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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>The InstructionCombining pass causes alignment of globals to
be ignored.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I’ve attached a replacement of Fibonacci.cpp which
reproduces this (I used 2.3 release). Here’s the x86 code it produces:<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'>03C20019
movaps xmm0,xmmword ptr ds:[164E799h] <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'>03C20020
mulps xmm0,xmmword ptr ds:[164E79Ah] <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'>03C20027
movaps xmmword ptr ds:[164E799h],xmm0 <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'>03C2002E
mov esp,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'>03C20030
pop ebp <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03C20031
ret </span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>All three SSE instructions will generate a fault for
accessing unaligned memory. Disabling InstructionCombining gives me the
following correct code:<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'>03B10010
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'>03B10011
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'>03B10013
and esp,0FFFFFFF0h <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'>03B10019
movups xmm0,xmmword ptr ds:[164E79Ah] <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'>03B10020
movups xmm1,xmmword ptr ds:[164E799h] <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'>03B10027
mulps xmm1,xmm0 <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'>03B1002A
movups xmmword ptr ds:[164E799h],xmm1 <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'>03B10031
mov esp,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'>03B10033
pop ebp <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Courier New";
color:gray'>03B10034 ret </span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Unless I’m missing something this is quite clearly a
bug. I’ll give it a try to locate the faulty code but all help is very
welcome.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Cheers,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Nicolas Capens<o:p></o:p></p>
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