[cfe-commits] r76911 - /cfe/trunk/lib/Analysis/CFG.cpp

[Eli Friedman]

On Thu, Jul 23, 2009 at 9:19 PM, Ted Kremenek<kremenek at apple.com> wrote:
> On Jul 23, 2009, at 4:25 PM, Mike Stump wrote:
>
>> +    // See if this is a known constant.
>> +    int KnownVal = TryEvaluateBool(B->getLHS());
>> +    if (KnownVal != -1 && (B->getOpcode() == BinaryOperator::LOr))
>> +      KnownVal = !KnownVal;
>> +
>>     // Now link the LHSBlock with RHSBlock.
>>     if (B->getOpcode() == BinaryOperator::LOr) {
>> -      if (KnownTrue)
>> +      if (KnownVal == true)
>>         LHSBlock->addSuccessor(0);
>>       else
>>         LHSBlock->addSuccessor(ConfluenceBlock);
>> -      if (KnownFalse)
>> +      if (KnownVal == false)
>>         LHSBlock->addSuccessor(0);
>
> Hi Mike,
>
> This looks a little suspicious to me.  Doesn't '-1' convert to 'true'
> when an int is casted to a bool?  This would cause 'KnowVal == true'
> to evaluate to true even when 'KnownVal' is -1.

(int)x == false is semantically equivalent to (int)x == 0 due to
integer promotion rules.  That said, it is slightly confusing the way
it's written.

-Eli