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    <body><span class="vcard"><a class="email" href="mailto:spatel+llvm@rotateright.com" title="Sanjay Patel <spatel+llvm@rotateright.com>"> <span class="fn">Sanjay Patel</span></a>
</span> changed
          <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED INVALID - narrow casted FMA op?"
   href="https://bugs.llvm.org/show_bug.cgi?id=43841">bug 43841</a>
          <br>
             <table border="1" cellspacing="0" cellpadding="8">
          <tr>
            <th>What</th>
            <th>Removed</th>
            <th>Added</th>
          </tr>

         <tr>
           <td style="text-align:right;">Resolution</td>
           <td>---
           </td>
           <td>INVALID
           </td>
         </tr>

         <tr>
           <td style="text-align:right;">Status</td>
           <td>NEW
           </td>
           <td>RESOLVED
           </td>
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            <b><a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED INVALID - narrow casted FMA op?"
   href="https://bugs.llvm.org/show_bug.cgi?id=43841#c4">Comment # 4</a>
              on <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED INVALID - narrow casted FMA op?"
   href="https://bugs.llvm.org/show_bug.cgi?id=43841">bug 43841</a>
              from <span class="vcard"><a class="email" href="mailto:spatel+llvm@rotateright.com" title="Sanjay Patel <spatel+llvm@rotateright.com>"> <span class="fn">Sanjay Patel</span></a>
</span></b>
        <pre>(In reply to Steve Canon from <a href="show_bug.cgi?id=43841#c3">comment #3</a>)
<span class="quote">> Figueroa doesn't cover it, so don't feel bad. The necessary width is so
> staggeringly huge as to be basically useless for every case except half (you
> basically need emax - emin + p bits to prevent double rounding, so more than
> 256 bits for float). Half only needs 39 bits though, so yes, double suffices.</span >

Thanks - I figured there had to be some limit, but I didn't know how to
formulate it. We could leave this report open to handle the extreme cases with
half, but I don't think that's a common case. 

I'd still like to be able to do this transform generally when given enough
compiler flag rope, so I've opened <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - narrow truncated FP math with 'reassoc' fast-math-flag FMF"
   href="show_bug.cgi?id=43847">bug 43847</a> for that (it requires a different
set of fixes within clang/LLVM).</pre>
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