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// Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// A simple interpreter for the Irregexp byte code.
#include "vm/regexp_interpreter.h"
#include "vm/regexp_bytecodes.h"
#include "vm/regexp_assembler.h"
#include "vm/object.h"
#include "vm/unicode.h"
#include "vm/unibrow.h"
#include "vm/unibrow-inl.h"
namespace dart {
DEFINE_FLAG(bool, trace_regexp_bytecodes, false, "trace_regexp_bytecodes");
typedef unibrow::Mapping<unibrow::Ecma262Canonicalize> Canonicalize;
template<typename Char>
static bool BackRefMatchesNoCase(Canonicalize* interp_canonicalize,
intptr_t from,
intptr_t current,
intptr_t len,
const String& subject);
template <>
bool BackRefMatchesNoCase<uint16_t>(Canonicalize* interp_canonicalize,
intptr_t from,
intptr_t current,
intptr_t len,
const String& subject) {
for (int i = 0; i < len; i++) {
int32_t old_char = subject.CharAt(from++);
int32_t new_char = subject.CharAt(current++);
if (old_char == new_char) continue;
int32_t old_string[1] = { old_char };
int32_t new_string[1] = { new_char };
interp_canonicalize->get(old_char, '\0', old_string);
interp_canonicalize->get(new_char, '\0', new_string);
if (old_string[0] != new_string[0]) {
return false;
}
}
return true;
}
template <>
bool BackRefMatchesNoCase<uint8_t>(Canonicalize* interp_canonicalize,
intptr_t from,
intptr_t current,
intptr_t len,
const String& subject) {
for (int i = 0; i < len; i++) {
unsigned int old_char = subject.CharAt(from++);
unsigned int new_char = subject.CharAt(current++);
if (old_char == new_char) continue;
// Convert both characters to lower case.
old_char |= 0x20;
new_char |= 0x20;
if (old_char != new_char) return false;
// Not letters in the ASCII range and Latin-1 range.
if (!(old_char - 'a' <= 'z' - 'a') &&
!(old_char - 224 <= 254 - 224 && old_char != 247)) {
return false;
}
}
return true;
}
#ifdef DEBUG
static void TraceInterpreter(const uint8_t* code_base,
const uint8_t* pc,
int stack_depth,
int current_position,
uint32_t current_char,
int bytecode_length,
const char* bytecode_name) {
if (FLAG_trace_regexp_bytecodes) {
bool printable = (current_char < 127 && current_char >= 32);
const char* format =
printable ?
"pc = %02x, sp = %d, curpos = %d, curchar = %08x (%c), bc = %s" :
"pc = %02x, sp = %d, curpos = %d, curchar = %08x .%c., bc = %s";
OS::Print(format,
pc - code_base,
stack_depth,
current_position,
current_char,
printable ? current_char : '.',
bytecode_name);
for (int i = 0; i < bytecode_length; i++) {
OS::Print(", %02x", pc[i]);
}
OS::Print(" ");
for (int i = 1; i < bytecode_length; i++) {
unsigned char b = pc[i];
if (b < 127 && b >= 32) {
OS::Print("%c", b);
} else {
OS::Print(".");
}
}
OS::Print("\n");
}
}
#define BYTECODE(name) \
case BC_##name: \
TraceInterpreter(code_base, \
pc, \
static_cast<int>(backtrack_sp - backtrack_stack_base), \
current, \
current_char, \
BC_##name##_LENGTH, \
#name);
#else
#define BYTECODE(name) \
case BC_##name:
#endif
static int32_t Load32Aligned(const uint8_t* pc) {
ASSERT((reinterpret_cast<intptr_t>(pc) & 3) == 0);
return *reinterpret_cast<const int32_t *>(pc);
}
static int32_t Load16Aligned(const uint8_t* pc) {
ASSERT((reinterpret_cast<intptr_t>(pc) & 1) == 0);
return *reinterpret_cast<const uint16_t *>(pc);
}
// A simple abstraction over the backtracking stack used by the interpreter.
