Date: Thu, 06 Jun 2002 14:00:33 +0000 From: henry tieman <henryt_NOSPAM@aracnet.com> To: freebsd-questions@FreeBSD.ORG Subject: gcc -O and xsane crash Message-ID: <3CFF6B01.3080500@aracnet.com>
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I found a compiler problem with optimizations in Xsane-0.85. Gcc
generates a test against an uninitialised variable in the function
preview_autoselect_scanarea which can cause a memory overrun. Turning
off optimazations cures the problem.
The details are: the second loop in the function generates a stopping
comparison of (x < y), y is a register variable, and not (x <
p->image_width) like the source code says. I used ddd's "Machine Code
Window" to see this. y is uninitialized at this point so the memory
overrun seems to depend on the picture being scanned.
Since I have a workaround, I'm not too interested in solving this
myself. I just thought it would be helpfull to other users to pass the
information on.
I had a friend in collage that always complained the compiler was wrong
and he was never right. So I really really hate to say it myself.
I should probably include I'm using FreeBSD 4.5 with
gcc version 2.95.3 20010315 (release) [FreeBSD]
--
Henry Tieman
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