/* Optimized strrchr implementation for PowerPC64/POWER7 using cmpb insn.
Copyright (C) 2017-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
. */
#include
/* char *[r3] strrchr (char *s [r3], int c [r4]) */
#ifdef __LITTLE_ENDIAN__
/* Find the match position from v6 and place result in r6. */
# define CALCULATE_MATCH() \
vbpermq v6, v6, v10; \
vsldoi v6, v6, v6, 6; \
mfvrd r7, v6; \
cntlzd r6, r7; \
subfic r6, r6, 15;
/*
* Find the first null position to mask bytes after null.
* (reg): vcmpequb result: v2 for 1st qw v3 for 2nd qw.
* Result placed at v2.
*/
# define FIND_NULL_POS(reg) \
vspltisb v11, -1; \
vadduqm v11, reg, v11; \
vandc v11, v11, reg; \
vpopcntd v2, v11; \
vspltb v11, v2, 15; \
vcmpequb. v11, v11, v9; \
blt cr6, 1f; \
vsldoi v9, v0, v9, 1; \
vslo v2, v2, v9; \
1: \
vsumsws v2, v2, v0;
#else
# define CALCULATE_MATCH() \
vbpermq v6, v6, v10; \
mfvrd r7, v6; \
addi r6, r7, -1; \
andc r6, r6, r7; \
popcntd r6, r6; \
subfic r6, r6, 15;
# define FIND_NULL_POS(reg) \
vclzd v2, reg; \
vspltb v11, v2, 7; \
vcmpequb. v11, v11, v9; \
blt cr6, 1f; \
vsldoi v9, v0, v9, 1; \
vsro v2, v2, v9; \
1: \
vsumsws v2, v2, v0;
#endif /* !__LITTLE_ENDIAN__ */
#ifndef STRRCHR
# define STRRCHR strrchr
#endif
.machine power8
ENTRY_TOCLESS (STRRCHR)
CALL_MCOUNT 2
dcbt 0,r3
clrrdi r8,r3,3 /* Align the address to doubleword boundary. */
cmpdi cr7,r4,0
ld r12,0(r8) /* Load doubleword from memory. */
li r9,0 /* Used to store last occurence. */
li r0,0 /* Doubleword with null chars to use
with cmpb. */
rlwinm r6,r3,3,26,28 /* Calculate padding. */
beq cr7,L(null_match)
/* Replicate byte to doubleword. */
insrdi r4,r4,8,48
insrdi r4,r4,16,32
insrdi r4,r4,32,0
/* r4 is changed now. If it's passed more chars, then
check for null again. */
cmpdi cr7,r4,0
beq cr7,L(null_match)
/* Now r4 has a doubleword of c bytes and r0 has
a doubleword of null bytes. */
cmpb r10,r12,r4 /* Compare each byte against c byte. */
cmpb r11,r12,r0 /* Compare each byte against null byte. */
/* Move the doublewords left and right to discard the bits that are
not part of the string and bring them back as zeros. */
#ifdef __LITTLE_ENDIAN__
srd r10,r10,r6
srd r11,r11,r6
sld r10,r10,r6
sld r11,r11,r6
#else
sld r10,r10,r6
sld r11,r11,r6
srd r10,r10,r6
srd r11,r11,r6
#endif
or r5,r10,r11 /* OR the results to speed things up. */
cmpdi cr7,r5,0 /* If r5 == 0, no c or null bytes
have been found. */
bne cr7,L(done)
L(align):
andi. r12, r8, 15
/* Are we now aligned to a doubleword boundary? If so, skip to
the main loop. Otherwise, go through the alignment code. */
bne cr0, L(loop)
/* Handle WORD2 of pair. */
ldu r12,8(r8)
cmpb r10,r12,r4
cmpb r11,r12,r0
or r5,r10,r11
cmpdi cr7,r5,0
bne cr7,L(done)
b L(loop) /* We branch here (rather than falling through)
to skip the nops due to heavy alignment
of the loop below. */
.p2align 5
L(loop):
/* Load two doublewords, compare and merge in a
single register for speed. This is an attempt
to speed up the null-checking process for bigger strings. */
ld r12,8(r8)
ldu r7,16(r8)
cmpb r10,r12,r4
cmpb r11,r12,r0
cmpb r6,r7,r4
cmpb r7,r7,r0
or r12,r10,r11
or r5,r6,r7
or r5,r12,r5
cmpdi cr7,r5,0
beq cr7,L(vector)
/* OK, one (or both) of the doublewords contains a c/null byte. Check
the first doubleword and decrement the address in case the first
doubleword really contains a c/null byte. */
cmpdi cr6,r12,0
