<div><div dir="auto">And -feature will remove all other features that depend on the feature. So for x86, -sse2 will disable sse2, sse3, sse4.1, sse4.2, avx, avx2, etc.</div></div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Sep 27, 2019 at 8:13 AM Krzysztof Parzyszek via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal">This thread is getting from bad to worse… Certain features are assumed as default for a given processor, so -feature will actually have an effect of removing it from the feature string that is parsed in the subtarget. Back to “no”…<u></u><u></u></p></div></div><div lang="EN-US" link="#0563C1" vlink="#954F72"><div class="m_-4063644645419090788WordSection1">
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<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas">Krzysztof Parzyszek
<a href="mailto:kparzysz@quicinc.com" target="_blank">kparzysz@quicinc.com</a> AI tools development<u></u><u></u></span></p>
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<p class="MsoNormal"><b>From:</b> llvm-dev <<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a>> <b>On Behalf Of
</b>Krzysztof Parzyszek via llvm-dev<br>
<b>Sent:</b> Friday, September 27, 2019 10:07 AM<br>
<b>To:</b> Dangeti Tharun kumar <<a href="mailto:cs15mtech11002@iith.ac.in" target="_blank">cs15mtech11002@iith.ac.in</a>>; <a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><br>
<b>Subject:</b> [EXT] Re: [llvm-dev] Question on target-features<u></u><u></u></p>
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<p class="MsoNormal">Ugh, that would be a “yes” then…<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Consolas">-- <u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas">Krzysztof Parzyszek
<a href="mailto:kparzysz@quicinc.com" target="_blank">kparzysz@quicinc.com</a> AI tools development<u></u><u></u></span></p>
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<p class="MsoNormal"><b>From:</b> llvm-dev <<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a>>
<b>On Behalf Of </b>Krzysztof Parzyszek via llvm-dev<br>
<b>Sent:</b> Friday, September 27, 2019 10:05 AM<br>
<b>To:</b> Dangeti Tharun kumar <<a href="mailto:cs15mtech11002@iith.ac.in" target="_blank">cs15mtech11002@iith.ac.in</a>>;
<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><br>
<b>Subject:</b> [EXT] Re: [llvm-dev] Question on target-features<u></u><u></u></p>
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<p class="MsoNormal">No. The way +feature works is that it causes the assignment Attribute=Value to happen, where Attribute and Value are strings defined in a td file. With -feature, this assignment does not happen, so whatever the default value is of Attribute,
it will remain unchanged.<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Consolas">-- <u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas">Krzysztof Parzyszek
<a href="mailto:kparzysz@quicinc.com" target="_blank">kparzysz@quicinc.com</a> AI tools development<u></u><u></u></span></p>
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<p class="MsoNormal"><b>From:</b> llvm-dev <<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a>>
<b>On Behalf Of </b>Dangeti Tharun kumar via llvm-dev<br>
<b>Sent:</b> Friday, September 27, 2019 9:23 AM<br>
<b>To:</b> llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>><br>
<b>Subject:</b> [EXT] [llvm-dev] Question on target-features<u></u><u></u></p>
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<p class="MsoNormal">Hi,<u></u><u></u></p>
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<p class="MsoNormal">In "target-features" list in LLVM-IR, there are "+feature", "-feature". My question is, does "-feature" is equivalent to not specifying a feature at all?<u></u><u></u></p>
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<p class="MsoNormal">For example:<u></u><u></u></p>
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<p class="MsoNormal"><b>attributes #0 = { "target-cpu"="znver2" "target-features"="+avx -avx2" }</b><u></u><u></u></p>
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<p class="MsoNormal">Wheather it is equalent to omitting the avx2 from list?<u></u><u></u></p>
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<p class="MsoNormal"><b>attributes #0 = { "target-cpu"="znver2" "target-features"="+avx" }</b><u></u><u></u></p>
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<p class="MsoNormal">-- <u></u><u></u></p>
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<p class="MsoNormal">Regards,<u></u><u></u></p>
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<p class="MsoNormal">DTharun<u></u><u></u></p>
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</blockquote></div></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">~Craig</div>