RFR(XS): 8143307: Crash in C2 local code motion

Lindenmaier, Goetz goetz.lindenmaier at sap.com
Thu Nov 19 13:21:45 UTC 2015


We see assert(i < _max) failed: oob: i=1, _max=1  in C2s local code motion.

lcm.cpp:502 accesses e->in(1)->in(1) where e is an Op_CountedLoopEnd.

e->in(1) should return a loop iteration node. In the failing case the loop iteration node has been optimized out and replaced by a Proj, which has no in(1).

In detail, in the ideal world, I could observe the following optimization steps:

1.) If( Proj_lt (Cmp(AddI(Proj_res(Call(...)), -1) LoadI(...) ) )

2.) CountedLoopEnd( Proj_lt (Cmp(AddI(Proj_res(Call(...)), -1) LoadI(...) ) )

3.) CountedLoopEnd( Proj_le (Cmp(Proj_res(Call(...)), LoadI(...) ) )

4.) CountedLoopEnd( Proj_le(Cmp(x,y))) was matched into one mach node:

     Branch_loopEnd(Proj_res(Call(...)), LoadI(...) )

On pattern 4.) e->in(1)->in(1) fails.

Fix: check whether e->in(1)->req() > 1.

Please review this change. I please need a sponsor.


Best regards,

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/attachments/20151119/4a0eabdd/attachment-0001.html>

More information about the hotspot-compiler-dev mailing list