Anders Carlsson | c7436af | 2008-07-03 04:20:39 +0000 | [diff] [blame^] | 1 | //===--- Expr.cpp - Expression Constant Evaluator -------------------------===// |
| 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This file implements the Expr constant evaluator. |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
| 14 | #include "clang/AST/APValue.h" |
| 15 | #include "clang/AST/ASTContext.h" |
| 16 | #include "clang/AST/Expr.h" |
| 17 | |
| 18 | using namespace clang; |
| 19 | |
| 20 | |
| 21 | static bool CalcFakeICEVal(const Expr* Expr, |
| 22 | llvm::APSInt& Result, |
| 23 | ASTContext& Context) { |
| 24 | // Calculate the value of an expression that has a calculatable |
| 25 | // value, but isn't an ICE. Currently, this only supports |
| 26 | // a very narrow set of extensions, but it can be expanded if needed. |
| 27 | if (const ParenExpr *PE = dyn_cast<ParenExpr>(Expr)) |
| 28 | return CalcFakeICEVal(PE->getSubExpr(), Result, Context); |
| 29 | |
| 30 | if (const CastExpr *CE = dyn_cast<CastExpr>(Expr)) { |
| 31 | QualType CETy = CE->getType(); |
| 32 | if ((CETy->isIntegralType() && !CETy->isBooleanType()) || |
| 33 | CETy->isPointerType()) { |
| 34 | if (CalcFakeICEVal(CE->getSubExpr(), Result, Context)) { |
| 35 | Result.extOrTrunc(Context.getTypeSize(CETy)); |
| 36 | // FIXME: This assumes pointers are signed. |
| 37 | Result.setIsSigned(CETy->isSignedIntegerType() || |
| 38 | CETy->isPointerType()); |
| 39 | return true; |
| 40 | } |
| 41 | } |
| 42 | } |
| 43 | |
| 44 | if (Expr->getType()->isIntegralType()) |
| 45 | return Expr->isIntegerConstantExpr(Result, Context); |
| 46 | |
| 47 | return false; |
| 48 | } |
| 49 | |
| 50 | bool Expr::tryEvaluate(APValue& Result, ASTContext &Ctx) const |
| 51 | { |
| 52 | llvm::APSInt sInt(1); |
| 53 | |
| 54 | if (CalcFakeICEVal(this, sInt, Ctx)) { |
| 55 | Result = APValue(sInt); |
| 56 | return true; |
| 57 | } |
| 58 | |
| 59 | return false; |
| 60 | } |