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<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I agree, that it’s not desirable thing in Clang, however it seems to me the lesser evil.<o:p></o:p></span></a></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">The long compilation time will hurt many projects, I’m not sure if it’s reasonable even for the ones trying to use AVX intrinsics intentionally.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Another issue is, that the “_mm_” prefixed identifiers are not reserved for the compiler - the C99 spec says that identifiers that start with two underscores
or an underscore and a capital letter are reserved. So, Clang should recognize the “_mm_” prefix, check if the right header was indeed included, and then try to identify the x86 intrinsic. If this fails, the identifier should be considered a standard identifier.<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">Of course, there is the case of x86 intrinsics that should be compiled to pure LLVM IR, rather than LLVM intrinsic calls. I see two possible solutions:<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="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span dir="LTR"></span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Make CGBuiltin.cpp/EmitX86BuiltinExpr generate the IR using the IR builder. This approach might be less intuitive, and may become
very long as we change more and more intrinsics to pure LLVM IR<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span dir="LTR"></span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Leave the intrinsics implemented in C language in the header, rather than making these “_mm_” builtins. Then, again, as we move
more and more intrinsics to C representation, the header might get big and heavy again.<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">I think in the short term I would prefer the 2<sup>nd</sup> solution as for its simplicity. Any other ideas to overcome this issue?<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"> Guy Benyei<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"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><img width="431" height="116" id="Picture_x0020_2" src="cid:image001.png@01D1C75C.B204E940" alt="signature"><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"><a name="_____replyseparator"></a><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"> cfe-dev [mailto:cfe-dev-bounces@lists.llvm.org]
<b>On Behalf Of </b>Eric Christopher via cfe-dev<br>
<b>Sent:</b> Tuesday, June 14, 2016 23:53<br>
<b>To:</b> Demikhovsky, Elena <elena.demikhovsky@intel.com>; Nico Weber <thakis@chromium.org><br>
<b>Cc:</b> cfe-dev <cfe-dev@lists.llvm.org>; David Majnemer <majnemer@google.com>; Badouh, Asaf <asaf.badouh@intel.com>; Zuckerman, Michael <michael.zuckerman@intel.com><br>
<b>Subject:</b> Re: [cfe-dev] The intrinsics headers (especially avx512) are too big. What to do about it?<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">So have clang magically emit the generated code based on the intrinsic header? That'll be a lot of typing, but ultimately shouldn't be terrible. You'll effectively turn the _mm_ interface into __builtin as far as automatic recognition etc
and I'm not sure we'd want to do that sort of thing.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-eric<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 Tue, Jun 14, 2016 at 6:43 AM Demikhovsky, Elena via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="m_8737318308697110693__MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">We are still trying to find a suitable solution.</span></a><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Keeping declarations only inside header files will save compile time.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">In this case the implementation will be hidden inside clang.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Can somebody help me to estimate impact and complexity of this solution?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thank you.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
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<span style="font-family:"Calibri",sans-serif;color:#2F5496">-</span><span style="font-size:7.0pt;color:#2F5496">
</span><b><i><span style="color:#2F5496"> Elena</span></i></b><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="m_8737318308697110693______replyseparato"></a><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">
<a href="mailto:thakis@google.com" target="_blank">thakis@google.com</a> [mailto:<a href="mailto:thakis@google.com" target="_blank">thakis@google.com</a>]
<b>On Behalf Of </b>Nico Weber<br>
<b>Sent:</b> Tuesday, June 14, 2016 15:50<br>
<b>To:</b> Demikhovsky, Elena <<a href="mailto:elena.demikhovsky@intel.com" target="_blank">elena.demikhovsky@intel.com</a>><br>
<b>Cc:</b> Hal Finkel <<a href="mailto:hfinkel@anl.gov" target="_blank">hfinkel@anl.gov</a>>; Reid Kleckner <<a href="mailto:rnk@google.com" target="_blank">rnk@google.com</a>>; cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>>;
Badouh, Asaf <<a href="mailto:asaf.badouh@intel.com" target="_blank">asaf.badouh@intel.com</a>>; Zuckerman, Michael <<a href="mailto:michael.zuckerman@intel.com" target="_blank">michael.zuckerman@intel.com</a>>; David Majnemer <<a href="mailto:majnemer@google.com" target="_blank">majnemer@google.com</a>>;
Chandler Carruth (<a href="mailto:chandlerc@google.com" target="_blank">chandlerc@google.com</a>) <<a href="mailto:chandlerc@google.com" target="_blank">chandlerc@google.com</a>></span><o:p></o:p></p>
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<b>Subject:</b> Re: [cfe-dev] The intrinsics headers (especially avx512) are too big. What to do about it?</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Tue, May 17, 2016 at 3:49 PM, Demikhovsky, Elena <<a href="mailto:elena.demikhovsky@intel.com" target="_blank">elena.demikhovsky@intel.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> >Indeed. It is not clear to me, however, that this situation is desirable. We<br>
>had a general policy that our intrinsics headers should generate generic IR<br>
>whenever possible, and if we've strayed from that, we should discuss that<br>
>first.<br>
<br>
Let's take a look at this intrinsic:<br>
<br>
static __inline__ __m512i __DEFAULT_FN_ATTRS<br>
_mm512_mask_add_epi64 (__m512i __W, __mmask8 __U, __m512i __A, __m512i __B)<br>
{<br>
return (__m512i) __builtin_ia32_paddq512_mask ((__v8di) __A,<br>
(__v8di) __B,<br>
(__v8di) __W,<br>
(__mmask8) __U);<br>
}<br>
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The IR that should be generated:<br>
%C = add <8 x double> %B, %A<br>
%res = select <8 x i1> %mask, <8 x double> %C, %W<br>
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If we parse __builtin_ia32_paddq512_mask in CGBuiltin.cpp and generate IR there, will it help?<br>
<br>
(Please do not consider my question as a general Intel solution. I just want to understand the problem.)<o:p></o:p></p>
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The bit I care most about is that adding `#include <intrin.h>` shouldn't add megabytes of stuff to my translation unit.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hve you discussed making immintrin.h more modular? It looks like many more avx512 builtins keep landing, making this problem bigger and bigger. It'd be good if I only had to pay
for this if I explicitly included an avx512.h, and even then it'd be nice if that wasn't one huge header, but several smaller ones, so I only have to pay compile time for the bits I need.<o:p></o:p></p>
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