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