mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-02 09:40:13 +00:00
581c785bf3
I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 7061 files FOO. I then removed trailing white space from math/tgmath.h, support/tst-support-open-dev-null-range.c, and sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following obscure pre-commit check failure diagnostics from Savannah. I don't know why I run into these diagnostics whereas others evidently do not. remote: *** 912-#endif remote: *** 913: remote: *** 914- remote: *** error: lines with trailing whitespace found ... remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
249 lines
5.7 KiB
ArmAsm
249 lines
5.7 KiB
ArmAsm
/* Optimized strcmp implementation for PowerPC64/POWER8.
|
|
Copyright (C) 2015-2022 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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <sysdep.h>
|
|
|
|
#ifndef STRCMP
|
|
# define STRCMP strcmp
|
|
#endif
|
|
|
|
/* Implements the function
|
|
|
|
size_t [r3] strcmp (const char *s1 [r3], const char *s2 [r4])
|
|
|
|
The implementation uses unaligned doubleword access to avoid specialized
|
|
code paths depending of data alignment. Although recent powerpc64 uses
|
|
64K as default, the page cross handling assumes minimum page size of
|
|
4k. */
|
|
|
|
.machine power8
|
|
ENTRY_TOCLESS (STRCMP, 4)
|
|
li r0,0
|
|
|
|
/* Check if [s1]+16 or [s2]+16 will cross a 4K page boundary using
|
|
the code:
|
|
|
|
(((size_t) s1) % PAGE_SIZE > (PAGE_SIZE - ITER_SIZE))
|
|
|
|
with PAGE_SIZE being 4096 and ITER_SIZE begin 16. */
|
|
|
|
rldicl r7,r3,0,52
|
|
rldicl r9,r4,0,52
|
|
cmpldi cr7,r7,4096-16
|
|
bgt cr7,L(pagecross_check)
|
|
cmpldi cr5,r9,4096-16
|
|
bgt cr5,L(pagecross_check)
|
|
|
|
/* For short string up to 16 bytes, load both s1 and s2 using
|
|
unaligned dwords and compare. */
|
|
ld r8,0(r3)
|
|
ld r10,0(r4)
|
|
cmpb r12,r8,r0
|
|
cmpb r11,r8,r10
|
|
orc. r9,r12,r11
|
|
bne cr0,L(different_nocmpb)
|
|
|
|
ld r8,8(r3)
|
|
ld r10,8(r4)
|
|
cmpb r12,r8,r0
|
|
cmpb r11,r8,r10
|
|
orc. r9,r12,r11
|
|
bne cr0,L(different_nocmpb)
|
|
|
|
addi r7,r3,16
|
|
addi r4,r4,16
|
|
|
|
L(align_8b):
|
|
/* Now it has checked for first 16 bytes, align source1 to doubleword
|
|
and adjust source2 address. */
|
|
rldicl r9,r7,0,61 /* source1 alignment to doubleword */
|
|
subf r4,r9,r4 /* Adjust source2 address based on source1
|
|
alignment. */
|
|
rldicr r7,r7,0,60 /* Align source1 to doubleword. */
|
|
|
|
/* At this point, source1 alignment is 0 and source2 alignment is
|
|
between 0 and 7. Check is source2 alignment is 0, meaning both
|
|
sources have the same alignment. */
|
|
andi. r9,r4,0x7
|
|
bne cr0,L(loop_diff_align)
|
|
|
|
/* If both source1 and source2 are doubleword aligned, there is no
|
|
need for page boundary cross checks. */
|
|
|
|
ld r8,0(r7)
|
|
ld r10,0(r4)
|
|
cmpb r12,r8,r0
|
|
cmpb r11,r8,r10
|
|
orc. r9,r12,r11
|
|
bne cr0,L(different_nocmpb)
|
|
|
|
.align 4
|
|
L(loop_equal_align):
|
|
ld r8,8(r7)
|
|
ld r10,8(r4)
|
|
cmpb r12,r8,r0
|
|
cmpb r11,r8,r10
|
|
orc. r9,r12,r11
|
|
bne cr0,L(different_nocmpb)
|
|
|
|
ld r8,16(r7)
|
|
ld r10,16(r4)
|
|
cmpb r12,r8,r0
|
|
cmpb r11,r8,r10
|
|
orc. r9,r12,r11
|
|
bne cr0,L(different_nocmpb)
