Re: [dpdk-dev] [PATCH v7 1/3] eal/x86: run-time dispatch over memcpy

[Thomas Monjalon <thomas@monjalon.net>]

13/10/2017 03:06, Li, Xiaoyun:
> Hi
> Sorry for the late reply. I took AL last 3 days.
> 
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > 05/10/2017 14:33, Xiaoyun Li:
> > > +/**
> > > + * Macro for copying unaligned block from one location to another
> > > +with constant load offset,
> > > + * 47 bytes leftover maximum,
> > > + * locations should not overlap.
> > > + * Requirements:
> > > + * - Store is aligned
> > > + * - Load offset is <offset>, which must be immediate value within
> > > +[1, 15]
> > > + * - For <src>, make sure <offset> bit backwards & <16 - offset> bit
> > > +forwards are available for loading
> > > + * - <dst>, <src>, <len> must be variables
> > > + * - __m128i <xmm0> ~ <xmm8> must be pre-defined  */ #define
> > > +MOVEUNALIGNED_LEFT47_IMM(dst, src, len,
> > 
> > Naive question:
> > Is there a real benefit of using a macro compared to a static inline function
> > optimized by a modern compiler?
> > 
> The macro is in the existing DPDK codes. I didn't touch it. I just change the file name and the function name to rte_memcpy_internal.
> So I am not clear about if there is real benefit.
> In my opinion, I think it is the same as static inline function.
> 
> Do I need to change them to inline function?

In this patch, it appears as a new macro.
If you can, inline function is cleaner for the new one.

> > Anyway, if you are doing a new version, please reduce lines length and fix
> > the indent from spaces to tabs.
> > 
> They are original DPDK codes so I didn't touch them.
> But in next version, I will fix them.

Just to be sure: we are talking about fixing checkpatch warnings
only for the code added, changed or moved.

Thanks