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 Post subject: 請問如__builtin_memset 這些API有無文件說明
PostPosted: Thu Jan 24, 2013 6:05 pm 
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Q: 請問如__builtin_memset 這些API有無文件說明?

A:相關GCC預設所支援的built-in function可在這底下這個連結查到:
http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html

“GCC includes built-in versions of many of the functions in the standard C library. The versions prefixed with __builtin_ are always treated as having the same meaning as the C library function... “

簡而言之就是像 __builtin_memset,它是和memset語意一模一樣的~

__builtin_ function本來是內建給compiler自己使用的,
user如果要用也可以。compiler會認得__builtin_ function的語意,
自動產生code,而且是呼叫function。
少了呼叫function的overhead.


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