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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I’m targeting a language that uses virtual
registers and not physical registers. So the easiest way to implement this is
to use virtual registers, except that they are being restarted after each
function and clobbering registers in previous functions. For example:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>start function 0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>r1024 = mov %var0.0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>r1025 = mov %var0.1<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>lots of intermediate code<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>call function1 w/ 3 parameters<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>more intermediate code<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>%r1300 = add %call.result,
%r1024<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>end function 0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>start function 1<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>%r1024 = mov %var1.0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>%r1025 = mov %var1.1<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>%r1026 = mov %var1.2<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>some code<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>return some value<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'>end function 0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The mov to r1024 in function 1 clobbers
the data from function 0. The only ways I can think to get around this, is to push
every virtual register used in a function to a stack or some internal data
structure and then pull them back out for each function call. The other option
is to run a separate pass just to renumber register. This is not what I would
like to do as the easiest solution is just to get a variable start point.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Any other ideas that might accomplish what
I want, that I might be missing?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Thanks,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
llvmdev-bounces@cs.uiuc.edu [mailto:llvmdev-bounces@cs.uiuc.edu] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Evan Cheng<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, October 20, 2008
2:03 PM<br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on">LLVM
Developers Mailing List</st1:PersonName><br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [LLVMdev] Virtual
Register allocation across functions</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>No, there isn't something like that right now. What are you trying to
accomplish?<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>If you wish to implement this, it shouldn't be hard to do. Right now,
MachineRegisterInfo re-starts virtual register number
at TargetRegisterInfo::FirstVirtualRegister. You can add a mechanism to
change that to a variable instead.<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Evan<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On Oct 20, 2008, at 1:43 PM, <st1:PersonName w:st="on">Villmow, Micah</st1:PersonName>
wrote:<o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
<br>
<o:p></o:p></span></font></p>
<span style='orphans: 2;text-align:auto;widows: 2;-webkit-border-horizontal-spacing: 0px;
-webkit-border-vertical-spacing: 0px;-webkit-text-decorations-in-effect: none;
-webkit-text-size-adjust: auto;-webkit-text-stroke-width: 0;word-spacing:0px'><u1:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="Street"><u1:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="address"><u1:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="City"><u1:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place">
<div link=blue vlink=purple>
<div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Is there currently a way to have virtual
register allocation information be saved across functions so that if I create a
new virtual register in a function that it doesn’t use a virtual register
allocated in any previous function?<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'><u1:p> </u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Thanks,<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'><u1:p> </u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Micah Villmow<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Systems Engineer<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Advanced Technology & Performance<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Advanced Micro Devices Inc.<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><ns7:street u2:insauthor="Micah Villmow" u2:insdate="2008-10-20T13:42:00Z" u2:endinsauthor="Micah Villmow" u2:endinsdate="2008-10-20T13:42:00Z"><ns7:address u2:insauthor="Micah Villmow" u2:insdate="2008-10-20T13:42:00Z" u2:endinsauthor="Micah Villmow" u2:endinsdate="2008-10-20T13:42:00Z"><st1:street u2:st="on"><st1:address u2:st="on"><st1:Street
w:st="on"><st1:address w:st="on"><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black'>4555 Great America Pkwy</st1:address></st1:street></ns7:address></ns7:street></span></font></st1:address></st1:Street><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'>,<u1:p></u1:p></span></font><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><ns7:place u2:insauthor="Micah Villmow" u2:insdate="2008-10-20T13:42:00Z" u2:endinsauthor="Micah Villmow" u2:endinsdate="2008-10-20T13:42:00Z"><ns7:city u2:insauthor="Micah Villmow" u2:insdate="2008-10-20T13:42:00Z" u2:endinsauthor="Micah Villmow" u2:endinsdate="2008-10-20T13:42:00Z"><st1:city u2:st="on"><st1:place u2:st="on"><st1:City
w:st="on"><st1:place w:st="on"><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black'>Santa Clara</st1:place></st1:city></ns7:city></ns7:place></span></font></st1:place></st1:City><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'>, CA. 95054<u1:p></u1:p></span></font><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>P: 408-572-6219<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>F: 408-572-6596</span></font><font
color=black><span style='color:black'><u1:p></u1:p><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'><u1:p> </u1:p><o:p></o:p></span></font></p>
</div>
</div>
<p class=MsoNormal><font size=1 color=black face=Helvetica><span
style='font-size:9.0pt;font-family:Helvetica;color:black'>_______________________________________________<br>
LLVM Developers mailing list<br>
<a href="mailto:LLVMdev@cs.uiuc.edu">LLVMdev@cs.uiuc.edu</a>
<a
href="http://llvm.cs.uiuc.edu">http://llvm.cs.uiuc.edu</a><br>
<a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev</a><br>
<br>
<o:p></o:p></span></font></p>
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</u1:smarttagtype></u1:smarttagtype></u1:smarttagtype></u1:smarttagtype>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'></span><o:p> </o:p></span></font></p>
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