commit 7b59899e869fd1520ca45c6eb9f418402ec9ce59
author Olivier Flückiger <olivf@chromium.org> Fri Nov 10 10:15:12 2023
committer V8 LUCI CQ <v8-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Nov 10 13:55:21 2023
tree ac3a8f38644a2fa971ee9dc644237873da6906b5
parent 19ebfc7d159dfe1c3a28880c14d07e8724094956

[maglev] Hoist some phi input untagging out of loops

Implement the ability to hoist untagging operations for untagged loop
phis out of the loop.

If we can hoist the untagging we ignore the input edge in
representation inference, since it should always be cheaper to untag
before the loop.

For now the optimization is only enabled for OSR values. The reason is
that in normal code we could have a deopt loop if we can't learn when
the speculative untagging failed.

To be able to insert checked untaggings we create a use a new
checkpointed jump instruction that has a deopt frame attached.

Bug: v8:7700
Change-Id: Ic3f3b0809374ffad412ef9028bb047dd6cd57ad0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5008116
Reviewed-by: Darius Mercadier <dmercadier@chromium.org>
Auto-Submit: Olivier Flückiger <olivf@chromium.org>
Commit-Queue: Olivier Flückiger <olivf@chromium.org>
Cr-Commit-Position: refs/heads/main@{#90861}