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<p class=MsoNormal>Hi all,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>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></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The attached replacement of fibonacci.cpp generates x86 code
like this:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:8.0pt;
font-family:"Courier New";color:gray'>03A70010
push ebp <o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:8.0pt;
font-family:"Courier New";color:gray'>03A70011
mov ebp,esp <o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:8.0pt;
font-family:"Courier New";color:gray'>03A70013
and esp,0FFFFFFF0h <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70019 sub
esp,1A0h<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>...<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A7006C movups xmmword ptr
[esp+180h],xmm7<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>...</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70229 mulps xmm1,xmmword
ptr [esp+180h]<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>...<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03A70682 movups xmm0,xmmword
ptr [esp+180h]</span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>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></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Is there something I’m doing wrong (again), or is this
already known?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks a lot,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Nicolas Capens<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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