https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78995
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to feiz from comment #4)
> (In reply to Richard Biener from comment #2)
> > static inline void
> > rte_memcpy(void *dst, const void *src, size_t n)
> > {
> > uintptr_t dstu = (uintptr_t)dst;
> > uintptr_t srcu = (uintptr_t)src;
> >
> > *(uint32_t *)dstu = *(const uint32_t *)srcu;
> >
> > this is violating strict aliasing rules as you are copying
> >
> > typedef unsigned short WORD;
> >
> > struct TFieldHeader
> > {
> > WORD FieldID;
> > WORD Size;
> > };
>
> Well, that's right. I add the compile option -fno-strict-aliasing, and it
> works.
> To get a better performance, I got the rte_memcpy code from dpdk codes to
> replace memcpy in our project.
>
> Very thanks for your help. And I have one more question about this.
>
> I check some instruction about aliasing, like
> "Strict aliasing is an assumption, made by the C (or C++) compiler, that
> dereferencing pointers to objects of different types will never refer to the
> same memory location (i.e. alias eachother.)".
>
> I am confused, we always use the following actions, does this safe?
yes
> char buf[1024];
> struct A {
> int a;
> int b;
> };
>
> struct p * = (struct A*)buf;
> p->a =01;
> p->b = 02;
