//===----- 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 "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/IR/Value.h"

// FIXME: Restructure so we don't have to expose so much stuff.

#include "ABIInfo.h"

namespace llvm {

class AttributeList;

class Function;

class Type;

class Value;

} // namespace llvm

namespace clang {

class ASTContext;

class Decl;

class FunctionDecl;

class ObjCMethodDecl;

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), CalleeDecl() {}

  CGCalleeInfo(const FunctionProtoType *calleeProtoTy, GlobalDecl calleeDecl)

      : CalleeProtoTy(calleeProtoTy), CalleeDecl(calleeDecl) {}

  CGCalleeInfo(const FunctionProtoType *calleeProtoTy)

      : CalleeProtoTy(calleeProtoTy), CalleeDecl() {}

  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 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 {

    CGCalleeInfo AbstractInfo;

    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)

      : KindOrFunctionPointer(SpecialKind(uintptr_t(functionPtr))) {

    AbstractInfo = abstractInfo;

    assert(functionPtr && "configuring callee without function pointer");

    assert(functionPtr->getType()->isPointerTy());

    assert(functionPtr->getType()->getPointerElementType()->isFunctionTy());

  }

  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 AbstractInfo;

  }

  llvm::Value *getFunctionPointer() const {

    assert(isOrdinary());

    return reinterpret_cast<llvm::Value *>(uintptr_t(KindOrFunctionPointer));

  }

  void setFunctionPointer(llvm::Value *functionPtr) {

    assert(isOrdinary());

    KindOrFunctionPointer = SpecialKind(uintptr_t(functionPtr));

  }

  bool isVirtual() const {

    return KindOrFunctionPointer == SpecialKind::Virtual;

  }

  const CallExpr *getVirtualCallExpr() const {

    assert(isVirtual());

    return VirtualInfo.CE;

  }

  GlobalDecl getVirtualMethodDecl() const {

    assert(isVirtual());

    return VirtualInfo.MD;

  }

  Address getThisAddress() const {

    assert(isVirtual());

    return VirtualInfo.Addr;

  }

  llvm::FunctionType *getVirtualFunctionType() const {

    assert(isVirtual());

    return VirtualInfo.FTy;

  }

  /// If this is a delayed callee computation of some sort, prepare

  /// a concrete callee.

  CGCallee prepareConcreteCallee(CodeGenFunction &CGF) const;

};

struct CallArg {

private:

  union {

    RValue RV;

    LValue LV; /// The argument is semantically a load from this l-value.

  };

  bool HasLV;

  /// A data-flow flag to make sure getRValue and/or copyInto are not

  /// called twice for duplicated IR emission.

  mutable bool IsUsed;

public:

  QualType Ty;

  CallArg(RValue rv, QualType ty)

      : RV(rv), HasLV(false), IsUsed(false), Ty(ty) {}

  CallArg(LValue lv, QualType ty)

      : LV(lv), HasLV(true), IsUsed(false), Ty(ty) {}

  bool hasLValue() const { return HasLV; }

  QualType getType() const { return Ty; }

  /// \returns an independent RValue. If the CallArg contains an LValue,

  /// a temporary copy is returned.

  RValue getRValue(CodeGenFunction &CGF) const;

  LValue getKnownLValue() const {

    assert(HasLV && !IsUsed);

    return LV;

  }

  RValue getKnownRValue() const {

    assert(!HasLV && !IsUsed);

    return RV;

  }

  void setRValue(RValue _RV) {

    assert(!HasLV);

    RV = _RV;

  }

  bool isAggregate() const { return HasLV || 
RV.isAggregate()529k
; }

  void copyInto(CodeGenFunction &CGF, Address A) const;

};

/// CallArgList - Type for representing both the value and type of

/// arguments in a call.

class CallArgList : public SmallVector<CallArg, 8> {

public:

  CallArgList() : StackBase(nullptr) {}

  struct Writeback {

    /// The original argument.  Note that the argument l-value

    /// is potentially null.

    LValue Source;

    /// The temporary alloca.

