[LLVMbugs] [Bug 17852] Assertion `!ValuesPerBlock[0].isUndefValue() && "Dead BB dominate this block"' failed.

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Mon Nov 11 16:47:41 PST 2013


Andrew Trick <atrick at apple.com> changed:

           What    |Removed                     |Added
             Status|REOPENED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #7 from Andrew Trick <atrick at apple.com> ---
Author: shuxin_yang
Date: Mon Nov 11 16:00:23 2013
New Revision: 194424

URL: http://llvm.org/viewvc/llvm-project?rev=194424&view=rev
 Fix PR17952.

The symptom is that an assertion is triggered. The assertion was added by
me to detect the situation when value is propagated from dead blocks.
(We can certainly get rid of assertion; it is safe to do so, because
value from dead block to alive join node is certainly ok.)

 The root cause of this bug is : edge-splitting is conducted on the fly,
the edge being split could be a dead edge, therefore the block that 
split the critial edge needs to be flagged "dead" as well.

 There are 3 ways to fix this bug:
 1) Get rid of the assertion as I mentioned eariler 
 2) When an dead edge is split, flag the inserted block "dead".
 3) proactively split the critical edges connecting dead and live blocks when
    new dead blocks are revealed.

 This fix go for 3) with additional 2 LOC.

You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20131112/cfcc6ce6/attachment.html>

More information about the llvm-bugs mailing list