Files
archived-llvm/test/CodeGen/PowerPC
Sanjay Patel 8209d78723 [CGP] use subtract or subtract-of-cmps for result of memcmp expansion
As noted in the code comment, transforming this in the other direction might require 
a separate transform here in CGP given the block-at-a-time DAG constraint.

Besides that theoretical motivation, there are 2 practical motivations for the 
subtract-of-cmps form:

1. The codegen for both x86 and PPC is better for this IR (though PPC could be better still). 
   There is discussion about canonicalizing IR to the select form 
   ( http://lists.llvm.org/pipermail/llvm-dev/2017-July/114885.html ), 
   so we probably need to add DAG transforms for those patterns anyway, but this improves the 
   memcmp output without waiting for that step.

2. If we allow vector-sized chunks for the load and compare, x86 is better prepared to convert
   that to optimal code when using subtract-of-cmps, so another prerequisite patch is avoided
   if we choose to enable that.

Differential Revision: https://reviews.llvm.org/D34904



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@309597 91177308-0d34-0410-b5e6-96231b3b80d8
2017-07-31 18:08:24 +00:00
..
2016-10-19 16:58:59 +00:00
2016-02-29 16:42:27 +00:00
2017-01-22 20:28:56 +00:00
2017-06-20 18:43:14 +00:00