<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [arm64] Missed optimizations in __int128_t comparisons"
   href="https://bugs.llvm.org/show_bug.cgi?id=45284">45284</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[arm64] Missed optimizations in __int128_t comparisons
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>new-bugs
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>new bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>rth@twiddle.net
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>void doit(void);
void test(unsigned long addr, unsigned long size, unsigned long limit)
{
    if ((__uint128_t)addr + size <= (__uint128_t)limit + 1) doit();
}

with HEAD (85c30f3374d9), compiles to

        adds    x8, x1, x0
        adcs    x9, xzr, xzr
        adds    x10, x2, #1
        adcs    x11, xzr, xzr
        cmp     x8, x10                 // comparison start
        cset    w8, hi
        cmp     x9, x11
        cset    w9, hi
        csel    w8, w8, w9, eq          // comparison end
        tbz     w8, #0, .LBB1_2

The comparison can be done with

        cmp     x8, x10
        sbcs    xzr, x9, x11
        b.cs    .LBB1_2

a reduction of 3 insns.</pre>
        </div>
      </p>


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