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/* Optimized memrchr implementation for PowerPC64/POWER8.
Copyright (C) 2017-2018 Free Software Foundation, Inc.
Contributed by Luis Machado <luisgpm@br.ibm.com>.
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
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
/* int [r3] memrchr (char *s [r3], int byte [r4], int size [r5]) */
/* TODO: change these to the actual instructions when the minimum required
binutils allows it. */
#define MTVRD(v, r) .long (0x7c000167 | ((v)<<(32-11)) | ((r)<<(32-16)))
#define MFVRD(r, v) .long (0x7c000067 | ((v)<<(32-11)) | ((r)<<(32-16)))
#define VBPERMQ(t, a, b) .long (0x1000054c \
| ((t)<<(32-11)) \
| ((a)<<(32-16)) \
| ((b)<<(32-21)) )
#ifndef MEMRCHR
# define MEMRCHR __memrchr
#endif
.machine power7
ENTRY_TOCLESS (MEMRCHR)
CALL_MCOUNT 3
add r7, r3, r5 /* Calculate the last acceptable address. */
neg r0, r7
addi r7, r7, -1
mr r10, r3
clrrdi r6, r7, 7
li r9, 3<<5
dcbt r9, r6, 8 /* Stream hint, decreasing addresses. */
/* Replicate BYTE to doubleword. */
insrdi r4, r4, 8, 48
insrdi r4, r4, 16, 32
insrdi r4, r4, 32, 0
li r6, -8
li r9, -1
rlwinm r0, r0, 3, 26, 28 /* Calculate padding. */
clrrdi r8, r7, 3
srd r9, r9, r0
cmpldi r5, 32
clrrdi r0, r10, 3
ble L(small_range)
#ifdef __LITTLE_ENDIAN__
ldx r12, 0, r8
#else
ldbrx r12, 0, r8 /* Load reversed doubleword from memory. */
#endif
cmpb r3, r12, r4 /* Check for BYTE in DWORD1. */
and r3, r3, r9
cmpldi cr7, r3, 0 /* If r3 == 0, no BYTEs have been found. */
bne cr7, L(done)
/* Are we now aligned to a quadword boundary? If so, skip to
the main loop. Otherwise, go through the alignment code. */
andi. r12, r8, 15
beq cr0, L(align_qw)
/* Handle DWORD2 of pair. */
#ifdef __LITTLE_ENDIAN__
ldx r12, r8, r6
#else
ldbrx r12, r8, r6
#endif
addi r8, r8, -8
cmpb r3, r12, r4
cmpldi cr7, r3, 0
bne cr7, L(done)
.align 4
/* At this point, r8 is 16B aligned. */
L(align_qw):
sub r5, r8, r0
vspltisb v0, 0
/* Precompute vbpermq constant. */
vspltisb v10, 3
li r0, 0
lvsl v11, r0, r0
vslb v10, v11, v10
MTVRD(v1, r4)
vspltb v1, v1, 7
cmpldi r5, 64
ble L(tail64)
/* Are we 64-byte aligned? If so, jump to the vectorized loop.
Note: aligning to 64-byte will necessarily slow down performance for
strings around 64 bytes in length due to the extra comparisons
required to check alignment for the vectorized loop. This is a
necessary tradeoff we are willing to take in order to speed up the
calculation for larger strings. */
andi. r11, r8, 63
beq cr0, L(preloop_64B)
/* In order to begin the 64B loop, it needs to be 64
bytes aligned. So read until it is 64B aligned. */
addi r8, r8, -16
lvx v4, 0, r8
vcmpequb v6, v1, v4
vcmpequb. v11, v0, v6
bnl cr6, L(found_16B)
addi r5, r5, -16
andi. r11, r8, 63
beq cr0, L(preloop_64B)
addi r8, r8, -16
lvx v4, 0, r8
vcmpequb v6, v1, v4
vcmpequb. v11, v0, v6
bnl cr6, L(found_16B)
addi r5, r5, -16
andi. r11, r8, 63
beq cr0, L(preloop_64B)
addi r8, r8, -16
lvx v4, 0, r8
vcmpequb v6, v1, v4
vcmpequb. v11, v0, v6
bnl cr6, L(found_16B)
addi r5, r5, -16
/* At this point it should be 64B aligned.
