[PATCH] D87163: [DSE] Switch to MemorySSA-backed DSE by default.

Mon Sep 14 14:02:28 PDT 2020

fhahn added a comment.

In D87163#2271998 <https://reviews.llvm.org/D87163#2271998>, @dmajor wrote:

> In D87163#2270871 <https://reviews.llvm.org/D87163#2270871>, @fhahn wrote:
>
>> In D87163#2270444 <https://reviews.llvm.org/D87163#2270444>, @thakis wrote:
>>
>>> Heads-up: We're seeing fairly widespread test failures with this in Chromium that go away when we force this flag off. It's possible that it's due to only a small number of issues and they might be previously-benign UB (no idea), but I figured I'd give an early note. We'll send an update once we've reduced a failing test.
>>
>> Thanks for the heads-up. I just pushed another fix for the issue @uabelho. I'd guess at least some of the failures you are seeing should be related. If not, I think it makes sense to revert this once we have the reproducers and can work in ironing out the remaining issues.
>
> We're also seeing test failures in Firefox that are not fixed by f715d81c9df3 <https://reviews.llvm.org/rGf715d81c9df3fb3e047a54899fc749f57c84aeb5>. I'll attempt to reduce but it may take some time.

I also pushed a fix for a MemorySSA issue that was exposed through DSE + MemorySSA in c4f1b3144184 <https://reviews.llvm.org/rGc4f1b3144184e4c276a7e7c801cbcd4ac3c573ba>. This might also fix (some) of the failures you are seeing.

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https://reviews.llvm.org/D87163