blob: 43e7621b6261cdc6a3e2a7df3b0ff304d30ec0b2 [file] [log] [blame]
* strcpy/stpcpy - copy a string returning pointer to start/end.
* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
* See for license information.
* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/* Assumptions:
* ARMv8-a, AArch64
* SVE Available.
.arch armv8-a+sve
/* To build as stpcpy, define BUILD_STPCPY before compiling this file. */
#define FUNC __stpcpy_aarch64_sve
#define FUNC __strcpy_aarch64_sve
.globl FUNC
.type FUNC, %function
.p2align 4
setffr /* initialize FFR */
ptrue p2.b, all /* all ones; loop invariant */
mov x2, 0 /* initialize offset */
.p2align 4
/* Read a vector's worth of bytes, stopping on first fault. */
0: ldff1b z0.b, p2/z, [x1, x2]
rdffrs p0.b, p2/z
b.nlast 1f
/* First fault did not fail: the whole vector is valid.
Avoid depending on the contexts of FFR beyond the branch. */
cmpeq p1.b, p2/z, z0.b, 0 /* search for zeros */
b.any 2f
/* No zero found. Store the whole vector and loop. */
st1b z0.b, p2, [x0, x2]
incb x2, all
b 0b
/* First fault failed: only some of the vector is valid.
Perform the comparison only on the valid bytes. */
1: cmpeq p1.b, p0/z, z0.b, 0 /* search for zeros */
b.any 2f
/* No zero found. Store the valid portion of the vector and loop. */
setffr /* re-init FFR */
st1b z0.b, p0, [x0, x2]
incp x2, p0.b
b 0b
/* Zero found. Crop the vector to the found zero and finish. */
2: brka p0.b, p2/z, p1.b
st1b z0.b, p0, [x0, x2]
add x0, x0, x2
sub x0, x0, 1
incp x0, p0.b
.size FUNC, . - FUNC