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1 // Copyright 2014 the V8 project authors. All rights reserved. | 1 // Copyright 2014 the V8 project authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "src/runtime/runtime-utils.h" | 5 #include "src/runtime/runtime-utils.h" |
6 | 6 |
7 #include "src/arguments.h" | 7 #include "src/arguments.h" |
8 #include "src/regexp/jsregexp-inl.h" | 8 #include "src/regexp/jsregexp-inl.h" |
9 #include "src/string-builder.h" | 9 #include "src/string-builder.h" |
10 #include "src/string-search.h" | 10 #include "src/string-search.h" |
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672 return result; | 672 return result; |
673 } else { | 673 } else { |
674 // If we didn't actually change anything in doing the conversion | 674 // If we didn't actually change anything in doing the conversion |
675 // we simple return the result and let the converted string | 675 // we simple return the result and let the converted string |
676 // become garbage; there is no reason to keep two identical strings | 676 // become garbage; there is no reason to keep two identical strings |
677 // alive. | 677 // alive. |
678 return string; | 678 return string; |
679 } | 679 } |
680 } | 680 } |
681 | 681 |
682 | |
683 static const uintptr_t kOneInEveryByte = kUintptrAllBitsSet / 0xFF; | |
684 static const uintptr_t kAsciiMask = kOneInEveryByte << 7; | |
685 | |
686 // Given a word and two range boundaries returns a word with high bit | |
687 // set in every byte iff the corresponding input byte was strictly in | |
688 // the range (m, n). All the other bits in the result are cleared. | |
689 // This function is only useful when it can be inlined and the | |
690 // boundaries are statically known. | |
691 // Requires: all bytes in the input word and the boundaries must be | |
692 // ASCII (less than 0x7F). | |
693 static inline uintptr_t AsciiRangeMask(uintptr_t w, char m, char n) { | |
694 // Use strict inequalities since in edge cases the function could be | |
695 // further simplified. | |
696 DCHECK(0 < m && m < n); | |
697 // Has high bit set in every w byte less than n. | |
698 uintptr_t tmp1 = kOneInEveryByte * (0x7F + n) - w; | |
699 // Has high bit set in every w byte greater than m. | |
700 uintptr_t tmp2 = w + kOneInEveryByte * (0x7F - m); | |
701 return (tmp1 & tmp2 & (kOneInEveryByte * 0x80)); | |
702 } | |
703 | |
704 | |
705 #ifdef DEBUG | |
706 static bool CheckFastAsciiConvert(char* dst, const char* src, int length, | |
707 bool changed, bool is_to_lower) { | |
708 bool expected_changed = false; | |
709 for (int i = 0; i < length; i++) { | |
710 if (dst[i] == src[i]) continue; | |
711 expected_changed = true; | |
712 if (is_to_lower) { | |
713 DCHECK('A' <= src[i] && src[i] <= 'Z'); | |
714 DCHECK(dst[i] == src[i] + ('a' - 'A')); | |
715 } else { | |
716 DCHECK('a' <= src[i] && src[i] <= 'z'); | |
717 DCHECK(dst[i] == src[i] - ('a' - 'A')); | |
718 } | |
719 } | |
720 return (expected_changed == changed); | |
721 } | |
722 #endif | |
723 | |
724 | |
725 template <class Converter> | |
726 static bool FastAsciiConvert(char* dst, const char* src, int length, | |
727 bool* changed_out) { | |
728 #ifdef DEBUG | |
729 char* saved_dst = dst; | |
730 const char* saved_src = src; | |
731 #endif | |
732 DisallowHeapAllocation no_gc; | |
733 // We rely on the distance between upper and lower case letters | |
734 // being a known power of 2. | |
735 DCHECK('a' - 'A' == (1 << 5)); | |
736 // Boundaries for the range of input characters than require conversion. | |
737 static const char lo = Converter::kIsToLower ? 'A' - 1 : 'a' - 1; | |
738 static const char hi = Converter::kIsToLower ? 'Z' + 1 : 'z' + 1; | |
739 bool changed = false; | |
740 uintptr_t or_acc = 0; | |
741 const char* const limit = src + length; | |
742 | |
743 // dst is newly allocated and always aligned. | |
744 DCHECK(IsAligned(reinterpret_cast<intptr_t>(dst), sizeof(uintptr_t))); | |
745 // Only attempt processing one word at a time if src is also aligned. | |
746 if (IsAligned(reinterpret_cast<intptr_t>(src), sizeof(uintptr_t))) { | |
747 // Process the prefix of the input that requires no conversion one aligned | |
748 // (machine) word at a time. | |
749 while (src <= limit - sizeof(uintptr_t)) { | |
750 const uintptr_t w = *reinterpret_cast<const uintptr_t*>(src); | |
751 or_acc |= w; | |
752 if (AsciiRangeMask(w, lo, hi) != 0) { | |
753 changed = true; | |
754 break; | |
755 } | |
756 *reinterpret_cast<uintptr_t*>(dst) = w; | |
757 src += sizeof(uintptr_t); | |
758 dst += sizeof(uintptr_t); | |
759 } | |
760 // Process the remainder of the input performing conversion when | |
761 // required one word at a time. | |
762 while (src <= limit - sizeof(uintptr_t)) { | |
763 const uintptr_t w = *reinterpret_cast<const uintptr_t*>(src); | |
764 or_acc |= w; | |
765 uintptr_t m = AsciiRangeMask(w, lo, hi); | |
766 // The mask has high (7th) bit set in every byte that needs | |