Prepare for the 64B loop. */
L(preloop_64B):
cmpldi r5, 64 /* Check if r5 < 64. */
ble L(tail64)
srdi r9, r5, 6 /* Number of loop iterations. */
mtctr r9 /* Setup the counter. */
li r11, 16 /* Load required offsets. */
li r9, 32
li r7, 48
/* Handle r5 > 64. Loop over the bytes in strides of 64B. */
.align 4
L(loop):
addi r8, r8, -64 /* Adjust address for the next iteration. */
lvx v2, 0, r8 /* Load 4 quadwords. */
lvx v3, r8, r11
lvx v4, v8, r9
lvx v5, v8, r7
vcmpequb v6, v1, v2
vcmpequb v7, v1, v3
vcmpequb v8, v1, v4
vcmpequb v9, v1, v5
vor v11, v6, v7
vor v12, v8, v9
vor v11, v11, v12 /* Compare and merge into one VR for speed. */
vcmpequb. v11, v0, v11
bnl cr6, L(found)
bdnz L(loop)
clrldi r5, r5, 58
/* Handle remainder of 64B loop or r5 > 64. */
.align 4
L(tail64):
cmpldi r5, 0
beq L(null)
addi r8, r8, -16
lvx v4, 0, r8
vcmpequb v6, v1, v4
vcmpequb. v11, v0, v6
bnl cr6, L(found_16B)
cmpldi cr6, r5, 16
ble cr6, L(null)
addi r5, r5, -16
addi r8, r8, -16
lvx v4, 0, r8
vcmpequb v6, v1, v4
vcmpequb. v11, v0, v6
bnl cr6, L(found_16B)
cmpldi cr6, r5, 16
ble cr6, L(null)
addi r5, r5, -16
addi r8, r8, -16
lvx v4, 0, r8
vcmpequb v6, v1, v4
vcmpequb. v11, v0, v6
bnl cr6, L(found_16B)
cmpldi cr6, r5, 16
ble cr6, L(null)
addi r5, r5, -16
addi r8, r8, -16
lvx v4, 0, r8
vcmpequb v6, v1, v4
vcmpequb. v11, v0, v6
bnl cr6, L(found_16B)
li r3, 0
blr
/* Found a match in 64B loop. */
.align 4
L(found):
/* Permute the first bit of each byte into bits 48-63. */
VBPERMQ(v6, v6, v10)
VBPERMQ(v7, v7, v10)
VBPERMQ(v8, v8, v10)
VBPERMQ(v9, v9, v10)
/* Shift each component into its correct position for merging. */
#ifdef __LITTLE_ENDIAN__
vsldoi v7, v7, v7, 2
vsldoi v8, v8, v8, 4
vsldoi v9, v9, v9, 6
#else
vsldoi v6, v6, v6, 6
vsldoi v7, v7, v7, 4
vsldoi v8, v8, v8, 2
#endif
/* Merge the results and move to a GPR. */
vor v11, v6, v7
vor v4, v9, v8
vor v4, v11, v4
MFVRD(r5, v4)
#ifdef __LITTLE_ENDIAN__
cntlzd r6, r5 /* Count leading zeros before the match. */
#else
addi r6, r5, -1
andc r6, r6, r5
popcntd r6, r6
#endif
addi r8, r8, 63
sub r3, r8, r6 /* Compute final address. */
cmpld cr7, r3, r10
bgelr cr7
li r3, 0
blr
/* Found a match in last 16 bytes. */
.align 4
L(found_16B):
cmpld r8, r10 /* Are we on the last QW? */
bge L(last)
/* Now discard bytes before starting address. */
sub r9, r10, r8
MTVRD(v9, r9)
vspltisb v8, 3
/* Mask unwanted bytes. */
#ifdef __LITTLE_ENDIAN__
lvsr v7, 0, r10
vperm v6, v0, v6, v7
vsldoi v9, v0, v9, 8
vsl v9, v9, v8
vslo v6, v6, v9
#else
lvsl v7, 0, r10
vperm v6, v6, v0, v7
vsldoi v9, v0, v9, 8
vsl v9, v9, v8
vsro v6, v6, v9
#endif
L(last):
/* Permute the first bit of each byte into bits 48-63. */
VBPERMQ(v6, v6, v10)
/* Shift each component into its correct position for merging. */
#ifdef __LITTLE_ENDIAN__
vsldoi v6, v6, v6, 6
MFVRD(r7, v6)
cntlzd r6, r7 /* Count leading zeros before the match. */
#else
MFVRD(r7, v6)
addi r6, r7, -1
andc r6, r6, r7
popcntd r6, r6
#endif
addi r8, r8, 15
sub r3, r8, r6 /* Compute final address. */
cmpld r6, r5
bltlr
li r3, 0
blr
/* r3 has the output of the cmpb instruction, that is, it contains
0xff in the same position as BYTE in the original
word from the string. Use that to calculate the pointer.
We need to make sure BYTE is *before* the end of the
range. */
L(done):
cntlzd r9, r3 /* Count leading zeros before the match. */
cmpld r8, r0 /* Are we on the last word? */
srdi r6, r9, 3 /* Convert leading zeros to bytes. */
addi r0, r6, -7
sub r3, r8, r0
cmpld cr7, r3, r10
bnelr
bgelr cr7
li r3, 0
blr
.align 4
L(null):
li r3, 0
blr
/* Deals with size <= 32. */
.align 4
L(small_range):
cmpldi r5, 0
beq L(null)
#ifdef __LITTLE_ENDIAN__
ldx r12, 0, r8
#else
ldbrx r12, 0, r8 /* Load reversed doubleword from memory. */
#endif
cmpb r3, r12, r4 /* Check for BYTE in DWORD1. */
and r3, r3, r9
cmpldi cr7, r3, 0
bne cr7, L(done)
/* Are we done already? */
cmpld r8, r0
addi r8, r8, -8
beqlr
.align 5
L(loop_small):
#ifdef __LITTLE_ENDIAN__
ldx r12, 0, r8
#else
ldbrx r12, 0, r8
#endif
cmpb r3, r12, r4
cmpld r8, r0
cmpldi cr7, r3, 0
bne cr7, L(done)
addi r8, r8, -8
bne L(loop_small)
blr
END (MEMRCHR)
weak_alias (__memrchr, memrchr)
libc_hidden_builtin_def (memrchr)
|
