------- Comment #23 from tkho at ucla dot edu 2005-11-10 22:43 -------
Created an attachment (id=10211)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10211&action=view)
Another long long rotate test case
Hi Michael,
I tried your patch in comment #16, and it didn't optimize our code. Attached is
another minimal testcase. I hope it helps and you can do something with it.
Here is a rough instruction-count comparison for f() compiled at -O2,
march=pentiumpro with icc9 and gcc head 20051108 with your patch applied:
icc: 11
gcc: 23
`icc -O2 -march=pentiumpro -S test3.c` gives:
movl 4(%esp), %eax
movl 8(%esp), %ecx
movl %eax, %edx
shrl $24, %edx
shll $8, %eax
shll $8, %ecx
orl %ecx, %edx
movzwl 18(%esp), %ecx
movzbl %cl, %ecx
orl %ecx, %eax
ret
`g++ -c test3.c -save-temps -O2 -march=pentiumpro -momit-leaf-frame-pointer`
gives:
subl $12, %esp
movl %edi, 8(%esp)
movl 28(%esp), %edi
movl 16(%esp), %eax
movl 20(%esp), %edx
movl %esi, 4(%esp)
movl 24(%esp), %esi
movl %edi, %esi
xorl %edi, %edi
movl 8(%esp), %edi
movl %ebx, (%esp)
shrl $16, %esi
xorl %ebx, %ebx
shldl $8, %eax, %edx
movl %esi, %ecx
movl 4(%esp), %esi
orl %ebx, %edx
movl (%esp), %ebx
andl $255, %ecx
sall $8, %eax
addl $12, %esp
orl %ecx, %eax
ret
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17886
