gcc4 optimization problems on intel mac
gcc4 optimization problems on intel mac
- Subject: gcc4 optimization problems on intel mac
- From: Nik Reiman <email@hidden>
- Date: Tue, 23 Jan 2007 20:55:41 +0100
Hi,
In the last few weeks, we have found a number of small, but weird
bugs in a large piece of software which is being compiled using Xcode
2.4.1 on OSX 10.4.8. The software in question is a rather large
(160,000+ lines) VST/AU audio instrument plugin, and until now, we
have had relatively few problems on the intel platform under OSX.
The first bug we discovered was that the plugin wasn't properly
saving it's cache files during destruction, which lead to very long
startup times, as the plugin had to recache everything each time it
was started. The second problem we found was in the plugin's GUI,
which is written using the VSTGUI framework. Some controls, it
appeared, could only be dragged in the x-axis, but not the y-axis.
Both of these problems only existed in our release builds, and after
some tweaking and testing, I determined that the problem was related
specifically to the optimization settings in GCC4. Under *any*
setting except -O0, these strange behaviors would reappear, though
without optimization everything runs normally. Other optimization-
related settings, such as loop unrolling, do not seem to effect the
software's stability. We are not aware how many other problems were
caused by enabling optimization, as we have been forced to disable it
for our release builds until the issues are resolved.
I should also note that I did extensive build tests under PPC mac and
was unable to replicate any of these problems. The issue seems
specifically related to the intel platform.
Has anybody else experienced anything like this? Also, does anyone
have some debugging tips for problems like this? My x86 ASM is a bit
rusty, and I'm also not thrilled about the prospect of manually going
through massive assembly dumps to try to diagnose this problem...
Cheers,
Nik
--
Nik Reiman :: email@hidden
Teragon Audio :: http://www.teragon.org
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