Jit64: divwx - Optimize power-of-two divisors

Power-of-two divisors can be done more elegantly, so handle them
separately.

- Division by 4
Before:
41 BD 04 00 00 00    mov         r13d,4
41 8B C0             mov         eax,r8d
45 85 ED             test        r13d,r13d
74 0D                je          overflow
3D 00 00 00 80       cmp         eax,80000000h
75 0E                jne         normal_path
41 83 FD FF          cmp         r13d,0FFFFFFFFh
75 08                jne         normal_path
overflow:
C1 F8 1F             sar         eax,1Fh
44 8B E8             mov         r13d,eax
EB 07                jmp         done
normal_path:
99                   cdq
41 F7 FD             idiv        eax,r13d
44 8B E8             mov         r13d,eax
done:

After:
45 85 C0             test        r8d,r8d
45 8D 68 03          lea         r13d,[r8+3]
45 0F 49 E8          cmovns      r13d,r8d
41 C1 FD 02          sar         r13d,2

0 files changed, 0 insertions, 0 deletions