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Diffstat (limited to 'contrib/arm-optimized-routines/string/aarch64/strncmp-mte.S')
| -rw-r--r-- | contrib/arm-optimized-routines/string/aarch64/strncmp-mte.S | 307 |
1 files changed, 0 insertions, 307 deletions
diff --git a/contrib/arm-optimized-routines/string/aarch64/strncmp-mte.S b/contrib/arm-optimized-routines/string/aarch64/strncmp-mte.S deleted file mode 100644 index c9d6fc8a158b..000000000000 --- a/contrib/arm-optimized-routines/string/aarch64/strncmp-mte.S +++ /dev/null @@ -1,307 +0,0 @@ -/* - * strncmp - compare two strings - * - * Copyright (c) 2013-2021, Arm Limited. - * SPDX-License-Identifier: MIT - */ - -/* Assumptions: - * - * ARMv8-a, AArch64 - */ - -#include "../asmdefs.h" - -#define REP8_01 0x0101010101010101 -#define REP8_7f 0x7f7f7f7f7f7f7f7f - -/* Parameters and result. */ -#define src1 x0 -#define src2 x1 -#define limit x2 -#define result x0 - -/* Internal variables. */ -#define data1 x3 -#define data1w w3 -#define data2 x4 -#define data2w w4 -#define has_nul x5 -#define diff x6 -#define syndrome x7 -#define tmp1 x8 -#define tmp2 x9 -#define tmp3 x10 -#define zeroones x11 -#define pos x12 -#define mask x13 -#define endloop x14 -#define count mask -#define offset pos -#define neg_offset x15 - -/* Define endian dependent shift operations. - On big-endian early bytes are at MSB and on little-endian LSB. - LS_FW means shifting towards early bytes. - LS_BK means shifting towards later bytes. - */ -#ifdef __AARCH64EB__ -#define LS_FW lsl -#define LS_BK lsr -#else -#define LS_FW lsr -#define LS_BK lsl -#endif - -ENTRY (__strncmp_aarch64_mte) - PTR_ARG (0) - PTR_ARG (1) - SIZE_ARG (2) - cbz limit, L(ret0) - eor tmp1, src1, src2 - mov zeroones, #REP8_01 - tst tmp1, #7 - and count, src1, #7 - b.ne L(misaligned8) - cbnz count, L(mutual_align) - - /* NUL detection works on the principle that (X - 1) & (~X) & 0x80 - (=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and - can be done in parallel across the entire word. */ - .p2align 4 -L(loop_aligned): - ldr data1, [src1], #8 - ldr data2, [src2], #8 -L(start_realigned): - subs limit, limit, #8 - sub tmp1, data1, zeroones - orr tmp2, data1, #REP8_7f - eor diff, data1, data2 /* Non-zero if differences found. */ - csinv endloop, diff, xzr, hi /* Last Dword or differences. */ - bics has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */ - ccmp endloop, #0, #0, eq - b.eq L(loop_aligned) - /* End of main loop */ - -L(full_check): -#ifndef __AARCH64EB__ - orr syndrome, diff, has_nul - add limit, limit, 8 /* Rewind limit to before last subs. */ -L(syndrome_check): - /* Limit was reached. Check if the NUL byte or the difference - is before the limit. */ - rev syndrome, syndrome - rev data1, data1 - clz pos, syndrome - rev data2, data2 - lsl data1, data1, pos - cmp limit, pos, lsr #3 - lsl data2, data2, pos - /* But we need to zero-extend (char is unsigned) the value and then - perform a signed 32-bit subtraction. */ - lsr data1, data1, #56 - sub result, data1, data2, lsr #56 - csel result, result, xzr, hi - ret -#else - /* Not reached the limit, must have found the end or a diff. */ - tbz limit, #63, L(not_limit) - add tmp1, limit, 8 - cbz limit, L(not_limit) - - lsl limit, tmp1, #3 /* Bits -> bytes. */ - mov mask, #~0 - lsr mask, mask, limit - bic data1, data1, mask - bic data2, data2, mask - - /* Make sure that the NUL byte is marked in the syndrome. */ - orr has_nul, has_nul, mask - -L(not_limit): - /* For big-endian we cannot use the trick with the syndrome value - as carry-propagation can corrupt the upper bits if the trailing - bytes in the string contain 0x01. */ - /* However, if there is no NUL byte in the dword, we can generate - the result directly. We can't just subtract the bytes as the - MSB might be significant. */ - cbnz has_nul, 1f - cmp data1, data2 - cset result, ne - cneg result, result, lo - ret -1: - /* Re-compute the NUL-byte detection, using a byte-reversed value. */ - rev tmp3, data1 - sub tmp1, tmp3, zeroones - orr tmp2, tmp3, #REP8_7f - bic has_nul, tmp1, tmp2 - rev has_nul, has_nul - orr syndrome, diff, has_nul - clz pos, syndrome - /* The most-significant-non-zero bit of the syndrome marks either the - first bit that is different, or the top bit of the first zero byte. - Shifting left now will bring the critical information into the - top bits. */ -L(end_quick): - lsl data1, data1, pos - lsl data2, data2, pos - /* But we need to zero-extend (char is unsigned) the value and then - perform a signed 32-bit subtraction. */ - lsr data1, data1, #56 - sub result, data1, data2, lsr #56 - ret -#endif - -L(mutual_align): - /* Sources are mutually aligned, but are not currently at an - alignment boundary. Round down the addresses and then mask off - the bytes that precede the start point. - We