Bug 153287 – [JSC] The register allocator can use a dangling pointer when selecting a spill candidate

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Benjamin Poulain]

[JSC] The register allocator can use a dangling pointer when selecting a spill candidate

[Benjamin Poulain]

Created attachment 269386 [details]
Patch

[WebKit Commit Bot]

Attachment 269386 [details] did not pass style-queue:


ERROR: Source/JavaScriptCore/ChangeLog:28:  Need whitespace between colon and description  [changelog/filechangedescriptionwhitespace] [5]
Total errors found: 1 in 3 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Mark Lam]

Comment on attachment 269386 [details]
Patch

r=me

[Benjamin Poulain]

Created attachment 269388 [details]
Patch for landing

[Mark Lam]

Comment on attachment 269388 [details]
Patch for landing

View in context: https://bugs.webkit.org/attachment.cgi?id=269388&action=review

> Source/JavaScriptCore/dfg/DFGCommon.h:42
> -#define FTL_USES_B3 0
> +#define FTL_USES_B3 1
>  

Please undo this.

[Benjamin Poulain]

Created attachment 269390 [details]
Patch for landing

[WebKit Commit Bot]

Comment on attachment 269390 [details]
Patch for landing

Clearing flags on attachment: 269390

Committed r195387: <http://trac.webkit.org/changeset/195387>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Filip Pizlo]

I encountered the same thing.  I think I'll keep my version of UseCounts from https://bugs.webkit.org/show_bug.cgi?id=153200, which returns a pointer that may be null, since it feels perfectly ordinary for a phase to add tmps and still query UseCounts.

I'm not sure whether to keep your version or my version of the fix in IRC.  The benefit of my fix is that querying unspillableTmps before adding to spillWorklist is probably better than querying unspillableTmps for every member of spillWorklist every time selectSpill() is called.