Index: include/llvm/IR/Instructions.h =================================================================== --- include/llvm/IR/Instructions.h +++ include/llvm/IR/Instructions.h @@ -98,6 +98,10 @@ return cast(Instruction::getType()); } + /// Get allocation size in bits. Returns None if size can't be determined, + /// e.g. in case of a VLA. + Optional getAllocationSizeInBits(const DataLayout &DL) const; + /// Return the type that is being allocated by the instruction. Type *getAllocatedType() const { return AllocatedType; } /// for use only in special circumstances that need to generically Index: lib/IR/Instructions.cpp =================================================================== --- lib/IR/Instructions.cpp +++ lib/IR/Instructions.cpp @@ -44,6 +44,22 @@ using namespace llvm; +//===----------------------------------------------------------------------===// +// AllocaInst Class +//===----------------------------------------------------------------------===// + +Optional +AllocaInst::getAllocationSizeInBits(const DataLayout &DL) const { + uint64_t Size = DL.getTypeAllocSizeInBits(getAllocatedType()); + if (isArrayAllocation()) { + auto C = dyn_cast(getArraySize()); + if (!C) + return None; + Size *= C->getZExtValue(); + } + return Size; +} + //===----------------------------------------------------------------------===// // CallSite Class //===----------------------------------------------------------------------===// Index: lib/Transforms/Utils/Local.cpp =================================================================== --- lib/Transforms/Utils/Local.cpp +++ lib/Transforms/Utils/Local.cpp @@ -1242,6 +1242,14 @@ uint64_t ValueSize = DL.getTypeAllocSizeInBits(ValTy); if (auto FragmentSize = DII->getFragmentSizeInBits()) return ValueSize >= *FragmentSize; + // We can't always calculate the size of the DI variable (e.g. if it is a + // VLA). Try to use the size of the alloca that the dbg intrinsic describes + // intead. + if (DII->isAddressOfVariable()) + if (auto *AI = dyn_cast_or_null(DII->getVariableLocation())) + if (auto FragmentSize = AI->getAllocationSizeInBits(DL)) + return ValueSize >= *FragmentSize; + // Could not determine size of variable. Conservatively return false. return false; } @@ -1313,6 +1321,15 @@ if (LdStHasDebugValue(DIVar, DIExpr, LI)) return; + if (!valueCoversEntireFragment(LI->getType(), DII)) { + // FIXME: If only referring to a part of the variable described by the + // dbg.declare, then we want to insert a dbg.value for the corresponding + // fragment. + LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: " + << *DII << '\n'); + return; + } + // We are now tracking the loaded value instead of the address. In the // future if multi-location support is added to the IR, it might be // preferable to keep tracking both the loaded value and the original @@ -1333,6 +1350,15 @@ if (PhiHasDebugValue(DIVar, DIExpr, APN)) return; + if (!valueCoversEntireFragment(APN->getType(), DII)) { + // FIXME: If only referring to a part of the variable described by the + // dbg.declare, then we want to insert a dbg.value for the corresponding + // fragment. + LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: " + << *DII << '\n'); + return; + } + BasicBlock *BB = APN->getParent(); auto InsertionPt = BB->getFirstInsertionPt(); Index: test/Transforms/Mem2Reg/debug-alloca-vla-1.ll =================================================================== --- /dev/null +++ test/Transforms/Mem2Reg/debug-alloca-vla-1.ll @@ -0,0 +1,62 @@ +; RUN: opt < %s -mem2reg -S | FileCheck %s + +; Testing conversion from dbg.declare to dbg.value when the variable is a VLA. +; +; We can't derive the size of the variable simply by looking at the +; metadata. But we can find out the size by examining the alloca, so we should +; know that the load/store instructions are referencing the whole variable, +; and we expect to get dbg.value intrinsics that maps %entryN (aka %[[PHI]]) +; and %t0 to the variable allocated as %vla1. + +; ModuleID = 'debug-alloca-vla.ll' +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-apple-macosx10.12.0" + +; Function Attrs: nounwind ssp uwtable +define void @scan() #0 !dbg !4 { +entry: + %vla1 = alloca i32, i32 1, align 8 + call void @llvm.dbg.declare(metadata i32* %vla1, metadata !10, metadata !DIExpression()), !dbg !18 + br label %for.cond, !dbg !18 + +for.cond: ; preds = %for.cond, %entry +; CHECK: %[[PHI:.