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Overflow detection for multiply and divide. Fix a bug handling 'usual 

arithmetic conversions'.

llvm-svn: 39405
This commit is contained in:
Chris Lattner 2007-04-11 04:04:29 +00:00
parent 7e61ac5a3c
commit 8ec9355a48
1 changed files with 6 additions and 1 deletions
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7
clang/Lex/PPExpressions.cpp
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@ -428,14 +428,15 @@ static bool EvaluateDirectiveSubExpr(APSInt &LHS, unsigned MinPrec,
// Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
// either operand is unsigned. Don't do this for x and y in "x ? y : z".
APSInt Res(LHS.getBitWidth());
if (Operator != tok::question) {
if (RHS.isUnsigned()) LHS.setIsUnsigned(true);
RHS.setIsUnsigned(LHS.isUnsigned());
Res.setIsUnsigned(LHS.isUnsigned());
}
// FIXME: All of these should detect and report overflow??
bool Overflow = false;
APSInt Res(LHS.getBitWidth());
switch (Operator) {
default: assert(0 && "Unknown operator token!");
case tok::percent:
@ -451,9 +452,13 @@ static bool EvaluateDirectiveSubExpr(APSInt &LHS, unsigned MinPrec,
return true;
}
Res = LHS / RHS;
if (LHS.isSigned())
Overflow = LHS.isMinSignedValue() && RHS.isAllOnesValue(); // MININT/-1
break;
case tok::star:
Res = LHS * RHS;
if (LHS != 0 && RHS != 0)
Overflow = Res/RHS != LHS || Res/LHS != RHS;
break;
case tok::lessless: {
// Determine whether overflow is about to happen.