// This backtracking stack does not grow automatically, but it ensures that the
// the memory held by the stack is released or remembered in a cache if the
// matching terminates.
class BacktrackStack {
public:
explicit BacktrackStack(Zone* zone) {
data_ = zone->Alloc<intptr_t>(kBacktrackStackSize);
}
intptr_t* data() const { return data_; }
intptr_t max_size() const { return kBacktrackStackSize; }
private:
static const intptr_t kBacktrackStackSize = 10000;
intptr_t* data_;
DISALLOW_COPY_AND_ASSIGN(BacktrackStack);
};
template <typename Char>
static IrregexpInterpreter::IrregexpResult RawMatch(const uint8_t* code_base,
const String& subject,
int32_t* registers,
intptr_t current,
uint32_t current_char,
Zone* zone) {
const uint8_t* pc = code_base;
// BacktrackStack ensures that the memory allocated for the backtracking stack
// is returned to the system or cached if there is no stack being cached at
// the moment.
BacktrackStack backtrack_stack(zone);
intptr_t* backtrack_stack_base = backtrack_stack.data();
intptr_t* backtrack_sp = backtrack_stack_base;
intptr_t backtrack_stack_space = backtrack_stack.max_size();
// TODO(zerny): Optimize as single instance. V8 has this as an
// isolate member.
unibrow::Mapping<unibrow::Ecma262Canonicalize> canonicalize;
intptr_t subject_length = subject.Length();
#ifdef DEBUG
if (FLAG_trace_regexp_bytecodes) {
OS::Print("Start irregexp bytecode interpreter\n");
}
#endif
while (true) {
int32_t insn = Load32Aligned(pc);
switch (insn & BYTECODE_MASK) {
BYTECODE(BREAK)
UNREACHABLE();
return IrregexpInterpreter::RE_FAILURE;
BYTECODE(PUSH_CP)
if (--backtrack_stack_space < 0) {
return IrregexpInterpreter::RE_EXCEPTION;
}
*backtrack_sp++ = current;
pc += BC_PUSH_CP_LENGTH;
break;
BYTECODE(PUSH_BT)
if (--backtrack_stack_space < 0) {
return IrregexpInterpreter::RE_EXCEPTION;
}
*backtrack_sp++ = Load32Aligned(pc + 4);
pc += BC_PUSH_BT_LENGTH;
break;
BYTECODE(PUSH_REGISTER)
if (--backtrack_stack_space < 0) {
return IrregexpInterpreter::RE_EXCEPTION;
}
*backtrack_sp++ = registers[insn >> BYTECODE_SHIFT];
pc += BC_PUSH_REGISTER_LENGTH;
break;
BYTECODE(SET_REGISTER)
registers[insn >> BYTECODE_SHIFT] = Load32Aligned(pc + 4);
pc += BC_SET_REGISTER_LENGTH;
break;
BYTECODE(ADVANCE_REGISTER)
registers[insn >> BYTECODE_SHIFT] += Load32Aligned(pc + 4);
pc += BC_ADVANCE_REGISTER_LENGTH;
break;
BYTECODE(SET_REGISTER_TO_CP)
registers[insn >> BYTECODE_SHIFT] = current + Load32Aligned(pc + 4);
pc += BC_SET_REGISTER_TO_CP_LENGTH;
break;
BYTECODE(SET_CP_TO_REGISTER)
current = registers[insn >> BYTECODE_SHIFT];
pc += BC_SET_CP_TO_REGISTER_LENGTH;
break;
BYTECODE(SET_REGISTER_TO_SP)
registers[insn >> BYTECODE_SHIFT] =
static_cast<int>(backtrack_sp - backtrack_stack_base);
pc += BC_SET_REGISTER_TO_SP_LENGTH;
break;
BYTECODE(SET_SP_TO_REGISTER)
backtrack_sp = backtrack_stack_base + registers[insn >> BYTECODE_SHIFT];
backtrack_stack_space = backtrack_stack.max_size() -
static_cast<int>(backtrack_sp - backtrack_stack_base);
