1874456 - jit::EliminateDeadResumePointOperands never worked as expected.

Status: ASSIGNED

(Core :: JavaScript Engine: JIT, enhancement, P1)

Description

[Nicolas B. Pierron [:nbp]]

jit::EliminateDeadResumePointOperands is supposed to remove resume point operands, but the way it is implemented it removes resume point operands of resume points which are in the same block but keeps them for resume points which are in subsequent blocks, which is a non sense.

However, fixing it highlighted a set of other errors which would be fixed as dependencies of this issue.

Fixing this issue should solve the problem highlighted in Bug 1845728 comment 12.

Comment 1

[Nicolas B. Pierron [:nbp]]

Attachment: Bug 1874456 part 2 - Fix EliminateDeadResumePointOperands logic.

The prinicple of EliminateDeadResumePointOperands apparently might never
have worked, except for cases where the only resume point capturing the
values where in the same block as the instruction being captured as
operands of resume points.

This change rename the local variable to better describe what it holds
as well as fixing the logic and adding a few extra comments to better
describe the reasoning behind this optimization.

Comment 2

[Nicolas B. Pierron [:nbp]]

Attachment: Bug 1874456 part 1 - Improve the BigInt tests cases to properly check the recovery path.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/65b9194067b4
part 1 - Improve the BigInt tests cases to properly check the recovery path. r=iain
https://hg.mozilla.org/integration/autoland/rev/7ad5c59c746b
part 2 - Fix EliminateDeadResumePointOperands logic. r=iain

Comment 4

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/65b9194067b4
https://hg.mozilla.org/mozilla-central/rev/7ad5c59c746b

Comment 5

[Nicolas B. Pierron [:nbp]]

Reopening this bug given that the part 2 has been reverted by Bug 1876978:
https://hg.mozilla.org/mozilla-central/rev/42aa41fca836