[llvm-commits] [PATCH] extend fix to PR12312 to support 256-bit vector

[Nadav Rotem]

Hi, 

The PTEST changes look okay.  However, I would like to see a new LLVM builtin function for checking all-one or all-zero on vectors.  

Are the changes in LegalizeTypesGeneric related to the ptest changes ?  Can you separate them to a different patch ?

Otherwise, LGTM. 
  
Nadav   


On Sep 6, 2012, at 9:58 AM, Michael Liao <michael.liao at intel.com> wrote:

> Hi
> 
> Fix to PR12312 only supports 128-bit vector. This patch extends the
> support to 256-bit vector as well. The patch includes 2 major changes:
> 
> + one change to, when bitcasting 256-bit vector (or wider) to 256-bit
> integer, allow type legalization to extract elements instead of storing
> whole vector followed by loading each element.
>  Suppose a N-bit vector into a N-bit integer. Type legalization will
> try cast that N-bit vector into <2 x (N/2)> vector first and extract the
> lo/hi part. When N = 128, <2 x (N/2>) is legal. But, when N =256, <2 x
> i128> is illegal (on x86) and type legalization falls back to store/load
> approach.
>  When <2 x (N/2)> is found illegal, this patch tries to check <M x
> ExtVT>, where ExtVT is the type which N-bit integer is extended onto,
> e.g. on x86, 256-bit integer will be extended to 64-bit integers and we
> will try <4 x i64>. If <M x ExtVT> is legal, we will extract elements
> from it and build N/2-bit lo/hi parts.
> 
> + the other change is X86-specific. This patch moves the previous logic
> recognizing OR'd tree into IR lowering phase to reduce DAG combination
> overhead. In addition, it's enhanced to handle OR'd tree from elements
> extracted from 1+ 128-/256-bit vectors. If more than more than input
> vectors are found, it will POR first and finally PTEST. Otherwise, just
> a single PTEST.
> 
> Test cases are enhanced with 256-bit vectors.
> 
> Thanks for review.
> 
> Yours
> - Michael
> 
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