1//===--- Context.h - Context for the constexpr VM ---------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Defines the constexpr execution context.
10//
11// The execution context manages cached bytecode and the global context.
12// It invokes the compiler and interpreter, propagating errors.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_CLANG_AST_INTERP_CONTEXT_H
17#define LLVM_CLANG_AST_INTERP_CONTEXT_H
18
19#include "Context.h"
20#include "InterpStack.h"
21#include "clang/AST/APValue.h"
22#include "llvm/ADT/PointerIntPair.h"
23
24namespace clang {
25class ASTContext;
26class LangOptions;
27class Stmt;
28class FunctionDecl;
29class VarDecl;
30
31namespace interp {
32class Function;
33class Program;
34class State;
35enum PrimType : unsigned;
36
37/// Holds all information required to evaluate constexpr code in a module.
38class Context {
39public:
40  /// Initialises the constexpr VM.
41  Context(ASTContext &Ctx);
42
43  /// Cleans up the constexpr VM.
44  ~Context();
45
46  /// Checks if a function is a potential constant expression.
47  bool isPotentialConstantExpr(State &Parent, const FunctionDecl *FnDecl);
48
49  /// Evaluates a toplevel expression as an rvalue.
50  bool evaluateAsRValue(State &Parent, const Expr *E, APValue &Result);
51
52  /// Evaluates a toplevel initializer.
53  bool evaluateAsInitializer(State &Parent, const VarDecl *VD, APValue &Result);
54
55  /// Returns the AST context.
56  ASTContext &getASTContext() const { return Ctx; }
57  /// Returns the language options.
58  const LangOptions &getLangOpts() const;
59  /// Returns the interpreter stack.
60  InterpStack &getStack() { return Stk; }
61  /// Returns CHAR_BIT.
62  unsigned getCharBit() const;
63
64  /// Classifies an expression.
65  llvm::Optional<PrimType> classify(QualType T);
66
67private:
68  /// Runs a function.
69  bool Run(State &Parent, Function *Func, APValue &Result);
70
71  /// Checks a result fromt the interpreter.
72  bool Check(State &Parent, llvm::Expected<bool> &&R);
73
74private:
75  /// Current compilation context.
76  ASTContext &Ctx;
77  /// Interpreter stack, shared across invocations.
78  InterpStack Stk;
79  /// Constexpr program.
80  std::unique_ptr<Program> P;
81};
82
83} // namespace interp
84} // namespace clang
85
86#endif
87