Index: include/llvm/Transforms/Utils/Local.h =================================================================== --- include/llvm/Transforms/Utils/Local.h +++ include/llvm/Transforms/Utils/Local.h @@ -32,6 +32,7 @@ class Instruction; class CallInst; class DbgDeclareInst; +class DbgValueInst; class StoreInst; class LoadInst; class Value; @@ -48,6 +49,8 @@ template class SmallVectorImpl; +typedef SmallVector DbgValueList; + //===----------------------------------------------------------------------===// // Local constant propagation. // @@ -263,6 +266,11 @@ bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI, LoadInst *LI, DIBuilder &Builder); +/// Inserts a llvm.dbg.value intrinsic after a phi of an alloca'd value +/// that has an associated llvm.dbg.decl intrinsic. +bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI, + PHINode *LI, DIBuilder &Builder); + /// Lowers llvm.dbg.declare intrinsics into appropriate set of /// llvm.dbg.value intrinsics. bool LowerDbgDeclare(Function &F); @@ -270,6 +278,9 @@ /// Finds the llvm.dbg.declare intrinsic corresponding to an alloca, if any. DbgDeclareInst *FindAllocaDbgDeclare(Value *V); +/// Finds the llvm.dbg.value intrinsics corresponding to an alloca, if any. +void FindAllocaDbgValues(DbgValueList &DbgValues, Value *V); + /// Replaces llvm.dbg.declare instruction when the address it describes /// is replaced with a new value. If Deref is true, an additional DW_OP_deref is /// prepended to the expression. If Offset is non-zero, a constant displacement Index: lib/Transforms/Utils/Local.cpp =================================================================== --- lib/Transforms/Utils/Local.cpp +++ lib/Transforms/Utils/Local.cpp @@ -1053,6 +1053,24 @@ return false; } +/// See if there is a dbg.value intrinsic for DIVar for the PHI node. +static bool PhiHasDebugValue(DILocalVariable *DIVar, + DIExpression *DIExpr, + PHINode *APN) { + // Since we can't guarantee that the original dbg.declare instrinsic + // is removed by LowerDbgDeclare(), we need to make sure that we are + // not inserting the same dbg.value intrinsic over and over. + DbgValueList DbgValues; + FindAllocaDbgValues(DbgValues, APN); + for (auto DVI : DbgValues) { + assert (DVI->getValue() == APN); + assert (DVI->getOffset() == 0); + if ((DVI->getVariable() == DIVar) && (DVI->getExpression() == DIExpr)) + return true; + } + return false; +} + /// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value /// that has an associated llvm.dbg.decl intrinsic. bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI, @@ -1120,6 +1138,23 @@ return true; } +/// Inserts a llvm.dbg.value intrinsic after a phi +/// that has an associated llvm.dbg.decl intrinsic. +bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI, + PHINode *APN, DIBuilder &Builder) { + auto *DIVar = DDI->getVariable(); + auto *DIExpr = DDI->getExpression(); + assert(DIVar && "Missing variable"); + + if (PhiHasDebugValue(DIVar, DIExpr, APN)) + return true; + + Instruction *DbgValue = Builder.insertDbgValueIntrinsic( + APN, 0, DIVar, DIExpr, DDI->getDebugLoc(), (Instruction *)nullptr); + DbgValue->insertBefore(&*APN->getParent()->getFirstInsertionPt()); + return true; +} + /// Determine whether this alloca is either a VLA or an array. static bool isArray(AllocaInst *AI) { return AI->isArrayAllocation() || @@ -1187,6 +1222,16 @@ return nullptr; } +/// FindAllocaDbgValues - Finds the llvm.dbg.value intrinsics describing the +/// alloca 'V', if any. +void llvm::FindAllocaDbgValues(DbgValueList &DbgValues, Value *V) { + if (auto *L = LocalAsMetadata::getIfExists(V)) + if (auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L)) + for (User *U : MDV->users()) + if (DbgValueInst *DVI = dyn_cast(U)) + DbgValues.push_back(DVI); +} + static void DIExprAddDeref(SmallVectorImpl &Expr) { Expr.push_back(dwarf::DW_OP_deref); } Index: lib/Transforms/Utils/PromoteMemoryToRegister.cpp =================================================================== --- lib/Transforms/Utils/PromoteMemoryToRegister.cpp +++ lib/Transforms/Utils/PromoteMemoryToRegister.cpp @@ -907,6 +907,8 @@ // The currently active variable for this block is now the PHI. IncomingVals[AllocaNo] = APN; + if (DbgDeclareInst *DDI = AllocaDbgDeclares[AllocaNo]) + ConvertDebugDeclareToDebugValue(DDI, APN, DIB); // Get the next phi node. ++PNI; Index: test/Transforms/Util/mem2reg-dbg.ll =================================================================== --- test/Transforms/Util/mem2reg-dbg.ll +++ test/Transforms/Util/mem2reg-dbg.ll @@ -0,0 +1,76 @@ +; RUN: opt -mem2reg -S < %s | FileCheck %s + +; Test that a @llvm.dbg.value node is created to describe the value returned by a phi node when +; lowering a @llvm.dbg.declare node + +; Created from the C code, compiled with -O0 -g: +; +; int func(int a) +; { +; int c = 1; +; if (a < 0 ) { +; c = 12; +; } +; return c; +; } + +; Function Attrs: nounwind +define i32 @func(i32 %a) #0 !dbg !8 { +entry: + %a.addr = alloca i32, align 4 + %c = alloca i32, align 4 + store i32 %a, i32* %a.addr, align 4 + call void @llvm.dbg.declare(metadata i32* %a.addr, metadata !12, metadata !13), !dbg !14 + call void @llvm.dbg.declare(metadata i32* %c, metadata !15, metadata !13), !dbg !16 + store i32 1, i32* %c, align 4, !dbg !16 + %0 = load i32, i32* %a.addr, align 4, !dbg !17 + %cmp = icmp slt i32 %0, 0, !dbg !19 + br i1 %cmp, label %if.then, label %if.end, !dbg !20 + +if.then: ; preds = %entry + store i32 12, i32* %c, align 4, !dbg !21 + br label %if.end, !dbg !23 + +if.end: ; preds = %if.then, %entry + %1 = load i32, i32* %c, align 4, !dbg !24 +; CHECK: [[PHI:%.*]] = phi i32 [ 12, {{.*}} ], [ 1, {{.*}} ] +; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 [[PHI]], i64 0, metadata !15, metadata !13), !dbg !16 + ret i32 %1, !dbg !25 +} + +; Function Attrs: nounwind readnone +declare void @llvm.dbg.declare(metadata, metadata, metadata) #1 + +attributes #1 = { nounwind readnone } + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!3, !4, !5, !6} +!llvm.ident = !{!7} + +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2) +!1 = !DIFile(filename: "a.c", directory: "/tmp") +!2 = !{} +!3 = !{i32 2, !"Dwarf Version", i32 4} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!5 = !{i32 1, !"wchar_size", i32 4} +!6 = !{i32 1, !"min_enum_size", i32 4} +!7 = !{!"clang"} +!8 = distinct !DISubprogram(name: "func", scope: !1, file: !1, line: 1, type: !9, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2) +!9 = !DISubroutineType(types: !10) +!10 = !{!11, !11} +!11 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed) +!12 = !DILocalVariable(name: "a", arg: 1, scope: !8, file: !1, line: 1, type: !11) +!13 = !DIExpression() +!14 = !DILocation(line: 1, column: 14, scope: !8) +!15 = !DILocalVariable(name: "c", scope: !8, file: !1, line: 3, type: !11) +!16 = !DILocation(line: 3, column: 6, scope: !8) +!17 = !DILocation(line: 4, column: 6, scope: !18) +!18 = distinct !DILexicalBlock(scope: !8, file: !1, line: 4, column: 6) +!19 = !DILocation(line: 4, column: 8, scope: !18) +!20 = !DILocation(line: 4, column: 6, scope: !8) +!21 = !DILocation(line: 5, column: 5, scope: !22) +!22 = distinct !DILexicalBlock(scope: !18, file: !1, line: 4, column: 14) +!23 = !DILocation(line: 6, column: 2, scope: !22) +!24 = !DILocation(line: 7, column: 9, scope: !8) +!25 = !DILocation(line: 7, column: 2, scope: !8) +