<html>
    <head>
      <base href="https://llvm.org/bugs/" />
    </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 --- - Compiler crash inside SLP Vectorizer ("Use still stuck around after Def is destroyed")"
   href="https://llvm.org/bugs/show_bug.cgi?id=30626">30626</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Compiler crash inside SLP Vectorizer ("Use still stuck around after Def is destroyed")
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>tools
          </td>
        </tr>

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

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

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

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

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>opt
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>charles_li@playstation.sony.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=17409" name="attach_17409" title="test case that causes ICE">attachment 17409</a> <a href="attachment.cgi?id=17409&action=edit" title="test case that causes ICE">[details]</a></span>
test case that causes ICE

Hi Everyone,

I have found a compiler crash bug. 
Attached are the test case and the crash log.
To reproduce this ICE, compile using the following command.

  $ clang  -c -ffast-math -fslp-vectorize -O1 -march=btver2 test.cpp


I have triaged the history of this bug.

  1. ICE started at commit r253240.
  2. ICE went away at commit r258830.
  3. ICE resurfaced when commit r258830 was reverted at r278938.
  4. As of today, this ICE still exists.


FYI, the Commit Logs for r253240, r258830 and r278938.

$ svn log -r 253240
------------------------------------------------------------------------
r253240 | resistor | 2015-11-16 10:07:30 -0800 (Mon, 16 Nov 2015) | 7 lines

Add intermediate subtract instructions to reassociation worklist.

We sometimes create intermediate subtract instructions during
reassociation.  Adding these to the worklist to revisit exposes many
additional reassociation opportunities.

Patch by Aditya Nandakumar.
------------------------------------------------------------------------

$ svn log -r 258830
------------------------------------------------------------------------
r258830 | aditya_nandakumar | 2016-01-26 10:42:36 -0800 (Tue, 26 Jan 2016) | 7
lines

Reassociate: Reprocess RedoInsts after each inst

Previously the RedoInsts was processed at the end of the block.
However it was possible that it left behind some instructions that
were not canonicalized.
This should guarantee that any previous instruction in the basic
block is canonicalized before we process a new instruction.
------------------------------------------------------------------------

$ svn log -r 278938
------------------------------------------------------------------------
r278938 | mcrosier | 2016-08-17 08:54:39 -0700 (Wed, 17 Aug 2016) | 5 lines

Revert "Reassociate: Reprocess RedoInsts after each inst".

This reverts commit r258830, which introduced a bug described in PR28367.

PR28367
------------------------------------------------------------------------</pre>
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