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Re: Change x86 default arch for 4.5?
On 21/02/2010 11:21, Paolo Carlini wrote:
> On 02/19/2010 01:46 AM, 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.
>>
>> http://gcc.gnu.org/ml/gcc/2008-06/msg00223.html
>> http://gcc.gnu.org/ml/gcc/2008-08/msg00445.html
>>
>> Perhaps someone would like to review HJ's patch to that effect?
>>
> Yes, please: for the record, I totally support this position.
>
> Paolo.
Likewise, I was very surprised when I found out that this wasn't already how
configure worked. It makes perfect sense that configuring for i686-*-* should
get you an i686 compiler and configuring for i586-*-* should get you an i586
compiler and so on, rather than that you get an i386 compiler no matter what
you asked for.
It seems a no-brainer that the default should match the target name that is
embedded into the compiler executable itself, so that it "does what it says on
the tin" (I'm all in favour of accuracy in labelling!), and since you can
always override the default with explicit command-line options, no generality
is lost.
cheers,
DaveK