"SSE instruction set disabled?"

[Scott Robert Ladd]

R. Kelly Cook wrote:
> "-mmmx", "-msse", "-msse2", and "-m3dnow" (and their coresponding
> -mno-xxx) should just go away.
>
> They already are implied by -march=blahblah that we have.  If someone
> wants code tuned for a pentium4, but without any SSE or MMX support then
> they can type "-march=pentiumpro -mcpu=pentium4"

I very much like this idea. The number of command-line options is very
confusing; anything that can rationally be done to simplify matters would be
in porgrammers' and gcc's) best interest.

> Although, in my opinion "-mcpu=" should be renamed "-mtune=" like was
> debated ages ago: http://gcc.gnu.org/ml/gcc/1999-01n/msg01004.html

The gcc docs state: "Moreover, specifying -march=cpu-type
implies -mcpu=cpu-type." That suggests that assuming "-msse" and such is
reasonable.

BTW, why would someone set "-mcpu" different from "-march" anyway? Why two
switches? Why wouldn't it be a good idea to always "tune" for the chosen
architecture?

..Scott