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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>This is on Windows / MSVC++ 2005. I’ll file a bug.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>
<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"'>
llvmdev-bounces@cs.uiuc.edu [mailto:llvmdev-bounces@cs.uiuc.edu] <b>On Behalf
Of </b>Evan Cheng<br>
<b>Sent:</b> Monday, 14 July, 2008 20:35<br>
<b>To:</b> LLVM Developers Mailing List<br>
<b>Cc:</b> anton@korobeynikov.info<br>
<b>Subject:</b> Re: [LLVMdev] Spilled variables using unaligned moves<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>This is on Windows / Cygwin? I think the dynamic stack
pointer re-alignment doesn't happen until post- register allocation.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>Assuming there aren't other instructions between the
prologue and the first movups that mess up esp (there shouldn't), this is
indeed a bug. Please file a bug and attach a bc file. Thanks.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>Evan<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>On Jul 14, 2008, at 7:43 AM, Nicolas Capens wrote:<o:p></o:p></p>
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<p class=MsoNormal><br>
<br>
<o:p></o:p></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Hi all,<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>It looks like vector spills don’t use aligned moves even though
the stack is aligned. This seems like an optimization opportunity.<o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>The attached replacement of fibonacci.cpp generates x86 code like
this:<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70010 push ebp </span><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70011 mov
ebp,esp</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70013 and
esp,0FFFFFFF0h</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70019 sub
esp,1A0h</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>...</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A7006C movups xmmword ptr
[esp+180h],xmm7</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'><o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>...</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70229 mulps
xmm1,xmmword ptr [esp+180h]</span><span style='font-size:11.0pt;
font-family:"Calibri","sans-serif";color:black'><o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>...</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70682 movups xmm0,xmmword
ptr [esp+180h]</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Note how stores and loads use unaligned moves while it could use
aligned moves. It’s also interesting that the multiply does correctly assume
the stack to be 16-byte aligned.<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Is there something I’m doing wrong (again), or is this already
known?<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Thanks a lot,<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Nicolas Capens<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:9.0pt;font-family:"Helvetica","sans-serif";
color:black'><fibonacci.cpp><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:9.0pt;font-family:"Helvetica","sans-serif";
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><o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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