The -msse* options are not enabled by -march=core2. The gcc doc states:
core2
Intel Core2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
instruction set support.
-mtune=core2 is not implied by -march=core2. The gcc doc states:
-march=cpu-type
... Moreover, specifying -march=cpu-type implies -mtune=cpu-type.
$ gcc -march=core2 -Q --help=target -v &> gcc.core2
$ gcc -march=native -Q --help=target -v &> gcc.native
$ diff gcc.core2 gcc.native
6,7c6,7
< COLLECT_GCC_OPTIONS='-march=core2' '-Q' '-fhelp=target' '-v'
< /usr/lib/gcc/x86_64-unknown-linux-gnu/4.4.3/cc1 -v help-dummy -dumpbase
help-dummy -march=core2 -auxbase help-dummy -version -fhelp=target -o
/tmp/ccEak63E.s
---
> COLLECT_GCC_OPTIONS= '-Q' '-fhelp=target' '-v'
> /usr/lib/gcc/x86_64-unknown-linux-gnu/4.4.3/cc1 -v help-dummy -march=core2
> -mcx16 -msahf -msse4.1 --param l1-cache-size=32 --param l1-cache-line-size=64
> --param l2-cache-size=3072 -mtune=core2 -dumpbase help-dummy -auxbase
> help-dummy -version -fhelp=target -o /tmp/cc5b5n0x.s
>
30c30
< -mcx16 [disabled]
---
> -mcx16 [enabled]
52c52
< -mno-sse4 [enabled]
---
> -mno-sse4 [disabled]
63c63
< -msahf [disabled]
---
> -msahf [enabled]
65,66c65,66
< -msse [disabled]
< -msse2 [disabled]
---
> -msse [enabled]
> -msse2 [enabled]
68c68
< -msse3 [disabled]
---
> -msse3 [enabled]
70c70
< -msse4.1 [disabled]
---
> -msse4.1 [enabled]
75c75
< -mssse3 [disabled]
---
> -mssse3 [enabled]
81c81
< -mtune=
---
> -mtune= core2
85,86c85,86
< COLLECT_GCC_OPTIONS='-march=core2' '-Q' '-fhelp=target' '-v'
< as -V -Qy -o /tmp/ccB1vZZ0.o /tmp/ccEak63E.s
---
> COLLECT_GCC_OPTIONS= '-Q' '-fhelp=target' '-v'
> as -V -Qy -o /tmp/ccxxWZjC.o /tmp/cc5b5n0x.s
$ uname -a
Linux J 2.6.33-ARCH #1 SMP PREEMPT Sun Apr 4 10:27:30 CEST 2010 x86_64 Intel(R)
Core(TM)2 Duo CPU T8300 @ 2.40GHz GenuineIntel GNU/Linux
Thanks
--
Summary: march doesn't conform to documentation
Product: gcc
Version: 4.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: kjslag at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43718
