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Hi Martin,<br>
<br>
Thanks for getting back to me about the test case. Although I
haven't seen any jbb2013 failures, the fix is still good. I'll push
it today.<br>
<br>
JohnC<br>
<br>
<div class="moz-cite-prefix">On 4/17/2013 5:00 AM, Doerr, Martin
wrote:<br>
</div>
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<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US">Hi John,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US">we have seen crashes when running SPEC jbb2013
on linux x86_64 with the following options (with our
SAPJVM):<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US">-XX:+UseCompressedOops -Xms8192m -Xmx8192m
-Xmn1600m -XX:+UseG1GC -XX:SurvivorRatio=4<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US">With these options, our VM uses zero based
compressed oops (shift 3).<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US">It crashed with SIGSEGV:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"># SIGSEGV (0xb) at pc=0x000000004a4c2e00,
pid=1961, tid=140227895330560<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"># accessing faulting address:
0x000000004a4c2e00<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US">#<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"># JRE version: 7.0_21<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"># Java VM: SAP Java Server VM (7.1.130414
23.5-b02 Apr 14 2013 19:29:41 - dev - optU - linux amd64 - 6
- bas2:193987 (mixed mode) compressed oops)<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"># Problematic frame:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"># C 0x000000004a4c2e00 (sp=0x00007f8959e37ad8)
(pc=0x000000004a4c2e00)<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US">The same test is passing since we fixed this
issue.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE">Best
regards,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE">Martin<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-family:"Courier
New";color:windowtext;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
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<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext;mso-fareast-language:DE"
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext;mso-fareast-language:DE"
lang="EN-US"> John Cuthbertson
[<a class="moz-txt-link-freetext" href="mailto:john.cuthbertson@oracle.com">mailto:john.cuthbertson@oracle.com</a>] <br>
<b>Sent:</b> Mittwoch, 17. April 2013 01:42<br>
<b>To:</b> Doerr, Martin<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:hotspot-gc-dev@openjdk.java.net">hotspot-gc-dev@openjdk.java.net</a><br>
<b>Subject:</b> Re: RFR (S): G1: Fix bug with compressed
oops on x86_64 and sparc<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Hi Martin,<br>
<br>
This looks good to me. Coleen has also reviewed the change and
given it the thumbs up. I'll let you get back to me regarding
a test case before pushing the changes.<br>
<br>
JohnC<o:p></o:p></p>
<div>
<p class="MsoNormal">On 4/16/2013 1:38 AM, Doerr, Martin
wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Hi all,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US">we found a G1 bug i</span><span
style="mso-fareast-language:DE" lang="EN-US">n the
template interpreter on x86_64 and sparc with compressed
Oops.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US">“do_oop_store” performs a “</span><span
style="background:silver;mso-highlight:silver"
lang="EN-US">store_heap_oop</span><span lang="EN-US">”
which compresses the input register.</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US">This compressed Oop is
passed to the succeeding
</span><span style="mso-fareast-language:DE" lang="EN-US">g1_write_barrier_post,
which is wrong.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US">Correctly, g1_write_barrier_post needs the
uncompressed Oop for the heap region crossing check.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US">This fix preserves the uncompressed Oop in a
register which gets passed to the g1_write_barrier_post:</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US"><a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Egoetz/webrevs/g1-cOops_bug/">http://cr.openjdk.java.net/~goetz/webrevs/g1-cOops_bug/</a></span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US">Please supply a bug id and review this
change.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US">Kind regards,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US">Martin</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"
lang="EN-US"> </span><o:p></o:p></p>
</blockquote>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif";mso-fareast-language:DE"><o:p> </o:p></span></p>
</div>
</blockquote>
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