[clang] [LLVMABI] Introduce the QualTypeMapper (PR #174634)
Nikita Popov via cfe-commits
cfe-commits at lists.llvm.org
Wed Mar 4 11:48:44 PST 2026
================
@@ -0,0 +1,570 @@
+//==---- QualTypeMapper.cpp - Maps Clang QualType to LLVMABI Types ---------==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Maps Clang QualType instances to corresponding LLVM ABI type
+/// representations. This mapper translates high-level type information from the
+/// AST into low-level ABI-specific types that encode size, alignment, and
+/// layout details required for code generation and cross-language
+/// interoperability.
+///
+//===----------------------------------------------------------------------===//
+#include "QualTypeMapper.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTFwd.h"
+#include "clang/AST/Attr.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/RecordLayout.h"
+#include "clang/AST/Type.h"
+#include "clang/Basic/AddressSpaces.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/TargetInfo.h"
+#include "llvm/ABI/Types.h"
+#include "llvm/Support/Alignment.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/TypeSize.h"
+#include <cstdint>
+
+namespace clang {
+namespace CodeGen {
+
+/// Main entry point for converting Clang QualType to LLVM ABI Type.
+/// This method performs type canonicalization, caching, and dispatches
+/// to specialized conversion methods based on the type kind.
+///
+/// \param QT The Clang QualType to convert
+/// \return Corresponding LLVM ABI Type representation
+const llvm::abi::Type *QualTypeMapper::convertType(QualType QT) {
+ // Canonicalize type and strip qualifiers
+ // This ensures consistent type representation across different contexts
+ QT = QT.getCanonicalType().getUnqualifiedType();
+
+ // Results are cached since type conversion may be expensive.
+ auto It = TypeCache.find(QT);
+ if (It != TypeCache.end())
+ return It->second;
+
+ const llvm::abi::Type *Result = convertTypeImpl(QT);
+ assert(Result && "convertTypeImpl returned nullptr");
+ TypeCache[QT] = Result;
+ return Result;
+}
+
+/// Dispatches to specialized conversion methods based on the type kind.
+const llvm::abi::Type *QualTypeMapper::convertTypeImpl(QualType QT) {
+ switch (QT->getTypeClass()) {
+ // Non-canonical and dependent types should have been stripped by
+ // getCanonicalType() above or cannot appear during code generation.
+#define TYPE(Class, Base)
+#define ABSTRACT_TYPE(Class, Base)
+#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
+#define DEPENDENT_TYPE(Class, Base) case Type::Class:
+#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
+#include "clang/AST/TypeNodes.inc"
+ llvm::reportFatalInternalError(
+ "Non-canonical or dependent types should not reach ABI lowering");
+
+ case Type::Builtin:
+ return convertBuiltinType(cast<BuiltinType>(QT));
+ case Type::Pointer:
+ return createPointerTypeForPointee(cast<PointerType>(QT)->getPointeeType());
+ case Type::LValueReference:
+ case Type::RValueReference:
+ return createPointerTypeForPointee(
+ cast<ReferenceType>(QT)->getPointeeType());
+ case Type::ConstantArray:
+ case Type::ArrayParameter:
+ case Type::IncompleteArray:
+ case Type::VariableArray:
+ return convertArrayType(cast<ArrayType>(QT));
+ case Type::Vector:
+ case Type::ExtVector:
+ return convertVectorType(cast<VectorType>(QT));
+ case Type::Record:
+ return convertRecordType(cast<RecordType>(QT));
+ case Type::Enum:
+ return convertEnumType(cast<EnumType>(QT));
+ case Type::Complex:
+ return convertComplexType(cast<ComplexType>(QT));
+ case Type::Atomic:
+ return convertType(cast<AtomicType>(QT)->getValueType());
+ case Type::BlockPointer:
+ case Type::Pipe:
+ return createPointerTypeForPointee(ASTCtx.VoidPtrTy);
+ case Type::ConstantMatrix: {
+ const auto *MT = cast<ConstantMatrixType>(QT);
+ return Builder.getArrayType(convertType(MT->getElementType()),
+ MT->getNumRows() * MT->getNumColumns(),
+ ASTCtx.getTypeSize(QT), /*IsMatrixType=*/true);
+ }
+ case Type::MemberPointer:
+ return convertMemberPointerType(cast<MemberPointerType>(QT));
+ case Type::BitInt: {
+ const auto *BIT = cast<BitIntType>(QT);
+ return Builder.getIntegerType(BIT->getNumBits(), getTypeAlign(QT),
+ /*Signed=*/BIT->isSigned(),
+ /*IsBitInt=*/true);
+ }
+ case Type::ObjCObject:
+ case Type::ObjCInterface:
+ case Type::ObjCObjectPointer:
+ // Objective-C objects are represented as pointers in the ABI.