    Address Temporary;

    /// A value to "use" after the writeback, or null.

    llvm::Value *ToUse;

  };

  struct CallArgCleanup {

    EHScopeStack::stable_iterator Cleanup;

    /// The "is active" insertion point.  This instruction is temporary and

    /// will be removed after insertion.

    llvm::Instruction *IsActiveIP;

  };

  void add(RValue rvalue, QualType type) { push_back(CallArg(rvalue, type)); }

  void addUncopiedAggregate(LValue LV, QualType type) {

    push_back(CallArg(LV, type));

  }

  /// Add all the arguments from another CallArgList to this one. After doing

  /// this, the old CallArgList retains its list of arguments, but must not

  /// be used to emit a call.

  void addFrom(const CallArgList &other) {

    insert(end(), other.begin(), other.end());

    Writebacks.insert(Writebacks.end(), other.Writebacks.begin(),

                      other.Writebacks.end());

    CleanupsToDeactivate.insert(CleanupsToDeactivate.end(),

                                other.CleanupsToDeactivate.begin(),

                                other.CleanupsToDeactivate.end());

    assert(!(StackBase && other.StackBase) && "can't merge stackbases");

    if (!StackBase)

      StackBase = other.StackBase;

  }

  void addWriteback(LValue srcLV, Address temporary, llvm::Value *toUse) {

    Writeback writeback = {srcLV, temporary, toUse};

    Writebacks.push_back(writeback);

  }

  bool hasWritebacks() const { return !Writebacks.empty(); }

  typedef llvm::iterator_range<SmallVectorImpl<Writeback>::const_iterator>

      writeback_const_range;

  writeback_const_range writebacks() const {

    return writeback_const_range(Writebacks.begin(), Writebacks.end());

  }

  void addArgCleanupDeactivation(EHScopeStack::stable_iterator Cleanup,

                                 llvm::Instruction *IsActiveIP) {

    CallArgCleanup ArgCleanup;

    ArgCleanup.Cleanup = Cleanup;

    ArgCleanup.IsActiveIP = IsActiveIP;

    CleanupsToDeactivate.push_back(ArgCleanup);

  }

  ArrayRef<CallArgCleanup> getCleanupsToDeactivate() const {

    return CleanupsToDeactivate;

  }

  void allocateArgumentMemory(CodeGenFunction &CGF);

  llvm::Instruction *getStackBase() const { return StackBase; }

  void freeArgumentMemory(CodeGenFunction &CGF) const;

  /// Returns if we're using an inalloca struct to pass arguments in

  /// memory.

  bool isUsingInAlloca() const { return StackBase; }

private:

  SmallVector<Writeback, 1> Writebacks;

  /// Deactivate these cleanups immediately before making the call.  This

  /// is used to cleanup objects that are owned by the callee once the call

  /// occurs.

  SmallVector<CallArgCleanup, 1> CleanupsToDeactivate;

  /// The stacksave call.  It dominates all of the argument evaluation.

  llvm::CallInst *StackBase;

};

/// FunctionArgList - Type for representing both the decl and type

/// of parameters to a function. The decl must be either a

/// ParmVarDecl or ImplicitParamDecl.

class FunctionArgList : public SmallVector<const VarDecl *, 16> {};

/// ReturnValueSlot - Contains the address where the return value of a

/// function can be stored, and whether the address is volatile or not.

class ReturnValueSlot {

  Address Addr = Address::invalid();

  // Return value slot flags

  unsigned IsVolatile : 1;

  unsigned IsUnused : 1;

  unsigned IsExternallyDestructed : 1;

public:

  ReturnValueSlot()

      : IsVolatile(false), IsUnused(false), IsExternallyDestructed(false) {}

  ReturnValueSlot(Address Addr, bool IsVolatile, bool IsUnused = false,

                  bool IsExternallyDestructed = false)

      : Addr(Addr), IsVolatile(IsVolatile), IsUnused(IsUnused),

        IsExternallyDestructed(IsExternallyDestructed) {}

  bool isNull() const { return !Addr.isValid(); }

  bool isVolatile() const { return IsVolatile; }

  Address getValue() const { return Addr; }

  bool isUnused() const { return IsUnused; }

  bool isExternallyDestructed() const { return IsExternallyDestructed; }

};

} // end namespace CodeGen

} // end namespace clang

#endif