For whatever reason, the attached program, when compiled with the options
gcc-3.4 -msse2 -O0 test.c -o test
will crash. This is not the case if -O2 is specified or -march=i686.
However, I have a larger testcase (the program this came from) which will fail
regardless of optimization flags or -march. It seems that this problem only
happens when gcc is given complicated enough code.
A quick look at it with gdb shows:
Program received signal SIGSEGV, Segmentation fault.
0x080483b0 in _mm_srli_epi32 (__A={51539607552, 51539607564}, __B=31)
at emmintrin.h:1261
1261 {
(gdb) up
#1 0x080483e3 in bar (x={4294967297, 4294967297}, y={4294967297, 4294967297})
at test.c:8
8 return _mm_sub_epi32(x, _mm_srli_epi32(y, 31));
(gdb) print &x
$1 = (__v2di *) 0xbffffa00
(gdb) down
#0 0x080483b0 in _mm_srli_epi32 (__A={51539607552, 51539607564}, __B=31)
at emmintrin.h:1261
1261 {
(gdb) print &__A
$2 = (__v2di *) 0xbffff9cc
This looks to me like the alignment has somehow gotten messed up.
--
Summary: gcc produces bad (misaligned?) sse2 code
Product: gcc
Version: 3.4.2
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: terpstra at ito dot tu-darmstadt dot de
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i386-linux-gnu
GCC host triplet: i386-linux-gnu
GCC target triplet: i386-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17934
