Current File : /home/vacivi36/vittasync.vacivitta.com.br/vittasync/node/deps/v8/src/regexp/regexp-compiler.cc
// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/regexp/regexp-compiler.h"
#include "src/base/safe_conversions.h"
#include "src/execution/isolate.h"
#include "src/objects/fixed-array-inl.h"
#include "src/regexp/regexp-macro-assembler-arch.h"
#include "src/strings/unicode-inl.h"
#include "src/zone/zone-list-inl.h"
#ifdef V8_INTL_SUPPORT
#include "src/regexp/special-case.h"
#include "unicode/locid.h"
#include "unicode/uniset.h"
#include "unicode/utypes.h"
#endif // V8_INTL_SUPPORT
namespace v8 {
namespace internal {
using namespace regexp_compiler_constants; // NOLINT(build/namespaces)
// -------------------------------------------------------------------
// Implementation of the Irregexp regular expression engine.
//
// The Irregexp regular expression engine is intended to be a complete
// implementation of ECMAScript regular expressions. It generates either
// bytecodes or native code.
// The Irregexp regexp engine is structured in three steps.
// 1) The parser generates an abstract syntax tree. See ast.cc.
// 2) From the AST a node network is created. The nodes are all
// subclasses of RegExpNode. The nodes represent states when
// executing a regular expression. Several optimizations are
// performed on the node network.
// 3) From the nodes we generate either byte codes or native code
// that can actually execute the regular expression (perform
// the search). The code generation step is described in more
// detail below.
// Code generation.
//
// The nodes are divided into four main categories.
// * Choice nodes
// These represent places where the regular expression can
// match in more than one way. For example on entry to an
// alternation (foo|bar) or a repetition (*, +, ? or {}).
// * Action nodes
// These represent places where some action should be
// performed. Examples include recording the current position
// in the input string to a register (in order to implement
// captures) or other actions on register for example in order
// to implement the counters needed for {} repetitions.
// * Matching nodes
// These attempt to match some element part of the input string.
// Examples of elements include character classes, plain strings
// or back references.
// * End nodes
// These are used to implement the actions required on finding
// a successful match or failing to find a match.
//
// The code generated (whether as byte codes or native code) maintains
// some state as it runs. This consists of the following elements:
//
// * The capture registers. Used for string captures.
// * Other registers. Used for counters etc.
// * The current position.
// * The stack of backtracking information. Used when a matching node
// fails to find a match and needs to try an alternative.
//
// Conceptual regular expression execution model:
//
// There is a simple conceptual model of regular expression execution
// which will be presented first. The actual code generated is a more
// efficient simulation of the simple conceptual model:
//
// * Choice nodes are implemented as follows:
// For each choice except the last {
// push current position
// push backtrack code location
// <generate code to test for choice>
// backtrack code location:
// pop current position
// }
// <generate code to test for last choice>
//
// * Actions nodes are generated as follows
// <push affected registers on backtrack stack>
// <generate code to perform action>
// push backtrack code location
// <generate code to test for following nodes>
// backtrack code location:
// <pop affected registers to restore their state>
// <pop backtrack location from stack and go to it>
//
// * Matching nodes are generated as follows:
// if input string matches at current position
// update current position
// <generate code to test for following nodes>
// else
// <pop backtrack location from stack and go to it>
//
// Thus it can be seen that the current position is saved and restored
// by the choice nodes, whereas the registers are saved and restored by
// by the action nodes that manipulate them.
//
// The other interesting aspect of this model is that nodes are generated
// at the point where they are needed by a recursive call to Emit(). If
// the node has already been code generated then the Emit() call will
// generate a jump to the previously generated code instead. In order to
// limit recursion it is possible for the Emit() function to put the node
// on a work list for later generation and instead generate a jump. The
// destination of the jump is resolved later when the code is generated.
//
// Actual regular expression code generation.
//
// Code generation is actually more complicated than the above. In order to
// improve the efficiency of the generated code some optimizations are
// performed
//
// * Choice nodes have 1-character lookahead.