767 // conversion and we know that the distance between cases is | |
768 // 1 << 5. | |
769 *reinterpret_cast<uintptr_t*>(dst) = w ^ (m >> 2); | |
770 src += sizeof(uintptr_t); | |
771 dst += sizeof(uintptr_t); | |
772 } | |
773 } | |
774 // Process the last few bytes of the input (or the whole input if | |
775 // unaligned access is not supported). | |
776 while (src < limit) { | |
777 char c = *src; | |
778 or_acc |= c; | |
779 if (lo < c && c < hi) { | |
780 c ^= (1 << 5); | |
781 changed = true; | |
782 } | |
783 *dst = c; | |
784 ++src; | |
785 ++dst; | |
786 } | |
787 | |
788 if ((or_acc & kAsciiMask) != 0) return false; | |
789 | |
790 DCHECK(CheckFastAsciiConvert(saved_dst, saved_src, length, changed, | |
791 Converter::kIsToLower)); | |
792 | |
793 *changed_out = changed; | |
794 return true; | |
795 } | |
796 | |
797 | |
798 template <class Converter> | 682 template <class Converter> |
799 MUST_USE_RESULT static Object* ConvertCase( | 683 MUST_USE_RESULT static Object* ConvertCase( |
800 Handle<String> s, Isolate* isolate, | 684 Handle<String> s, Isolate* isolate, |
801 unibrow::Mapping<Converter, 128>* mapping) { | 685 unibrow::Mapping<Converter, 128>* mapping) { |
802 s = String::Flatten(s); | 686 s = String::Flatten(s); |
803 int length = s->length(); | 687 int length = s->length(); |
804 // Assume that the string is not empty; we need this assumption later | 688 // Assume that the string is not empty; we need this assumption later |
805 if (length == 0) return *s; | 689 if (length == 0) return *s; |
806 | 690 |
807 // Simpler handling of ASCII strings. | 691 // Simpler handling of ASCII strings. |
808 // | 692 // |
809 // NOTE: This assumes that the upper/lower case of an ASCII | 693 // NOTE: This assumes that the upper/lower case of an ASCII |
810 // character is also ASCII. This is currently the case, but it | 694 // character is also ASCII. This is currently the case, but it |
811 // might break in the future if we implement more context and locale | 695 // might break in the future if we implement more context and locale |
812 // dependent upper/lower conversions. | 696 // dependent upper/lower conversions. |
813 if (s->IsOneByteRepresentationUnderneath()) { | 697 if (s->IsOneByteRepresentationUnderneath()) { |
814 // Same length as input. | 698 // Same length as input. |
815 Handle<SeqOneByteString> result = | 699 Handle<SeqOneByteString> result = |
816 isolate->factory()->NewRawOneByteString(length).ToHandleChecked(); | 700 isolate->factory()->NewRawOneByteString(length).ToHandleChecked(); |
817 DisallowHeapAllocation no_gc; | 701 DisallowHeapAllocation no_gc; |
818 String::FlatContent flat_content = s->GetFlatContent(); | 702 String::FlatContent flat_content = s->GetFlatContent(); |
819 DCHECK(flat_content.IsFlat()); | 703 DCHECK(flat_content.IsFlat()); |
820 bool has_changed_character = false; | 704 bool has_changed_character = false; |
821 bool is_ascii = FastAsciiConvert<Converter>( | 705 bool is_ascii = FastAsciiConvert<Converter::kIsToLower>( |
822 reinterpret_cast<char*>(result->GetChars()), | 706 reinterpret_cast<char*>(result->GetChars()), |
823 reinterpret_cast<const char*>(flat_content.ToOneByteVector().start()), | 707 reinterpret_cast<const char*>(flat_content.ToOneByteVector().start()), |
824 length, &has_changed_character); | 708 length, &has_changed_character); |
825 // If not ASCII, we discard the result and take the 2 byte path. | 709 // If not ASCII, we discard the result and take the 2 byte path. |
826 if (is_ascii) return has_changed_character ? *result : *s; | 710 if (is_ascii) return has_changed_character ? *result : *s; |
827 } | 711 } |
828 | 712 |
829 Handle<SeqString> result; // Same length as input. | 713 Handle<SeqString> result; // Same length as input. |
830 if (s->IsOneByteRepresentation()) { | 714 if (s->IsOneByteRepresentation()) { |
831 result = isolate->factory()->NewRawOneByteString(length).ToHandleChecked(); | 715 result = isolate->factory()->NewRawOneByteString(length).ToHandleChecked(); |
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984 SealHandleScope shs(isolate); | 868 SealHandleScope shs(isolate); |
985 DCHECK(args.length() == 2); | 869 DCHECK(args.length() == 2); |
986 if (!args[0]->IsString()) return isolate->heap()->undefined_value(); | 870 if (!args[0]->IsString()) return isolate->heap()->undefined_value(); |
987 if (!args[1]->IsNumber()) return isolate->heap()->undefined_value(); | 871 if (!args[1]->IsNumber()) return isolate->heap()->undefined_value(); |
988 if (std::isinf(args.number_at(1))) return isolate->heap()->nan_value(); | 872 if (std::isinf(args.number_at(1))) return isolate->heap()->nan_value(); |
989 return __RT_impl_Runtime_StringCharCodeAtRT(args, isolate); | 873 return __RT_impl_Runtime_StringCharCodeAtRT(args, isolate); |
990 } | 874 } |
991 | 875 |
992 } // namespace internal | 876 } // namespace internal |
993 } // namespace v8 | 877 } // namespace v8 |
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