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[Bug c/53083] New: gcc bug in moving from the SSE registers back onto the heap.
- From: "da_fox at mad dot scientist.com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 23 Apr 2012 07:47:15 +0000
- Subject: [Bug c/53083] New: gcc bug in moving from the SSE registers back onto the heap.
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53083
Bug #: 53083
Summary: gcc bug in moving from the SSE registers back onto the
heap.
Classification: Unclassified
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: da_fox@mad.scientist.com
After investigation of a suspected graphics-driver bug, it was found that the
issue lay with gcc. Please see
https://bugs.freedesktop.org/show_bug.cgi?id=47559 .
The problem as I understand is that gcc-4.6.0 miscompiles miarc.c from the
xorg-server package if -ftree-vectorize is enabled. This flag is enabled with
-O3.
The following minimal set of CFLAGS worked:
"-g -O2"
Adding the -ftree-vectorize separately, "-g -O2 -ftree-vectorize", caused the
program to misbehave at runtime.
I am running gentoo, the default CFLAGS for my system are:
CFLAGS="-march=native -O3 -pipe -fomit-frame-pointer -fweb -ffast-math
-mtune=native -mfpmath=sse"
I don't know if these match exactly with what is passed by portage for
compiling GCC.
Software versions (gentoo package versions):
sys-devel/gcc-4.6.0
x11-base/xorg-server-1.11.2-r2
My hardware is a Dell XPS 15 (L502x) laptop with a 'Intel(R) Core(TM) i7-2630QM
CPU @ 2.00GHz'
I additional information is required please let me know.