// A choice node looks at the following character and eliminates some of
// the choices immediately based on that character. This is not yet
// implemented.
// * Simple greedy loops store reduced backtracking information.
// A quantifier like /.*foo/m will greedily match the whole input. It will
// then need to backtrack to a point where it can match "foo". The naive
// implementation of this would push each character position onto the
// backtracking stack, then pop them off one by one. This would use space
// proportional to the length of the input string. However since the "."
// can only match in one way and always has a constant length (in this case
// of 1) it suffices to store the current position on the top of the stack
// once. Matching now becomes merely incrementing the current position and
// backtracking becomes decrementing the current position and checking the
// result against the stored current position. This is faster and saves
// space.
// * The current state is virtualized.
// This is used to defer expensive operations until it is clear that they
// are needed and to generate code for a node more than once, allowing
// specialized an efficient versions of the code to be created. This is
// explained in the section below.
//
// Execution state virtualization.
//
// Instead of emitting code, nodes that manipulate the state can record their
// manipulation in an object called the Trace. The Trace object can record a
// current position offset, an optional backtrack code location on the top of
// the virtualized backtrack stack and some register changes. When a node is
// to be emitted it can flush the Trace or update it. Flushing the Trace
// will emit code to bring the actual state into line with the virtual state.
// Avoiding flushing the state can postpone some work (e.g. updates of capture
// registers). Postponing work can save time when executing the regular
// expression since it may be found that the work never has to be done as a
// failure to match can occur. In addition it is much faster to jump to a
// known backtrack code location than it is to pop an unknown backtrack
// location from the stack and jump there.
//
// The virtual state found in the Trace affects code generation. For example
// the virtual state contains the difference between the actual current
// position and the virtual current position, and matching code needs to use
// this offset to attempt a match in the correct location of the input
// string. Therefore code generated for a non-trivial trace is specialized
// to that trace. The code generator therefore has the ability to generate
// code for each node several times. In order to limit the size of the
// generated code there is an arbitrary limit on how many specialized sets of
// code may be generated for a given node. If the limit is reached, the
// trace is flushed and a generic version of the code for a node is emitted.
// This is subsequently used for that node. The code emitted for non-generic
// trace is not recorded in the node and so it cannot currently be reused in
// the event that code generation is requested for an identical trace.
namespace {
constexpr base::uc32 MaxCodeUnit(const bool one_byte) {
static_assert(String::kMaxOneByteCharCodeU <=
std::numeric_limits<uint16_t>::max());
static_assert(String::kMaxUtf16CodeUnitU <=
std::numeric_limits<uint16_t>::max());
return one_byte ? String::kMaxOneByteCharCodeU : String::kMaxUtf16CodeUnitU;
}
constexpr uint32_t CharMask(const bool one_byte) {
static_assert(base::bits::IsPowerOfTwo(String::kMaxOneByteCharCodeU + 1));
static_assert(base::bits::IsPowerOfTwo(String::kMaxUtf16CodeUnitU + 1));
return MaxCodeUnit(one_byte);
}
} // namespace
void RegExpTree::AppendToText(RegExpText* text, Zone* zone) { UNREACHABLE(); }
void RegExpAtom::AppendToText(RegExpText* text, Zone* zone) {
text->AddElement(TextElement::Atom(this), zone);
}
void RegExpClassRanges::AppendToText(RegExpText* text, Zone* zone) {
text->AddElement(TextElement::ClassRanges(this), zone);
}
void RegExpText::AppendToText(RegExpText* text, Zone* zone) {
for (int i = 0; i < elements()->length(); i++)
text->AddElement(elements()->at(i), zone);
}
TextElement TextElement::Atom(RegExpAtom* atom) {
return TextElement(ATOM, atom);
}
TextElement TextElement::ClassRanges(RegExpClassRanges* class_ranges) {
return TextElement(CLASS_RANGES, class_ranges);
}
int TextElement::length() const {
switch (text_type()) {
case ATOM:
return atom()->length();
case CLASS_RANGES:
return 1;
}
UNREACHABLE();
}
class RecursionCheck {
public:
explicit RecursionCheck(RegExpCompiler* compiler) : compiler_(compiler) {
compiler->IncrementRecursionDepth();
}
~RecursionCheck() { compiler_->DecrementRecursionDepth(); }
private:
RegExpCompiler* compiler_;
};
// Attempts to compile the regexp using an Irregexp code generator. Returns
// a fixed array or a null handle depending on whether it succeeded.
