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Was a bit confused about this message (duplicate of the first mail?), but I guess you wanted to ping the thread?</div>
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I will reply to your last mail in the original thread, which I indeed didn't do yet.<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> cfe-dev <cfe-dev-bounces@lists.llvm.org> on behalf of Kito Cheng via cfe-dev <cfe-dev@lists.llvm.org><br>
<b>Sent:</b> 05 March 2021 08:23<br>
<b>To:</b> cfe-dev@lists.llvm.org <cfe-dev@lists.llvm.org><br>
<b>Cc:</b> Evandro Menezes <evandro.menezes@sifive.com>; Yi-Hsiu Hsu <yihsiu.hsu@sifive.com>; Zakk Chen <zakk.chen@sifive.com>; Craig Topper <craig.topper@sifive.com><br>
<b>Subject:</b> [cfe-dev] [RFC] Having different behavior for __fp16 on RISC-V</font>
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RISC-V has a draft extension for half-precision proposed last year[1],<br style="margin-top:0px">
so we think adding a new type for that would be great to make this<br>
easier to use that extension.</p>
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We found there is <tt class="x_gmail-remarkup-monospaced" style="background:rgba(71,87,120,0.1); padding:1px 4px; border-radius:3px; white-space:pre-wrap; line-break:anywhere; margin-top:0px">_Float16</tt> and <tt class="x_gmail-remarkup-monospaced" style="background:rgba(71,87,120,0.1); padding:1px 4px; border-radius:3px; white-space:pre-wrap; line-break:anywhere">__fp16</tt> types
are supported on GCC and<br>
Clang, but <tt class="x_gmail-remarkup-monospaced" style="background:rgba(71,87,120,0.1); padding:1px 4px; border-radius:3px; white-space:pre-wrap; line-break:anywhere">_Float16</tt> has C++ supporting issues on GCC site, so we think<br>
support both types is a reasonable choice to us.</p>
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However we would like have slight different behavior for <tt class="x_gmail-remarkup-monospaced" style="background:rgba(71,87,120,0.1); padding:1px 4px; border-radius:3px; white-space:pre-wrap; line-break:anywhere; margin-top:0px">__fp16</tt> other<br>
than ACLE: The evaluation format of <tt class="x_gmail-remarkup-monospaced" style="background:rgba(71,87,120,0.1); padding:1px 4px; border-radius:3px; white-space:pre-wrap; line-break:anywhere">__fp16</tt> set same as <tt class="x_gmail-remarkup-monospaced" style="background:rgba(71,87,120,0.1); padding:1px 4px; border-radius:3px; white-space:pre-wrap; line-break:anywhere">_Float16</tt>,<br>
which means no promotion are performed if there is no hardware half-precision<br>
supported.</p>
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The only concern to us is it's defined differnt with clang's document,<br style="margin-top:0px">
so we would put this RFC patch here, to make sure it's OK for make<br>
<tt class="x_gmail-remarkup-monospaced" style="background:rgba(71,87,120,0.1); padding:1px 4px; border-radius:3px; white-space:pre-wrap; line-break:anywhere">__fp16</tt> has differnt behavior between differnt targets.</p>
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This patch contains document change only, implementation would be in<br style="margin-top:0px">
other patches.</p>
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[1] <a href="https://github.com/riscv/riscv-isa-manual/pull/496" class="x_gmail-remarkup-link" target="_blank" rel="noreferrer" style="text-decoration-line:none; color:rgb(19,108,178); margin-top:0px">https://github.com/riscv/riscv-isa-manual/pull/496</a><br>
[2] <a href="https://github.com/riscv/riscv-elf-psabi-doc/pull/172" class="x_gmail-remarkup-link" target="_blank" rel="noreferrer" style="text-decoration-line:none; color:rgb(19,108,178)">https://github.com/riscv/riscv-elf-psabi-doc/pull/172</a></p>
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<div>Corresponding phabricator entry for this RFC:</div>
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<a href="https://reviews.llvm.org/D98012">https://reviews.llvm.org/D98012</a><br>
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