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1//===-- Strlen for generic SIMD types -------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef LLVM_LIBC_SRC_STRING_MEMORY_UTILS_GENERIC_INLINE_STRLEN_H10#define LLVM_LIBC_SRC_STRING_MEMORY_UTILS_GENERIC_INLINE_STRLEN_H11 12#include "src/__support/CPP/bit.h"13#include "src/__support/CPP/simd.h"14#include "src/__support/common.h"15 16namespace LIBC_NAMESPACE_DECL {17namespace internal {18 19// Exploit the underlying integer representation to do a variable shift.20LIBC_INLINE constexpr cpp::simd_mask<char> shift_mask(cpp::simd_mask<char> m,21 size_t shift) {22 using bitmask_ty = cpp::internal::get_as_integer_type_t<cpp::simd_mask<char>>;23 bitmask_ty r = cpp::bit_cast<bitmask_ty>(m) >> shift;24 return cpp::bit_cast<cpp::simd_mask<char>>(r);25}26 27LIBC_NO_SANITIZE_OOB_ACCESS LIBC_INLINE size_t string_length(const char *src) {28 constexpr cpp::simd<char> null_byte = cpp::splat('\0');29 30 size_t alignment = alignof(cpp::simd<char>);31 const cpp::simd<char> *aligned = reinterpret_cast<const cpp::simd<char> *>(32 __builtin_align_down(src, alignment));33 34 cpp::simd<char> chars = cpp::load<cpp::simd<char>>(aligned, /*aligned=*/true);35 cpp::simd_mask<char> mask = chars == null_byte;36 size_t offset = src - reinterpret_cast<const char *>(aligned);37 if (cpp::any_of(shift_mask(mask, offset)))38 return cpp::find_first_set(shift_mask(mask, offset));39 40 for (;;) {41 cpp::simd<char> chars = cpp::load<cpp::simd<char>>(++aligned,42 /*aligned=*/true);43 cpp::simd_mask<char> mask = chars == null_byte;44 if (cpp::any_of(mask))45 return (reinterpret_cast<const char *>(aligned) - src) +46 cpp::find_first_set(mask);47 }48}49} // namespace internal50 51namespace string_length_impl = internal;52} // namespace LIBC_NAMESPACE_DECL53 54#endif // LLVM_LIBC_SRC_STRING_MEMORY_UTILS_GENERIC_INLINE_STRLEN_H55