pc += BC_SET_SP_TO_REGISTER_LENGTH;
break;
BYTECODE(POP_CP)
backtrack_stack_space++;
--backtrack_sp;
current = *backtrack_sp;
pc += BC_POP_CP_LENGTH;
break;
BYTECODE(POP_BT)
backtrack_stack_space++;
--backtrack_sp;
pc = code_base + *backtrack_sp;
break;
BYTECODE(POP_REGISTER)
backtrack_stack_space++;
--backtrack_sp;
registers[insn >> BYTECODE_SHIFT] = *backtrack_sp;
pc += BC_POP_REGISTER_LENGTH;
break;
BYTECODE(FAIL)
return IrregexpInterpreter::RE_FAILURE;
BYTECODE(SUCCEED)
return IrregexpInterpreter::RE_SUCCESS;
BYTECODE(ADVANCE_CP)
current += insn >> BYTECODE_SHIFT;
pc += BC_ADVANCE_CP_LENGTH;
break;
BYTECODE(GOTO)
pc = code_base + Load32Aligned(pc + 4);
break;
BYTECODE(ADVANCE_CP_AND_GOTO)
current += insn >> BYTECODE_SHIFT;
pc = code_base + Load32Aligned(pc + 4);
break;
BYTECODE(CHECK_GREEDY)
if (current == backtrack_sp[-1]) {
backtrack_sp--;
backtrack_stack_space++;
pc = code_base + Load32Aligned(pc + 4);
} else {
pc += BC_CHECK_GREEDY_LENGTH;
}
break;
BYTECODE(LOAD_CURRENT_CHAR) {
int pos = current + (insn >> BYTECODE_SHIFT);
if (pos >= subject_length) {
pc = code_base + Load32Aligned(pc + 4);
} else {
current_char = subject.CharAt(pos);
pc += BC_LOAD_CURRENT_CHAR_LENGTH;
}
break;
}
BYTECODE(LOAD_CURRENT_CHAR_UNCHECKED) {
int pos = current + (insn >> BYTECODE_SHIFT);
current_char = subject.CharAt(pos);
pc += BC_LOAD_CURRENT_CHAR_UNCHECKED_LENGTH;
break;
}
BYTECODE(LOAD_2_CURRENT_CHARS) {
int pos = current + (insn >> BYTECODE_SHIFT);
if (pos + 2 > subject_length) {
pc = code_base + Load32Aligned(pc + 4);
} else {
Char next = subject.CharAt(pos + 1);
current_char = subject.CharAt(pos) |
(next << (kBitsPerByte * sizeof(Char)));
pc += BC_LOAD_2_CURRENT_CHARS_LENGTH;
}
break;
}
BYTECODE(LOAD_2_CURRENT_CHARS_UNCHECKED) {
int pos = current + (insn >> BYTECODE_SHIFT);
Char next = subject.CharAt(pos + 1);
current_char = subject.CharAt(pos) |
(next << (kBitsPerByte * sizeof(Char)));
pc += BC_LOAD_2_CURRENT_CHARS_UNCHECKED_LENGTH;
break;
}
BYTECODE(LOAD_4_CURRENT_CHARS) {
ASSERT(sizeof(Char) == 1);
int pos = current + (insn >> BYTECODE_SHIFT);
if (pos + 4 > subject_length) {
pc = code_base + Load32Aligned(pc + 4);
} else {
Char next1 = subject.CharAt(pos + 1);
Char next2 = subject.CharAt(pos + 2);
Char next3 = subject.CharAt(pos + 3);
current_char = (subject.CharAt(pos) |
(next1 << 8) |
(next2 << 16) |
(next3 << 24));
pc += BC_LOAD_4_CURRENT_CHARS_LENGTH;
}
break;
}
BYTECODE(LOAD_4_CURRENT_CHARS_UNCHECKED) {
ASSERT(sizeof(Char) == 1);
int pos = current + (insn >> BYTECODE_SHIFT);
Char next1 = subject.CharAt(pos + 1);
Char next2 = subject.CharAt(pos + 2);
Char next3 = subject.CharAt(pos + 3);
current_char = (subject.CharAt(pos) |
(next1 << 8) |
(next2 << 16) |
(next3 << 24));
pc += BC_LOAD_4_CURRENT_CHARS_UNCHECKED_LENGTH;
break;
}
BYTECODE(CHECK_4_CHARS) {
uint32_t c = Load32Aligned(pc + 4);
if (c == current_char) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_CHECK_4_CHARS_LENGTH;
}
break;
}
BYTECODE(CHECK_CHAR) {
uint32_t c = (insn >> BYTECODE_SHIFT);
