Commit Graph

3 Commits

Author SHA1 Message Date
Sanjay Patel e304bea010 optimize the AVX2 (integer) version of vperm2 into a shuffle
...because this is what happens when an instruction
set puts its underwear on after its pants.

This is an extension of r232852, r233100, and 233110:
http://llvm.org/viewvc/llvm-project?view=revision&revision=232852
http://llvm.org/viewvc/llvm-project?view=revision&revision=233100
http://llvm.org/viewvc/llvm-project?view=revision&revision=233110

llvm-svn: 233127
2015-03-24 22:39:29 +00:00
Sanjay Patel 43a87fdc79 [X86, AVX] instcombine vperm2 intrinsics with zero inputs into shuffles
This is the IR optimizer follow-on patch for D8563: the x86 backend patch
that converts this kind of shuffle back into a vperm2.

This is also a continuation of the transform that started in D8486. 
In that patch, Andrea suggested that we could convert vperm2 intrinsics that
use zero masks into a single shuffle. 

This is an implementation of that suggestion.

Differential Revision: http://reviews.llvm.org/D8567

llvm-svn: 233110
2015-03-24 20:36:42 +00:00
Sanjay Patel ccf5f24b7b [X86, AVX] instcombine common cases of vperm2* intrinsics into shuffles
vperm2* intrinsics are just shuffles. 
In a few special cases, they're not even shuffles.

Optimizing intrinsics in InstCombine is better than
handling this in the front-end for at least two reasons:

1. Optimizing custom-written SSE intrinsic code at -O0 makes vector coders
   really angry (and so I have regrets about some patches from last week).

2. Doing mask conversion logic in header files is hard to write and 
   subsequently read.

There are a couple of TODOs in this patch to complete this optimization.

Differential Revision: http://reviews.llvm.org/D8486

llvm-svn: 232852
2015-03-20 21:47:56 +00:00