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    <body><span class="vcard"><a class="email" href="mailto:simonbyrne@gmail.com" title="simonbyrne@gmail.com">simonbyrne@gmail.com</a>
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              <a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED --- - Constant folding for 'frem' is flaky"
   href="https://llvm.org/bugs/show_bug.cgi?id=3316">bug 3316</a>
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          <tr>
            <th>What</th>
            <th>Removed</th>
            <th>Added</th>
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         <tr>
           <td style="text-align:right;">Status</td>
           <td>RESOLVED
           </td>
           <td>REOPENED
           </td>
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         <tr>
           <td style="text-align:right;">CC</td>
           <td>
                
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           <td>simonbyrne@gmail.com
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           <td style="text-align:right;">Resolution</td>
           <td>FIXED
           </td>
           <td>---
           </td>
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            <b><a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED --- - Constant folding for 'frem' is flaky"
   href="https://llvm.org/bugs/show_bug.cgi?id=3316#c9">Comment # 9</a>
              on <a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED --- - Constant folding for 'frem' is flaky"
   href="https://llvm.org/bugs/show_bug.cgi?id=3316">bug 3316</a>
              from <span class="vcard"><a class="email" href="mailto:simonbyrne@gmail.com" title="simonbyrne@gmail.com">simonbyrne@gmail.com</a>
</span></b>
        <pre>I'm seeing a similar problem, though for different constant values, in LLVM
3.9.1:

$ cat frem.ll
define double @test1() {
entry:
    %y = frem double 3.000000e-01, 1.000000e-02
    ret double %y
}

Compiled without optimisations gives the correct answer:

$ llc frem.ll && ./frem
0x1.47ae147ae1471p-7

However applying a constprop pass gives an incorrect answer:

$ opt -S -constprop frem.ll
; ModuleID = 'frem.ll'
source_filename = "frem.ll"

define double @test1() {
entry:
  ret double 0.000000e+00
}

downstream issue: <a href="https://github.com/JuliaLang/julia/issues/14089">https://github.com/JuliaLang/julia/issues/14089</a></pre>
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