PATCH: Add --with-math=sse for x86

[H.J. Lu]

On Sun, Aug 10, 2008 at 12:29 PM, Richard Guenther
<richard.guenther@gmail.com> wrote:

>>> 1. Provide a way to configure gcc to generate faster 32bit FP code, which
>>> can run on majority of today's processors.
>>> 2. Provide a way to test SSE math in 32bit with existing gcc testsuite.
>
> Oh, and 2. is possible with RUNTESTFLAGS="--target_board=unix/-mfpmath=sse".

RUNTESTFLAGS="--target_board=unix/-mfpmath=sse" won't catch bootstrap
issues,  which I ran into with --with-math=sse. One of run-time
libraries failed to
build.

> Are you concerned about the SPEC rules limit for the number of compiler options
> for base numbers??

Not really.

>> 3. With the current x86 ABI it pessimizes -Os due to extra moves between
>> the x87 stack and SSE registers.  This also pessimizes interfacing to all
>> system libraries.

>> I think the user is better advised to choose -mfpmath=sse only for carefully
>> selected cases.
>>

I think it should be up to gcc users to decide.

-- 
H.J.