145 lines
4.6 KiB
Diff
145 lines
4.6 KiB
Diff
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commit 3ec7d8a6b30659b34693730a374c0265a191c4ba
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Author: Kyle McMartin <kyle@mcmartin.ca>
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Date: Wed Dec 3 12:26:23 2014 -0500
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Revert "[AArch64] Add optimized strchrnul."
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This reverts commit be9d4ccc7fe62751db1a5fdcb31958561dbbda9a.
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diff --git a/sysdeps/aarch64/strchrnul.S b/sysdeps/aarch64/strchrnul.S
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deleted file mode 100644
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index b98c2e9..0000000
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--- a/sysdeps/aarch64/strchrnul.S
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+++ /dev/null
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@@ -1,130 +0,0 @@
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-/* strchrnul - find a character or nul in a string
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-
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- Copyright (C) 2014 Free Software Foundation, Inc.
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-
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- This file is part of the GNU C Library.
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-
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- The GNU C Library is free software; you can redistribute it and/or
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- modify it under the terms of the GNU Lesser General Public
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- License as published by the Free Software Foundation; either
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- version 2.1 of the License, or (at your option) any later version.
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-
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- The GNU C Library is distributed in the hope that it will be useful,
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- but WITHOUT ANY WARRANTY; without even the implied warranty of
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- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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- Lesser General Public License for more details.
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-
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- You should have received a copy of the GNU Lesser General Public
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- License along with the GNU C Library. If not, see
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- <http://www.gnu.org/licenses/>. */
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-
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-#include <sysdep.h>
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-
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-/* Assumptions:
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- *
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- * ARMv8-a, AArch64
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- * Neon Available.
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- */
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-
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-/* Arguments and results. */
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-#define srcin x0
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-#define chrin w1
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-
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-#define result x0
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-
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-/* Locals and temporaries. */
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-
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-#define src x2
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-#define tmp1 x3
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-#define wtmp2 w4
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-#define tmp3 x5
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-
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-#define vrepchr v0
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-#define vdata1 v1
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-#define vdata2 v2
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-#define vhas_nul1 v3
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-#define vhas_nul2 v4
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-#define vhas_chr1 v5
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-#define vhas_chr2 v6
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-#define vrepmask v15
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-#define vend1 v16
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-
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-/* Core algorithm.
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-
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- For each 32-byte hunk we calculate a 64-bit syndrome value, with
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- two bits per byte (LSB is always in bits 0 and 1, for both big
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- and little-endian systems). For each tuple, bit 0 is set iff
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- the relevant byte matched the requested character or nul. Since the
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- bits in the syndrome reflect exactly the order in which things occur
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- in the original string a count_trailing_zeros() operation will
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- identify exactly which byte is causing the termination. */
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-
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-ENTRY (__strchrnul)
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- /* Magic constant 0x40100401 to allow us to identify which lane
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- matches the termination condition. */
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- mov wtmp2, #0x0401
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- movk wtmp2, #0x4010, lsl #16
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- dup vrepchr.16b, chrin
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- bic src, srcin, #31 /* Work with aligned 32-byte hunks. */
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- dup vrepmask.4s, wtmp2
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- ands tmp1, srcin, #31
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- b.eq L(loop)
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-
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- /* Input string is not 32-byte aligned. Rather than forcing
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- the padding bytes to a safe value, we calculate the syndrome
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- for all the bytes, but then mask off those bits of the
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- syndrome that are related to the padding. */
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- ld1 {vdata1.16b, vdata2.16b}, [src], #32
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- neg tmp1, tmp1
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- cmeq vhas_nul1.16b, vdata1.16b, #0
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- cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b
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- cmeq vhas_nul2.16b, vdata2.16b, #0
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- cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b
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- orr vhas_chr1.16b, vhas_chr1.16b, vhas_nul1.16b
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- orr vhas_chr2.16b, vhas_chr2.16b, vhas_nul2.16b
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- and vhas_chr1.16b, vhas_chr1.16b, vrepmask.16b
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- and vhas_chr2.16b, vhas_chr2.16b, vrepmask.16b
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- lsl tmp1, tmp1, #1
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- addp vend1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128
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- mov tmp3, #~0
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- addp vend1.16b, vend1.16b, vend1.16b // 128->64
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- lsr tmp1, tmp3, tmp1
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-
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- mov tmp3, vend1.2d[0]
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- bic tmp1, tmp3, tmp1 // Mask padding bits.
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- cbnz tmp1, L(tail)
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-
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-L(loop):
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- ld1 {vdata1.16b, vdata2.16b}, [src], #32
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- cmeq vhas_nul1.16b, vdata1.16b, #0
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- cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b
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- cmeq vhas_nul2.16b, vdata2.16b, #0
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- cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b
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- /* Use a fast check for the termination condition. */
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- orr vhas_chr1.16b, vhas_nul1.16b, vhas_chr1.16b
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- orr vhas_chr2.16b, vhas_nul2.16b, vhas_chr2.16b
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- orr vend1.16b, vhas_chr1.16b, vhas_chr2.16b
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- addp vend1.2d, vend1.2d, vend1.2d
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- mov tmp1, vend1.2d[0]
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- cbz tmp1, L(loop)
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-
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- /* Termination condition found. Now need to establish exactly why
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- we terminated. */
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- and vhas_chr1.16b, vhas_chr1.16b, vrepmask.16b
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- and vhas_chr2.16b, vhas_chr2.16b, vrepmask.16b
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- addp vend1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128
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- addp vend1.16b, vend1.16b, vend1.16b // 128->64
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-
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- mov tmp1, vend1.2d[0]
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-L(tail):
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- /* Count the trailing zeros, by bit reversing... */
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- rbit tmp1, tmp1
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- /* Re-bias source. */
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- sub src, src, #32
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- clz tmp1, tmp1 /* ... and counting the leading zeros. */
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- /* tmp1 is twice the offset into the fragment. */
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- add result, src, tmp1, lsr #1
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- ret
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-
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-END(__strchrnul)
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-weak_alias (__strchrnul, strchrnul)
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