1020141 - IonMonkey: (ARM) remove the unused 'offset' field from RelativePatch.

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, defect)

Description

[Douglas Crosher [:dougc]]

The 'offset' field of RelativePatch is not used. There is even code to update this offset to it's actualOffset() in finish(). If it has no planned use then can we remove it.

Comment 1

[Douglas Crosher [:dougc]]

Attachment: Remove the unused 'offset' field from RelativePatch.

Comment 2

[Douglas Crosher [:dougc]]

https://tbpl.mozilla.org/?tree=Try&rev=b07160726858

Comment 3

[Douglas Crosher [:dougc]]

Double checked this patch, and it still looks good. The x86 and x64 backends use pc relative jumps which need to be patched in executableCopy() so they need the 'offset' field. Whereas the ARM backend jumps to an absolute address that is inlined or stored in a constant pool and these do no need patching, so the 'offset' field is not needed by the ARM backend.

Comment 4

[Douglas Crosher [:dougc]]

Comment on attachment 8433966 [details] [diff] [review]
Remove the unused 'offset' field from RelativePatch.

[Approval Request Comment]
Bug caused by (feature/regressing bug #): long standing issue.

User impact if declined: None, but 31 is an ESR release and a lot of ARM backend patches need uplifting for this, and lowering the differences between 31 and m-c will help this work.

Testing completed (on m-c, etc.): locally, and try build

Risk to taking this patch (and alternatives if risky): very low.

String or IDL/UUID changes made by this patch: n/a

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/309e938cbe53

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/309e938cbe53

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/4da73f25390a
https://hg.mozilla.org/releases/mozilla-beta/rev/ebba60c06474