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Bug ID: JDK-8010437 guarantee(this->is8bit(imm8)) failed: Short forward jump exceeds 8-bit offset
JDK-8010437 : guarantee(this->is8bit(imm8)) failed: Short forward jump exceeds 8-bit offset

Details
Type:
Bug
Submit Date:
2013-03-21
Status:
Resolved
Updated Date:
2014-01-23
Project Name:
JDK
Resolved Date:
2013-04-04
Component:
hotspot
OS:
Sub-Component:
compiler
CPU:
Priority:
P3
Resolution:
Fixed
Affected Versions:
Fixed Versions:
hs25 (b26)

Related Reports
Backport:
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Relates:

Sub Tasks

Description
http://cr.openjdk.java.net/~rasbold/XXXXXXX/webrev.00/

We occasionally get this guarantee failure from an older JVM (HotSpot
22):

#  Internal Error (assembler_x86.inline.hpp:46)
#  guarantee(this->is8bit(imm8)) failed: Short forward jump exceeds
#  8-bit offset

I'm encountering a case in C2 where a branch is incorrectly
converted to a short branch under very specific conditions. The root
cause occurs when a call and safepoint are adjacent in
consecutive blocks.  In shorten_branches(), an off-by-one
error exists in calculating the size of the trailing (safepoint) block when it
potentially requires loop padding.

This bug still exists in the current HotSpot 25, although I don't have
a testcase that reproduces there.

However, with the improved guarantee from my webrev, but without the
actual fix, a hs25 CTW run on rt.jar fails.

Can a bug be opened? Can I get an Oracle engineer to sponsor and
review my change?

                                    

Comments
URL:   http://hg.openjdk.java.net/hsx/hotspot-comp/hotspot/rev/0a8c2ea3902d
User:  kvn
Date:  2013-04-04 01:29:59 +0000

                                     
2013-04-04
URL:   http://hg.openjdk.java.net/hsx/hsx25/hotspot/rev/0a8c2ea3902d
User:  amurillo
Date:  2013-04-05 07:34:34 +0000

                                     
2013-04-05
7u25-b34 was released on Jul 29, 2013.
                                     
2013-07-29



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