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//===--- Context.h - Context for the constexpr 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
//
//===----------------------------------------------------------------------===//
//
// Defines the constexpr execution context.
//
// The execution context manages cached bytecode and the global context.
// It invokes the compiler and interpreter, propagating errors.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_AST_INTERP_CONTEXT_H
#define LLVM_CLANG_AST_INTERP_CONTEXT_H
#include "Context.h"
#include "InterpStack.h"
#include "clang/AST/APValue.h"
#include "llvm/ADT/PointerIntPair.h"
namespace clang {
class ASTContext;
class LangOptions;
class Stmt;
class FunctionDecl;
class VarDecl;
namespace interp {
class Function;
class Program;
class State;
enum PrimType : unsigned;
/// Wrapper around interpreter termination results.
enum class InterpResult {
/// Interpreter successfully computed a value.
Success,
/// Interpreter encountered an error and quit.
Fail,
/// Interpreter encountered an unimplemented feature, AST fallback.
Bail,
};
/// Holds all information required to evaluate constexpr code in a module.
class Context {
public:
/// Initialises the constexpr VM.
Context(ASTContext &Ctx);
/// Cleans up the constexpr VM.
~Context();
/// Checks if a function is a potential constant expression.
InterpResult isPotentialConstantExpr(State &Parent,
const FunctionDecl *FnDecl);
/// Evaluates a toplevel expression as an rvalue.
InterpResult evaluateAsRValue(State &Parent, const Expr *E, APValue &Result);
/// Evaluates a toplevel initializer.
InterpResult evaluateAsInitializer(State &Parent, const VarDecl *VD,
APValue &Result);
/// Returns the AST context.
ASTContext &getASTContext() const { return Ctx; }
/// Returns the language options.
const LangOptions &getLangOpts() const;
/// Returns the interpreter stack.
InterpStack &getStack() { return Stk; }
/// Returns CHAR_BIT.
unsigned getCharBit() const;
/// Classifies an expression.
llvm::Optional<PrimType> classify(QualType T);
private:
/// Runs a function.
InterpResult Run(State &Parent, Function *Func, APValue &Result);
/// Checks a result fromt the interpreter.
InterpResult Check(State &Parent, llvm::Expected<bool> &&R);
private:
/// Current compilation context.
ASTContext &Ctx;
/// Flag to indicate if the use of the interpreter is mandatory.
bool ForceInterp;
/// Interpreter stack, shared across invocations.
InterpStack Stk;
/// Constexpr program.
std::unique_ptr<Program> P;
};
} // namespace interp
} // namespace clang
#endif
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