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  1. 24 Mar, 2022 7 commits
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    • Darius M's avatar
      Reland^2 [compiler] Simplify "==0" branches in MachineOperatorReducer · 0719ace6
      Darius M authored 
      This is a reland of 6b690a6b.

The previous version of this CL was a bit too aggressive in the
duplication of branch conditions. This caused an increase in
register pressure in some cases, thus reducing performance.

In fact, duplicating branch conditions that require an "== 0" to be
added provides no benefits. We are thus now a bit less aggressive, and
only duplicate comparisons.

Original change's description:
> Reland [compiler] Simplify "==0" branches in MachineOperatorReducer
>
> This is a reland of 48b443f6.
>
> While fixing the initial CL, we stumbled upon a few bugs that
> we had to fix:
>
>  - CommonOperatorReducer and SimplifiedOperatorReducer were applied
>    before and after SimplifiedLowering, but always assumed that it
>    was before SimplifiedLowering, and thus had the wrong semantics
>    for branches in some cases. They now have an added parameter to
>    know which semantics of branch they should use.
>
>  - The lowering of StaticAssert was wrong and could leave kHeapConstant
>    in the assert (instead of machine Booleans).
>
> Original change's description:
> > [compiler] Simplify "==0" branches in MachineOperatorReducer
> >
> > Bug: v8:12484
> > Change-Id: I0667c7464c0dd71338bc199a24a69248a7a0a525
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3497303
> > Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> > Owners-Override: Tobias Tebbi <tebbi@chromium.org>
> > Commit-Queue: Darius Mercadier <dmercadier@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#79379}
>
> Bug: v8:12484
> Change-Id: Ibbf5df96fce5ccb04868dc517539479bf69f5703
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3516869
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Commit-Queue: Darius Mercadier <dmercadier@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#79528}

Bug: v8:12484
Change-Id: I31f575a59811a83c7c1acb4c14bf5ded63a8f536
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3540102Reviewed-by: 's avatarTobias Tebbi <tebbi@chromium.org>
Commit-Queue: Darius Mercadier <dmercadier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79560}
      0719ace6