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Diffstat (limited to 'sysdeps/arm/armv7/strcmp.S')
| -rw-r--r-- | sysdeps/arm/armv7/strcmp.S | 519 |
1 files changed, 0 insertions, 519 deletions
diff --git a/sysdeps/arm/armv7/strcmp.S b/sysdeps/arm/armv7/strcmp.S deleted file mode 100644 index 25d055754e..0000000000 --- a/sysdeps/arm/armv7/strcmp.S +++ /dev/null @@ -1,519 +0,0 @@ -/* strcmp implementation for ARMv7-A, optimized for Cortex-A15. - Copyright (C) 2012-2017 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 <arm-features.h> -#include <sysdep.h> - -/* Implementation of strcmp for ARMv7 when DSP instructions are - available. Use ldrd to support wider loads, provided the data - is sufficiently aligned. Use saturating arithmetic to optimize - the compares. */ - -/* Build Options: - STRCMP_PRECHECK: Run a quick pre-check of the first byte in the - string. If comparing completely random strings the pre-check will - save time, since there is a very high probability of a mismatch in - the first character: we save significant overhead if this is the - common case. However, if strings are likely to be identical (e.g. - because we're verifying a hit in a hash table), then this check - is largely redundant. */ - -#define STRCMP_PRECHECK 1 - - .syntax unified - -#ifdef __ARM_BIG_ENDIAN -# define S2LO lsl -# define S2LOEQ lsleq -# define S2HI lsr -# define MSB 0x000000ff -# define LSB 0xff000000 -# define BYTE0_OFFSET 24 -# define BYTE1_OFFSET 16 -# define BYTE2_OFFSET 8 -# define BYTE3_OFFSET 0 -#else /* not __ARM_BIG_ENDIAN */ -# define S2LO lsr -# define S2LOEQ lsreq -# define S2HI lsl -# define BYTE0_OFFSET 0 -# define BYTE1_OFFSET 8 -# define BYTE2_OFFSET 16 -# define BYTE3_OFFSET 24 -# define MSB 0xff000000 -# define LSB 0x000000ff -#endif /* not __ARM_BIG_ENDIAN */ - -/* Parameters and result. */ -#define src1 r0 -#define src2 r1 -#define result r0 /* Overlaps src1. */ - -/* Internal variables. */ -#define tmp1 r4 -#define tmp2 r5 -#define const_m1 r12 - -/* Additional internal variables for 64-bit aligned data. */ -#define data1a r2 -#define data1b r3 -#define data2a r6 -#define data2b r7 -#define syndrome_a tmp1 -#define syndrome_b tmp2 - -/* Additional internal variables for 32-bit aligned data. */ -#define data1 r2 -#define data2 r3 -#define syndrome tmp2 - - -#ifndef NO_THUMB -/* This code is best on Thumb. */ - .thumb - -/* In Thumb code we can't use MVN with a register shift, but we do have ORN. */ -.macro prepare_mask mask_reg, nbits_reg - S2HI \mask_reg, const_m1, \nbits_reg -.endm -.macro apply_mask data_reg, mask_reg - orn \data_reg, \data_reg, \mask_reg -.endm -#else -/* In ARM code we don't have ORN, but we can use MVN with a register shift. */ -.macro prepare_mask mask_reg, nbits_reg - mvn \mask_reg, const_m1, S2HI \nbits_reg -.endm -.macro apply_mask data_reg, mask_reg - orr \data_reg, \data_reg, \mask_reg -.endm - -/* These clobber the condition codes, which the real Thumb cbz/cbnz - instructions do not. But it doesn't matter for any of the uses here. */ -.macro cbz reg, label - cmp \reg, #0 - beq \label -.endm -.macro cbnz reg, label - cmp \reg, #0 - bne \label -.endm -#endif - - - /* Macro to compute