+ return Builder.getPointerType(
+ ASTCtx.getTargetInfo().getPointerWidth(QT.getAddressSpace()),
+ llvm::Align(
+ ASTCtx.getTargetInfo().getPointerAlign(QT.getAddressSpace()) / 8),
+ ASTCtx.getTargetInfo().getTargetAddressSpace(QT.getAddressSpace()));
+ case Type::OverflowBehavior:
+ return convertType(cast<OverflowBehaviorType>(QT)->getUnderlyingType());
+ case Type::Auto:
+ case Type::DeducedTemplateSpecialization:
+ case Type::FunctionProto:
+ case Type::FunctionNoProto:
+ case Type::HLSLAttributedResource:
+ case Type::HLSLInlineSpirv:
+ llvm::reportFatalInternalError("Type not supported in ABI lowering");
+ }
+ llvm_unreachable("unhandled type class in convertTypeImpl");
+}
+
+/// Converts C/C++ builtin types to LLVM ABI types.
+/// This handles all fundamental scalar types including integers, floats,
+/// and special types like void and bool.
+const llvm::abi::Type *
+QualTypeMapper::convertBuiltinType(const BuiltinType *BT) {
+ QualType QT(BT, 0);
+
+ switch (BT->getKind()) {
+ case BuiltinType::Void:
+ return Builder.getVoidType();
+
+ case BuiltinType::NullPtr:
+ return createPointerTypeForPointee(QT);
+
+ case BuiltinType::Bool:
+ return Builder.getIntegerType(1, getTypeAlign(QT), /*Signed=*/false,
+ /*IsBitInt=*/false);
+
+ case BuiltinType::Char_S:
+ case BuiltinType::Char_U:
+ case BuiltinType::SChar:
+ case BuiltinType::UChar:
+ case BuiltinType::WChar_S:
+ case BuiltinType::WChar_U:
+ case BuiltinType::Char8:
+ case BuiltinType::Char16:
+ case BuiltinType::Char32:
+ case BuiltinType::Short:
+ case BuiltinType::UShort:
+ case BuiltinType::Int:
+ case BuiltinType::UInt:
+ case BuiltinType::Long:
+ case BuiltinType::ULong:
+ case BuiltinType::LongLong:
+ case BuiltinType::ULongLong:
+ case BuiltinType::Int128:
+ case BuiltinType::UInt128:
+ return Builder.getIntegerType(ASTCtx.getTypeSize(QT), getTypeAlign(QT),
+ /*Signed=*/BT->isSignedInteger(),
+ /*IsBitInt=*/false);
+
+ case BuiltinType::Half:
+ case BuiltinType::Float16:
+ case BuiltinType::BFloat16:
+ case BuiltinType::Float:
+ case BuiltinType::Double:
+ case BuiltinType::LongDouble:
+ case BuiltinType::Float128:
+ return Builder.getFloatType(ASTCtx.getFloatTypeSemantics(QT),
+ getTypeAlign(QT));
+
+ // TODO: IBM 128-bit extended double
+ case BuiltinType::Ibm128:
+ llvm::reportFatalInternalError(
+ "IBM128 is not yet supported in the ABI lowering libary");
+
+ // TODO: Fixed-point types
+ case BuiltinType::ShortAccum:
+ case BuiltinType::Accum:
+ case BuiltinType::LongAccum:
+ case BuiltinType::UShortAccum:
+ case BuiltinType::UAccum:
+ case BuiltinType::ULongAccum:
+ case BuiltinType::ShortFract:
+ case BuiltinType::Fract:
+ case BuiltinType::LongFract:
+ case BuiltinType::UShortFract:
+ case BuiltinType::UFract:
+ case BuiltinType::ULongFract:
+ case BuiltinType::SatShortAccum:
+ case BuiltinType::SatAccum:
+ case BuiltinType::SatLongAccum:
+ case BuiltinType::SatUShortAccum:
+ case BuiltinType::SatUAccum:
+ case BuiltinType::SatULongAccum:
+ case BuiltinType::SatShortFract:
