Instructions referencing registers r8-r15 take an additional byte to
encode. `reg_downcount` may be assigned to one of these registers, so it
is a small size win to store the downcount value in `RSCRATCH` first.
Before:
33 D2 xor edx,edx
44 8B 6D 64 mov r13d,dword ptr [rbp+64h]
45 85 ED test r13d,r13d
7E 30 jle 0000023546B43F6D
44 8B B5 D4 02 00 00 mov r14d,dword ptr [rbp+2D4h]
41 8B C5 mov eax,r13d
BF 07 00 00 00 mov edi,7
F7 F7 div eax,edi
After:
33 D2 xor edx,edx
8B 45 64 mov eax,dword ptr [rbp+64h]
85 C0 test eax,eax
7E 30 jle 000001AFBBAE359D
44 8B B5 D4 02 00 00 mov r14d,dword ptr [rbp+2D4h]
44 8B E8 mov r13d,eax
BF 07 00 00 00 mov edi,7
F7 F7 div eax,edi
Sintendo
dd58a8d65e