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| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | NEWS | 5 | ||||
| -rw-r--r-- | sysdeps/aarch64/strrchr.S | 165 |
3 files changed, 173 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog index 604ce52ec3..212569b1c3 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2015-01-07 Richard Earnshaw <rearnsha@arm.com> + + * sysdeps/aarch64/strrchr.S: New file. + * NEWS: Updated. + 2015-01-07 Eric Biggers <ebiggers3@gmail.com> [BZ #17658] diff --git a/NEWS b/NEWS index bec70dc04c..a233cf9bb8 100644 --- a/NEWS +++ b/NEWS @@ -19,6 +19,9 @@ Version 2.21 17744, 17745, 17746, 17747, 17775, 17777, 17780, 17781, 17782, 17793, 17796, 17797, 17806 +* Optimized strchrnul and strrchr implementations for AArch64. + Contributed by ARM Ltd. + * i386 memcpy functions optimized with SSE2 unaligned load/store. * CVE-2104-7817 The wordexp function could ignore the WRDE_NOCMD flag @@ -71,8 +74,6 @@ Version 2.20 17084, 17086, 17088, 17092, 17097, 17125, 17135, 17137, 17150, 17153, 17187, 17213, 17259, 17261, 17262, 17263, 17319, 17325, 17354. -* Optimized strchrnul implementation for AArch64. Contributed by ARM Ltd. - * Reverted change of ABI data structures for s390 and s390x: On s390 and s390x the size of struct ucontext and jmp_buf was increased in 2.19. This change is reverted in 2.20. The introduced 2.19 symbol versions diff --git a/sysdeps/aarch64/strrchr.S b/sysdeps/aarch64/strrchr.S new file mode 100644 index 0000000000..b49e81dd19 --- /dev/null +++ b/sysdeps/aarch64/strrchr.S @@ -0,0 +1,165 @@ +/* strrchr: find the last instance of a character in a string. + + Copyright (C) 2014-2015 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 + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + +/* Assumptions: + * + * ARMv8-a, AArch64 + * Neon Available. + */ + +/* Arguments and results. */ +#define srcin x0 +#define chrin w1 + +#define result x0 + +#define src x2 +#define tmp1 x3 +#define wtmp2 w4 +#define tmp3 x5 +#define src_match x6 +#define src_offset x7 +#define const_m1 x8 +#define tmp4 x9 +#define nul_match x10 +#define chr_match x11 + +#define vrepchr v0 +#define vdata1 v1 +#define vdata2 v2 +#define vhas_nul1 v3 +#define vhas_nul2 v4 +#define vhas_chr1 v5 +#define vhas_chr2 v6 +#define vrepmask_0 v7 +#define vrepmask_c v16 +#define vend1 v17 +#define vend2 v18 + +/* Core algorithm. + + For each 32-byte hunk we calculate a 64-bit syndrome value, with + two bits per byte (LSB is always in bits 0 and 1, for both big + and little-endian systems). For each tuple, bit 0 is set iff + the relevant byte matched the requested character; bit 1 is set + iff the relevant byte matched the NUL end of string (we trigger + off bit0 for the special case of looking for NUL). Since the bits + in the syndrome reflect exactly the order in which things occur + in the original string a count_trailing_zeros() operation will + identify exactly which byte is causing the termination, and why. */ + +ENTRY(strrchr) + cbz x1, L(null_search) + /* Magic constant 0x40100401 to allow us to identify which lane + matches the requested byte. Magic constant 0x80200802 used + similarly for NUL termination. */ + mov wtmp2, #0x0401 + movk wtmp2, #0x4010, lsl #16 + dup vrepchr.16b, chrin + bic src, srcin, #31 /* Work with aligned 32-byte