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<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">could someone please have a look at this fix?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"> Goetz<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:DE">From:</span></b><span lang="EN-US" style="mso-fareast-language:DE"> Lindenmaier, Goetz
<br>
<b>Sent:</b> Dienstag, 3. November 2015 15:36<br>
<b>To:</b> hotspot compiler<br>
<b>Subject:</b> RFR(S): 8141137: C2 fails rematerializing nodes using flag registers.<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">This change fixes an issue with rematerializing nodes that have a single
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">RegFlags input.<o:p></o:p></span></p>
<p class="MsoNormal"><a href="http://cr.openjdk.java.net/~goetz/webrevs/8141137-spillFlag/webrev.00/"><span lang="EN-US">http://cr.openjdk.java.net/~goetz/webrevs/8141137-spillFlag/webrev.00/</span></a><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Please review this change. I please need a sponsor.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">We see assert(false, "attempted to spill a non-spillable item") running jck tests with the ppc64 port.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">This assertion in get_spillcopy_wide() is reached from split_Rematerialize() that inserts a SpillCopy<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">of kind InputToRematerialization into the prolonged live range. In the opt build this results<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">in a not compilable method.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">In our case, 'def' is a node consuming a condition register defined by 'in'. Get_spillcopy_wide()
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">aborts because condition registers (Op_RegFlags) can not be spilled.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">As register allocation can not spill condition registers, it will rematerialize 'in' later on, too.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">So actually, the SpillCopy in the prolonged live range is not needed.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">As a fix, we skip adding the SpillCopy in case split_Rematerialze handles an operation consuming a condition register.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">We only do so, if the ‘in’ can be rematerialized, too. Else we assert and stop the compilation as before.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Also, this change adds code in rematerialize () that avoids that this pattern causes several live ranges to be stretched.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">(I like a lot the detailed naming of the SpillCopy nodes!)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> Goetz.<o:p></o:p></span></p>
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