+ case BuiltinType::SatFract:
+ case BuiltinType::SatLongFract:
+ case BuiltinType::SatUShortFract:
+ case BuiltinType::SatUFract:
+ case BuiltinType::SatULongFract:
+ llvm::reportFatalInternalError(
+ "Fixed Point types not yet implemented in the ABI lowering library");
+
+ // OpenCL image types are represented as opaque pointers.
+#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
+ case BuiltinType::Id:
+#include "clang/Basic/OpenCLImageTypes.def"
+ // OpenCL extension types are represented as opaque pointers.
+#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) case BuiltinType::Id:
+#include "clang/Basic/OpenCLExtensionTypes.def"
+ case BuiltinType::OCLSampler:
+ case BuiltinType::OCLEvent:
+ case BuiltinType::OCLClkEvent:
+ case BuiltinType::OCLQueue:
+ case BuiltinType::OCLReserveID:
+ return createPointerTypeForPointee(QT);
+
+ // Objective-C builtin types are represented as opaque pointers.
+ case BuiltinType::ObjCId:
+ case BuiltinType::ObjCClass:
+ case BuiltinType::ObjCSel:
+ return createPointerTypeForPointee(QT);
+
+ // Target-specific vector/matrix types — not yet implemented.
+#define SVE_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
+#include "clang/Basic/AArch64ACLETypes.def"
+ llvm::reportFatalInternalError(
+ "AArch64 SVE types not yet supported in ABI lowering library");
+#define PPC_VECTOR_TYPE(Name, Id, Size) case BuiltinType::Id:
+#include "clang/Basic/PPCTypes.def"
+ llvm::reportFatalInternalError(
+ "PPC MMA types not yet supported in ABI lowering library");
+#define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
+#include "clang/Basic/RISCVVTypes.def"
+ llvm::reportFatalInternalError(
+ "RISC-V vector types not yet supported in ABI lowering library");
+#define WASM_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
+#include "clang/Basic/WebAssemblyReferenceTypes.def"
+ llvm::reportFatalInternalError("WebAssembly reference types not yet "
+ "supported in ABI lowering library");
+#define AMDGPU_TYPE(Name, Id, SingletonId, Width, Align) case BuiltinType::Id:
+#include "clang/Basic/AMDGPUTypes.def"
+ llvm::reportFatalInternalError(
+ "AMDGPU types not yet supported in ABI lowering library");
+#define HLSL_INTANGIBLE_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
+#include "clang/Basic/HLSLIntangibleTypes.def"
+ llvm::reportFatalInternalError(
+ "HLSL intangible types not yet Supported in ABI lowering library");
+
+ // Placeholder types should never reach ABI lowering.
+#define PLACEHOLDER_TYPE(Id, SingletonId) case BuiltinType::Id:
+#define BUILTIN_TYPE(Id, SingletonId)
+#include "clang/AST/BuiltinTypes.def"
+ llvm::reportFatalInternalError(
+ "Placeholder type should not reach ABI lowering");
+
+ case BuiltinType::Dependent:
+ llvm::reportFatalInternalError(
+ "Dependent builtin type should not reach ABI lowering");
+ }
+ llvm_unreachable("unhandled builtin type kind in convertBuiltinType");
+}
+
+/// Converts array types to LLVM ABI array representations.
