https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107812
Roger Sayle <roger at nextmovesoftware dot com> changed:
What |Removed |Added
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CC| |roger at nextmovesoftware dot
com
--- Comment #3 from Roger Sayle <roger at nextmovesoftware dot com> ---
Things are better but not perfect on trunk (GCC 14.0.0):
pushl %esi
pushl %ebx
movl 16(%esp), %eax ; y
movl 20(%esp), %ecx ; z
movl 12(%esp), %edx ; x
movl 4(%eax), %ebx ; y[1]
movl (%eax), %esi ; y[0]
movl %ebx, %eax
shrdl %esi, %eax
movl %eax, (%edx)
popl %ebx
popl %esi
ret
So the xorl and orl are gone, and we're down to two pushs/pops.
It looks like the additional spill is just a difference in register allocation.
Perhaps i386.md's *concatsidi3_3 could be cleverer (to avoid the early clobber
&r when both operands are mem, and their addressing mode is sufficently
simple).
i.e.
movl (%eax), %esi ; y[0]
movl 4(%eax), %eax ; y[1]
instead of
movl 4(%eax), %ebx ; y[1]
movl (%eax), %esi ; y[0]
movl %ebx, %eax