|
|
|
|
ldu r8,24(r7)
|
|
ldu r10,24(r4)
|
|
cmpb r12,r8,r0
|
|
cmpb r11,r8,r10
|
|
orc. r9,r12,r11
|
|
bne cr0,L(different_nocmpb)
|
|
|
|
b L(loop_equal_align)
|
|
|
|
/* A zero byte was found in r8 (s1 dword), r9 contains the cmpb
|
|
result and r10 the dword from s2. To code isolate the byte
|
|
up to end (including the '\0'), masking with 0xFF the remaining
|
|
ones:
|
|
|
|
#if __LITTLE_ENDIAN__
|
|
(__builtin_ffsl (x) - 1) = counting trailing zero bits
|
|
r9 = (__builtin_ffsl (r9) - 1) + 8;
|
|
r9 = -1UL << r9
|
|
#else
|
|
r9 = __builtin_clzl (r9) + 8;
|
|
r9 = -1UL >> r9
|
|
#endif
|
|
r8 = r8 | r9
|
|
r10 = r10 | r9 */
|
|
|
|
#ifdef __LITTLE_ENDIAN__
|
|
nor r9,r9,r9
|
|
L(different_nocmpb):
|
|
neg r3,r9
|
|
and r9,r9,r3
|
|
cntlzd r9,r9
|
|
subfic r9,r9,63
|
|
#else
|
|
not r9,r9
|
|
L(different_nocmpb):
|
|
cntlzd r9,r9
|
|
subfic r9,r9,56
|
|
#endif
|
|
srd r3,r8,r9
|
|
srd r10,r10,r9
|
|
rldicl r10,r10,0,56
|
|
rldicl r3,r3,0,56
|
|
subf r3,r10,r3
|
|
extsw r3,r3
|
|
blr
|
|
|
|
.align 4
|
|
L(pagecross_check):
|
|
subfic r9,r9,4096
|
|
subfic r7,r7,4096
|
|
cmpld cr7,r7,r9
|
|
bge cr7,L(pagecross)
|
|
mr r7,r9
|
|
|
|
/* If unaligned 16 bytes reads across a 4K page boundary, it uses
|
|
a simple byte a byte comparison until the page alignment for s1
|
|
is reached. */
|
|
L(pagecross):
|
|
add r7,r3,r7
|
|
subf r9,r3,r7
|
|
mtctr r9
|
|
|
|
.align 4
|
|
L(pagecross_loop):
|
|
/* Loads a byte from s1 and s2, compare if *s1 is equal to *s2
|
|
and if *s1 is '\0'. */
|
|
lbz r9,0(r3)
|
|
lbz r10,0(r4)
|
|
addi r3,r3,1
|
|
addi r4,r4,1
|
|
cmplw cr7,r9,r10
|
|
cmpdi cr5,r9,r0
|
|
bne cr7,L(pagecross_ne)
|
|
beq cr5,L(pagecross_nullfound)
|
|
bdnz L(pagecross_loop)
|
|
b L(align_8b)
|
|
|
|
.align 4
|
|
/* The unaligned read of source2 will cross a 4K page boundary,
|
|
and the different byte or NULL maybe be in the remaining page
|
|
bytes. Since it can not use the unaligned load, the algorithm
|
|
reads and compares 8 bytes to keep source1 doubleword aligned. */
|
|
L(check_source2_byte):
|
|
li r9,8
|
|
mtctr r9
|
|
|
|
.align 4
|
|
L(check_source2_byte_loop):
|
|
lbz r9,0(r7)
|
|
lbz r10,0(r4)
|
|
addi r7,r7,1
|
|
addi r4,r4,1
|
|
cmplw cr7,r9,10
|
|
cmpdi r5,r9,0
|
|
bne cr7,L(pagecross_ne)
|
|
beq cr5,L(pagecross_nullfound)
|
|
bdnz L(check_source2_byte_loop)
|
|
|
|
/* If source2 is unaligned to doubleword, the code needs to check
|
|
on each interation if the unaligned doubleword access will cross
|
|
a 4k page boundary. */
|
|
.align 5
|
|
L(loop_unaligned):
|
|
ld r8,0(r7)
|
|
ld r10,0(r4)
|
|
cmpb r12,r8,r0
|
|
cmpb r11,r8,r10
|
|
orc. r9,r12,r11
|
|
bne cr0,L(different_nocmpb)
|
|
addi r7,r7,8
|
|
addi r4,r4,8
|
|
|
|
L(loop_diff_align):
|
|
/* Check if [src2]+8 cross a 4k page boundary:
|
|
|
|
srcin2 % PAGE_SIZE > (PAGE_SIZE - 8)
|
|
|
|
with PAGE_SIZE being 4096. */
|
|
rldicl r9,r4,0,52
|
|
cmpldi cr7,r9,4088
|
|
ble cr7,L(loop_unaligned)
|
|
b L(check_source2_byte)
|
|
|
|
.align 4
|
|
L(pagecross_ne):
|
|
extsw r3,r9
|
|
mr r9,r10
|
|
L(pagecross_retdiff):
|
|
subf r9,r9,r3
|
|
extsw r3,r9
|
|
blr
|
|
|
|
.align 4
|
|
L(pagecross_nullfound):
|
|
li r3,0
|
|
b L(pagecross_retdiff)
|
|
END (STRCMP)
|
|
libc_hidden_builtin_def (strcmp)
|