addi r8,r8,-8
bne cr6,L(done)
/* The c/null byte must be in the second doubleword. Adjust the
address again and move the result of cmpb to r10 so we can calculate
the pointer. */
mr r10,r6
mr r11,r7
addi r8,r8,8
/* r10/r11 have the output of the cmpb instructions, that is,
0xff in the same position as the c/null byte in the original
doubleword from the string. Use that to calculate the pointer. */
L(done):
/* If there are more than one 0xff in r11, find the first position of
0xff in r11 and fill r10 with 0 from that position. */
cmpdi cr7,r11,0
beq cr7,L(no_null)
#ifdef __LITTLE_ENDIAN__
addi r3,r11,-1
andc r3,r3,r11
popcntd r0,r3
#else
cntlzd r0,r11
#endif
subfic r0,r0,63
li r6,-1
#ifdef __LITTLE_ENDIAN__
srd r0,r6,r0
#else
sld r0,r6,r0
#endif
and r10,r0,r10
L(no_null):
#ifdef __LITTLE_ENDIAN__
cntlzd r0,r10 /* Count leading zeros before c matches. */
addi r3,r10,-1
andc r3,r3,r10
addi r10,r11,-1
andc r10,r10,r11
cmpld cr7,r3,r10
bgt cr7,L(no_match)
#else
addi r3,r10,-1 /* Count trailing zeros before c matches. */
andc r3,r3,r10
popcntd r0,r3
cmpld cr7,r11,r10
bgt cr7,L(no_match)
#endif
srdi r0,r0,3 /* Convert trailing zeros to bytes. */
subfic r0,r0,7
add r9,r8,r0 /* Return address of the matching c byte
or null in case c was not found. */
li r0,0
cmpdi cr7,r11,0 /* If r11 == 0, no null's have been found. */
beq cr7,L(align)
.align 4
L(no_match):
mr r3,r9
blr
/* Check the first 32B in GPR's and move to vectorized loop. */
.p2align 5
L(vector):
addi r3, r8, 8
/* Make sure 32B aligned. */
andi. r10, r3, 31
bne cr0, L(loop)
vspltisb v0, 0
/* Precompute vbpermq constant. */
vspltisb v10, 3
lvsl v11, r0, r0
vslb v10, v11, v10
mtvrd v1, r4
li r5, 16
vspltb v1, v1, 7
/* Compare 32 bytes in each loop. */
L(continue):
lvx v4, 0, r3
lvx v5, r3, r5
vcmpequb v2, v0, v4
vcmpequb v3, v0, v5
vcmpequb v6, v1, v4
vcmpequb v7, v1, v5
vor v8, v2, v3
vor v9, v6, v7
vor v11, v8, v9
vcmpequb. v11, v0, v11
addi r3, r3, 32
blt cr6, L(continue)
vcmpequb. v8, v0, v8
blt cr6, L(match)
/* One (or both) of the quadwords contains c/null. */
vspltisb v8, 2
vspltisb v9, 5
/* Precompute values used for comparison. */
vsl v9, v8, v9 /* v9 = 0x4040404040404040. */
vaddubm v8, v9, v9
vsldoi v8, v0, v8, 1 /* v8 = 0x80. */
/* Check if null is in second qw. */
vcmpequb. v11, v0, v2
blt cr6, L(secondqw)
/* Null found in first qw. */
addi r8, r3, -32
/* Calculate the null position. */
FIND_NULL_POS(v2)
/* Check if null is in the first byte. */
vcmpequb. v11, v0, v2
blt cr6, L(no_match)
vsububm v2, v8, v2
/* Mask unwanted bytes after null. */
#ifdef __LITTLE_ENDIAN__
vslo v6, v6, v2
vsro v6, v6, v2
#else
vsro v6, v6, v2
vslo v6, v6, v2
#endif
vcmpequb. v11, v0, v6
blt cr6, L(no_match)
/* Found a match before null. */
CALCULATE_MATCH()
add r3, r8, r6
blr
L(secondqw):
addi r8, r3, -16
FIND_NULL_POS(v3)
vcmpequb. v11, v0, v2
blt cr6, L(no_match1)
vsububm v2, v8, v2
/* Mask unwanted bytes after null. */
#ifdef __LITTLE_ENDIAN__
vslo v7, v7, v2
vsro v7, v7, v2
#else
vsro v7, v7, v2
vslo v7, v7, v2
#endif
vcmpequb. v11, v0, v7
blt cr6, L(no_match1)
addi r8, r8, 16
vor v6, v0, v7
L(no_match1):
addi r8, r8, -16
vcmpequb. v11, v0, v6
blt cr6, L(no_match)
/* Found a match before null. */
CALCULATE_MATCH()
add r3, r8, r6
blr
L(match):
/* One (or both) of the quadwords contains a match. */
mr r8, r3
vcmpequb. v8, v0, v7
blt cr6, L(firstqw)
