From: Adrian Prantl Date: Sat, 22 Apr 2017 20:54:06 +0000 (+0000) Subject: Use DW_OP_stack_value when reconstructing variable values with arithmetic. X-Git-Tag: llvmorg-5.0.0-rc1~6944 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a2d25ac14a9555eb23207a7b4007302de9182d04;p=platform%2Fupstream%2Fllvm.git Use DW_OP_stack_value when reconstructing variable values with arithmetic. When the location description of a source variable involves arithmetic on the value itself, it needs to be marked with DW_OP_stack_value since it is not describing the variable's location, but rather its value. This is a follow-up to r297971 and fixes the source testcase quoted in the comment in debuginfo-dce.ll. rdar://problem/30725338 llvm-svn: 301093 --- diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp index 09924d1..357c303 100644 --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -1268,21 +1268,37 @@ static void appendOffset(SmallVectorImpl &Ops, int64_t Offset) { } } -/// Prepend \p DIExpr with a deref and offset operation. +enum { WithStackValue = true }; + +/// Prepend \p DIExpr with a deref and offset operation and optionally turn it +/// into a stack value. static DIExpression *prependDIExpr(DIBuilder &Builder, DIExpression *DIExpr, - bool Deref, int64_t Offset) { - if (!Deref && !Offset) + bool Deref, int64_t Offset = 0, + bool StackValue = false) { + if (!Deref && !Offset && !StackValue) return DIExpr; - // Create a copy of the original DIDescriptor for user variable, prepending - // "deref" operation to a list of address elements, as new llvm.dbg.declare - // will take a value storing address of the memory for variable, not - // alloca itself. - SmallVector Ops; + + SmallVector Ops; + appendOffset(Ops, Offset); if (Deref) Ops.push_back(dwarf::DW_OP_deref); - appendOffset(Ops, Offset); if (DIExpr) - Ops.append(DIExpr->elements_begin(), DIExpr->elements_end()); + for (auto Op : DIExpr->expr_ops()) { + // A DW_OP_stack_value comes at the end, but before a DW_OP_LLVM_fragment. + if (StackValue) { + if (Op.getOp() == dwarf::DW_OP_stack_value) + StackValue = false; + else if (Op.getOp() == dwarf::DW_OP_LLVM_fragment) { + Ops.push_back(dwarf::DW_OP_stack_value); + StackValue = false; + } + } + Ops.push_back(Op.getOp()); + for (unsigned I = 0; I < Op.getNumArgs(); ++I) + Ops.push_back(Op.getArg(I)); + } + if (StackValue) + Ops.push_back(dwarf::DW_OP_stack_value); return Builder.createExpression(Ops); } @@ -1374,12 +1390,15 @@ void llvm::salvageDebugInfo(Instruction &I) { unsigned BitWidth = M.getDataLayout().getPointerSizeInBits(GEP->getPointerAddressSpace()); APInt Offset(BitWidth, 0); - // Rewrite a constant GEP into a DIExpression. + // Rewrite a constant GEP into a DIExpression. Since we are performing + // arithmetic to compute the variable's *value* in the DIExpression, we + // need to mark the expression with a DW_OP_stack_value. if (GEP->accumulateConstantOffset(M.getDataLayout(), Offset)) { auto *DIExpr = DVI->getExpression(); DIBuilder DIB(M, /*AllowUnresolved*/ false); // GEP offsets are i32 and thus always fit into an int64_t. - DIExpr = prependDIExpr(DIB, DIExpr, NoDeref, Offset.getSExtValue()); + DIExpr = prependDIExpr(DIB, DIExpr, NoDeref, Offset.getSExtValue(), + WithStackValue); DVI->setOperand(0, MDWrap(I.getOperand(0))); DVI->setOperand(3, MetadataAsValue::get(I.getContext(), DIExpr)); DEBUG(dbgs() << "SALVAGE: " << *DVI << '\n'); @@ -1391,7 +1410,7 @@ void llvm::salvageDebugInfo(Instruction &I) { // Rewrite the load into DW_OP_deref. auto *DIExpr = DVI->getExpression(); DIBuilder DIB(M, /*AllowUnresolved*/ false); - DIExpr = prependDIExpr(DIB, DIExpr, WithDeref, 0); + DIExpr = prependDIExpr(DIB, DIExpr, WithDeref); DVI->setOperand(0, MDWrap(I.getOperand(0))); DVI->setOperand(3, MetadataAsValue::get(I.getContext(), DIExpr)); DEBUG(dbgs() << "SALVAGE: " << *DVI << '\n'); diff --git a/llvm/test/Transforms/InstCombine/debuginfo-dce.ll b/llvm/test/Transforms/InstCombine/debuginfo-dce.ll index e23aef7..58e9d7d 100644 --- a/llvm/test/Transforms/InstCombine/debuginfo-dce.ll +++ b/llvm/test/Transforms/InstCombine/debuginfo-dce.ll @@ -23,7 +23,6 @@ target triple = "x86_64-apple-macosx10.12.0" %struct.entry = type { %struct.entry* } -; Function Attrs: nounwind ssp uwtable define void @salvage_load(%struct.entry** %queue) local_unnamed_addr #0 !dbg !14 { entry: %im_not_dead = alloca %struct.entry* @@ -38,7 +37,6 @@ entry: ret void, !dbg !21 } -; Function Attrs: nounwind ssp uwtable define void @salvage_bitcast(%struct.entry* %queue) local_unnamed_addr #0 !dbg !14 { entry: %im_not_dead = alloca i8* @@ -53,24 +51,54 @@ entry: ret void, !dbg !21 } -; Function Attrs: nounwind ssp uwtable -define void @salvage_gep(%struct.entry* %queue, %struct.entry* %end) local_unnamed_addr #0 !dbg !14 { +define void @salvage_gep0(%struct.entry* %queue, %struct.entry* %end) local_unnamed_addr #0 !dbg !14 { entry: %im_not_dead = alloca %struct.entry** %0 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19 %1 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19 call void @llvm.dbg.value(metadata %struct.entry** %1, i64 0, metadata !18, metadata !20), !dbg !19 -; CHECK: define void @salvage_gep +; CHECK: define void @salvage_gep0 ; CHECK-NEXT: entry: ; CHECK-NEXT: call void @llvm.dbg.value(metadata %struct.entry* %queue, i64 0, -; CHECK-SAME: metadata ![[GEP_EXPR:[0-9]+]]) +; CHECK-SAME: metadata ![[GEP0_EXPR:[0-9]+]]) + store %struct.entry** %1, %struct.entry*** %im_not_dead, align 8 + ret void, !dbg !21 +} + +define void @salvage_gep1(%struct.entry* %queue, %struct.entry* %end) local_unnamed_addr #0 !dbg !14 { +entry: + %im_not_dead = alloca %struct.entry** + %0 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19 + %1 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19 + call void @llvm.dbg.value(metadata %struct.entry** %1, i64 0, metadata !18, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)), !dbg !19 +; CHECK: define void @salvage_gep1 +; CHECK-NEXT: entry: +; CHECK-NEXT: call void @llvm.dbg.value(metadata %struct.entry* %queue, i64 0, +; CHECK-SAME: metadata ![[GEP1_EXPR:[0-9]+]]) + store %struct.entry** %1, %struct.entry*** %im_not_dead, align 8 + ret void, !dbg !21 +} + +define void @salvage_gep2(%struct.entry* %queue, %struct.entry* %end) local_unnamed_addr #0 !dbg !14 { +entry: + %im_not_dead = alloca %struct.entry** + %0 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19 + %1 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19 + call void @llvm.dbg.value(metadata %struct.entry** %1, i64 0, metadata !18, metadata !DIExpression(DW_OP_stack_value)), !dbg !19 +; CHECK: define void @salvage_gep2 +; CHECK-NEXT: entry: +; CHECK-NEXT: call void @llvm.dbg.value(metadata %struct.entry* %queue, i64 0, +; CHECK-SAME: metadata ![[GEP2_EXPR:[0-9]+]]) store %struct.entry** %1, %struct.entry*** %im_not_dead, align 8 ret void, !dbg !21 } ; CHECK: ![[LOAD_EXPR]] = !DIExpression(DW_OP_deref, DW_OP_plus, 0) ; CHECK: ![[BITCAST_EXPR]] = !DIExpression(DW_OP_plus, 0) -; CHECK: ![[GEP_EXPR]] = !DIExpression(DW_OP_minus, 8, DW_OP_plus, 0) +; CHECK: ![[GEP0_EXPR]] = !DIExpression(DW_OP_minus, 8, DW_OP_plus, 0, DW_OP_stack_value) +; CHECK: ![[GEP1_EXPR]] = !DIExpression(DW_OP_minus, 8, DW_OP_stack_value, +; CHECK-SAME: DW_OP_LLVM_fragment, 0, 32) +; CHECK: ![[GEP2_EXPR]] = !DIExpression(DW_OP_minus, 8, DW_OP_stack_value) ; Function Attrs: nounwind readnone declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1