Closed Bug 622903 Opened 14 years ago Closed 14 years ago

Valgrind/memcheck false positive on thisPage in TraceConservatePointer()

Categories

(Tamarin Graveyard :: Garbage Collection (mmGC), defect, P3)

defect

Tracking

(Not tracked)

RESOLVED FIXED
Future

People

(Reporter: edwsmith, Unassigned)

References

Details

Attachments

(1 file)

Rarely, a false positive occurs with tamarin on valgrind due to using the value of (thisPage = val & kBlockMask) in TraceConservativePointer(), prior to telling valgrind that is defined.

Easy fix appears to be to sink the calculation of thisPage to just before it is needed.  The problem apparently showed up when TraceConservativePointer() was refactored in this changeset:

  changeset:   5579:3c36f7b25333
  user:        Lars T Hansen <lhansen@adobe.com>
  date:        Mon Nov 29 15:46:48 2010 +0100
  summary:     ExactGC work: refactor conservative tracer (lhansen/fklockii)
Blocks: 509020
Summary: Move thisPage calculation to suppress VG error → Valgrind/memcheck false positive on thisPage in TraceConservatePointer()
Attachment #501076 - Attachment is patch: true
Attachment #501076 - Attachment mime type: application/octet-stream → text/plain
Attachment #501076 - Flags: review?(fklockii)
OS: Mac OS X → All
Priority: -- → P3
Hardware: x86 → All
Target Milestone: --- → Future
Comment on attachment 501076 [details] [diff] [review]
Move calculation of thisPage to avoid memcheck false positives.

Great catch; I was too mechanical in my refactoring of TraceConservativePointer.
Attachment #501076 - Flags: review?(fklockii) → review+
changeset: 5711:93a6f1d1128f
user:      Edwin Smith <edwsmith@adobe.com>
summary:   Bug 622903 - Valgrind/memcheck false positive on thisPage in TraceConservatePointer() (r=fklockii+)

http://hg.mozilla.org/tamarin-redux/rev/93a6f1d1128f
Status: NEW → RESOLVED
Closed: 14 years ago
Resolution: --- → FIXED
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