1746594 - Inconsistent pending exception with AllowGC::NoGC

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P3)

Description

[Tooru Fujisawa [:arai]]

string allocation code has AllowGC allowGC template parameter,
and allowGC==NoGC mostly means:

• if failure happens, it's out of memory due to "no GC"
• if failure happens, there's no pending exception

but JSString::validateLength called inside those functions can call js::ReportAllocationOverflow regardless of AllowGC.

So, failure case for NoGC has 2 modes:

• needs GC. there's no pending exception
  • the caller can fallback to slow path that does GC and then allocate again
• allocation overflow. there's pending exception
  • the caller has no fallback way

I wonder if the length validation must be done in other place, or maybe the behavior must be clearly documented.

Comment 1

[Tooru Fujisawa [:arai]]

Attachment: Bug 1746594 - Part 1: Add MOZ_UNLIKELY to JSString::validateLength call. r?iain!

Comment 2

[Tooru Fujisawa [:arai]]

Attachment: Bug 1746594 - Part 2: Add JSString::validateLengthInternal with AllowGC template parameter to control pending exception. r?iain!

Depends on D134171

Comment 3

[Tooru Fujisawa [:arai]]

Attachment: Bug 1746594 - Part 3: Call ReportOutOfMemory only for CanGC in NumberToStringWithBase. r?iain!

Depends on D134172

Comment 4

[Tooru Fujisawa [:arai]]

Attachment: Bug 1746594 - Part 4: Call ReportOutOfMemory after NoGC in PrintShapeProperties. r?iain!

Depends on D134173

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/406cc8559fcc
Part 1: Add MOZ_UNLIKELY to JSString::validateLength call. r=iain
https://hg.mozilla.org/integration/autoland/rev/0cffd4eac5d4
Part 2: Add JSString::validateLengthInternal with AllowGC template parameter to control pending exception. r=iain
https://hg.mozilla.org/integration/autoland/rev/4e2fade0a654
Part 3: Call ReportOutOfMemory only for CanGC in NumberToStringWithBase. r=iain
https://hg.mozilla.org/integration/autoland/rev/278328d4983f
Part 4: Call ReportOutOfMemory after NoGC in PrintShapeProperties. r=iain

Comment 6

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/406cc8559fcc
https://hg.mozilla.org/mozilla-central/rev/0cffd4eac5d4
https://hg.mozilla.org/mozilla-central/rev/4e2fade0a654
https://hg.mozilla.org/mozilla-central/rev/278328d4983f