| /* |
| * memchr - find a character in a memory zone |
| * |
| * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| * See https://llvm.org/LICENSE.txt for license information. |
| * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| */ |
| |
| #if __ARM_FEATURE_SVE |
| /* Assumptions: |
| * |
| * ARMv8-a, AArch64 |
| * SVE Available. |
| */ |
| |
| .arch armv8-a+sve |
| .text |
| |
| .globl __memchr_aarch64_sve |
| .type __memchr_aarch64_sve, %function |
| .p2align 4 |
| __memchr_aarch64_sve: |
| dup z1.b, w1 /* duplicate c to a vector */ |
| setffr /* initialize FFR */ |
| mov x3, 0 /* initialize off */ |
| nop |
| |
| 0: whilelo p1.b, x3, x2 /* make sure off < max */ |
| b.none 9f |
| |
| /* Read a vector's worth of bytes, bounded by max, |
| stopping on first fault. */ |
| ldff1b z0.b, p1/z, [x0, x3] |
| rdffrs p0.b, p1/z |
| b.nlast 2f |
| |
| /* First fault did not fail: the vector bounded by max is valid. |
| Avoid depending on the contents of FFR beyond the branch. */ |
| incb x3 /* speculate increment */ |
| cmpeq p2.b, p1/z, z0.b, z1.b /* search for c */ |
| b.none 0b |
| decb x3 /* undo speculate */ |
| |
| /* Found C. */ |
| 1: brkb p2.b, p1/z, p2.b /* find the first c */ |
| add x0, x0, x3 /* form partial pointer */ |
| incp x0, p2.b /* form final pointer to c */ |
| ret |
| |
| /* First fault failed: only some of the vector is valid. |
| Perform the comparison only on the valid bytes. */ |
| 2: cmpeq p2.b, p0/z, z0.b, z1.b |
| b.any 1b |
| |
| /* No C found. Re-init FFR, increment, and loop. */ |
| setffr |
| incp x3, p0.b |
| b 0b |
| |
| /* Found end of count. */ |
| 9: mov x0, 0 /* return null */ |
| ret |
| |
| .size __memchr_aarch64_sve, . - __memchr_aarch64_sve |
| #endif |
