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//===------ EvaluationResult.h - Result class for the VM -------*- 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_AST_INTERP_EVALUATION_RESULT_H
#define LLVM_CLANG_AST_INTERP_EVALUATION_RESULT_H
#include "FunctionPointer.h"
#include "Pointer.h"
#include "clang/AST/APValue.h"
#include "clang/AST/Decl.h"
#include "clang/AST/Expr.h"
#include <optional>
#include <variant>
namespace clang {
namespace interp {
class EvalEmitter;
class Context;
/// Defines the result of an evaluation.
///
/// The result might be in different forms--one of the pointer types,
/// an APValue, or nothing.
///
/// We use this class to inspect and diagnose the result, as well as
/// convert it to the requested form.
class EvaluationResult final {
public:
enum ResultKind {
Empty, // Initial state.
LValue, // Result is an lvalue/pointer.
RValue, // Result is an rvalue.
Invalid, // Result is invalid.
Valid, // Result is valid and empty.
};
using DeclTy = llvm::PointerUnion<const Decl *, const Expr *>;
private:
const Context *Ctx = nullptr;
std::variant<std::monostate, Pointer, FunctionPointer, APValue> Value;
ResultKind Kind = Empty;
DeclTy Source = nullptr; // Currently only needed for dump().
EvaluationResult(ResultKind Kind) : Kind(Kind) {
// Leave everything empty. Can be used as an
// error marker or for void return values.
assert(Kind == Valid || Kind == Invalid);
}
void setSource(DeclTy D) { Source = D; }
void setValue(const APValue &V) {
// V could still be an LValue.
assert(empty());
Value = std::move(V);
Kind = RValue;
}
void setFunctionPointer(const FunctionPointer &P) {
assert(empty());
Value = P;
Kind = LValue;
}
void setInvalid() {
// We are NOT asserting empty() here, since setting it to invalid
// is allowed even if there is already a result.
Kind = Invalid;
}
void setValid() {
assert(empty());
Kind = Valid;
}
public:
EvaluationResult(const Context *Ctx) : Ctx(Ctx) {}
bool empty() const { return Kind == Empty; }
bool isInvalid() const { return Kind == Invalid; }
bool isLValue() const { return Kind == LValue; }
bool isRValue() const { return Kind == RValue; }
bool isPointer() const { return std::holds_alternative<Pointer>(Value); }
/// Returns an APValue for the evaluation result. The returned
/// APValue might be an LValue or RValue.
APValue toAPValue() const;
/// If the result is an LValue, convert that to an RValue
/// and return it. This may fail, e.g. if the result is an
/// LValue and we can't read from it.
std::optional<APValue> toRValue() const;
/// Check that all subobjects of the given pointer have been initialized.
bool checkFullyInitialized(InterpState &S, const Pointer &Ptr) const;
/// Check that none of the blocks the given pointer (transitively) points
/// to are dynamically allocated.
bool checkReturnValue(InterpState &S, const Context &Ctx, const Pointer &Ptr,
const SourceInfo &Info);
QualType getSourceType() const {
if (const auto *D =
dyn_cast_if_present<ValueDecl>(Source.dyn_cast<const Decl *>()))
return D->getType();
else if (const auto *E = Source.dyn_cast<const Expr *>())
return E->getType();
return QualType();
}
/// Dump to stderr.
void dump() const;
friend class EvalEmitter;
friend class InterpState;
};
} // namespace interp
} // namespace clang
#endif
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