Edward wrote:
Jumps often take longer, and jumps without explicitly named targets are a recipe for future frustration.
Yes, I remember the days when I used to spend hours just for that very reason, but it's become such a habit now, that whenever I anticipate a change, if there isn't an explicit reference I look up in code to see where that register was initialized. What I plan on doing in the future is commenting as such;
cld ; Just to be sure indices auto increment.; RDX has been set to winsize structure by previous ; sys_ioctl call to TIOCGWINSZ, as has RAX been set to zero. cmp word [edx+2], 132 ; Expect a minimum 132 columns adc al, al shl al, 1 ; Move to next bit position cmp byte [edx], 43 ; Expect a minimum 43 rows adc al, 0; Save new data where ws_xpixel was and erase any extraneous; data @ ws_ypixel mov [edx+4], eax ; Overwrite ws_xpixel & ws_ypixel.I think this would be a step in the right direction for those reading my code that they wouldn't have to search all over. This example saves another 5 bytes using implicit references instead of explicit.
A significant size and by that extension speed saving was realized with this change.
22: 89 c2 mov edx,eax 24: 66 ad lods ax,WORD PTR ds:[rsi] 26: 66 83 e8 2b sub ax,0x2b 2a: 79 03 jns 2f <_start+0x2f> 2c: 80 ca 01 or dl,0x1 2f: 66 ad lods ax,WORD PTR ds:[rsi] 31: 66 2d 84 00 sub ax,0x84 35: 79 03 jns 3a <_start+0x3a> 37: 80 ca 02 or dl,0x2 3a: 89 16 mov DWORD PTR [rsi],edx 0x3c - 0x22 = 26 bytesversus
20: 66 67 81 7a 02 84 00 cmp WORD PTR [edx+0x2],0x84 27: 10 c0 adc al,al 29: d0 e0 shl al,1 2b: 67 80 3a 2b cmp BYTE PTR [edx],0x2b 2f: 14 00 adc al,0x0 31: 67 89 42 04 mov DWORD PTR [edx+0x4],eax 0x35 - 0x20 = 21 bytesHad I used explicit references, then the size saving would have been completely negated, but speed is still significantly improved in either context.
