1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * arch/alpha/lib/strrchr.S 3 * arch/alpha/lib/strrchr.S
4 * Contributed by Richard Henderson (rth@tamu. 4 * Contributed by Richard Henderson (rth@tamu.edu)
5 * 5 *
6 * Return the address of the last occurrence o 6 * Return the address of the last occurrence of a given character
7 * within a null-terminated string, or null if 7 * within a null-terminated string, or null if it is not found.
8 */ 8 */
9 #include <linux/export.h> 9 #include <linux/export.h>
10 #include <asm/regdef.h> 10 #include <asm/regdef.h>
11 11
12 .set noreorder 12 .set noreorder
13 .set noat 13 .set noat
14 14
15 .align 3 15 .align 3
16 .ent strrchr 16 .ent strrchr
17 .globl strrchr 17 .globl strrchr
18 strrchr: 18 strrchr:
19 .frame sp, 0, ra 19 .frame sp, 0, ra
20 .prologue 0 20 .prologue 0
21 21
22 zapnot a1, 1, a1 # e0 : zero 22 zapnot a1, 1, a1 # e0 : zero extend our test character
23 mov zero, t6 # .. e1 : t6 i 23 mov zero, t6 # .. e1 : t6 is last match aligned addr
24 sll a1, 8, t5 # e0 : repl 24 sll a1, 8, t5 # e0 : replicate our test character
25 mov zero, t8 # .. e1 : t8 i 25 mov zero, t8 # .. e1 : t8 is last match byte compare mask
26 or t5, a1, a1 # e0 : 26 or t5, a1, a1 # e0 :
27 ldq_u t0, 0(a0) # .. e1 : load 27 ldq_u t0, 0(a0) # .. e1 : load first quadword
28 sll a1, 16, t5 # e0 : 28 sll a1, 16, t5 # e0 :
29 andnot a0, 7, v0 # .. e1 : alig 29 andnot a0, 7, v0 # .. e1 : align source addr
30 or t5, a1, a1 # e0 : 30 or t5, a1, a1 # e0 :
31 lda t4, -1 # .. e1 : buil 31 lda t4, -1 # .. e1 : build garbage mask
32 sll a1, 32, t5 # e0 : 32 sll a1, 32, t5 # e0 :
33 cmpbge zero, t0, t1 # .. e1 : bits 33 cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero
34 mskqh t4, a0, t4 # e0 : 34 mskqh t4, a0, t4 # e0 :
35 or t5, a1, a1 # .. e1 : char 35 or t5, a1, a1 # .. e1 : character replication complete
36 xor t0, a1, t2 # e0 : make 36 xor t0, a1, t2 # e0 : make bytes == c zero
37 cmpbge zero, t4, t4 # .. e1 : bits 37 cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
38 cmpbge zero, t2, t3 # e0 : bits 38 cmpbge zero, t2, t3 # e0 : bits set iff byte == c
39 andnot t1, t4, t1 # .. e1 : clea 39 andnot t1, t4, t1 # .. e1 : clear garbage from null test
40 andnot t3, t4, t3 # e0 : clea 40 andnot t3, t4, t3 # e0 : clear garbage from char test
41 bne t1, $eos # .. e1 : did 41 bne t1, $eos # .. e1 : did we already hit the terminator?
42 42
43 /* Character search main loop */ 43 /* Character search main loop */
44 $loop: 44 $loop:
45 ldq t0, 8(v0) # e0 : load 45 ldq t0, 8(v0) # e0 : load next quadword
46 cmovne t3, v0, t6 # .. e1 : save 46 cmovne t3, v0, t6 # .. e1 : save previous comparisons match
47 cmovne t3, t3, t8 # e0 : 47 cmovne t3, t3, t8 # e0 :
48 addq v0, 8, v0 # .. e1 : 48 addq v0, 8, v0 # .. e1 :
49 xor t0, a1, t2 # e0 : 49 xor t0, a1, t2 # e0 :
50 cmpbge zero, t0, t1 # .. e1 : bits 50 cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero
51 cmpbge zero, t2, t3 # e0 : bits 51 cmpbge zero, t2, t3 # e0 : bits set iff byte == c
52 beq t1, $loop # .. e1 : if w 52 beq t1, $loop # .. e1 : if we havnt seen a null, loop
53 53
54 /* Mask out character matches after te 54 /* Mask out character matches after terminator */
55 $eos: 55 $eos:
56 negq t1, t4 # e0 : isol 56 negq t1, t4 # e0 : isolate first null byte match
57 and t1, t4, t4 # e1 : 57 and t1, t4, t4 # e1 :
58 subq t4, 1, t5 # e0 : buil 58 subq t4, 1, t5 # e0 : build a mask of the bytes up to...
59 or t4, t5, t4 # e1 : ... 59 or t4, t5, t4 # e1 : ... and including the null
60 60
61 and t3, t4, t3 # e0 : mask 61 and t3, t4, t3 # e0 : mask out char matches after null
62 cmovne t3, t3, t8 # .. e1 : save 62 cmovne t3, t3, t8 # .. e1 : save it, if match found
63 cmovne t3, v0, t6 # e0 : 63 cmovne t3, v0, t6 # e0 :
64 64
65 /* Locate the address of the last matc 65 /* Locate the address of the last matched character */
66 66
67 /* Retain the early exit for the ev4 - 67 /* Retain the early exit for the ev4 -- the ev5 mispredict penalty
68 is 5 cycles -- the same as just fal 68 is 5 cycles -- the same as just falling through. */
69 beq t8, $retnull # .. e1 : 69 beq t8, $retnull # .. e1 :
70 70
71 and t8, 0xf0, t2 # e0 : bina 71 and t8, 0xf0, t2 # e0 : binary search for the high bit set
72 cmovne t2, t2, t8 # .. e1 (zdb) 72 cmovne t2, t2, t8 # .. e1 (zdb)
73 cmovne t2, 4, t2 # e0 : 73 cmovne t2, 4, t2 # e0 :
74 and t8, 0xcc, t1 # .. e1 : 74 and t8, 0xcc, t1 # .. e1 :
75 cmovne t1, t1, t8 # e0 : 75 cmovne t1, t1, t8 # e0 :
76 cmovne t1, 2, t1 # .. e1 : 76 cmovne t1, 2, t1 # .. e1 :
77 and t8, 0xaa, t0 # e0 : 77 and t8, 0xaa, t0 # e0 :
78 cmovne t0, 1, t0 # .. e1 (zdb) 78 cmovne t0, 1, t0 # .. e1 (zdb)
79 addq t2, t1, t1 # e0 : 79 addq t2, t1, t1 # e0 :
80 addq t6, t0, v0 # .. e1 : add 80 addq t6, t0, v0 # .. e1 : add our aligned base ptr to the mix
81 addq v0, t1, v0 # e0 : 81 addq v0, t1, v0 # e0 :
82 ret # .. e1 : 82 ret # .. e1 :
83 83
84 $retnull: 84 $retnull:
85 mov zero, v0 # e0 : 85 mov zero, v0 # e0 :
86 ret # .. e1 : 86 ret # .. e1 :
87 87
88 .end strrchr 88 .end strrchr
89 EXPORT_SYMBOL(strrchr) 89 EXPORT_SYMBOL(strrchr)
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