Messages in this thread | | | Date | Tue, 16 Jun 2015 14:41:31 +0300 | Subject | Re: [PATCH] small update for strlen, strnlen, use less cpu instructions | From | Alexey Dobriyan <> |
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> Now strlen() increments a variable for each character it faces, > hence it will consume more cycles.
It doesn't matter if there is a dependency in a loop:
Before: 520: 48 83 c0 01 add $0x1,%rax 524: 80 38 00 cmpb $0x0,(%rax) 527: 75 f7 jne 520
After: 500: 48 83 c0 01 add $0x1,%rax 504: 80 3c 07 00 cmpb $0x0,(%rdi,%rax,1) 508: 75 f6 jne 500
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