if (c == current_char) {
pc = code_base + Load32Aligned(pc + 4);
} else {
pc += BC_CHECK_CHAR_LENGTH;
}
break;
}
BYTECODE(CHECK_NOT_4_CHARS) {
uint32_t c = Load32Aligned(pc + 4);
if (c != current_char) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_CHECK_NOT_4_CHARS_LENGTH;
}
break;
}
BYTECODE(CHECK_NOT_CHAR) {
uint32_t c = (insn >> BYTECODE_SHIFT);
if (c != current_char) {
pc = code_base + Load32Aligned(pc + 4);
} else {
pc += BC_CHECK_NOT_CHAR_LENGTH;
}
break;
}
BYTECODE(AND_CHECK_4_CHARS) {
uint32_t c = Load32Aligned(pc + 4);
if (c == (current_char & Load32Aligned(pc + 8))) {
pc = code_base + Load32Aligned(pc + 12);
} else {
pc += BC_AND_CHECK_4_CHARS_LENGTH;
}
break;
}
BYTECODE(AND_CHECK_CHAR) {
uint32_t c = (insn >> BYTECODE_SHIFT);
if (c == (current_char & Load32Aligned(pc + 4))) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_AND_CHECK_CHAR_LENGTH;
}
break;
}
BYTECODE(AND_CHECK_NOT_4_CHARS) {
uint32_t c = Load32Aligned(pc + 4);
if (c != (current_char & Load32Aligned(pc + 8))) {
pc = code_base + Load32Aligned(pc + 12);
} else {
pc += BC_AND_CHECK_NOT_4_CHARS_LENGTH;
}
break;
}
BYTECODE(AND_CHECK_NOT_CHAR) {
uint32_t c = (insn >> BYTECODE_SHIFT);
if (c != (current_char & Load32Aligned(pc + 4))) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_AND_CHECK_NOT_CHAR_LENGTH;
}
break;
}
BYTECODE(MINUS_AND_CHECK_NOT_CHAR) {
uint32_t c = (insn >> BYTECODE_SHIFT);
uint32_t minus = Load16Aligned(pc + 4);
uint32_t mask = Load16Aligned(pc + 6);
if (c != ((current_char - minus) & mask)) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_MINUS_AND_CHECK_NOT_CHAR_LENGTH;
}
break;
}
BYTECODE(CHECK_CHAR_IN_RANGE) {
uint32_t from = Load16Aligned(pc + 4);
uint32_t to = Load16Aligned(pc + 6);
if (from <= current_char && current_char <= to) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_CHECK_CHAR_IN_RANGE_LENGTH;
}
break;
}
BYTECODE(CHECK_CHAR_NOT_IN_RANGE) {
uint32_t from = Load16Aligned(pc + 4);
uint32_t to = Load16Aligned(pc + 6);
if (from > current_char || current_char > to) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_CHECK_CHAR_NOT_IN_RANGE_LENGTH;
}
break;
}
BYTECODE(CHECK_BIT_IN_TABLE) {
int mask = RegExpMacroAssembler::kTableMask;
uint8_t b = pc[8 + ((current_char & mask) >> kBitsPerByteLog2)];
int bit = (current_char & (kBitsPerByte - 1));
if ((b & (1 << bit)) != 0) {
pc = code_base + Load32Aligned(pc + 4);
} else {
pc += BC_CHECK_BIT_IN_TABLE_LENGTH;
}
break;
}
BYTECODE(CHECK_LT) {
uint32_t limit = (insn >> BYTECODE_SHIFT);
if (current_char < limit) {
pc = code_base + Load32Aligned(pc + 4);
} else {
pc += BC_CHECK_LT_LENGTH;
}
break;
}
BYTECODE(CHECK_GT) {
uint32_t limit = (insn >> BYTECODE_SHIFT);
if (current_char > limit) {
pc = code_base + Load32Aligned(pc + 4);
} else {
pc += BC_CHECK_GT_LENGTH;
}
break;
}
BYTECODE(CHECK_REGISTER_LT)
if (registers[insn >> BYTECODE_SHIFT] < Load32Aligned(pc + 4)) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_CHECK_REGISTER_LT_LENGTH;
}
break;
BYTECODE(CHECK_REGISTER_GE)