and return the result value for word-aligned - cases. */ - .macro strcmp_epilogue_aligned synd d1 d2 restore_r6 -#ifdef __ARM_BIG_ENDIAN - /* If data1 contains a zero byte, then syndrome will contain a 1 in - bit 7 of that byte. Otherwise, the highest set bit in the - syndrome will highlight the first different bit. It is therefore - sufficient to extract the eight bits starting with the syndrome - bit. */ - clz tmp1, \synd - lsl r1, \d2, tmp1 - .if \restore_r6 - ldrd r6, r7, [sp, #8] - .endif - lsl \d1, \d1, tmp1 - lsr result, \d1, #24 - ldrd r4, r5, [sp], #16 - cfi_remember_state - cfi_def_cfa_offset (0) - cfi_restore (r4) - cfi_restore (r5) - cfi_restore (r6) - cfi_restore (r7) - sub result, result, r1, lsr #24 - bx lr -#else - /* To use the big-endian trick we'd have to reverse all three words. - that's slower than this approach. */ - rev \synd, \synd - clz tmp1, \synd - bic tmp1, tmp1, #7 - lsr r1, \d2, tmp1 - .if \restore_r6 - ldrd r6, r7, [sp, #8] - .endif - lsr \d1, \d1, tmp1 - and result, \d1, #255 - and r1, r1, #255 - ldrd r4, r5, [sp], #16 - cfi_remember_state - cfi_def_cfa_offset (0) - cfi_restore (r4) - cfi_restore (r5) - cfi_restore (r6) - cfi_restore (r7) - sub result, result, r1 - - bx lr -#endif - .endm - - .text - .p2align 5 -.Lstrcmp_start_addr: -#if STRCMP_PRECHECK == 1 -.Lfastpath_exit: - sub r0, r2, r3 - bx lr - nop -#endif -ENTRY (strcmp) -#if STRCMP_PRECHECK == 1 - ldrb r2, [src1] - ldrb r3, [src2] - cmp r2, #1 - it cs - cmpcs r2, r3 - bne .Lfastpath_exit -#endif - strd r4, r5, [sp, #-16]! - cfi_def_cfa_offset (16) - cfi_offset (r4, -16) - cfi_offset (r5, -12) - orr tmp1, src1, src2 - strd r6, r7, [sp, #8] - cfi_offset (r6, -8) - cfi_offset (r7, -4) - mvn const_m1, #0 - lsl r2, tmp1, #29 - cbz r2, .Lloop_aligned8 - -.Lnot_aligned: - eor tmp1, src1, src2 - tst tmp1, #7 - bne .Lmisaligned8 - - /* Deal with mutual misalignment by aligning downwards and then - masking off the unwanted loaded data to prevent a difference. */ - and tmp1, src1, #7 - bic src1, src1, #7 - and tmp2, tmp1, #3 - bic src2, src2, #7 - lsl tmp2, tmp2, #3 /* Bytes -> bits. */ - ldrd data1a, data1b, [src1], #16 - tst tmp1, #4 - ldrd data2a, data2b, [src2], #16 - prepare_mask tmp1, tmp2 - apply_mask data1a, tmp1 - apply_mask data2a, tmp1 - beq .Lstart_realigned8 - apply_mask data1b, tmp1 - mov data1a, const_m1 - apply_mask data2b, tmp1 - mov data2a, const_m1 - b .Lstart_realigned8 - - /* Unwind the inner loop by a factor of 2, giving 16 bytes per - pass. */ - .p2align 5,,12 /* Don't start in the tail bytes of a cache line. */ - .p2align 2 /* Always word aligned. */ -.Lloop_aligned8: - ldrd data1a, data1b, [src1], #16 - ldrd data2a, data2b, [src2], #16 -.Lstart_realigned8: - uadd8 syndrome_b, data1a, const_m1 /* Only want GE bits, */ - eor syndrome_a, data1a, data2a - sel syndrome_a, syndrome_a, const_m1 - cbnz syndrome_a, .Ldiff_in_a - uadd8 syndrome_b, data1b, const_m1 /* Only want GE bits. */ - eor syndrome_b, data1b, data2b - sel syndrome_b, syndrome_b, const_m1 - cbnz syndrome_b, .Ldiff_in_b - - ldrd data1a, data1b, [src1, #-8] - ldrd data2a, data2b, [src2, #-8] - uadd8 syndrome_b, data1a, const_m1 /* Only want GE bits, */ - eor