Re: [lwip-devel] [PATCH] Fix aliasing violation.

[address@hidden]

David Woodhouse wrote:
> > But we should use SMEMCPY.  I use a macro that converts this to a
> > series of inline load/stores.
> >     
> Isn't that the compiler's job?
>   

In 1.3.0, we converted all calls to 'memcpy' to either 'MEMCPY' or 
'SMEMCPY' (s for short). The goal is optimization: SMEMCPY is defined to 
memcpy (which the compiler may inline e.g. if size is known at compile 
time and small); whil MEMCPY can be overridden to provide a better copy 
mechanism (on my platform, for example, copying non-aligned data can be 
solved much better when loading full words and shifting in registers).

Therfore, using 'memcpy' directly should be avoided: when you know your 
compiler can't optimize it, you can redefine SMEMCPY to inlining yourself.

Simon