Bug 68606 - 32-bit call code clobbers the function cell tag
Summary: 32-bit call code clobbers the function cell tag
Alias: None
Product: WebKit
Classification: Unclassified
Component: JavaScriptCore (show other bugs)
Version: 528+ (Nightly build)
Hardware: All All
: P2 Normal
Assignee: Nobody
Depends on:
Blocks: 68557
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Reported: 2011-09-22 03:22 PDT by Filip Pizlo
Modified: 2011-09-22 04:04 PDT (History)
3 users (show)

See Also:

the patch (2.02 KB, patch)
2011-09-22 03:24 PDT, Filip Pizlo
no flags Details | Formatted Diff | Diff

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Description Filip Pizlo 2011-09-22 03:22:15 PDT
The change to use emitJumpIfNotType results in problems, because this function is often called (in 32-bit mode) with the tag register as the scratch register.  If the jump is taken, the slow path code then expects the tag register to be intact, and passes the no-longer-valid tag to a stub function.  This results in failures when attempting to make InternalFunction calls.
Comment 1 Filip Pizlo 2011-09-22 03:24:22 PDT
Created attachment 108305 [details]
the patch
Comment 2 Csaba Osztrogonác 2011-09-22 04:02:36 PDT
Comment on attachment 108305 [details]
the patch

r+ to go ahead. I tested it on a 32-bit Qt environment and it works for me.
Comment 3 Csaba Osztrogonác 2011-09-22 04:04:45 PDT
Comment on attachment 108305 [details]
the patch

Clearing flags on attachment: 108305

Committed r95707: <http://trac.webkit.org/changeset/95707>
Comment 4 Csaba Osztrogonác 2011-09-22 04:04:52 PDT
All reviewed patches have been landed.  Closing bug.