if (registers[insn >> BYTECODE_SHIFT] >= Load32Aligned(pc + 4)) {
pc = code_base + Load32Aligned(pc + 8);
} else {
pc += BC_CHECK_REGISTER_GE_LENGTH;
}
break;
BYTECODE(CHECK_REGISTER_EQ_POS)
if (registers[insn >> BYTECODE_SHIFT] == current) {
pc = code_base + Load32Aligned(pc + 4);
} else {
pc += BC_CHECK_REGISTER_EQ_POS_LENGTH;
}
break;
BYTECODE(CHECK_NOT_REGS_EQUAL)
if (registers[insn >> BYTECODE_SHIFT] ==
registers[Load32Aligned(pc + 4)]) {
pc += BC_CHECK_NOT_REGS_EQUAL_LENGTH;
} else {
pc = code_base + Load32Aligned(pc + 8);
}
break;
BYTECODE(CHECK_NOT_BACK_REF) {
int from = registers[insn >> BYTECODE_SHIFT];
int len = registers[(insn >> BYTECODE_SHIFT) + 1] - from;
if (from < 0 || len <= 0) {
pc += BC_CHECK_NOT_BACK_REF_LENGTH;
break;
}
if (current + len > subject_length) {
pc = code_base + Load32Aligned(pc + 4);
break;
} else {
int i;
for (i = 0; i < len; i++) {
if (subject.CharAt(from + i) != subject.CharAt(current + i)) {
pc = code_base + Load32Aligned(pc + 4);
break;
}
}
if (i < len) break;
current += len;
}
pc += BC_CHECK_NOT_BACK_REF_LENGTH;
break;
}
BYTECODE(CHECK_NOT_BACK_REF_NO_CASE) {
int from = registers[insn >> BYTECODE_SHIFT];
int len = registers[(insn >> BYTECODE_SHIFT) + 1] - from;
if (from < 0 || len <= 0) {
pc += BC_CHECK_NOT_BACK_REF_NO_CASE_LENGTH;
break;
}
if (current + len > subject_length) {
pc = code_base + Load32Aligned(pc + 4);
break;
} else {
if (BackRefMatchesNoCase<Char>(&canonicalize,
from, current, len, subject)) {
current += len;
pc += BC_CHECK_NOT_BACK_REF_NO_CASE_LENGTH;
} else {
pc = code_base + Load32Aligned(pc + 4);
}
}
break;
}
BYTECODE(CHECK_AT_START)
if (current == 0) {
pc = code_base + Load32Aligned(pc + 4);
} else {
pc += BC_CHECK_AT_START_LENGTH;
}
break;
BYTECODE(CHECK_NOT_AT_START)
if (current == 0) {
pc += BC_CHECK_NOT_AT_START_LENGTH;
} else {
pc = code_base + Load32Aligned(pc + 4);
}
break;
BYTECODE(SET_CURRENT_POSITION_FROM_END) {
int by = static_cast<uint32_t>(insn) >> BYTECODE_SHIFT;
if (subject_length - current > by) {
current = subject_length - by;
current_char = subject.CharAt(current - 1);
}
pc += BC_SET_CURRENT_POSITION_FROM_END_LENGTH;
break;
}
default:
UNREACHABLE();
break;
}
}
}
IrregexpInterpreter::IrregexpResult IrregexpInterpreter::Match(
const TypedData& bytecode,
const String& subject,
int32_t* registers,
intptr_t start_position,
Zone* zone) {
NoSafepointScope no_safepoint;
const uint8_t* code_base = reinterpret_cast<uint8_t*>(bytecode.DataAddr(0));
uint16_t previous_char = '\n';
if (start_position != 0) {
previous_char = subject.CharAt(start_position - 1);
}
if (subject.IsOneByteString() || subject.IsExternalOneByteString()) {
return RawMatch<uint8_t>(code_base,
subject,
registers,
start_position,
previous_char,
zone);
} else if (subject.IsTwoByteString() || subject.IsExternalTwoByteString()) {
return RawMatch<uint16_t>(code_base,
subject,
registers,
start_position,
previous_char,
zone);
} else {
UNREACHABLE();
return IrregexpInterpreter::RE_FAILURE;
}
}
} // namespace dart