[PATCH] LoopVectorizer: Don't attempt to vectorize extractelement instructions

[Nadav Rotem]

LGTM. Thanks!


On Oct 25, 2013, at 1:13 PM, Hal Finkel <hfinkel at anl.gov> wrote:

> [With the patch this time].
> 
> ----- Original Message -----
>> Nadav, Arnold,
>> 
>> The loop vectorizer does not currently understand how to vectorize
>> extractelement instructions. The existing check, which excluded all
>> vector-valued instructions, did not catch extractelement instructions
>> because
>> it checked only the return value. As a result, vectorization would
>> proceed,
>> producing illegal instructions like this:
>> 
>>  %58 = extractelement <2 x i32> %15, i32 0
>>  %59 = extractelement i32 %58, i32 0
>> 
>> where the second extractelement is illegal because its first operand
>> is not a vector. Later passes (or the verifier) would then crash.
>> 
>> We could teach the vectorizer to handle this case when vectorizing,
>> but I think that might be a task better associated with a larger
>> effort in vectorizing vectorized loops. Please review.
>> 
>> Thanks again,
>> Hal
>> 
>> --
>> Hal Finkel
>> Assistant Computational Scientist
>> Leadership Computing Facility
>> Argonne National Laboratory
>> 
> 
> -- 
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
> <lv-ee-crash.patch>