The fixmuldiv functions don't need inline assembly to be fast
in this architecture; the compiler (both clang and GCC) figure
out to use the optimal instructions for this (which is 2 instruction
sequence), and when letting the compiler emit the instructions
instead of using inline assembly, the compiler is able to
interleave those instructions with other instructions,
improving scheduling, making it even faster than when using
inline assembly.
Overall, this gives about 50% speedup.
Replace the assembler code by the equivalent in C. This way it will work
for every MIPS ISA. Now the check for __mips_isa_rev < 6 is no longer
necessary, so remove it.
Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Only enable code using mips32/mips64 instructions if the compiler is targetting
this ISA. (integer madd and msub instructions aren't available in the
``canonical'' mips ISAs)
