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Bug ID: JDK-6784930 server jvm fails with assert(!n->is_SpillCopy(),"") in -Xcomp mode with fastdebug bits
JDK-6784930 : server jvm fails with assert(!n->is_SpillCopy(),"") in -Xcomp mode with fastdebug bits

Details
Type:
Bug
Submit Date:
2008-12-14
Status:
Closed
Updated Date:
2011-03-08
Project Name:
JDK
Resolved Date:
2011-03-08
Component:
hotspot
OS:
generic
Sub-Component:
compiler
CPU:
generic
Priority:
P3
Resolution:
Fixed
Affected Versions:
hs11
Fixed Versions:
hs15 (b02)

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Description
server jvm fails with assertion (!n->is_SpillCopy(),"") in -Xcomp mode with fastdebug bits (both 2 and 64 bits) on all platforms.

                                    

Comments
EVALUATION

http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/011517bbcd7b
                                     
2009-01-13
SUGGESTED FIX

Set minimum block frequency MIN_BLOCK_FREQUENCY 1.e-35f.
Add the assert to check a block frequency.
                                     
2009-01-13
PUBLIC COMMENTS

The LRG's _area value 0. is used by RA to avoid additional splits
of a spill copy which has one immediately following use.
But _area value 0. could be also produced if a block has frequency 0.
caused by a long chain of conditional branches with small
probability P <= 0.1 so that a float value underflow.
As result all LRGs in such blocks have the same high score 1e35
and RA can not make progress producing a lot of spill copies.

Solution:
Set minimum block frequency MIN_BLOCK_FREQUENCY 1.e-35f.
Add the assert to check a block frequency.
                                     
2009-01-13
EVALUATION

The fix has been verified as part of hs15-b02 pit.
                                     
2009-02-24



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