[PATCH] Teach BaseIndexOffset::match to identify base pointers in loops

[Juergen Ributzka]

Thanks for the warm welcome - although it wasn’t my first patch ;-)

Cheers,
Juergen

On Aug 28, 2013, at 3:46 PM, Eric Christopher <echristo at gmail.com> wrote:

> Sweet, thanks.
> 
> Great first patch.
> 
> -eric
> 
> On Wed, Aug 28, 2013 at 3:37 PM, Juergen Ributzka <juergen at apple.com> wrote:
>> Yup, it was already committed in r188936. I fixed the style in r189526 as
>> you suggested.
>> 
>> Thanks
>> 
>> -Juergen
>> 
>> 
>> On Aug 28, 2013, at 3:20 PM, Eric Christopher <echristo at gmail.com> wrote:
>> 
>> Haven't looked to see if it was ever committed (it also LGTM and
>> awesome for the better comments), one style nit:
>> 
>> +    if (Ptr->getOperand(1)->getOpcode() == ISD::MUL) {
>> +      return BaseIndexOffset(Ptr, SDValue(), 0, IsIndexSignExt);
>> +    }
>> 
>> No need for braces here I don't think.
>> 
>> -eric
>> 
>> 
>> On Wed, Aug 21, 2013 at 2:44 PM, Juergen Ributzka <juergen at apple.com> wrote:
>> 
>> Hi @ll,
>> 
>> the small utility function that pattern matches Base + Index + Offset
>> patterns for loads and stores fails to recognize the base pointer for
>> loads/stores from/into an array at offset 0 inside a loop. As a result
>> DAGCombiner::MergeConsecutiveStores was not able to merge all stores.
>> 
>> Example:
>> for(int i=0; i <N; i+=4) {
>>       a[i+0] = 1;
>>       a[i+1] = 1;
>>       a[i+2] = 1;
>>       a[i+3] = 1;
>> }
>> 
>> In this example BaseIndexOffset::match would identify a different base
>> pointer for a[i+0] then for all the others.
>> 
>> This small patch adds an additional pattern match to recognize this special
>> case and a test case.
>> 
>> Cheers,
>> Juergen
>> 
>> 
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