src/regexp-macro-assembler.cc

// Copyright 2012 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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#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()
  : slow_safe_compiler_(false),
    global_(false) {
}


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()
    : RegExpMacroAssembler() {
}


NativeRegExpMacroAssembler::~NativeRegExpMacroAssembler() {
}


bool NativeRegExpMacroAssembler::CanReadUnaligned() {
#ifdef V8_TARGET_CAN_READ_UNALIGNED
  return !slow_safe();
#else
  return false;
#endif
}

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