dom/base/nsTextFragmentSSE2.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 // This file should only be compiled if you're on x86 or x86_64.  Additionally,
   8 // you'll need to compile this file with -msse2 if you're using gcc.
   9
  10 #include <emmintrin.h>
  11 #include "nscore.h"
  12 #include "nsAlgorithm.h"
  13 #include "nsTextFragmentImpl.h"
  14 #include <algorithm>
  15
  16 namespace mozilla::SSE2 {
  17
  18 static inline bool is_zero(__m128i x) {
  19   return _mm_movemask_epi8(_mm_cmpeq_epi8(x, _mm_setzero_si128())) == 0xffff;
  20 }
  21
  22 int32_t FirstNon8Bit(const char16_t* str, const char16_t* end) {
  23   const uint32_t numUnicharsPerVector = 8;
  24   using p = Non8BitParameters<sizeof(size_t)>;
  25   const size_t mask = p::mask();
  26   const uint32_t numUnicharsPerWord = p::numUnicharsPerWord();
  27   const int32_t len = end - str;
  28   int32_t i = 0;
  29
  30   // Align ourselves to a 16-byte boundary, as required by _mm_load_si128
  31   // (i.e. MOVDQA).
  32   int32_t alignLen = std::min(
  33       len, int32_t(((-NS_PTR_TO_INT32(str)) & 0xf) / sizeof(char16_t)));
  34   for (; i < alignLen; i++) {
  35     if (str[i] > 255) return i;
  36   }
  37
  38   // Check one XMM register (16 bytes) at a time.
  39   const int32_t vectWalkEnd =
  40       ((len - i) / numUnicharsPerVector) * numUnicharsPerVector;
  41   const uint16_t shortMask = 0xff00;
  42   __m128i vectmask = _mm_set1_epi16(static_cast<int16_t>(shortMask));
  43   for (; i < vectWalkEnd; i += numUnicharsPerVector) {
  44     const __m128i vect = *reinterpret_cast<const __m128i*>(str + i);
  45     if (!is_zero(_mm_and_si128(vect, vectmask))) return i;
  46   }
  47
  48   // Check one word at a time.
  49   const int32_t wordWalkEnd =
  50       ((len - i) / numUnicharsPerWord) * numUnicharsPerWord;
  51   for (; i < wordWalkEnd; i += numUnicharsPerWord) {
  52     const size_t word = *reinterpret_cast<const size_t*>(str + i);
  53     if (word & mask) return i;
  54   }
  55
  56   // Take care of the remainder one character at a time.
  57   for (; i < len; i++) {
  58     if (str[i] > 255) {
  59       return i;
  60     }
  61   }
  62
  63   return -1;
  64 }
  65
  66 }  // namespace mozilla::SSE2