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

[Nikita Popov via cfe-commits]

================
@@ -0,0 +1,244 @@
+//===---- ABITypeMapper.cpp - Maps LLVM ABI Types to LLVM IR 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 LLVM ABI type representations back to corresponding LLVM IR types.
+/// This reverse mapper translates low-level ABI-specific types back into
+/// LLVM IR types suitable for code generation and optimization passes.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ABI/ABITypeMapper.h"
+#include "llvm/ABI/Types.h"
+#include "llvm/ADT/APFloat.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Type.h"
+
+using namespace llvm;
+
+Type *ABITypeMapper::convertType(const abi::Type *ABIType) {
+  if (!ABIType)
+    return nullptr;
+
+  auto It = TypeCache.find(ABIType);
+  if (It != TypeCache.end())
+    return It->second;
+
+  Type *Result = nullptr;
+
+  switch (ABIType->getKind()) {
+  case abi::TypeKind::Integer: {
+    const auto *IT = cast<abi::IntegerType>(ABIType);
+    unsigned Bitwidth = IT->getSizeInBits().getFixedValue();
+    Result = IntegerType::get(Context, Bitwidth);
+    break;
+  }
+  case abi::TypeKind::Float:
+    Result = convertFloatType(cast<abi::FloatType>(ABIType));
+    break;
+  case abi::TypeKind::Pointer:
+    Result = PointerType::get(Context,
+                              cast<abi::PointerType>(ABIType)->getAddrSpace());
+    break;
+  case abi::TypeKind::Array:
+    Result = convertArrayType(cast<abi::ArrayType>(ABIType));
+    break;
+  case abi::TypeKind::Vector:
+    Result = convertVectorType(cast<abi::VectorType>(ABIType));
+    break;
+  case abi::TypeKind::Struct:
+    Result = convertStructType(cast<abi::StructType>(ABIType));
+    break;
+  case abi::TypeKind::Void:
+    Result = Type::getVoidTy(Context);
+    break;
+  case abi::TypeKind::Complex:
+    Result = convertComplexType(cast<abi::ComplexType>(ABIType));
+    break;
+  case abi::TypeKind::MemberPointer:
+    Result = convertMemberPointerType(cast<abi::MemberPointerType>(ABIType));
+    break;
----------------
nikic wrote:

We should add a `default: llvm_unreachable()` here. This is supposed to cover all types, right?

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