text: // Copyright 2012 the V8 project authors. All rights reserved.
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  //       notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  //       copyright notice, this list of conditions and the following
  //       disclaimer in the documentation and/or other materials provided
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include "v8.h"
  #include "ast.h"
  #include "assembler.h"
  #include "regexp-stack.h"
  #include "regexp-macro-assembler.h"
  #include "simulator.h"
  
  namespace v8 {
  namespace internal {
  
  RegExpMacroAssembler::RegExpMacroAssembler(Zone* zone)
    : slow_safe_compiler_(false),
      global_mode_(NOT_GLOBAL),
      zone_(zone) {
  }
  
  
  RegExpMacroAssembler::~RegExpMacroAssembler() {
  }
  
  
  bool RegExpMacroAssembler::CanReadUnaligned() {
  #ifdef V8_HOST_CAN_READ_UNALIGNED
    return true;
  #else
    return false;
  #endif
  }
  
  
  #ifndef V8_INTERPRETED_REGEXP  // Avoid unused code, e.g., on ARM.
  
  NativeRegExpMacroAssembler::NativeRegExpMacroAssembler(Zone* zone)
      : RegExpMacroAssembler(zone) {
  }
  
  
  NativeRegExpMacroAssembler::~NativeRegExpMacroAssembler() {
  }
  
  
  bool NativeRegExpMacroAssembler::CanReadUnaligned() {
    return FLAG_enable_unaligned_accesses && !slow_safe();
  }
  
  const byte* NativeRegExpMacroAssembler::StringCharacterPosition(
      String* subject,
      int start_index) {
    // Not just flat, but ultra flat.
    ASSERT(subject->IsExternalString() || subject->IsSeqString());
    ASSERT(start_index >= 0);
    ASSERT(start_index <= subject->length());
    if (subject->IsAsciiRepresentation()) {
      const byte* address;
      if (StringShape(subject).IsExternal()) {
        const char* data = ExternalAsciiString::cast(subject)->GetChars();
        address = reinterpret_cast<const byte*>(data);
      } else {
        ASSERT(subject->IsSeqAsciiString());
        char* data = SeqAsciiString::cast(subject)->GetChars();
        address = reinterpret_cast<const byte*>(data);
      }
      return address + start_index;
    }
    const uc16* data;
    if (StringShape(subject).IsExternal()) {
      data = ExternalTwoByteString::cast(subject)->GetChars();
    } else {
      ASSERT(subject->IsSeqTwoByteString());
      data = SeqTwoByteString::cast(subject)->GetChars();
    }
    return reinterpret_cast<const byte*>(data + start_index);
  }
  
  
  NativeRegExpMacroAssembler::Result NativeRegExpMacroAssembler::Match(
      Handle<Code> regexp_code,
      Handle<String> subject,
      int* offsets_vector,
      int offsets_vector_length,
      int previous_index,
      Isolate* isolate) {
  
    ASSERT(subject->IsFlat());
    ASSERT(previous_index >= 0);
    ASSERT(previous_index <= subject->length());
  
    // No allocations before calling the regexp, but we can't use
    // AssertNoAllocation, since regexps might be preempted, and another thread
    // might do allocation anyway.
  
    String* subject_ptr = *subject;
    // Character offsets into string.
    int start_offset = previous_index;
    int char_length = subject_ptr->length() - start_offset;
    int slice_offset = 0;
  
    // The string has been flattened, so if it is a cons string it contains the
    // full string in the first part.
    if (StringShape(subject_ptr).IsCons()) {
      ASSERT_EQ(0, ConsString::cast(subject_ptr)->second()->length());
      subject_ptr = ConsString::cast(subject_ptr)->first();
    } else if (StringShape(subject_ptr).IsSliced()) {
      SlicedString* slice = SlicedString::cast(subject_ptr);
      subject_ptr = slice->parent();
      slice_offset = slice->offset();
    }
    // Ensure that an underlying string has the same ASCII-ness.
    bool is_ascii = subject_ptr->IsAsciiRepresentation();
    ASSERT(subject_ptr->IsExternalString() || subject_ptr->IsSeqString());
    // String is now either Sequential or External
    int char_size_shift = is_ascii ? 0 : 1;
  
    const byte* input_start =
        StringCharacterPosition(subject_ptr, start_offset + slice_offset);
    int byte_length = char_length << char_size_shift;
    const byte* input_end = input_start + byte_length;
    Result res = Execute(*regexp_code,
                         *subject,
                         start_offset,
                         input_start,
                         input_end,
                         offsets_vector,
                         offsets_vector_length,
                         isolate);
    return res;
  }
  
