copying memory in phobos

[Artur Skawina]

On 04/08/14 14:35, Mike wrote:
> On Tuesday, 8 April 2014 at 11:56:43 UTC, ketmar wrote:
>>> I understand that.  But why is dest[] = src[] not good enough for run-time?
>> 'cause some compilers (gcc, for example) has memcpy() as 'intrinsic' and generates better inline code for it sometimes. it's just a small hint for compiler backend, and faster code is good, isn't it? ;-)
> 
> a[] = b[] causes the compiler to generate a call to _d_arraycopy, and _d_arraycopy calls, you guessed it, memcpy!  (verified with GDC 4.8.2)  So, there is no performance benefit calling memcpy directly.  It's going to be called anyway.

'memcoy' being a built-in compiler intrinsic means that when the compiler
sees a 'memcpy' call, it does some checks (eg is the length statically
known and small enough?) and then can generated the copy instructions
directly, instead of calling the lib function.

artur