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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 "CGValue.h"
+#include "EHScopeStack.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 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(); }
+
+ 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 {
+ llvm::PointerIntPair<llvm::Value *, 2, unsigned int> Value;
+ CharUnits Alignment;
+
+ // Return value slot flags
+ enum Flags {
+ IS_VOLATILE = 0x1,
+ IS_UNUSED = 0x2,
+ };
+
+ public:
+ ReturnValueSlot() {}
+ ReturnValueSlot(Address Addr, bool IsVolatile, bool IsUnused = false)
+ : Value(Addr.isValid() ? Addr.getPointer() : nullptr,
+ (IsVolatile ? IS_VOLATILE : 0) | (IsUnused ? IS_UNUSED : 0)),
+ Alignment(Addr.isValid() ? Addr.getAlignment() : CharUnits::Zero()) {}
+
+ bool isNull() const { return !getValue().isValid(); }
+
+ bool isVolatile() const { return Value.getInt() & IS_VOLATILE; }
+ Address getValue() const { return Address(Value.getPointer(), Alignment); }
+ bool isUnused() const { return Value.getInt() & IS_UNUSED; }
+ };
+
+} // end namespace CodeGen
+} // end namespace clang
+
+#endif