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Re: PATCH: Mention x86 configure changes for gcc 4.5.0
On Sun, Feb 28, 2010 at 12:54 PM, Gerald Pfeifer <gerald@pfeifer.com> wrote:
> On Sat, 27 Feb 2010, H.J. Lu wrote:
>> Here is the updated gcc 4.5 change for IA32/Intel64. OK to install?
>
> Index: htdocs/gcc-4.5/changes.html
> ===================================================================
> + ? ?<li>A new <code>-mmovbe</code> option is now available to enable GCC
> + ? ?to use <code>movbe</code> instruction to implement
> + ? ?<code>__builtin_bswap32</code> and <code>__builtin_bswap64</code>.
>
> Should this read "to use the..."? ?Or "...instructions" (Plural) if
> there are more options?
There is a single "movbe" instruction which supports both 32bit and 64bit
operand. I will leave it alone.
> + ? ?<li>Gcc now will set the default arch for <code>-march=</code>
> + ? ?based on the configure target.</li>
>
> GCC (all uppercase).
Will do.
> Perhaps say "the default for", omitting this "arch" occurrence of arch?
Will do.
> Also, given the importance of this, let's make this the very first item
> of this section.
Will do.
> Okay with the changes above.
>
>
> For bonus points, what is the configure target if none is provided
> explicitly, by the way? Given the importance of this change, I expect
> we'll get a lot of users wondering, so let's try to be as clear as
> possible.
>
I think the default target comes from config.guess.
--
H.J.