/* * strncmp - compare two strings with limit * * 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 __strncmp_aarch64_sve .type __strncmp_aarch64_sve, %function .p2align 4 __strncmp_aarch64_sve: setffr /* initialize FFR */ mov x3, 0 /* initialize off */ 0: whilelo p0.b, x3, x2 /* while off < max */ b.none 9f ldff1b z0.b, p0/z, [x0, x3] ldff1b z1.b, p0/z, [x1, x3] rdffrs p1.b, p0/z b.nlast 2f /* First fault did not fail: the vector up to max is valid. Avoid depending on the contents of FFR beyond the branch. Increment for a whole vector, even if we've only read a partial. This is significantly cheaper than INCP, and since OFF is not used after the loop it is ok to increment OFF past MAX. */ incb x3 cmpeq p1.b, p0/z, z0.b, z1.b /* compare strings */ cmpne p2.b, p0/z, z0.b, 0 /* search for ~zero */ nands p2.b, p0/z, p1.b, p2.b /* ~(eq & ~zero) -> ne | zero */ b.none 0b /* Found end-of-string or inequality. */ 1: brkb p2.b, p0/z, p2.b /* find first such */ lasta w0, p2, z0.b /* extract each char */ lasta w1, p2, z1.b sub x0, x0, x1 /* return comparison */ ret /* First fault failed: only some of the vector is valid. Perform the comparison only on the valid bytes. */ 2: cmpeq p2.b, p1/z, z0.b, z1.b /* compare strings, as above */ cmpne p3.b, p1/z, z0.b, 0 nands p2.b, p1/z, p2.b, p3.b b.any 1b /* No inequality or zero found. Re-init FFR, incr and loop. */ setffr incp x3, p1.b b 0b /* Found end-of-count. */ 9: mov x0, 0 /* return equal */ ret .size __strncmp_aarch64_sve, . - __strncmp_aarch64_sve #endif