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