<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 --- - exception handling crashes on i386 only when using -Os optimization, maybe stack unwind bug"

   href="https://llvm.org/bugs/show_bug.cgi?id=24792">24792</a>

          </td>

        </tr>

        <tr>

          <th>Summary</th>

          <td>exception handling crashes on i386 only when using -Os optimization, maybe stack unwind bug

          </td>

        </tr>

        <tr>

          <th>Product</th>

          <td>tools

          </td>

        </tr>

        <tr>

          <th>Version</th>

          <td>3.7

          </td>

        </tr>

        <tr>

          <th>Hardware</th>

          <td>PC

          </td>

        </tr>

        <tr>

          <th>OS</th>

          <td>FreeBSD

          </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>truckman@FreeBSD.org

          </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=14870" name="attach_14870" title="simple test case to reproduce exception handling crash">attachment 14870</a> <a href="attachment.cgi?id=14870&action=edit" title="simple test case to reproduce exception handling crash">[details]</a></span>

simple test case to reproduce exception handling crash

I've seen a number of crashes in the code for OpenOffice whose commonality is

exception handling.  This only occur when the code is compiled with -Os

optimization and only on i386.  The code operates correctly when compiled with

-O2 optimization.  If the code is compiled on amd64, it operates correctly with

any optimization level.

Compiling with either of these compiler versions results in crashing

executables:

clang version 3.7.0 (tags/RELEASE_370/final)

Target: i386-unknown-freebsd11.0

Thread model: posix

FreeBSD clang version 3.6.1 (tags/RELEASE_361/final 237755) 20150525

Target: i386-unknown-freebsd11.0

Thread model: posix

Clang versions 3.4 and 3.5 do not exhibit this problem.

The attached code fails with this stack trace when compiled with DEBUG

undefined:

% c++ -Os clangexceptionbug.cxx 

% gdb a.out

GNU gdb 6.1.1 [FreeBSD]

Copyright 2004 Free Software Foundation, Inc.

GDB is free software, covered by the GNU General Public License, and you are

welcome to change it and/or distribute copies of it under certain conditions.

Type "show copying" to see the conditions.

There is absolutely no warranty for GDB.  Type "show warranty" for details.

This GDB was configured as "i386-marcel-freebsd"...(no debugging symbols

found)...

(gdb) run

Starting program: /home/dl/a.out 

(no debugging symbols found)...(no debugging symbols found)...(no debugging

symbols found)...(no debugging symbols found)...(no debugging symbols

found)...(no debugging symbols found)...

Program received signal SIGSEGV, Segmentation fault.

0x08048808 in typeinfo for X ()

(gdb) bt

#0  0x08048808 in typeinfo for X ()

#1  0x080487ba in main ()

(gdb) 

With DEBUG defined:

% c++ -Os -DDEBUG clangexceptionbug.cxx

% gdb a.out

GNU gdb 6.1.1 [FreeBSD]