https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70039
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. The reason is that we really represent those initializers
differently,
one is a STRING_CST (handled) and one is a CONSTRUCTOR (not handled). memcpy
expansion does
src_str = c_getstr (src);
/* If SRC is a string constant and block move would be done
by pieces, we can avoid loading the string from memory
and only stored the computed constants. */
if (src_str
&& CONST_INT_P (len_rtx)
&& (unsigned HOST_WIDE_INT) INTVAL (len_rtx) <= strlen (src_str) + 1
&& can_store_by_pieces (INTVAL (len_rtx), builtin_memcpy_read_str,
CONST_CAST (char *, src_str),
dest_align, false))
{
dest_mem = store_by_pieces (dest_mem, INTVAL (len_rtx),
builtin_memcpy_read_str,
CONST_CAST (char *, src_str),
dest_align, false, 0);
dest_mem = force_operand (XEXP (dest_mem, 0), target);
dest_mem = convert_memory_address (ptr_mode, dest_mem);
return dest_mem;
which doesn't apply to the constructor case or any other non-string static
constant.