also need to adjust the limit calculations, but without - overflowing if the limit is near ULONG_MAX. */ - bic src1, src1, #7 - bic src2, src2, #7 - ldr data1, [src1], #8 - neg tmp3, count, lsl #3 /* 64 - bits(bytes beyond align). */ - ldr data2, [src2], #8 - mov tmp2, #~0 - LS_FW tmp2, tmp2, tmp3 /* Shift (count & 63). */ - /* Adjust the limit and ensure it doesn't overflow. */ - adds limit, limit, count - csinv limit, limit, xzr, lo - orr data1, data1, tmp2 - orr data2, data2, tmp2 - b L(start_realigned) - - .p2align 4 - /* Don't bother with dwords for up to 16 bytes. */ -L(misaligned8): - cmp limit, #16 - b.hs L(try_misaligned_words) - -L(byte_loop): - /* Perhaps we can do better than this. */ - ldrb data1w, [src1], #1 - ldrb data2w, [src2], #1 - subs limit, limit, #1 - ccmp data1w, #1, #0, hi /* NZCV = 0b0000. */ - ccmp data1w, data2w, #0, cs /* NZCV = 0b0000. */ - b.eq L(byte_loop) -L(done): - sub result, data1, data2 - ret - /* Align the SRC1 to a dword by doing a bytewise compare and then do - the dword loop. */ -L(try_misaligned_words): - cbz count, L(src1_aligned) - - neg count, count - and count, count, #7 - sub limit, limit, count - -L(page_end_loop): - ldrb data1w, [src1], #1 - ldrb data2w, [src2], #1 - cmp data1w, #1 - ccmp data1w, data2w, #0, cs /* NZCV = 0b0000. */ - b.ne L(done) - subs count, count, #1 - b.hi L(page_end_loop) - - /* The following diagram explains the comparison of misaligned strings. - The bytes are shown in natural order. For little-endian, it is - reversed in the registers. The "x" bytes are before the string. - The "|" separates data that is loaded at one time. - src1 | a a a a a a a a | b b b c c c c c | . . . - src2 | x x x x x a a a a a a a a b b b | c c c c c . . . - - After shifting in each step, the data looks like this: - STEP_A STEP_B STEP_C - data1 a a a a a a a a b b b c c c c c b b b c c c c c - data2 a a a a a a a a b b b 0 0 0 0 0 0 0 0 c c c c c - - The bytes with "0" are eliminated from the syndrome via mask. - - Align SRC2 down to 16 bytes. This way we can read 16 bytes at a - time from SRC2. The comparison happens in 3 steps. After each step - the loop can exit, or read from SRC1 or SRC2. */ -L(src1_aligned): - /* Calculate offset from 8 byte alignment to string start in bits. No - need to mask offset since shifts are ignoring upper bits. */ - lsl offset, src2, #3 - bic src2, src2, #0xf - mov mask, -1 - neg neg_offset, offset - ldr data1, [src1], #8 - ldp tmp1, tmp2, [src2], #16 - LS_BK mask, mask, neg_offset - and neg_offset, neg_offset, #63 /* Need actual value for cmp later. */ - /* Skip the first compare if data in tmp1 is irrelevant. */ - tbnz offset, 6, L(misaligned_mid_loop) - -L(loop_misaligned): - /* STEP_A: Compare full 8 bytes when there is enough data from SRC2.*/ - LS_FW data2, tmp1, offset - LS_BK tmp1, tmp2, neg_offset - subs limit, limit, #8 - orr data2, data2, tmp1 /* 8 bytes from SRC2 combined from two regs.*/ - sub has_nul, data1, zeroones - eor diff, data1, data2 /* Non-zero if differences found. */ - orr tmp3, data1, #REP8_7f - csinv endloop, diff, xzr, hi /* If limit, set to all ones. */ - bic has_nul, has_nul, tmp3 /* Non-zero if NUL byte found in SRC1. */ - orr tmp3, endloop, has_nul - cbnz tmp3, L(full_check) - - ldr data1, [src1], #8 -L(misaligned_mid_loop): - /* STEP_B: Compare first part of data1 to second part of tmp2. */ - LS_FW data2, tmp2, offset -#ifdef __AARCH64EB__ - /* For big-endian we do a byte reverse to avoid carry-propagation - problem described above. This way we can reuse the has_nul in the - next step and also use syndrome value trick at the end. */ - rev tmp3, data1 - #define data1_fixed tmp3 -#else - #define data1_fixed data1 -#endif - sub has_nul, data1_fixed, zeroones - orr tmp3, data1_fixed, #REP8_7f - eor diff, data2, data1 /* Non-zero if differences found. */ - bic has_nul, has_nul, tmp3 /* Non-zero if NUL terminator. */ -#ifdef __AARCH64EB__ - rev has_nul, has_nul -#endif - cmp limit, neg_offset, lsr #3 - orr syndrome, diff, has_nul - bic syndrome, syndrome, mask /* Ignore later bytes. */ - csinv tmp3, syndrome, xzr, hi /* If limit, set to all ones. */ - cbnz tmp3, L(syndrome_check) - - /* STEP_C: Compare second part of data1 to first part of tmp1. */ - ldp tmp1, tmp2, [src2], #16 - cmp limit, #8 - LS_BK data2, tmp1, neg_offset - eor diff, data2, data1 /* Non-zero if differences found. */ - orr syndrome, diff, has_nul - and syndrome, syndrome, mask /* Ignore earlier bytes. */ - csinv tmp3, syndrome, xzr, hi /* If limit, set to all ones. */ - cbnz tmp3, L(syndrome_check) - - ldr data1, [src1], #8 - sub limit, limit, #8 - b L(loop_misaligned) - -#ifdef __AARCH64EB__ -L(syndrome_check): - clz pos, syndrome - cmp pos, limit, lsl #3 - b.lo L(end_quick) -#endif - -L(ret0): - mov result, #0 - ret -END(__strncmp_aarch64_mte) - |