1366470 - Ion compile functions with an extra var environment

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement, P3)

Description

[Tom S [:evilpie]]

Currently we don't compile scripts with an extra var environment. The source code for this cites bug 1273858, which is fixed nowadays. Apparently we ran into this with bug 1366372, where we didn't ion compile Array.fom!

Comment 1

[Tom S [:evilpie]]

It would be good to know what actually needs to be done to remove this abort.

Comment 2

[Shu-yu Guo [:shu]]

There are at least two pieces: 

1. Support PUSHVARENV/POPVARENV, which are like PUSHLEXICALENV/POPLEXICALENV for var envs instead of lexical envs.
2. Check that Ion doesn't assume anywhere that the var environment is already on the env chain at the start of function code.

Comment 3

[Jan de Mooij [:jandem]]

Attachment: Bug 1366470 part 1 - Add VarEnvironmentObject::create for Warp. r?iain!

Some refactoring to have a function we can call for Warp. This is similar to
other environment objects.

Comment 4

[Jan de Mooij [:jandem]]

Attachment: Bug 1366470 part 2 - Bailout changes to support var environments. r?iain!

For function frames, the "initial environment" includes the Call and NamedLambda
environments but never VarEnvironmentObject.

For eval frames, the initial environment is a VarEnvironmentObject, but we don't
support optimizing eval scripts yet.

This means the bailout code doesn't need to do anything special to support this,
similar to lexical environments.

Depends on D145429

Comment 5

[Jan de Mooij [:jandem]]

Attachment: Bug 1366470 part 3 - Warp-compile JSOp::PushVarEnv. r?iain!

Depends on D145430

Comment 6

[Jan de Mooij [:jandem]]

Attachment: Bug 1366470 part 4 - Add tests. r?iain!

Depends on D145431

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/04f478b31ca6
part 1 - Add VarEnvironmentObject::create for Warp. r=iain
https://hg.mozilla.org/integration/autoland/rev/ed69fc85ccbf
part 2 - Bailout changes to support var environments. r=iain
https://hg.mozilla.org/integration/autoland/rev/91027e567af6
part 3 - Warp-compile JSOp::PushVarEnv. r=iain
https://hg.mozilla.org/integration/autoland/rev/e8ff2e01409a
part 4 - Add tests. r=iain

Comment 8

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/04f478b31ca6
https://hg.mozilla.org/mozilla-central/rev/ed69fc85ccbf
https://hg.mozilla.org/mozilla-central/rev/91027e567af6
https://hg.mozilla.org/mozilla-central/rev/e8ff2e01409a