On May 13, 2007, at 4:57 PM, Reid Spencer wrote:
> On Sun, 2007-05-13 at 16:49 -0700, Chris Lattner wrote:
>> On May 13, 2007, at 4:45 PM, Reid Spencer wrote:
>>
>>> +APInt APInt::rotl(uint32_t rotateAmt) const {
>>> + // Don't get too fancy, just use existing shift/or facilities
>>> + APInt hi(*this);
>>> + APInt lo(*this);
>>> + hi.shl(rotateAmt);
>>> + lo.lshr(BitWidth - rotateAmt);
>>> + return hi | lo;
>>> +}
>>> +
>>> +APInt APInt::rotr(uint32_t rotateAmt) const {
>>> + // Don't get too fancy, just use existing shift/or facilities
>>> + APInt hi(*this);
>>> + APInt lo(*this);
>>> + lo.lshr(rotateAmt);
>>> + hi.shl(BitWidth - rotateAmt);
>>> + return hi | lo;
>>> +}
>>
>> Do these work for rotamt = 0 ?
>
> Yes, but results are undefined (in our case value 0). This behavior is
> implemented in lshr and shl.
I don't understand. Rotate by 0 is well defined. Rotate by "32"
isn't. does lshl/lshr do the 'right' thing with "32" ?
-Chris
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