1/* 2 * strnlen - calculate the length of a string with limit. 3 * 4 * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 * See https://llvm.org/LICENSE.txt for license information. 6 * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 */ 8 9#if __ARM_FEATURE_SVE 10/* Assumptions: 11 * 12 * ARMv8-a, AArch64 13 * SVE Available. 14 */ 15 16 .arch armv8-a+sve 17 .text 18 19 .globl __strnlen_aarch64_sve 20 .type __strnlen_aarch64_sve, %function 21 .p2align 4 22__strnlen_aarch64_sve: 23 setffr /* initialize FFR */ 24 mov x2, 0 /* initialize len */ 25 b 1f 26 27 .p2align 4 28 /* We have off + vl <= max, and so may read the whole vector. */ 290: ldff1b z0.b, p0/z, [x0, x2] 30 rdffrs p1.b, p0/z 31 b.nlast 2f 32 33 /* First fault did not fail: the whole vector is valid. 34 Avoid depending on the contents of FFR beyond the branch. */ 35 cmpeq p2.b, p0/z, z0.b, 0 36 b.any 8f 37 incb x2 38 391: whilelo p0.b, x2, x1 40 b.last 0b 41 42 /* We have off + vl < max. Test for off == max before proceeding. */ 43 b.none 9f 44 45 ldff1b z0.b, p0/z, [x0, x2] 46 rdffrs p1.b, p0/z 47 b.nlast 2f 48 49 /* First fault did not fail: the vector up to max is valid. 50 Avoid depending on the contents of FFR beyond the branch. 51 Compare for end-of-string, but there are no more bytes. */ 52 cmpeq p2.b, p0/z, z0.b, 0 53 54 /* Found end-of-string or zero. */ 558: brkb p2.b, p0/z, p2.b 56 mov x0, x2 57 incp x0, p2.b 58 ret 59 60 /* First fault failed: only some of the vector is valid. 61 Perform the comparison only on the valid bytes. */ 622: cmpeq p2.b, p1/z, z0.b, 0 63 b.any 8b 64 65 /* No inequality or zero found. Re-init FFR, incr and loop. */ 66 setffr 67 incp x2, p1.b 68 b 1b 69 70 /* End of count. Return max. */ 719: mov x0, x2 72 ret 73 74 .size __strnlen_aarch64_sve, . - __strnlen_aarch64_sve 75#endif 76