<div dir="ltr">It's already the case that the compiler needs to be in almost-exact-sync with the intrinsics headers, due to the use of internal builtins functions which seem to be typically introduced or removed at the same time as updating the header. I don't think modules would make this any worse than it is already?</div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jun 20, 2016 at 6:52 AM, Benyei, Guy via cfe-dev <span dir="ltr"><<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div lang="EN-US" link="blue" vlink="purple">
<div>
<p class="MsoNormal"><a name="m_3806616979892601209__MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Modules could be a good solution for this issue, however I’m a bit concerned about some technical issues with keeping the modules in
sync with the Clang compiler.<u></u><u></u></span></a></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Building the actual module files as part of the build system doesn’t seem really hard, but still need to think about the location it should be installed (with
the headers?), and need to make sure, that for any Clang we run we can find the suiting module files, or fall back to the headers approach.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">We could add the module as some kind of resource to the executable. This way it couldn’t get out of sync. I would also add some way to disable this optimization
entirely.</span><span lang="HE" dir="RTL" style="font-size:11.0pt;font-family:"Arial",sans-serif;color:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">What do you think?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><img width="431" height="116" src="cid:image001.png@01D1CADD.9F923F40" alt="signature"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><a name="m_3806616979892601209______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"> Chandler Carruth [mailto:<a href="mailto:chandlerc@google.com" target="_blank">chandlerc@google.com</a>]
<br>
<b>Sent:</b> Thursday, June 16, 2016 00:20<br>
<b>To:</b> Benyei, Guy <<a href="mailto:guy.benyei@intel.com" target="_blank">guy.benyei@intel.com</a>>; Eric Christopher <<a href="mailto:echristo@gmail.com" target="_blank">echristo@gmail.com</a>>; Demikhovsky, Elena <<a href="mailto:elena.demikhovsky@intel.com" target="_blank">elena.demikhovsky@intel.com</a>>; Nico Weber <<a href="mailto:thakis@chromium.org" target="_blank">thakis@chromium.org</a>>; <a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a><br>
<b>Cc:</b> David Majnemer <<a href="mailto:majnemer@google.com" target="_blank">majnemer@google.com</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>></span></p><div><div class="h5"><br>
<b>Subject:</b> Re: [cfe-dev] The intrinsics headers (especially avx512) are too big. What to do about it?<u></u><u></u></div></div><p></p><div><div class="h5">
<p class="MsoNormal"><u></u> <u></u></p>
<div>
<p class="MsoNormal">As I said up the thread, I think the *right* way to solve this is with modules.<u></u><u></u></p>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">We have the infrastructure in clang to lazily load things like the intrinsics headers in a very efficient way. All we are missing is:<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal">1) The ability to enable this by default exclusively for the intrinsic headers. (or more generally for any subset of the builtin headers where we would like this behavior...)<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal">2) To build the actual module files for the builtin headers (much the way we generate some of them) as part of the build system<u></u><u></u></p>
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<div>
<p class="MsoNormal"><u></u> <u></u></p>
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<div>
<p class="MsoNormal">So far I've not seen any suggestions that really seem superior to this...<u></u><u></u></p>
</div>
</div>
<p class="MsoNormal"><u></u> <u></u></p>
<div>
<div>
<p class="MsoNormal">On Wed, Jun 15, 2016 at 1:23 PM Benyei, Guy via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>> wrote:<u></u><u></u></p>
</div>
<blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<div>
<p class="MsoNormal"><a name="m_3806616979892601209_m_-8845244803083863933__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.</span></a><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></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.</span><u></u><u></u></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.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></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:</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></p>
<p><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">1.</span><span style="font-size:7.0pt;color:#1f497d">
</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</span><u></u><u></u></p>
<p><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">2.</span><span style="font-size:7.0pt;color:#1f497d">
</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.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></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?</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Thanks</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> Guy Benyei</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><img border="0" width="431" height="116" alt="signature"></span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><a name="m_3806616979892601209_m_-8845244803083863933______replyseparat"></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:<a href="mailto:cfe-dev-bounces@lists.llvm.org" target="_blank">cfe-dev-bounces@lists.llvm.org</a>]
<b>On Behalf Of </b>Eric Christopher via cfe-dev</span><u></u><u></u></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><br>
<b>Sent:</b> Tuesday, June 14, 2016 23:53<br>
<b>To:</b> Demikhovsky, Elena <<a href="mailto:elena.demikhovsky@intel.com" target="_blank">elena.demikhovsky@intel.com</a>>; Nico Weber <<a href="mailto:thakis@chromium.org" target="_blank">thakis@chromium.org</a>></span><u></u><u></u></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Cc:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>>;
David Majnemer <<a href="mailto:majnemer@google.com" target="_blank">majnemer@google.com</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>></span><u></u><u></u></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><br>
<b>Subject:</b> Re: [cfe-dev] The intrinsics headers (especially avx512) are too big. What to do about it?</span><u></u><u></u></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal"> <u></u><u></u></p>
<div>
<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.<u></u><u></u></p>
<div>
<p class="MsoNormal"> <u></u><u></u></p>
</div>
<div>
<p class="MsoNormal">-eric<u></u><u></u></p>
</div>
<p class="MsoNormal"> <u></u><u></u></p>
<div>
<div>
<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" target="_blank">cfe-dev@lists.llvm.org</a>> wrote:<u></u><u></u></p>
</div>
<blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt">
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">We are still trying to find a suitable solution.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Keeping declarations only inside header files will save compile time.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">In this case the implementation will be hidden inside clang.</span><u></u><u></u></p>
<p class="MsoNormal"><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><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Thank you.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal" style="margin-left:.5in">
<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><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span><u></u><u></u></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt">
<div>
<div style="border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><a name="m_3806616979892601209_m_-8845244803083863933_m_873731830869711"></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><u></u><u></u></p>
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<div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt">
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<div style="border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><br>
<b>Subject:</b> Re: [cfe-dev] The intrinsics headers (especially avx512) are too big. What to do about it?</span><u></u><u></u></p>
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<div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt">
<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">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:<u></u><u></u></p>
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<div>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt">
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<blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt">
<p class="MsoNormal"> >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>
<br>
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>
<br>
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.)<u></u><u></u></p>
</blockquote>
<div>
<p class="MsoNormal"><br>
The bit I care most about is that adding `#include <intrin.h>` shouldn't add megabytes of stuff to my translation unit.<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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