Bug 68606

Summary: 32-bit call code clobbers the function cell tag
Product: WebKit Reporter: Filip Pizlo <fpizlo>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Severity: Normal CC: barraclough, fpizlo, ossy
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: All   
OS: All   
Bug Depends on:    
Bug Blocks: 68557    
Description Flags
the patch none

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.