[Bug target/80689] 128 loads generated for structure copying with gcc 7.1.0 and leads to STLF stalls in avx2 targets.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80689

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
             Target|                            |x86_64-*-*

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
That you use noinline tells that glibc memcpy has the very same issue.  Note
that similarly having bytes/shorts in the structure and using longs or ints
to implement inlined memcpy has the same issue.

So I don't see how to easily fix this, or rather I don't think we can fix it at
all apart from the case where we can see both the struct copy and previous
stores to the source (thus when you enable inlining).