[Bug target/44046] New: Intel Core i5 M520 CPU detected as atom with -march=native

["dirtyepic at gentoo dot org" <gcc-bugzilla at gcc dot gnu dot org>]

We have a user that is getting illegal instruction errors while building
xulrunner.

/var/tmp/portage/net-libs/xulrunner-1.9.2.3-r1/work/mozilla-1.9.2/dist/bin/xpidl
-m typelib -w -I. -I../../dist/idl -e _xpidlgen/nsIConsoleListener.xpt -d
.deps/nsIConsoleListener.pp nsIConsoleListener.idl
make[4]: *** [_xpidlgen/nsIConsoleListener.xpt] Illegal instruction

It turns out that using -march=native with his Core i5 processor results in
-march=atom being used, specifically:

gcc version 4.5.0 (Gentoo 4.5.0 p1.0) 
COLLECT_GCC_OPTIONS= '-v' '-o' 'test'
 /usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.0/cc1 -quiet -v test.c
-D_FORTIFY_SOURCE=2 -march=atom -mcx16 -msahf -maes -mpclmul -mpopcnt -msse4.2
--param l1-cache-size=32 --param l1-cache-line-size=64 --param
l2-cache-size=3072 -mtune=core2 -quiet -dumpbase test.c -auxbase test -version
-o /tmp/ccmAagyo.s

I believe the issue is that this processor doesn't support mmovbe, which
-march=atom enables (the error doesn't occur w/ -march=atom -mno-movbe).  Am I
right in guessing that it should instead be using -march=core2 + a bunch of -m
flags?

I will attach his /proc/cpuinfo.  Let me know what other info you need.

http://bugs.gentoo.org/317513


-- 
           Summary: Intel Core i5 M520 CPU detected as atom with -
                    march=native
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dirtyepic at gentoo dot org
 GCC build triplet: x86_64-pc-linux-gnu
  GCC host triplet: x86_64-pc-linux-gnu
GCC target triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44046