From 8c59921ca3284ced1c358c4c86ec2c830db0bd70 Mon Sep 17 00:00:00 2001 From: Adrian Prantl Date: Tue, 6 Feb 2018 23:45:59 +0000 Subject: Add DWARF for discriminated unions n Rust, an enum that carries data in the variants is, essentially, a discriminated union. Furthermore, the Rust compiler will perform space optimizations on such enums in some situations. Previously, DWARF for these constructs was emitted using a hack (a magic field name); but this approach stopped working when more space optimizations were added in https://github.com/rust-lang/rust/pull/45225. This patch changes LLVM to allow discriminated unions to be represented in DWARF. It adds createDiscriminatedUnionType and createDiscriminatedMemberType to DIBuilder and then arranges for this to be emitted using DWARF's DW_TAG_variant_part and DW_TAG_variant. Note that DWARF requires that a discriminated union be represented as a structure with a variant part. However, as Rust only needs to emit pure discriminated unions, this is what I chose to expose on DIBuilder. Patch by Tom Tromey! Differential Revision: https://reviews.llvm.org/D42082 llvm-svn: 324426 --- llvm/lib/IR/DIBuilder.cpp | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'llvm/lib/IR/DIBuilder.cpp') diff --git a/llvm/lib/IR/DIBuilder.cpp b/llvm/lib/IR/DIBuilder.cpp index 5ef3cdd88fd..ed3e28144d1 100644 --- a/llvm/lib/IR/DIBuilder.cpp +++ b/llvm/lib/IR/DIBuilder.cpp @@ -333,6 +333,19 @@ static ConstantAsMetadata *getConstantOrNull(Constant *C) { return nullptr; } +DIDerivedType *DIBuilder::createVariantMemberType(DIScope *Scope, StringRef Name, + DIFile *File, unsigned LineNumber, + uint64_t SizeInBits, + uint32_t AlignInBits, + uint64_t OffsetInBits, + Constant *Discriminant, + DINode::DIFlags Flags, DIType *Ty) { + return DIDerivedType::get(VMContext, dwarf::DW_TAG_member, Name, File, + LineNumber, getNonCompileUnitScope(Scope), Ty, + SizeInBits, AlignInBits, OffsetInBits, None, Flags, + getConstantOrNull(Discriminant)); +} + DIDerivedType *DIBuilder::createBitFieldMemberType( DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber, uint64_t SizeInBits, uint64_t OffsetInBits, uint64_t StorageOffsetInBits, @@ -458,6 +471,18 @@ DICompositeType *DIBuilder::createUnionType( return R; } +DICompositeType *DIBuilder::createVariantPart( + DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber, + uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags, + DIDerivedType *Discriminator, DINodeArray Elements, StringRef UniqueIdentifier) { + auto *R = DICompositeType::get( + VMContext, dwarf::DW_TAG_variant_part, Name, File, LineNumber, + getNonCompileUnitScope(Scope), nullptr, SizeInBits, AlignInBits, 0, Flags, + Elements, 0, nullptr, nullptr, UniqueIdentifier, Discriminator); + trackIfUnresolved(R); + return R; +} + DISubroutineType *DIBuilder::createSubroutineType(DITypeRefArray ParameterTypes, DINode::DIFlags Flags, unsigned CC) { -- cgit v1.2.3