-msse, -mmmx and other "-m"-Options impossible?

-msse, -mmmx and other "-m"-Options impossible?

[benjaminkuester]

Hi guys,

First I had made an interesting experience:

If i added -mmmx to my CFLAGS, it got disabled automatically.
But I knew my Pentium2 supports MMX.
Example:

gcc -v -Q -march=pentium2 -mmmx testfile.cpp

|
|
V

[...]

options enabled:  -fpeephole -ffunction-cse -fkeep-static-consts
 -fpcc-struct-return -fgcse-lm -fgcse-sm -fsched-interblock -fsched-spec
 -fbranch-count-reg -fexceptions -fcommon -fgnu-linker -fargument-alias
 -fident -fmath-errno -ftrapping-math -m80387 -mhard-float -mno-soft-float
 -mieee-fp -mfp-ret-in-387 -mmmx -mno-mmx -mcpu=pentium2 -march=pentium2

[...]

"-mno-mmx" got added after my nice -mmmx. :-(

This also happened if I didn't use -march=pentium2 but -mmmx.

Then I saw in the gentoo-linux forum that other users also had this problem,
also with -msse -maccumulate-outgoing-args etc., and with gcc-3.1.1 and 3.2.

It finally seemes that gcc automatically disables the
"-m"-optimization-options.

Why does it do that?
Are future releases of gcc going to support -mmmx, -msse etc.?
 
I'm really confused...

Ypsilon

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Re: -msse, -mmmx and other "-m"-Options impossible?

[Richard Henderson]

On Thu, Oct 03, 2002 at 01:17:20AM +0200, benjaminkuester@gmx.de wrote:
>  -mieee-fp -mfp-ret-in-387 -mmmx -mno-mmx -mcpu=pentium2 -march=pentium2

That's no doubt confused by the fact that we had separate MASK_MMX 
and MASK_MMX_SET bits.  Ignore it.  Only pay attention to whether
you can get MMX code out the backend.


r~