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sparc64: simple microoptimizations for atomic functions
Simple microoptimizations for sparc64 atomic functions:
Save one instruction by using a delay slot.
Use %g1 instead of %g7, because %g1 is written earlier.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
authored by Mikulas Patocka and committed by David S. Miller 6ec27475 9b3bb86a
+8
-12
arch/sparc/lib/atomic_64.S
+8
-12
arch/sparc/lib/atomic_64.S
···
52
52
cas [%o1], %g1, %g7
53
53
cmp %g1, %g7
54
54
bne,pn %icc, 2f
55
-
add %g7, %o0, %g7
56
-
sra %g7, 0, %o0
55
+
add %g1, %o0, %g1
57
56
retl
58
-
nop
57
+
sra %g1, 0, %o0
59
58
2: BACKOFF_SPIN(%o2, %o3, 1b)
60
59
.size atomic_add_ret, .-atomic_add_ret
61
60
···
67
68
cas [%o1], %g1, %g7
68
69
cmp %g1, %g7
69
70
bne,pn %icc, 2f
70
-
sub %g7, %o0, %g7
71
-
sra %g7, 0, %o0
71
+
sub %g1, %o0, %g1
72
72
retl
73
-
nop
73
+
sra %g1, 0, %o0
74
74
2: BACKOFF_SPIN(%o2, %o3, 1b)
75
75
.size atomic_sub_ret, .-atomic_sub_ret
76
76
···
112
114
casx [%o1], %g1, %g7
113
115
cmp %g1, %g7
114
116
bne,pn %xcc, 2f
115
-
add %g7, %o0, %g7
116
-
mov %g7, %o0
117
-
retl
118
117
nop
118
+
retl
119
+
add %g1, %o0, %o0
119
120
2: BACKOFF_SPIN(%o2, %o3, 1b)
120
121
.size atomic64_add_ret, .-atomic64_add_ret
121
122
···
127
130
casx [%o1], %g1, %g7
128
131
cmp %g1, %g7
129
132
bne,pn %xcc, 2f
130
-
sub %g7, %o0, %g7
131
-
mov %g7, %o0
132
-
retl
133
133
nop
134
+
retl
135
+
sub %g1, %o0, %o0
134
136
2: BACKOFF_SPIN(%o2, %o3, 1b)
135
137
.size atomic64_sub_ret, .-atomic64_sub_ret