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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The problem which we are trying to solve is that when we enable register scavenging for X86, the register scavenger sees X87 stack registers (which are unallocatable)
and then triggers an assertion failure saying “Using an undefined physical register”. We want to ignore unallocatable registers in the registers as per the patch that you committed last July (r136541). That patch was reverted because it apparently negatively
affected ARM. We want to ignore unallocatable registers for X86 so that we can use the register scavenger which in turn we need for post RA scheduling for Intel Atom.<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Jakob Stoklund Olesen [mailto:stoklund@2pi.dk]
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<b>Sent:</b> Monday, April 30, 2012 5:56 PM<br>
<b>To:</b> Gurd, Preston<br>
<b>Cc:</b> llvm-commits@cs.uiuc.edu<br>
<b>Subject:</b> Re: [llvm][PATCH][Review Requested]<o:p></o:p></span></p>
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<p class="MsoNormal">On Apr 30, 2012, at 2:40 PM, "Gurd, Preston" <<a href="mailto:preston.gurd@intel.com">preston.gurd@intel.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">For X86, don't check liveness of unallocatable registers.<o:p></o:p></span></p>
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<p class="MsoNormal">I don't think we should have different rules for different targets. What problem are you trying to solve?<o:p></o:p></p>
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<p class="MsoNormal">/jakob<o:p></o:p></p>
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