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[Bug rtl-optimization/21150] Suboptimal byte extraction from 64bits
- From: "rask at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 9 Nov 2007 19:48:12 -0000
- Subject: [Bug rtl-optimization/21150] Suboptimal byte extraction from 64bits
- References: <bug-21150-1101@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #4 from rask at gcc dot gnu dot org 2007-11-09 19:48 -------
I think this might be a middle-end issue related to PR 7061 or PR 15184. We're
doing slightly better with GCC 4.3.0 (because of subreg lowering, I guess), but
not much (asm output with -dp for readability):
a:
movl v+44, %eax # 53 *movsi_1/1 [length = 5]
movl v+8, %edx # 23 *movsi_1/1 [length = 6]
shrl $8, %eax # 54 *lshrsi3_1/1 [length = 3]
xorb v+36, %al # 11 *xorqi_1/1 [length = 6]
xorb v, %al # 13 *xorqi_1/1 [length = 6]
xorb v+54, %al # 17 *xorqi_1/1 [length = 6]
xorb v+63, %al # 21 *xorqi_1/1 [length = 6]
shrl $8, %edx # 24 *lshrsi3_1/1 [length = 3]
xorl %edx, %eax # 66 *xorsi_1/1 [length = 2]
xorb v+18, %al # 29 *xorqi_1/1 [length = 6]
xorb v+27, %al # 33 *xorqi_1/1 [length = 6]
ret # 69 return_internal [length = 1]
b:
pushl %ebx # 75 *pushsi2 [length = 1]
movl v+20, %edx # 69 *movsi_1/1 [length = 6]
movl v+12, %ebx # 67 *movsi_1/1 [length = 6]
movl v+8, %ecx # 66 *movsi_1/1 [length = 6]
movl v+16, %eax # 68 *movsi_1/1 [length = 5]
shrdl $8, %ebx, %ecx # 81 x86_shrd_1/1 [length = 4]
shrdl $16, %edx, %eax # 83 x86_shrd_1/1 [length = 4]
movl v+24, %edx # 71 *movsi_1/1 [length = 6]
xorl %ecx, %eax # 70 *xorsi_1/1 [length = 2]
movl v+28, %ecx # 72 *movsi_1/1 [length = 6]
xorb v, %al # 13 *xorqi_1/1 [length = 6]
popl %ebx # 78 popsi1 [length = 1]
shrdl $24, %ecx, %edx # 85 x86_shrd_1/1 [length = 4]
xorl %edx, %eax # 73 *xorsi_1/1 [length = 2]
movl v+44, %edx # 53 *movsi_1/1 [length = 6]
xorb v+36, %al # 21 *xorqi_1/1 [length = 6]
shrl $8, %edx # 54 *lshrsi3_1/1 [length = 3]
xorl %edx, %eax # 74 *xorsi_1/1 [length = 2]
xorb v+54, %al # 29 *xorqi_1/1 [length = 6]
xorb v+63, %al # 33 *xorqi_1/1 [length = 6]
ret # 79 return_internal [length = 1]
c:
movzbl v+9, %eax # 7 *movqi_1/3 [length = 7]
xorb v+18, %al # 8 *xorqi_1/1 [length = 6]
xorb v, %al # 9 *xorqi_1/1 [length = 6]
xorb v+27, %al # 10 *xorqi_1/1 [length = 6]
xorb v+36, %al # 11 *xorqi_1/1 [length = 6]
xorb v+45, %al # 12 *xorqi_1/1 [length = 6]
xorb v+54, %al # 13 *xorqi_1/1 [length = 6]
xorb v+63, %al # 14 *xorqi_1/1 [length = 6]
ret # 33 return_internal [length = 1]
d:
pushl %ebx # 75 *pushsi2 [length = 1]
movl v+20, %edx # 69 *movsi_1/1 [length = 6]
movl v+12, %ebx # 67 *movsi_1/1 [length = 6]
movl v+8, %ecx # 66 *movsi_1/1 [length = 6]
movl v+16, %eax # 68 *movsi_1/1 [length = 5]
shrdl $8, %ebx, %ecx # 81 x86_shrd_1/1 [length = 4]
shrdl $16, %edx, %eax # 83 x86_shrd_1/1 [length = 4]
movl v+24, %edx # 71 *movsi_1/1 [length = 6]
xorl %ecx, %eax # 70 *xorsi_1/1 [length = 2]
movl v+28, %ecx # 72 *movsi_1/1 [length = 6]
xorb v, %al # 13 *xorqi_1/1 [length = 6]
popl %ebx # 78 popsi1 [length = 1]
shrdl $24, %ecx, %edx # 85 x86_shrd_1/1 [length = 4]
xorl %edx, %eax # 73 *xorsi_1/1 [length = 2]
movl v+44, %edx # 53 *movsi_1/1 [length = 6]
xorb v+36, %al # 21 *xorqi_1/1 [length = 6]
shrl $8, %edx # 54 *lshrsi3_1/1 [length = 3]
xorl %edx, %eax # 74 *xorsi_1/1 [length = 2]
xorb v+54, %al # 29 *xorqi_1/1 [length = 6]
xorb v+63, %al # 33 *xorqi_1/1 [length = 6]
ret # 79 return_internal [length = 1]
.ident "GCC: (GNU) 4.3.0 20071102 (experimental)"
--
rask at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to fail| |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21150