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//===--- Expr.cpp - Expression Constant Evaluator -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Expr constant evaluator.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Expr.h"
using namespace clang;
static bool CalcFakeICEVal(const Expr* Expr,
llvm::APSInt& Result,
ASTContext& Context) {
// Calculate the value of an expression that has a calculatable
// value, but isn't an ICE. Currently, this only supports
// a very narrow set of extensions, but it can be expanded if needed.
if (const ParenExpr *PE = dyn_cast<ParenExpr>(Expr))
return CalcFakeICEVal(PE->getSubExpr(), Result, Context);
if (const CastExpr *CE = dyn_cast<CastExpr>(Expr)) {
QualType CETy = CE->getType();
if ((CETy->isIntegralType() && !CETy->isBooleanType()) ||
CETy->isPointerType()) {
if (CalcFakeICEVal(CE->getSubExpr(), Result, Context)) {
Result.extOrTrunc(Context.getTypeSize(CETy));
// FIXME: This assumes pointers are signed.
Result.setIsSigned(CETy->isSignedIntegerType() ||
CETy->isPointerType());
return true;
}
}
}
if (Expr->getType()->isIntegralType())
return Expr->isIntegerConstantExpr(Result, Context);
return false;
}
bool Expr::tryEvaluate(APValue& Result, ASTContext &Ctx) const
{
llvm::APSInt sInt(1);
if (CalcFakeICEVal(this, sInt, Ctx)) {
Result = APValue(sInt);
return true;
}
return false;
}
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