1604098 - Use bytecode operands instead of SRC_CLASS_SPAN

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P2)

Description

[Jan de Mooij [:jandem]]

JSOP_CLASSCONSTRUCTOR and JSOP_DERIVEDCONSTRUCTOR always look up their SRC_CLASS_SPAN source note. This is not a good use of source notes: looking up source notes can be relatively slow and source notes should be used for metadata we typically don't need for bytecode execution (line, column, breakpoints, etc).

It seems nicer and more efficient to encode these offsets directly as bytecode immediates.

Comment 1

[Jan de Mooij [:jandem]]

Attachment: Bug 1604098 - Replace SRC_CLASS_SPAN source note with bytecode operands. r?arai!,tcampbell!

JSOP_CLASSCONSTRUCTOR and JSOP_DERIVEDCONSTRUCTOR always had to look up their
SRC_CLASS_SPAN source note. This means it's better and more efficient to encode
these offsets as bytecode operands. Source notes are for out-of-band data that
doesn't directly affect bytecode semantics.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7fd4e59c05ae
Replace SRC_CLASS_SPAN source note with bytecode operands. r=arai,tcampbell

Comment 3

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/7fd4e59c05ae