https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80645
--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
I have reproduced the warning in comment #0 with a powerpc64le-linux and
sparcv9-sun-solaris2.11 (but on x86_64-linux). Based on the dumps the warning
seems justified. Here's what I see in elemental_subroutine_3.f90.004t.gimple
for the second call to memcpy (the one that triggers the warning):
test ()
...
static struct mytype x[6] = {{.x=1}, {.x=20}, {.x=300}, {.x=4000},
{.x=50000}, {.x=1000000}};
...
parm.11.data = &x[3];
...
_15 = parm.11.data;
__builtin_memcpy (data.13, _15, 16);
I.e., memcpy is being called to copy 16 bytes from the six-element array x,
starting at element 4. With each element being 4 bytes wide, the last three
elements of x are only 12 bytes in size. This doesn't significantly change in
any of the subsequent dumps and the warning seems to be faithfully reporting
the same numbers: a read of 16 bytes from a region of size 12.
The reason the warning doesn't show up on x86_64 is because there GCC doesn't
emit memcpy to copy the elements. Instead it uses a MEM_REF.
