clang 18.0.0git
Context.h
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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
21namespace clang {
22class ASTContext;
23class LangOptions;
24class FunctionDecl;
25class VarDecl;
26class APValue;
27
28namespace interp {
29class Function;
30class Program;
31class State;
32enum PrimType : unsigned;
33
35 unsigned Offset;
36 bool IsPtr;
37};
38
39/// Holds all information required to evaluate constexpr code in a module.
40class Context final {
41public:
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.
50
51 /// Evaluates a toplevel expression as an rvalue.
53
54 /// Evaluates a toplevel initializer.
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
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
92private:
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
#define V(N, I)
Definition: ASTContext.h:3241
NodeId Parent
Definition: ASTDiff.cpp:191
APValue - This class implements a discriminated union of [uninitialized] [APSInt] [APFloat],...
Definition: APValue.h:122
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:182
unsigned getIntWidth(QualType T) const
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:2053
Represents a C++ struct/union/class.
Definition: DeclCXX.h:258
This represents one expression.
Definition: Expr.h:110
Represents a function declaration or definition.
Definition: Decl.h:1957
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:83
A (possibly-)qualified type.
Definition: Type.h:736
Represent the declaration of a variable (in which case it is an lvalue) a function (in which case it ...
Definition: Decl.h:704
Represents a variable declaration or definition.
Definition: Decl.h:916
Holds all information required to evaluate constexpr code in a module.
Definition: Context.h:40
const LangOptions & getLangOpts() const
Returns the language options.
Definition: Context.cpp:89
~Context()
Cleans up the constexpr VM.
Definition: Context.cpp:28
unsigned getCharBit() const
Returns CHAR_BIT.
Definition: Context.cpp:150
Program & getProgram() const
Returns the program. This is only needed for unittests.
Definition: Context.h:90
bool evaluateAsInitializer(State &Parent, const VarDecl *VD, APValue &Result)
Evaluates a toplevel initializer.
Definition: Context.cpp:71
const llvm::fltSemantics & getFloatSemantics(QualType T) const
Return the floating-point semantics for T.
Definition: Context.cpp:156
static bool shouldBeGloballyIndexed(const ValueDecl *VD)
Returns whether we should create a global variable for the given ValueDecl.
Definition: Context.h:82
ASTContext & getASTContext() const
Returns the AST context.
Definition: Context.h:58
uint32_t getBitWidth(QualType T) const
Return the size of T in bits.
Definition: Context.h:68
bool isPotentialConstantExpr(State &Parent, const FunctionDecl *FnDecl)
Checks if a function is a potential constant expression.
Definition: Context.cpp:30
bool evaluateAsRValue(State &Parent, const Expr *E, APValue &Result)
Evaluates a toplevel expression as an rvalue.
Definition: Context.cpp:54
InterpStack & getStack()
Returns the interpreter stack.
Definition: Context.h:62
const CXXMethodDecl * getOverridingFunction(const CXXRecordDecl *DynamicDecl, const CXXRecordDecl *StaticDecl, const CXXMethodDecl *InitialFunction) const
Definition: Context.cpp:191
std::optional< PrimType > classify(QualType T) const
Classifies an expression.
Definition: Context.cpp:91
const Function * getOrCreateFunction(const FunctionDecl *FD)
Definition: Context.cpp:224
Bytecode function.
Definition: Function.h:76
Stack frame storing temporaries and parameters.
Definition: InterpStack.h:26
The program contains and links the bytecode for all functions.
Definition: Program.h:40
Interface for the VM to interact with the AST walker's context.
Definition: State.h:55
PrimType
Enumeration of the primitive types of the VM.
Definition: PrimType.h:32
@ Result
The result type of a method or function.