CGCall.h

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//===----- CGCall.h - Encapsulate calling convention details ----*- 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
//
//===----------------------------------------------------------------------===//
//
// These classes wrap the information about a call or function
// definition used to handle ABI compliancy.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_LIB_CODEGEN_CGCALL_H
#define LLVM_CLANG_LIB_CODEGEN_CGCALL_H
 
#include "CGPointerAuthInfo.h"
#include "CGValue.h"
#include "EHScopeStack.h"
#include "clang/AST/ASTFwd.h"
#include "clang/AST/CanonicalType.h"
#include "clang/AST/GlobalDecl.h"
#include "clang/AST/Type.h"
#include "llvm/ADT/STLForwardCompat.h"
#include "llvm/IR/Value.h"
 
namespace llvm {
class Type;
class Value;
} // namespace llvm
 
namespace clang {
class Decl;
class FunctionDecl;
class TargetOptions;
class VarDecl;
 
namespace CodeGen {
 
/// Abstract information about a function or function prototype.
class CGCalleeInfo {
  /// The function prototype of the callee.
  const FunctionProtoType *CalleeProtoTy;
  /// The function declaration of the callee.
  GlobalDecl CalleeDecl;
 
public:
  explicit CGCalleeInfo() : CalleeProtoTy(nullptr) {}
  CGCalleeInfo(const FunctionProtoType *calleeProtoTy, GlobalDecl calleeDecl)
      : CalleeProtoTy(calleeProtoTy), CalleeDecl(calleeDecl) {}
  CGCalleeInfo(const FunctionProtoType *calleeProtoTy)
      : CalleeProtoTy(calleeProtoTy) {}
  CGCalleeInfo(GlobalDecl calleeDecl)
      : CalleeProtoTy(nullptr), CalleeDecl(calleeDecl) {}
 
  const FunctionProtoType *getCalleeFunctionProtoType() const {
    return CalleeProtoTy;
  }
  const GlobalDecl getCalleeDecl() const { return CalleeDecl; }
};
 
/// All available information about a concrete callee.
class CGCallee {
  enum class SpecialKind : uintptr_t {
    Invalid,
    Builtin,
    PseudoDestructor,
    Virtual,
 
    Last = Virtual
  };
 
  struct OrdinaryInfoStorage {
    CGCalleeInfo AbstractInfo;
    CGPointerAuthInfo PointerAuthInfo;
  };
  struct BuiltinInfoStorage {
    const FunctionDecl *Decl;
    unsigned ID;
  };
  struct PseudoDestructorInfoStorage {
    const CXXPseudoDestructorExpr *Expr;
  };
  struct VirtualInfoStorage {
    const CallExpr *CE;
    GlobalDecl MD;
    Address Addr;
    llvm::FunctionType *FTy;
  };
 
  SpecialKind KindOrFunctionPointer;
  union {
    OrdinaryInfoStorage OrdinaryInfo;
    BuiltinInfoStorage BuiltinInfo;
    PseudoDestructorInfoStorage PseudoDestructorInfo;
    VirtualInfoStorage VirtualInfo;
  };
 
  explicit CGCallee(SpecialKind kind) : KindOrFunctionPointer(kind) {}
 
  CGCallee(const FunctionDecl *builtinDecl, unsigned builtinID)
      : KindOrFunctionPointer(SpecialKind::Builtin) {
    BuiltinInfo.Decl = builtinDecl;
    BuiltinInfo.ID = builtinID;
  }
 
public:
  CGCallee() : KindOrFunctionPointer(SpecialKind::Invalid) {}
 
  /// Construct a callee.  Call this constructor directly when this
  /// isn't a direct call.
  CGCallee(const CGCalleeInfo &abstractInfo, llvm::Value *functionPtr,
           /* FIXME: make parameter pointerAuthInfo mandatory */
           const CGPointerAuthInfo &pointerAuthInfo = CGPointerAuthInfo())
      : KindOrFunctionPointer(
            SpecialKind(reinterpret_cast<uintptr_t>(functionPtr))) {
    OrdinaryInfo.AbstractInfo = abstractInfo;
    OrdinaryInfo.PointerAuthInfo = pointerAuthInfo;
    assert(functionPtr && "configuring callee without function pointer");
    assert(functionPtr->getType()->isPointerTy());
  }
 
  static CGCallee forBuiltin(unsigned builtinID,
                             const FunctionDecl *builtinDecl) {
    CGCallee result(SpecialKind::Builtin);
    result.BuiltinInfo.Decl = builtinDecl;
    result.BuiltinInfo.ID = builtinID;
    return result;
  }
 
  static CGCallee forPseudoDestructor(const CXXPseudoDestructorExpr *E) {
    CGCallee result(SpecialKind::PseudoDestructor);
    result.PseudoDestructorInfo.Expr = E;
    return result;
  }
 
  static CGCallee forDirect(llvm::Constant *functionPtr,
                            const CGCalleeInfo &abstractInfo = CGCalleeInfo()) {
    return CGCallee(abstractInfo, functionPtr);
  }
 
  static CGCallee forDirect(llvm::FunctionCallee functionPtr,
                            const CGCalleeInfo &abstractInfo = CGCalleeInfo()) {
    return CGCallee(abstractInfo, functionPtr.getCallee());
  }
 
  static CGCallee forVirtual(const CallExpr *CE, GlobalDecl MD, Address Addr,
                             llvm::FunctionType *FTy) {
    CGCallee result(SpecialKind::Virtual);
    result.VirtualInfo.CE = CE;
    result.VirtualInfo.MD = MD;
    result.VirtualInfo.Addr = Addr;
    result.VirtualInfo.FTy = FTy;
    return result;
  }
 
  bool isBuiltin() const {
    return KindOrFunctionPointer == SpecialKind::Builtin;
  }
  const FunctionDecl *getBuiltinDecl() const {
    assert(isBuiltin());
    return BuiltinInfo.Decl;
  }
  unsigned getBuiltinID() const {
    assert(isBuiltin());
    return BuiltinInfo.ID;
  }
 
  bool isPseudoDestructor() const {
    return KindOrFunctionPointer == SpecialKind::PseudoDestructor;
  }
  const CXXPseudoDestructorExpr *getPseudoDestructorExpr() const {
    assert(isPseudoDestructor());
    return PseudoDestructorInfo.Expr;
  }
 
  bool isOrdinary() const {
    return uintptr_t(KindOrFunctionPointer) > uintptr_t(SpecialKind::Last);
  }
  CGCalleeInfo getAbstractInfo() const {
    if (isVirtual())
      return VirtualInfo.MD;
    assert(isOrdinary());
    return OrdinaryInfo.AbstractInfo;
  }
  const CGPointerAuthInfo &getPointerAuthInfo() const {
    assert(isOrdinary());
    return OrdinaryInfo.PointerAuthInfo;
  }
  llvm::Value *getFunctionPointer() const {
    assert(isOrdinary());
    return reinterpret_cast<llvm::Value *>(uintptr_t(KindOrFunctionPointer));
  }
  void setFunctionPointer(llvm::Value *functionPtr) {
    assert(isOrdinary());
    KindOrFunctionPointer =
        SpecialKind(reinterpret_cast<uintptr_t>(functionPtr));
  }
  void setPointerAuthInfo(CGPointerAuthInfo PointerAuth) {
    assert(isOrdinary());
    OrdinaryInfo.PointerAuthInfo = PointerAuth;
  }