syndrome_a, data1a, data2a - sel syndrome_a, syndrome_a, const_m1 - uadd8 syndrome_b, data1b, const_m1 /* Only want GE bits. */ - eor syndrome_b, data1b, data2b - sel syndrome_b, syndrome_b, const_m1 - /* Can't use CBZ for backwards branch. */ - orrs syndrome_b, syndrome_b, syndrome_a /* Only need if s_a == 0 */ - beq .Lloop_aligned8 - -.Ldiff_found: - cbnz syndrome_a, .Ldiff_in_a - -.Ldiff_in_b: - strcmp_epilogue_aligned syndrome_b, data1b, data2b 1 - -.Ldiff_in_a: - cfi_restore_state - strcmp_epilogue_aligned syndrome_a, data1a, data2a 1 - - cfi_restore_state -.Lmisaligned8: - tst tmp1, #3 - bne .Lmisaligned4 - ands tmp1, src1, #3 - bne .Lmutual_align4 - - /* Unrolled by a factor of 2, to reduce the number of post-increment - operations. */ -.Lloop_aligned4: - ldr data1, [src1], #8 - ldr data2, [src2], #8 -.Lstart_realigned4: - uadd8 syndrome, data1, const_m1 /* Only need GE bits. */ - eor syndrome, data1, data2 - sel syndrome, syndrome, const_m1 - cbnz syndrome, .Laligned4_done - ldr data1, [src1, #-4] - ldr data2, [src2, #-4] - uadd8 syndrome, data1, const_m1 - eor syndrome, data1, data2 - sel syndrome, syndrome, const_m1 - cmp syndrome, #0 - beq .Lloop_aligned4 - -.Laligned4_done: - strcmp_epilogue_aligned syndrome, data1, data2, 0 - -.Lmutual_align4: - cfi_restore_state - /* Deal with mutual misalignment by aligning downwards and then - masking off the unwanted loaded data to prevent a difference. */ - lsl tmp1, tmp1, #3 /* Bytes -> bits. */ - bic src1, src1, #3 - ldr data1, [src1], #8 - bic src2, src2, #3 - ldr data2, [src2], #8 - - prepare_mask tmp1, tmp1 - apply_mask data1, tmp1 - apply_mask data2, tmp1 - b .Lstart_realigned4 - -.Lmisaligned4: - ands tmp1, src1, #3 - beq .Lsrc1_aligned - sub src2, src2, tmp1 - bic src1, src1, #3 - lsls tmp1, tmp1, #31 - ldr data1, [src1], #4 - beq .Laligned_m2 - bcs .Laligned_m1 - -#if STRCMP_PRECHECK == 0 - ldrb data2, [src2, #1] - uxtb tmp1, data1, ror #BYTE1_OFFSET - subs tmp1, tmp1, data2 - bne .Lmisaligned_exit - cbz data2, .Lmisaligned_exit - -.Laligned_m2: - ldrb data2, [src2, #2] - uxtb tmp1, data1, ror #BYTE2_OFFSET - subs tmp1, tmp1, data2 - bne .Lmisaligned_exit - cbz data2, .Lmisaligned_exit - -.Laligned_m1: - ldrb data2, [src2, #3] - uxtb tmp1, data1, ror #BYTE3_OFFSET - subs tmp1, tmp1, data2 - bne .Lmisaligned_exit - add src2, src2, #4 - cbnz data2, .Lsrc1_aligned -#else /* STRCMP_PRECHECK */ - /* If we've done the pre-check, then we don't need to check the - first byte again here. */ - ldrb data2, [src2, #2] - uxtb tmp1, data1, ror #BYTE2_OFFSET - subs tmp1, tmp1, data2 - bne .Lmisaligned_exit - cbz data2, .Lmisaligned_exit - -.Laligned_m2: - ldrb data2, [src2, #3] - uxtb tmp1, data1, ror #BYTE3_OFFSET - subs tmp1, tmp1, data2 - bne .Lmisaligned_exit - cbnz data2, .Laligned_m1 -#endif - -.Lmisaligned_exit: - mov result, tmp1 - ldr r4, [sp], #16 - cfi_remember_state - cfi_def_cfa_offset (0) - cfi_restore (r4) - cfi_restore (r5) - cfi_restore (r6) - cfi_restore (r7) - bx lr - -#if STRCMP_PRECHECK == 1 -.Laligned_m1: - add src2, src2, #4 -#endif -.Lsrc1_aligned: - cfi_restore_state - /* src1 is word aligned, but src2 has no common alignment - with it. */ - ldr data1, [src1], #4 - lsls tmp1, src2, #31 /* C=src2[1], Z=src2[0]. */ - - bic src2, src2, #3 - ldr data2, [src2], #4 - bhi .Loverlap1 /* C=1, Z=0 => src2[1:0] = 0b11. */ - bcs .Loverlap2 /* C=1, Z=1 => src2[1:0] = 0b10. */ - - /* (overlap3) C=0, Z=0 => src2[1:0] = 0b01. */ -.Loverlap3: - bic tmp1, data1, #MSB - uadd8 syndrome, data1, const_m1 - eors syndrome, tmp1, data2, S2LO #8 - sel syndrome, syndrome, const_m1 - bne 4f - cbnz syndrome, 5f - ldr data2, [src2], #4 - eor tmp1, tmp1, data1 - cmp tmp1, data2, S2HI #24 - bne 6f - ldr data1, [src1], #4 - b .Loverlap3 -4: - S2LO data2, data2, #8 - b .Lstrcmp_tail - -5: - bics syndrome, syndrome, #MSB - bne .Lstrcmp_done_equal - - /* We can only get here if the MSB of data1 contains 0, so - fast-path the exit. */ - ldrb result, [src2] - ldrd r4, r5, [sp], #16 - cfi_remember_state - cfi_def_cfa_offset (0) - cfi_restore (r4) - cfi_restore (r5) - /* R6/7 Not used in this sequence. */ - cfi_restore (r6) - cfi_restore (r7) - neg result, result - bx lr - -6: - cfi_restore_state - S2LO data1, data1, #24 - and data2, data2, #LSB - b .Lstrcmp_tail - - .p2align 5,,12 /* Ensure at least 3 instructions in cache line. */ -.Loverlap2: - and tmp1, data1, const_m1, S2LO #16 - uadd8 syndrome, data1, const_m1 - eors syndrome, tmp1, data2, S2LO #16 - sel syndrome, syndrome, const_m1 - bne 4f - cbnz syndrome, 5f - ldr data2, [src2], #4 - eor tmp1, tmp1, data1 - cmp tmp1, data2, S2HI #16 - bne 6f - ldr data1, [src1], #4 - b .Loverlap2 -4: - S2LO data2, data2, #16 - b .Lstrcmp_tail -5: - ands syndrome, syndrome, const_m1, S2LO #16 - bne .Lstrcmp_done_equal - - ldrh data2, [src2] - S2LO data1, data1, #16 -#ifdef __ARM_BIG_ENDIAN - lsl data2, data2, #16 -#endif - b .Lstrcmp_tail - -6: - S2LO data1, data1, #16 - and data2, data2, const_m1, S2LO #16 - b .Lstrcmp_tail - - .p2align 5,,12 /* Ensure at least 3 instructions in cache line. */ -.Loverlap1: - and tmp1, data1, #LSB - uadd8 syndrome, data1, const_m1 - eors syndrome, tmp1, data2, S2LO #24 - sel syndrome, syndrome, const_m1 - bne 4f - cbnz syndrome, 5f - ldr data2, [src2], #4 - eor tmp1, tmp1, data1 - cmp tmp1, data2, S2HI #8 - bne 6f - ldr data1, [src1], #4 - b .Loverlap1 -4: - S2LO data2, data2, #24 - b .Lstrcmp_tail -5: - tst syndrome, #LSB - bne .Lstrcmp_done_equal - ldr data2, [src2] -6: - S2LO data1, data1, #8 - bic data2, data2, #MSB - b .Lstrcmp_tail - -.Lstrcmp_done_equal: - mov result, #0 - ldrd r4, r5, [sp], #16 - cfi_remember_state - cfi_def_cfa_offset (0) - cfi_restore (r4) - cfi_restore (r5) - /* R6/7 not used in this sequence. */ - cfi_restore (r6) - cfi_restore (r7) - bx lr - -.Lstrcmp_tail: - cfi_restore_state -#ifndef __ARM_BIG_ENDIAN - rev data1, data1 - rev data2, data2 - /* Now everything looks big-endian... */ -#endif - uadd8 tmp1, data1, const_m1 - eor tmp1, data1, data2 - sel syndrome, tmp1, const_m1 - clz tmp1, syndrome - lsl data1, data1, tmp1 - lsl data2, data2, tmp1 - lsr result, data1, #24 - ldrd r4, r5, [sp], #16 - cfi_def_cfa_offset (0) - cfi_restore (r4) - cfi_restore (r5) - /* R6/7 not used in this sequence. */ - cfi_restore (r6) - cfi_restore (r7) - sub result, result, data2, lsr #24 - bx lr -END (strcmp) -libc_hidden_builtin_def (strcmp) |