+/// Handles different array kinds: constant arrays, incomplete arrays,
+/// and variable-length arrays.
+///
+/// \param AT The ArrayType to convert
+/// \return LLVM ABI ArrayType or PointerType
+const llvm::abi::Type *
+QualTypeMapper::convertArrayType(const clang::ArrayType *AT) {
+ const llvm::abi::Type *ElementType = convertType(AT->getElementType());
+ uint64_t Size = ASTCtx.getTypeSize(AT);
+
+ if (const auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
+ auto NumElements = CAT->getZExtSize();
+ return Builder.getArrayType(ElementType, NumElements, Size);
+ }
+ if (isa<IncompleteArrayType>(AT))
+ return Builder.getArrayType(ElementType, 0, 0);
+ if (const auto *VAT = dyn_cast<VariableArrayType>(AT))
+ return createPointerTypeForPointee(VAT->getPointeeType());
+ llvm::reportFatalInternalError(
+ "unexpected array type in ABI lowering (dependent array types should be "
+ "resolved before reaching this point)");
+}
+
+const llvm::abi::Type *QualTypeMapper::convertVectorType(const VectorType *VT) {
+ const llvm::abi::Type *ElementType = convertType(VT->getElementType());
+ QualType VectorQualType(VT, 0);
+
+ unsigned NElems = VT->getNumElements();
+ llvm::ElementCount NumElements = llvm::ElementCount::getFixed(NElems);
+ llvm::Align VectorAlign = getTypeAlign(VectorQualType);
+
+ return Builder.getVectorType(ElementType, NumElements, VectorAlign);
+}
+
+/// Converts complex types to LLVM ABI complex representations.
+/// Complex types consist of two components of the element type
+/// (real and imaginary parts).
+///
+/// \param CT The ComplexType to convert
+/// \return LLVM ABI ComplexType with element type and alignment
+const llvm::abi::Type *
+QualTypeMapper::convertComplexType(const ComplexType *CT) {
+ const llvm::abi::Type *ElementType = convertType(CT->getElementType());
+ llvm::Align ComplexAlign = getTypeAlign(QualType(CT, 0));
+
+ return Builder.getComplexType(ElementType, ComplexAlign);
+}
+
+/// Converts member pointer types to LLVM ABI representations.
+/// Member pointers have different layouts depending on whether they
+/// point to functions or data members.
+///
+/// \param MPT The MemberPointerType to convert
+/// \return LLVM ABI MemberPointerType
+const llvm::abi::Type *
+QualTypeMapper::convertMemberPointerType(const clang::MemberPointerType *MPT) {
+ QualType QT(MPT, 0);
+ uint64_t Size = ASTCtx.getTypeSize(QT);
+ llvm::Align Align = getTypeAlign(QT);
+
+ bool IsFunctionPointer = MPT->isMemberFunctionPointerType();
+
+ return Builder.getMemberPointerType(IsFunctionPointer, Size, Align);
+}
+
+/// Converts record types (struct/class/union) to LLVM ABI representations.
+/// This is the main dispatch method that handles different record kinds
+/// and delegates to specialized converters.
+///
+/// \param RT The RecordType to convert
+/// \return LLVM ABI RecordType
+const llvm::abi::Type *QualTypeMapper::convertRecordType(const RecordType *RT) {
+ const RecordDecl *RD = RT->getDecl()->getDefinition();
+ if (!RD)
+ return Builder.getRecordType({}, llvm::TypeSize::getFixed(0),
+ llvm::Align(1));
+
+ if (RD->isUnion())
+ return convertUnionType(RD, RD->hasAttr<TransparentUnionAttr>());
----------------
nikic wrote:
nit: I don't think there's a reason to pass `RD->hasAttr<TransparentUnionAttr>()` as a separate parameter? We can make this call inside the method.
https://github.com/llvm/llvm-project/pull/174634
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