[PATCH] D40969: [DAG] Elide overlapping stores

[Chandler Carruth via Phabricator via llvm-commits]

chandlerc added subscribers: nemanjai, chandlerc.
chandlerc added a comment.

There was a comment by @nemanjai on the submitted revision in phab that I think got lost:

In https://reviews.llvm.org/rL321089#229740, @nemanjai wrote:

> This has broken all the PowerPC buildbots. I'll pull this patch to get the bots back to green unless you have a fix available. The smallest failing benchmark from the test-suite is `sieve.c`.
>  This patch removes half of the pre-inc stores that are actually needed. I imagine that the DAGCombiner is getting rid of these stores before they become pre-inc stores since there's a check for unindexed stores as part of this patch, but I haven't spent the time to really understand what this patch does.
>  I'm attaching both the IR generated for `sieve.c` as well as a bugpoint-reduced version of it (the reduction was done by comparing the number of pre-inc stores emitted before the patch and after it).F5703558: sieve.ll <https://reviews.llvm.org/F5703558>
>
> F5703557: reduced.ll <https://reviews.llvm.org/F5703557>


Notably, all PPC bots were broken by this, and it has stayed in tree for a long time. we should get it reverted.


Repository:
  rL LLVM

https://reviews.llvm.org/D40969