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

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,136 @@
+//===----- 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/Types.h"
+#include <cassert>
+
+namespace llvm {
+namespace abi {
+
+/// ABIArgInfo - Helper class to encapsulate information about how a
+/// specific C type should be passed to or returned from a function.
+class ABIArgInfo {
+public:
+  enum Kind { Direct, Indirect, Ignore, Expand, CoerceAndExpand, InAlloca };
+
+private:
+  Kind TheKind;
+  const Type *CoercionType;
+
+  bool InReg : 1;
+  bool PaddingInReg : 1;
+
+  unsigned IndirectAlign : 16;
+  bool IndirectByVal : 1;
+
+  ABIArgInfo(Kind K = Direct)
+      : TheKind(K), CoercionType(nullptr), InReg(false), PaddingInReg(false),
+        IndirectAlign(0), IndirectByVal(false) {}
+
+public:
+  static ABIArgInfo getDirect(const Type *T = nullptr) {
+    ABIArgInfo AI(Direct);
+    AI.CoercionType = T;
+    return AI;
+  }
+
+  static ABIArgInfo getDirectInReg(const Type *T = nullptr) {
+    ABIArgInfo AI = getDirect(T);
+    AI.InReg = true;
+    return AI;
+  }
+
+  static ABIArgInfo getIndirect(unsigned Align = 0, bool ByVal = true) {
+    ABIArgInfo AI(Indirect);
+    AI.IndirectAlign = Align;
+    AI.IndirectByVal = ByVal;
+    return AI;
+  }
+
+  static ABIArgInfo getIndirectInReg(unsigned Align = 0, bool ByVal = true) {
+    ABIArgInfo AI = getIndirect(Align, ByVal);
+    AI.InReg = true;
+    return AI;
+  }
+
+  static ABIArgInfo getIgnore() { return ABIArgInfo(Ignore); }
+
+  static ABIArgInfo getExpand() { return ABIArgInfo(Expand); }
+
+  static ABIArgInfo getCoerceAndExpand(const Type *CoercionType) {
+    ABIArgInfo AI(CoerceAndExpand);
+    AI.CoercionType = CoercionType;
+    return AI;
+  }
+
+  Kind getKind() const { return TheKind; }
+
+  bool isDirect() const { return TheKind == Direct; }
+  bool isIndirect() const { return TheKind == Indirect; }
+  bool isIgnore() const { return TheKind == Ignore; }
+  bool isExpand() const { return TheKind == Expand; }
+  bool isCoerceAndExpand() const { return TheKind == CoerceAndExpand; }
+  bool isInAlloca() const { return TheKind == InAlloca; }
+
+  bool isInReg() const { return InReg; }
+  bool hasPaddingInReg() const { return PaddingInReg; }
+
+  unsigned getIndirectAlign() const {
+    assert(isIndirect() && "Only indirect arguments have alignment");
+    return IndirectAlign;
+  }
+
+  bool getIndirectByVal() const {
+    assert(isIndirect() && "Only indirect arguments can be ByVal");
+    return IndirectByVal;
+  }
+
+  const Type *getCoerceToType() const {
+    assert((isDirect() || isCoerceAndExpand()) &&
+           "Only Direct and CoerceAndExpand arguments can have coercion types");
+    return CoercionType;
+  }
+
+  ABIArgInfo &setInReg(bool InReg = true) {
+    this->InReg = InReg;
+    return *this;
+  }
+
+  ABIArgInfo &setPaddingInReg(bool HasPadding = true) {
+    this->PaddingInReg = HasPadding;
+    return *this;
+  }
+};
+
+/// Abstract base class for target-specific ABI information.
+class ABIInfo {
+public:
+  virtual ~ABIInfo() = default;
+
+  virtual ABIArgInfo classifyReturnType(const Type *RetTy) const = 0;
+  virtual ABIArgInfo classifyArgumentType(const Type *ArgTy) const = 0;
+
+  virtual bool isPassByRef(const Type *Ty) const { return false; }
+
+  virtual unsigned getTypeAlignment(const Type *Ty) const = 0;
+
+  virtual unsigned getTypeSize(const Type *Ty) const = 0;
----------------
nikic wrote:

Why are getTypeAlignment / getTypeSize virtual functions on ABIInfo?

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