hunks. */ + dup vrepmask_c.4s, wtmp2 + mov src_offset, #0 + ands tmp1, srcin, #31 + add vrepmask_0.4s, vrepmask_c.4s, vrepmask_c.4s /* equiv: lsl #1 */ + b.eq L(aligned) + + /* Input string is not 32-byte aligned. Rather than forcing + the padding bytes to a safe value, we calculate the syndrome + for all the bytes, but then mask off those bits of the + syndrome that are related to the padding. */ + ld1 {vdata1.16b, vdata2.16b}, [src], #32 + neg tmp1, tmp1 + cmeq vhas_nul1.16b, vdata1.16b, #0 + cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b + cmeq vhas_nul2.16b, vdata2.16b, #0 + cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b + and vhas_nul1.16b, vhas_nul1.16b, vrepmask_0.16b + and vhas_chr1.16b, vhas_chr1.16b, vrepmask_c.16b + and vhas_nul2.16b, vhas_nul2.16b, vrepmask_0.16b + and vhas_chr2.16b, vhas_chr2.16b, vrepmask_c.16b + addp vhas_nul1.16b, vhas_nul1.16b, vhas_nul2.16b // 256->128 + addp vhas_chr1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128 + addp vhas_nul1.16b, vhas_nul1.16b, vhas_nul1.16b // 128->64 + addp vhas_chr1.16b, vhas_chr1.16b, vhas_chr1.16b // 128->64 + mov nul_match, vhas_nul1.2d[0] + lsl tmp1, tmp1, #1 + mov const_m1, #~0 + mov chr_match, vhas_chr1.2d[0] + lsr tmp3, const_m1, tmp1 + + bic nul_match, nul_match, tmp3 // Mask padding bits. + bic chr_match, chr_match, tmp3 // Mask padding bits. + cbnz nul_match, L(tail) + +L(loop): + cmp chr_match, #0 + csel src_match, src, src_match, ne + csel src_offset, chr_match, src_offset, ne +L(aligned): + ld1 {vdata1.16b, vdata2.16b}, [src], #32 + cmeq vhas_nul1.16b, vdata1.16b, #0 + cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b + cmeq vhas_nul2.16b, vdata2.16b, #0 + cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b + addp vend1.16b, vhas_nul1.16b, vhas_nul2.16b // 256->128 + and vhas_chr1.16b, vhas_chr1.16b, vrepmask_c.16b + and vhas_chr2.16b, vhas_chr2.16b, vrepmask_c.16b + addp vhas_chr1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128 + addp vend1.16b, vend1.16b, vend1.16b // 128->64 + addp vhas_chr1.16b, vhas_chr1.16b, vhas_chr1.16b // 128->64 + mov nul_match, vend1.2d[0] + mov chr_match, vhas_chr1.2d[0] + cbz nul_match, L(loop) + + and vhas_nul1.16b, vhas_nul1.16b, vrepmask_0.16b + and vhas_nul2.16b, vhas_nul2.16b, vrepmask_0.16b + addp vhas_nul1.16b, vhas_nul1.16b, vhas_nul2.16b + addp vhas_nul1.16b, vhas_nul1.16b, vhas_nul1.16b + mov nul_match, vhas_nul1.2d[0] + +L(tail): + /* Work out exactly where the string ends. */ + sub tmp4, nul_match, #1 + eor tmp4, tmp4, nul_match + ands chr_match, chr_match, tmp4 + /* And pick the values corresponding to the last match. */ + csel src_match, src, src_match, ne + csel src_offset, chr_match, src_offset, ne + + /* Count down from the top of the syndrome to find the last match. */ + clz tmp3, src_offset + /* Src_match points beyond the word containing the match, so we can + simply subtract half the bit-offset into the syndrome. Because + we are counting down, we need to go back one more character. */ + add tmp3, tmp3, #2 + sub result, src_match, tmp3, lsr #1 + /* But if the syndrome shows no match was found, then return NULL. */ + cmp src_offset, #0 + csel result, result, xzr, ne + + ret +L(null_search): + b __strchrnul + +END(strrchr) +weak_alias (strrchr, rindex) +libc_hidden_builtin_def (strrchr) |