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//===--- State.h - State chain for the VM and AST Walker --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Defines the base class of the interpreter and evaluator state.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_AST_INTERP_STATE_H
#define LLVM_CLANG_AST_INTERP_STATE_H
#include "clang/AST/ASTDiagnostic.h"
#include "clang/AST/Expr.h"
namespace clang {
class OptionalDiagnostic;
/// Kinds of access we can perform on an object, for diagnostics. Note that
/// we consider a member function call to be a kind of access, even though
/// it is not formally an access of the object, because it has (largely) the
/// same set of semantic restrictions.
enum AccessKinds {
AK_Read,
AK_ReadObjectRepresentation,
AK_Assign,
AK_Increment,
AK_Decrement,
AK_MemberCall,
AK_DynamicCast,
AK_TypeId,
AK_Construct,
AK_Destroy,
AK_IsWithinLifetime,
AK_Dereference
};
/// The order of this enum is important for diagnostics.
enum CheckSubobjectKind {
CSK_Base,
CSK_Derived,
CSK_Field,
CSK_ArrayToPointer,
CSK_ArrayIndex,
CSK_Real,
CSK_Imag,
CSK_VectorElement
};
enum class EvaluationMode {
/// Evaluate as a constant expression. Stop if we find that the expression
/// is not a constant expression.
ConstantExpression,
/// Evaluate as a constant expression. Stop if we find that the expression
/// is not a constant expression. Some expressions can be retried in the
/// optimizer if we don't constant fold them here, but in an unevaluated
/// context we try to fold them immediately since the optimizer never
/// gets a chance to look at it.
ConstantExpressionUnevaluated,
/// Fold the expression to a constant. Stop if we hit a side-effect that
/// we can't model.
ConstantFold,
/// Evaluate in any way we know how. Don't worry about side-effects that
/// can't be modeled.
IgnoreSideEffects,
};
namespace interp {
class Frame;
class SourceInfo;
/// Interface for the VM to interact with the AST walker's context.
class State {
public:
virtual ~State();
virtual bool noteUndefinedBehavior() = 0;
virtual bool keepEvaluatingAfterFailure() const = 0;
virtual bool keepEvaluatingAfterSideEffect() const = 0;
virtual Frame *getCurrentFrame() = 0;
virtual const Frame *getBottomFrame() const = 0;
virtual bool hasActiveDiagnostic() = 0;
virtual void setActiveDiagnostic(bool Flag) = 0;
virtual void setFoldFailureDiagnostic(bool Flag) = 0;
virtual Expr::EvalStatus &getEvalStatus() const = 0;
virtual ASTContext &getASTContext() const = 0;
virtual bool hasPriorDiagnostic() = 0;
virtual unsigned getCallStackDepth() = 0;
virtual bool noteSideEffect() = 0;
/// Are we checking whether the expression is a potential constant
/// expression?
bool checkingPotentialConstantExpression() const {
return CheckingPotentialConstantExpression;
}
/// Are we checking an expression for overflow?
bool checkingForUndefinedBehavior() const {
return CheckingForUndefinedBehavior;
}
public:
State() = default;
/// Diagnose that the evaluation could not be folded (FF => FoldFailure)
OptionalDiagnostic
FFDiag(SourceLocation Loc,
diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0);
OptionalDiagnostic
FFDiag(const Expr *E,
diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0);
OptionalDiagnostic
FFDiag(const SourceInfo &SI,
diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0);
/// Diagnose that the evaluation does not produce a C++11 core constant
/// expression.
///
/// FIXME: Stop evaluating if we're in EM_ConstantExpression or
/// EM_PotentialConstantExpression mode and we produce one of these.
OptionalDiagnostic
CCEDiag(SourceLocation Loc,
diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0);
OptionalDiagnostic
CCEDiag(const Expr *E,
diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0);
OptionalDiagnostic
CCEDiag(const SourceInfo &SI,
diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0);
/// Add a note to a prior diagnostic.
OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId);
/// Add a stack of notes to a prior diagnostic.
void addNotes(ArrayRef<PartialDiagnosticAt> Diags);
/// Directly reports a diagnostic message.
DiagnosticBuilder report(SourceLocation Loc, diag::kind DiagId);
/// Whether or not we're in a context where the front end requires a
/// constant value.
bool InConstantContext = false;
/// Whether we're checking that an expression is a potential constant
/// expression. If so, do not fail on constructs that could become constant
/// later on (such as a use of an undefined global).
bool CheckingPotentialConstantExpression = false;
/// Whether we're checking for an expression that has undefined behavior.
/// If so, we will produce warnings if we encounter an operation that is
/// always undefined.
///
/// Note that we still need to evaluate the expression normally when this
/// is set; this is used when evaluating ICEs in C.
bool CheckingForUndefinedBehavior = false;
EvaluationMode EvalMode;
private:
void addCallStack(unsigned Limit);
PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId);
OptionalDiagnostic diag(SourceLocation Loc, diag::kind DiagId,
unsigned ExtraNotes, bool IsCCEDiag);
};
} // namespace interp
} // namespace clang
#endif
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