------- Comment #9 from rask at gcc dot gnu dot org 2007-11-28 18:01 -------
Created an attachment (id=14657)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=14657&action=view)
Patch v2 to enhance cse.c
This patch also handles unsigned comparisons and thus optimizes the original
testcase too. Before:
foo:
movl 4(%esp), %edx # 2 *movsi_1/1 [length = 4]
movl 8(%esp), %eax # 3 *movsi_1/1 [length = 4]
movl %edx, %ecx # 35 *movsi_1/1 [length = 2]
subl %eax, %ecx # 7 *subsi_1/1 [length = 2]
cmpl %eax, %edx # 8 *cmpsi_1_insn/1 [length = 2]
jae .L2 # 9 *jcc_1 [length = 2]
addl $100, %ecx # 11 *addsi_1/1 [length = 3]
.L2:
movl %ecx, %eax # 18 *movsi_1/1 [length = 2]
ret # 38 return_internal [length = 1]
After:
foo:
movl 4(%esp), %eax # 2 *movsi_1/1 [length = 4]
subl 8(%esp), %eax # 8 *subsi3_cc_overflow/2 [length = 4]
jae .L2 # 9 *jcc_1 [length = 2]
addl $100, %eax # 11 *addsi_1/1 [length = 3]
.L2:
rep # 39 return_internal_long [length = 1]
ret
I was going to abandon this patch, but maybe it deserves a second chance. :-)
--
rask at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Attachment #14647|0 |1
is obsolete| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3507