  
  NativeRegExpMacroAssembler::Result NativeRegExpMacroAssembler::Execute(
      Code* code,
      String* input,  // This needs to be the unpacked (sliced, cons) string.
      int start_offset,
      const byte* input_start,
      const byte* input_end,
      int* output,
      int output_size,
      Isolate* isolate) {
    ASSERT(isolate == Isolate::Current());
    // Ensure that the minimum stack has been allocated.
    RegExpStackScope stack_scope(isolate);
    Address stack_base = stack_scope.stack()->stack_base();
  
    int direct_call = 0;
    int result = CALL_GENERATED_REGEXP_CODE(code->entry(),
                                            input,
                                            start_offset,
                                            input_start,
                                            input_end,
                                            output,
                                            output_size,
                                            stack_base,
                                            direct_call,
                                            isolate);
    ASSERT(result >= RETRY);
  
    if (result == EXCEPTION && !isolate->has_pending_exception()) {
      // We detected a stack overflow (on the backtrack stack) in RegExp code,
      // but haven't created the exception yet.
      isolate->StackOverflow();
    }
    return static_cast<Result>(result);
  }
  
  
  const byte NativeRegExpMacroAssembler::word_character_map[] = {
      0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
      0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
      0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
      0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
  
      0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
      0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
      0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu,  // '0' - '7'
      0xffu, 0xffu, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,  // '8' - '9'
  
      0x00u, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu,  // 'A' - 'G'
      0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu,  // 'H' - 'O'
      0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu,  // 'P' - 'W'
      0xffu, 0xffu, 0xffu, 0x00u, 0x00u, 0x00u, 0x00u, 0xffu,  // 'X' - 'Z', '_'
  
      0x00u, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu,  // 'a' - 'g'
      0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu,  // 'h' - 'o'
      0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu, 0xffu,  // 'p' - 'w'
      0xffu, 0xffu, 0xffu, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,  // 'x' - 'z'
  };
  
  
  int NativeRegExpMacroAssembler::CaseInsensitiveCompareUC16(
      Address byte_offset1,
      Address byte_offset2,
      size_t byte_length,
      Isolate* isolate) {
    ASSERT(isolate == Isolate::Current());
    unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize =
        isolate->regexp_macro_assembler_canonicalize();
    // This function is not allowed to cause a garbage collection.
    // A GC might move the calling generated code and invalidate the
    // return address on the stack.
    ASSERT(byte_length % 2 == 0);
    uc16* substring1 = reinterpret_cast<uc16*>(byte_offset1);
    uc16* substring2 = reinterpret_cast<uc16*>(byte_offset2);
    size_t length = byte_length >> 1;
  
    for (size_t i = 0; i < length; i++) {
      unibrow::uchar c1 = substring1[i];
      unibrow::uchar c2 = substring2[i];
      if (c1 != c2) {
        unibrow::uchar s1[1] = { c1 };
        canonicalize->get(c1, '\0', s1);
        if (s1[0] != c2) {
          unibrow::uchar s2[1] = { c2 };
          canonicalize->get(c2, '\0', s2);
          if (s1[0] != s2[0]) {
            return 0;
          }
        }
      }
    }
    return 1;
  }
  
  
  Address NativeRegExpMacroAssembler::GrowStack(Address stack_pointer,
                                                Address* stack_base,
                                                Isolate* isolate) {
    ASSERT(isolate == Isolate::Current());
    RegExpStack* regexp_stack = isolate->regexp_stack();
    size_t size = regexp_stack->stack_capacity();
    Address old_stack_base = regexp_stack->stack_base();
    ASSERT(old_stack_base == *stack_base);
    ASSERT(stack_pointer <= old_stack_base);
    ASSERT(static_cast<size_t>(old_stack_base - stack_pointer) <= size);
    Address new_stack_base = regexp_stack->EnsureCapacity(size * 2);
    if (new_stack_base == NULL) {
      return NULL;
    }
    *stack_base = new_stack_base;
    intptr_t stack_content_size = old_stack_base - stack_pointer;
    return new_stack_base - stack_content_size;
  }
  
  #endif  // V8_INTERPRETED_REGEXP
  
  } }  // namespace v8::internal
  