/* Match found in second qw. */
addi r8, r8, 16
vor v6, v0, v7
L(firstqw):
addi r8, r8, -32
CALCULATE_MATCH()
add r9, r8, r6 /* Compute final length. */
b L(continue)
/* We are here because strrchr was called with a null byte. */
.align 4
L(null_match):
/* r0 has a doubleword of null bytes. */
cmpb r5,r12,r0 /* Compare each byte against null bytes. */
/* Move the doublewords left and right to discard the bits that are
not part of the string and bring them back as zeros. */
#ifdef __LITTLE_ENDIAN__
srd r5,r5,r6
sld r5,r5,r6
#else
sld r5,r5,r6
srd r5,r5,r6
#endif
cmpdi cr7,r5,0 /* If r5 == 0, no c or null bytes
have been found. */
bne cr7,L(done_null)
andi. r12, r8, 15
/* Are we now aligned to a quadword boundary? If so, skip to
the main loop. Otherwise, go through the alignment code. */
bne cr0, L(loop_null)
/* Handle WORD2 of pair. */
ldu r12,8(r8)
cmpb r5,r12,r0
cmpdi cr7,r5,0
bne cr7,L(done_null)
b L(loop_null) /* We branch here (rather than falling through)
to skip the nops due to heavy alignment
of the loop below. */
/* Main loop to look for the end of the string. Since it's a
small loop (< 8 instructions), align it to 32-bytes. */
.p2align 5
L(loop_null):
/* Load two doublewords, compare and merge in a
single register for speed. This is an attempt
to speed up the null-checking process for bigger strings. */
ld r12,8(r8)
ldu r11,16(r8)
cmpb r5,r12,r0
cmpb r10,r11,r0
or r6,r5,r10
cmpdi cr7,r6,0
beq cr7,L(vector1)
/* OK, one (or both) of the doublewords contains a null byte. Check
the first doubleword and decrement the address in case the first
doubleword really contains a null byte. */
cmpdi cr6,r5,0
addi r8,r8,-8
bne cr6,L(done_null)
/* The null byte must be in the second doubleword. Adjust the address
again and move the result of cmpb to r10 so we can calculate the
pointer. */
mr r5,r10
addi r8,r8,8
/* r5 has the output of the cmpb instruction, that is, it contains
0xff in the same position as the null byte in the original
doubleword from the string. Use that to calculate the pointer. */
L(done_null):
#ifdef __LITTLE_ENDIAN__
addi r0,r5,-1
andc r0,r0,r5
popcntd r0,r0
#else
cntlzd r0,r5 /* Count leading zeros before the match. */
#endif
srdi r0,r0,3 /* Convert trailing zeros to bytes. */
add r3,r8,r0 /* Return address of the matching null byte. */
blr
/* Check the first 32B in GPR's and move to vectorized loop. */
.p2align 5
L(vector1):
addi r3, r8, 8
/* Make sure 32B aligned. */
andi. r10, r3, 31
bne cr0, L(loop_null)
vspltisb v0, 0
/* Precompute vbpermq constant. */
vspltisb v10, 3
lvsl v11, r0, r0
vslb v10, v11, v10
li r5, 16
/* Compare 32 bytes in each loop. */
L(continue1):
lvx v4, 0, r3
lvx v5, r3, r5
vcmpequb v2, v0, v4
vcmpequb v3, v0, v5
vor v8, v2, v3
vcmpequb. v11, v0, v8
addi r3, r3, 32
blt cr6, L(continue1)
addi r3, r3, -32
vbpermq v2, v2, v10
vbpermq v3, v3, v10
/* Shift each component into its correct position for merging. */
#ifdef __LITTLE_ENDIAN__
vsldoi v3, v3, v3, 2
#else
vsldoi v2, v2, v2, 6
vsldoi v3, v3, v3, 4
#endif
/* Merge the results and move to a GPR. */
vor v4, v3, v2
mfvrd r5, v4
#ifdef __LITTLE_ENDIAN__
addi r6, r5, -1
andc r6, r6, r5
popcntd r6, r6
#else
cntlzd r6, r5 /* Count leading zeros before the match. */
#endif
add r3, r3, r6 /* Compute final length. */
blr
END_GEN_TB (STRRCHR, TB_TOCLESS)
weak_alias (strrchr, rindex)
libc_hidden_builtin_def (strrchr)