On 02/18/2010 07:46 PM, Joseph S. Myers wrote:
On Thu, 18 Feb 2010, Jason Merrill wrote:
I periodically get bitten by bug 34115: a compiler configured without
--with-arch on i686-pc-linux-gnu doesn't support atomics. I think we would
only need to bump the default to i486 to get atomic support. Can we
reconsider the default for 4.5?
My position remains that configuring for i686-* should default to
-march=i686 rather than -mtune=i686.
That makes sense to me.
Perhaps someone would like to review HJ's patch to that effect?
http://gcc.gnu.org/ml/gcc-patches/2008-08/msg02078.html
Using all the noncanonical variants as arch defaults makes me a bit
nervous, but I suppose if someone actually writes $GCC/configure
nocona-pc-linux-gnu that's what they would expect to get...
This will probably break building glibc, as problems building when __i686
is a predefined macro have been known since at least 2002 but none of the
many patches proposed since then have been accepted.
I imagine changing the default would help with that...and packagers can
work around it.
Jason
