uwtable } +attributes #1 = { alwaysinline nounwind uwtable } +attributes #2 = { nounwind readnone speculatable } + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!3, !4} +!llvm.ident = !{!5} + +; CHECK: ![[LOCAL1]] = !DILocalVariable(name: "local1" +; CHECK: ![[LOCAL2]] = !DILocalVariable(name: "local2" + +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 8.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None) +!1 = !DIFile(filename: "pr23260.c", directory: "/") +!2 = !{} +!3 = !{i32 2, !"Dwarf Version", i32 4} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!5 = !{!"clang version 8.0.0"} +!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 3, type: !7, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2) +!7 = !DISubroutineType(types: !8) +!8 = !{null} +!9 = !DILocation(line: 4, column: 3, scope: !6) +!10 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 2, type: !11, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !14) +!11 = !DISubroutineType(types: !12) +!12 = !{!13, !13} +!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!14 = !{!15} +!15 = !DILocalVariable(name: "local1", arg: 1, scope: !10, file: !1, line: 2, type: !13) +!16 = !DILocalVariable(name: "local2", arg: 1, scope: !6, file: !1, line: 2, type: !13) +!17 = !DILocation(line: 2, column: 52, scope: !10)