commit e252cc3f671d826500cb3587d03e2cf1085d07d9
author Sanjay Patel <spatel@rotateright.com> Sat Jan 12 15:12:28 2019 +0000
committer Sanjay Patel <spatel@rotateright.com> Sat Jan 12 15:12:28 2019 +0000
tree 60191517f4633c259b60d7e21443f6fd76a7c7b3
parent 04fde6bab3538ede40931c418d04c9391da9c9ba

[DAGCombiner] fold insert_subvector of insert_subvector

This pattern:

    t33: v8i32 = insert_subvector undef:v8i32, t35, Constant:i64<0>
  t21: v16i32 = insert_subvector undef:v16i32, t33, Constant:i64<0>

...shows up in PR33758:
https://bugs.llvm.org/show_bug.cgi?id=33758
...although this patch doesn't make any difference to the final result on that yet.

In the affected tests here, it looks like it just makes RA wiggle. But we might 
as well squash this to prevent it interfering with other pattern-matching.

Differential Revision:
https://reviews.llvm.org/D56604


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351008 91177308-0d34-0410-b5e6-96231b3b80d8