All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=825647

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=136a5a7a5649cffec50448b61f95c4432f86987a079fcccef6f43306e9390538


Bot(s) for this bug's original alert(s):

chromium-rel-mac11-pro

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/14df8c93440000

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/14df8c93440000

Allow HSW stages to detect FMAs opportunistically. by mtklein@chromium.org
https://chromium.googlesource.com/chromium/src/+/670c468885c8ca351af506db4f44d07b2f4e2acb

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/811d1a139265b7d8c94fc1690184de2351d9230f

commit 811d1a139265b7d8c94fc1690184de2351d9230f
Author: Mike Klein <mtklein@chromium.org>
Date: Tue Mar 27 00:23:29 2018

Revert "Allow HSW stages to detect FMAs opportunistically."

This reverts commit 670c468885c8ca351af506db4f44d07b2f4e2acb.

Reason for revert:

Mysteriously, this has caused some regressions on a bunch of bots that do not support the Haswell instruction set.  Reverting just to see if that's real (and because this wasn't really a noticeable win anywhere when landing the first time).

Bug:  825647 ,  825586 ,  825646 ,  825104 

Original change's description:
> Allow HSW stages to detect FMAs opportunistically.
>
> We used to build the .S files with -ffp-contract=fast for this, and
> adding it here to the HSW opts will have the equivalent effect.  None of
> the other x86 targets support FMAs.
>
> In many key places we do call _mm256_fmadd_ps explicitly, but in several
> other stages we have been relying on Clang to sniff out opportunities,
> especially for fused-multiply-subtracts, which we're just not very good
> at seeing in our heads.
>
> Bug:  821012 
> Change-Id: I2767cbdb7151d60ea7553e83f51b28ff9340eb94
> Reviewed-on: https://chromium-review.googlesource.com/963141
> Reviewed-by: Florin Malita <fmalita@chromium.org>
> Commit-Queue: Mike Klein <mtklein@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#543262}

TBR=fmalita@chromium.org,herb@chromium.org,mtklein@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug:  821012 
Change-Id: I61c0627270853b8acdcf6b20fca17ba0fd8bba55
Reviewed-on: https://chromium-review.googlesource.com/980293
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545897}
[modify] https://crrev.com/811d1a139265b7d8c94fc1690184de2351d9230f/skia/BUILD.gn