*]] = phi i32 [ undef, %entry ], [ %t0, %for.cond ] + %entryN = load i32, i32* %vla1, align 8, !dbg !18 +; CHECK: call void @llvm.dbg.value(metadata i32 %[[PHI]], +; CHECK-SAME: metadata !DIExpression()) + %t0 = add i32 %entryN, 1 +; CHECK: %t0 = add i32 %[[PHI]], 1 +; CHECK: call void @llvm.dbg.value(metadata i32 %t0, +; CHECK-SAME: metadata !DIExpression()) + store i32 %t0, i32* %vla1, align 8, !dbg !18 + br label %for.cond, !dbg !18 +} + +; Function Attrs: nounwind readnone speculatable +declare void @llvm.dbg.declare(metadata, metadata, metadata) #1 + +attributes #0 = { nounwind ssp uwtable } +attributes #1 = { nounwind readnone speculatable } + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!2, !3} + +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "adrian", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug) +!1 = !DIFile(filename: "", directory: "/") +!2 = !{i32 2, !"Debug Info Version", i32 3} +!3 = !{i32 7, !"PIC Level", i32 2} +!4 = distinct !DISubprogram(name: "scan", scope: !1, file: !1, line: 4, type: !5, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !8) +!5 = !DISubroutineType(types: !6) +!6 = !{null, !7, !7} +!7 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char) +!8 = !{!9} +!9 = !DILocalVariable(name: "entry", scope: !4, file: !1, line: 6, type: !7) +!10 = !DILocalVariable(name: "ptr32", scope: !4, file: !1, line: 240, type: !11) +!11 = !DICompositeType(tag: DW_TAG_array_type, baseType: !12, elements: !14) +!12 = !DIDerivedType(tag: DW_TAG_typedef, name: "__uint32_t", file: !1, line: 41, baseType: !13) +!13 = !DIBasicType(name: "unsigned int", size: 32, encoding: DW_ATE_unsigned) +!14 = !{!15} +!15 = !DISubrange(count: !16) +!16 = !DILocalVariable(name: "__vla_expr", scope: !4, type: !17, flags: DIFlagArtificial) +!17 = !DIBasicType(name: "long unsigned int", size: 64, encoding: DW_ATE_unsigned) +!18 = !DILocation(line: 6, scope: !4) Index: test/Transforms/Mem2Reg/debug-alloca-vla-2.ll =================================================================== --- /dev/null +++ test/Transforms/Mem2Reg/debug-alloca-vla-2.ll @@ -0,0 +1,64 @@ +; RUN: opt < %s -mem2reg -S | FileCheck %s + +; Testing conversion from dbg.declare to dbg.value when the variable is a VLA. +; +; We can't derive the size of the variable since it is a VLA with an unknown +; number of element. +; +; Verify that we do not get a dbg.value after the phi node (we can't know if +; the phi nodes result describes the whole array or not). Also verify that we +; get a dbg.value that says that we do not know the value of the VLA in place +; of the store (since we do not know which part of the VLA the store is +; writing to). + +; ModuleID = 'debug-alloca-vla.ll' +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-apple-macosx10.12.0" + +; Function Attrs: nounwind ssp uwtable +define void @scan(i32 %n) #0 !dbg !4 { +entry: + %vla1 = alloca i32, i32 %n, align 8 + call void @llvm.dbg.declare(metadata i32* %vla1, metadata !10, metadata !DIExpression()), !dbg !18 + br label %for.cond, !dbg !18 + +for.cond: ; preds = %for.cond, %entry +; CHECK: %[[PHI:.*]] = phi i32 [ undef, %entry ], [ %t0, %for.cond ] + %entryN = load i32, i32* %vla1, align 8, !dbg !18 +; CHECK-NOT: call void @llvm.dbg.value + %t0 = add i32 %entryN, 1 +; CHECK: %t0 = add i32 %[[PHI]], 1 +; CHECK: call void @llvm.dbg.value(metadata i32 undef, +; CHECK-SAME: metadata !DIExpression()) + store i32 %t0, i32* %vla1, align 8, !dbg !18 + br label %for.cond, !dbg !18 +} + +; Function Attrs: nounwind readnone speculatable +declare void @llvm.dbg.declare(metadata, metadata, metadata) #1 + +attributes #0 = { nounwind ssp uwtable } +attributes #1 = { nounwind readnone speculatable } + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!2, !3} + +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "adrian", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug) +!1 = !DIFile(filename: "", directory: "/") +!2 = !{i32 2, !"Debug Info Version", i32 3} +!3 = !{i32 7, !"PIC Level", i32 2} +!4 = distinct !DISubprogram(name: "scan", scope: !1, file: !1, line: 4, type: !5, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !8) +!5 = !DISubroutineType(types: !6) +!6 = !{null, !7, !7} +!7 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char) +!8 = !{!9} +!9 = !DILocalVariable(name: "entry", scope: !4, file: !1, line: 6, type: !7) +!10 = !DILocalVariable(name: "ptr32", scope: !4, file: !1, line: 240, type: !11) +!11 = !DICompositeType(tag: DW_TAG_array_type, baseType: !12, elements: !14) +!12 = !DIDerivedType(tag: DW_TAG_typedef, name: "__uint32_t", file: !1, line: 41, baseType: !13) +!13 = !DIBasicType(name: "unsigned int", size: 32, encoding: DW_ATE_unsigned) +!14 = !{!15} +!15 = !DISubrange(count: !16) +!16 = !DILocalVariable(name: "__vla_expr", scope: !4, type: !17, flags: DIFlagArtificial) +!17 = !DIBasicType(name: "long unsigned int", size: 64, encoding: DW_ATE_unsigned) +!18 = !DILocation(line: 6, scope: !4)