Bug 7628

Summary:	Poppler 0.5.3 crashes with gcc-option -ftree-vectorize
Product:	poppler	Reporter:	Mathy Vanvoorden <matje>
Component:	general	Assignee:	poppler-bugs <poppler-bugs>
Status:	RESOLVED INVALID	QA Contact:
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	x86 (IA32)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Mathy Vanvoorden 2006-07-26 00:30:40 UTC

As asked in the following url, I am posting this bug here:

http://bugs.gentoo.org/show_bug.cgi?id=141676

As stated in the bug, running kpdf in gdb gives me this issue:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1235354704 (LWP 3544)]
0xb67b78bd in OutputDev::setDefaultCTM () from /usr/lib/libpoppler.so.1

I am not sure whether this is a poppler, or a gcc issue. gcc info:

matje@sidonia /home/matje $ gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: /var/tmp/portage/gcc-4.1.1/work/gcc-4.1.1/configure
--prefix=/usr --bindir=/usr/i686-pc-linux-gnu/gcc-bin/4.1.1
--includedir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.1/include
--datadir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.1
--mandir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.1/man
--infodir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.1/info
--with-gxx-include-dir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.1/include/g++-v4
--host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --disable-altivec
--disable-nls --with-system-zlib --disable-checking --disable-werror
--disable-libunwind-exceptions --disable-multilib --disable-libmudflap
--disable-libssp --disable-libgcj --enable-languages=c,c++,fortran
--enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
Thread model: posix
gcc version 4.1.1 (Gentoo 4.1.1)

I'm happy to do any testing for you to resolve this issue.

Comment 1 Mathy Vanvoorden 2006-07-26 02:59:36 UTC

After looking around a bit, it seems the problem is in the loop @ line 30. When
compiling it with -ftree-vectorizer-verbose=5 I get:

OutputDev.cc:30: note: Alignment of access forced using peeling.
OutputDev.cc:30: note: Vectorizing an unaligned access.
OutputDev.cc:30: note: LOOP VECTORIZED.
OutputDev.cc:30: note: vectorized 1 loops in function.

The problem seems to be that gcc can't detect if ctm is aligned properly
(because it's a pointer) for vectorization so it just guesses. I tried to find a
solution for this, but nothing really good turned up. The only viable
work-around I found is to replace the loop with individual assignments to copy
the array.

Gcc-devs are currently working on implementing #pragma novector to disable
vectorization for certain loops, but that isn't included yet. I guess that this
is in more ways a gcc-bug then a poppler-bug.

Comment 2 Albert Astals Cid 2011-06-19 14:52:36 UTC

Is this still a problem?

Comment 3 Albert Astals Cid 2011-10-27 11:30:10 UTC

No answer, closing the bug

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