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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks the for comprehensive reply.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hopefully the issue will be addressed some time later.<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>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Mikhail<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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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> Nadav Rotem [mailto:nrotem@apple.com]
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<b>Sent:</b> Monday, January 27, 2014 4:11 PM<br>
<b>To:</b> Mikhail Lyapunov<br>
<b>Cc:</b> <llvmdev@cs.uiuc.edu>; Yuri Dotsenko<br>
<b>Subject:</b> Re: [LLVMdev] ldmxcsr reordering issue<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi Mikhail, <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">At the moment we don’t model MXCSR. We don’t even have explicit dependencies between IR floating point instructions and the instructions that set the rounding mode (like MXCSR), so arithmetic instructions are likely to be moved across calls
that change the rounding mode. You can work around this problem by setting artificial barriers, such as placing your arithmetic calculations in external functions that can’t be inlined, etc. <o:p></o:p></p>
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<p class="MsoNormal">Thanks,<o:p></o:p></p>
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<p class="MsoNormal">Nadav<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 Jan 27, 2014, at 4:03 PM, Mikhail Lyapunov <<a href="mailto:mikhaill@microsoft.com">mikhaill@microsoft.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"">Hi,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">I met troubles with jitting x86 codes when using<span class="apple-converted-space"> </span><span style="background:white">Intrinsic::x86_sse_ldmxcsr</span>.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">The target code must execute some SSE2 instruction with DAZ/FTZ modes enabled and others with DAZ/FTZ disabled.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">I’m trying to get this by emitting LDMXCSR instructions with proper flag words.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">It appeared however that execution engine sometimes reorders these instructions with computational ones (say with<span class="apple-converted-space"> </span><span style="background:white">Intrinsic::x86_sse2_min_pd</span><span class="apple-converted-space"> </span>as
we have in the scenario).<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">As a result, wrong floating point values are produced.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";background:white">The issue disappears when using llvm::CodeGenOpt::None instead of Default</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">, but of
course this is too big hammer for using as a workaround.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Is it a bug, or am I missing some smart settings to prohibit reordering?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Regards,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Mikhail<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Helvetica","sans-serif"">_______________________________________________<br>
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<a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev"><span style="color:#954F72">http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev</span></a><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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