[Bug target/86819] Set min_divisions_for_recip_mul to 2

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86819

--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> ---
There are 2 independent things.

TARGET_MIN_DIVISIONS_FOR_RECIP_MUL controls replacing several divisions with
the same divisor (a/x, b/x, c/x) with one division (y=1/x) and several
multiplications (a*y, b*y, c*y). And indeed, starting from 3 divisions, I see
this happening on x86, but I'd like it to start at 2.

-mrecip controls replacing a single division (divss) with a multiplication by
RCPSS + Newton-Raphson, that is it controls how division is implemented.