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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