You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
61 lines
1.7 KiB
61 lines
1.7 KiB
/*
|
|
* __strcmp_aarch64_sve - compare two strings
|
|
*
|
|
* 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 __strcmp_aarch64_sve
|
|
.type __strcmp_aarch64_sve, %function
|
|
.p2align 4
|
|
__strcmp_aarch64_sve:
|
|
setffr /* initialize FFR */
|
|
ptrue p1.b, all /* all ones; loop invariant */
|
|
mov x2, 0 /* initialize offset */
|
|
nop
|
|
|
|
/* Read a vector's worth of bytes, stopping on first fault. */
|
|
0: ldff1b z0.b, p1/z, [x0, x2]
|
|
ldff1b z1.b, p1/z, [x1, x2]
|
|
rdffrs p0.b, p1/z
|
|
b.nlast 2f
|
|
|
|
/* First fault did not fail: the whole vector is valid.
|
|
Avoid depending on the contents of FFR beyond the branch. */
|
|
incb x2, all /* skip bytes for next round */
|
|
cmpeq p2.b, p1/z, z0.b, z1.b /* compare strings */
|
|
cmpne p3.b, p1/z, z0.b, 0 /* search for ~zero */
|
|
nands p2.b, p1/z, p2.b, p3.b /* ~(eq & ~zero) -> ne | zero */
|
|
b.none 0b
|
|
|
|
/* Found end-of-string or inequality. */
|
|
1: brkb p2.b, p1/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: incp x2, p0.b /* skip bytes for next round */
|
|
setffr /* re-init FFR for next round */
|
|
cmpeq p2.b, p0/z, z0.b, z1.b /* compare strings, as above */
|
|
cmpne p3.b, p0/z, z0.b, 0
|
|
nands p2.b, p0/z, p2.b, p3.b
|
|
b.none 0b
|
|
b 1b
|
|
|
|
.size __strcmp_aarch64_sve, . - __strcmp_aarch64_sve
|
|
#endif
|