[clang] [llvm] [WIP] ABI Lowering Library (PR #140112)

[Nikita Popov via cfe-commits]

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@@ -0,0 +1,554 @@
+//==---- 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 "clang/CodeGen/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, or nullptr on error
+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();
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nikic wrote:

Yes, I believe you're right. Is `__attribute__((aligned(N)))` the only relevant qualifier here, or are you aware of others?

https://github.com/llvm/llvm-project/pull/140112