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 "InterpStack.h" 20 21 namespace clang { 22 class ASTContext; 23 class LangOptions; 24 class FunctionDecl; 25 class VarDecl; 26 class APValue; 27 28 namespace interp { 29 class Function; 30 class Program; 31 class State; 32 enum PrimType : unsigned; 33 34 struct ParamOffset { 35 unsigned Offset; 36 bool IsPtr; 37 }; 38 39 /// Holds all information required to evaluate constexpr code in a module. 40 class Context final { 41 public: 42 /// Initialises the constexpr VM. 43 Context(ASTContext &Ctx); 44 45 /// Cleans up the constexpr VM. 46 ~Context(); 47 48 /// Checks if a function is a potential constant expression. 49 bool isPotentialConstantExpr(State &Parent, const FunctionDecl *FnDecl); 50 51 /// Evaluates a toplevel expression as an rvalue. 52 bool evaluateAsRValue(State &Parent, const Expr *E, APValue &Result); 53 54 /// Evaluates a toplevel initializer. 55 bool evaluateAsInitializer(State &Parent, const VarDecl *VD, APValue &Result); 56 57 /// Returns the AST context. 58 ASTContext &getASTContext() const { return Ctx; } 59 /// Returns the language options. 60 const LangOptions &getLangOpts() const; 61 /// Returns the interpreter stack. 62 InterpStack &getStack() { return Stk; } 63 /// Returns CHAR_BIT. 64 unsigned getCharBit() const; 65 /// Return the floating-point semantics for T. 66 const llvm::fltSemantics &getFloatSemantics(QualType T) const; 67 /// Return the size of T in bits. 68 uint32_t getBitWidth(QualType T) const { return Ctx.getIntWidth(T); } 69 70 /// Classifies an expression. 71 std::optional<PrimType> classify(QualType T) const; 72 73 const CXXMethodDecl * 74 getOverridingFunction(const CXXRecordDecl *DynamicDecl, 75 const CXXRecordDecl *StaticDecl, 76 const CXXMethodDecl *InitialFunction) const; 77 78 const Function *getOrCreateFunction(const FunctionDecl *FD); 79 80 /// Returns whether we should create a global variable for the 81 /// given ValueDecl. 82 static bool shouldBeGloballyIndexed(const ValueDecl *VD) { 83 if (const auto *V = dyn_cast<VarDecl>(VD)) 84 return V->hasGlobalStorage() || V->isConstexpr(); 85 86 return false; 87 } 88 89 /// Returns the program. This is only needed for unittests. 90 Program &getProgram() const { return *P.get(); } 91 92 private: 93 /// Runs a function. 94 bool Run(State &Parent, const Function *Func, APValue &Result); 95 96 /// Checks a result from the interpreter. 97 bool Check(State &Parent, llvm::Expected<bool> &&R); 98 99 /// Current compilation context. 100 ASTContext &Ctx; 101 /// Interpreter stack, shared across invocations. 102 InterpStack Stk; 103 /// Constexpr program. 104 std::unique_ptr<Program> P; 105 }; 106 107 } // namespace interp 108 } // namespace clang 109 110 #endif 111