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 /// Like evaluateAsRvalue(), but does no implicit lvalue-to-rvalue conversion. 55 bool evaluate(State &Parent, const Expr *E, APValue &Result); 56 57 /// Evaluates a toplevel initializer. 58 bool evaluateAsInitializer(State &Parent, const VarDecl *VD, APValue &Result); 59 60 /// Returns the AST context. 61 ASTContext &getASTContext() const { return Ctx; } 62 /// Returns the language options. 63 const LangOptions &getLangOpts() const; 64 /// Returns the interpreter stack. 65 InterpStack &getStack() { return Stk; } 66 /// Returns CHAR_BIT. 67 unsigned getCharBit() const; 68 /// Return the floating-point semantics for T. 69 const llvm::fltSemantics &getFloatSemantics(QualType T) const; 70 /// Return the size of T in bits. 71 uint32_t getBitWidth(QualType T) const { return Ctx.getIntWidth(T); } 72 73 /// Classifies a type. 74 std::optional<PrimType> classify(QualType T) const; 75 76 /// Classifies an expression. 77 std::optional<PrimType> classify(const Expr *E) const { 78 assert(E); 79 if (E->isGLValue()) { 80 if (E->getType()->isFunctionType()) 81 return PT_FnPtr; 82 return PT_Ptr; 83 } 84 85 return classify(E->getType()); 86 } 87 88 const CXXMethodDecl * 89 getOverridingFunction(const CXXRecordDecl *DynamicDecl, 90 const CXXRecordDecl *StaticDecl, 91 const CXXMethodDecl *InitialFunction) const; 92 93 const Function *getOrCreateFunction(const FunctionDecl *FD); 94 95 /// Returns whether we should create a global variable for the 96 /// given ValueDecl. 97 static bool shouldBeGloballyIndexed(const ValueDecl *VD) { 98 if (const auto *V = dyn_cast<VarDecl>(VD)) 99 return V->hasGlobalStorage() || V->isConstexpr(); 100 101 return false; 102 } 103 104 /// Returns the program. This is only needed for unittests. 105 Program &getProgram() const { return *P.get(); } 106 107 unsigned collectBaseOffset(const RecordDecl *BaseDecl, 108 const RecordDecl *DerivedDecl) const; 109 110 const Record *getRecord(const RecordDecl *D) const; 111 112 unsigned getEvalID() const { return EvalID; } 113 114 private: 115 /// Runs a function. 116 bool Run(State &Parent, const Function *Func, APValue &Result); 117 118 /// Current compilation context. 119 ASTContext &Ctx; 120 /// Interpreter stack, shared across invocations. 121 InterpStack Stk; 122 /// Constexpr program. 123 std::unique_ptr<Program> P; 124 /// ID identifying an evaluation. 125 unsigned EvalID = 0; 126 }; 127 128 } // namespace interp 129 } // namespace clang 130 131 #endif 132