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

[Nikita Popov via cfe-commits]

================
@@ -0,0 +1,69 @@
+//===----- ABIInfo.h - ABI information access & encapsulation ----- C++ ---===//
+//
+// 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
+/// ABI information access & encapsulation
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ABI_ABIINFO_H
+#define LLVM_ABI_ABIINFO_H
+
+#include "llvm/ABI/ABIFunctionInfo.h"
+#include "llvm/ABI/Types.h"
+#include <cassert>
+#include <climits>
+#include <cstdint>
+
+namespace llvm {
+namespace abi {
+
+struct ABICompatInfo {
+  unsigned Version = UINT_MAX;
+
+  struct ABIFlags {
+    bool PassInt128VectorsInMem : 1;
+    bool ReturnCXXRecordGreaterThan128InMem : 1;
+    bool ClassifyIntegerMMXAsSSE : 1;
+    bool HonorsRevision98 : 1;
+
+    ABIFlags()
+        : PassInt128VectorsInMem(true),
+          ReturnCXXRecordGreaterThan128InMem(true),
+          ClassifyIntegerMMXAsSSE(true), HonorsRevision98(true) {}
+
+  } Flags;
+
+  ABICompatInfo() : Version(UINT_MAX) {}
+  ABICompatInfo(unsigned Ver) : Version(Ver) {}
+};
+
+/// Abstract base class for target-specific ABI information.
+class ABIInfo {
+private:
+  ABICompatInfo CompatInfo;
+
+public:
+  ABIInfo() : CompatInfo() {}
+  explicit ABIInfo(const ABICompatInfo &Info) : CompatInfo(Info) {}
+
+  virtual ~ABIInfo() = default;
+
+  virtual ABIArgInfo classifyReturnType(const Type *RetTy) const = 0;
+  virtual ABIArgInfo classifyArgumentType(const Type *ArgTy) const = 0;
+  virtual void computeInfo(ABIFunctionInfo &FI) const = 0;
+  virtual bool isPassByRef(const Type *Ty) const { return false; }
+  const ABICompatInfo &getABICompatInfo() const { return CompatInfo; }
+
+  void setABICompatInfo(const struct ABICompatInfo &Info) { CompatInfo = Info; }
----------------
nikic wrote:

```suggestion
  void setABICompatInfo(const ABICompatInfo &Info) { CompatInfo = Info; }
```
Though this setter is probably not needed at all. (Probably don't need to touch this after construction?)

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