RegExpCompiler::RegExpCompiler(Isolate* isolate, Zone* zone, int capture_count,
RegExpFlags flags, bool one_byte)
: next_register_(JSRegExp::RegistersForCaptureCount(capture_count)),
unicode_lookaround_stack_register_(kNoRegister),
unicode_lookaround_position_register_(kNoRegister),
work_list_(nullptr),
recursion_depth_(0),
flags_(flags),
one_byte_(one_byte),
reg_exp_too_big_(false),
limiting_recursion_(false),
optimize_(v8_flags.regexp_optimization),
read_backward_(false),
current_expansion_factor_(1),
frequency_collator_(),
isolate_(isolate),
zone_(zone) {
accept_ = zone->New<EndNode>(EndNode::ACCEPT, zone);
DCHECK_GE(RegExpMacroAssembler::kMaxRegister, next_register_ - 1);
}
RegExpCompiler::CompilationResult RegExpCompiler::Assemble(
Isolate* isolate, RegExpMacroAssembler* macro_assembler, RegExpNode* start,
int capture_count, Handle<String> pattern) {
macro_assembler_ = macro_assembler;
ZoneVector<RegExpNode*> work_list(zone());
work_list_ = &work_list;
Label fail;
macro_assembler_->PushBacktrack(&fail);
Trace new_trace;
start->Emit(this, &new_trace);
macro_assembler_->BindJumpTarget(&fail);
macro_assembler_->Fail();
while (!work_list.empty()) {
RegExpNode* node = work_list.back();
work_list.pop_back();
node->set_on_work_list(false);
if (!node->label()->is_bound()) node->Emit(this, &new_trace);
}
if (reg_exp_too_big_) {
if (v8_flags.correctness_fuzzer_suppressions) {
FATAL("Aborting on excess zone allocation");
}
macro_assembler_->AbortedCodeGeneration();
return CompilationResult::RegExpTooBig();
}
Handle<HeapObject> code = macro_assembler_->GetCode(pattern);
isolate->IncreaseTotalRegexpCodeGenerated(code);
work_list_ = nullptr;
return {code, next_register_};
}
bool Trace::DeferredAction::Mentions(int that) {
if (action_type() == ActionNode::CLEAR_CAPTURES) {
Interval range = static_cast<DeferredClearCaptures*>(this)->range();
return range.Contains(that);
} else {
return reg() == that;
}
}
bool Trace::mentions_reg(int reg) {
for (DeferredAction* action = actions_; action != nullptr;
action = action->next()) {
if (action->Mentions(reg)) return true;
}
return false;
}
bool Trace::GetStoredPosition(int reg, int* cp_offset) {
DCHECK_EQ(0, *cp_offset);
for (DeferredAction* action = actions_; action != nullptr;
action = action->next()) {
if (action->Mentions(reg)) {
if (action->action_type() == ActionNode::STORE_POSITION) {
*cp_offset = static_cast<DeferredCapture*>(action)->cp_offset();
return true;
} else {
return false;
}
}
}
return false;
}
// A (dynamically-sized) set of unsigned integers that behaves especially well
// on small integers (< kFirstLimit). May do zone-allocation.
class DynamicBitSet : public ZoneObject {
public:
V8_EXPORT_PRIVATE bool Get(unsigned value) const {
if (value < kFirstLimit) {
return (first_ & (1 << value)) != 0;
} else if (remaining_ == nullptr) {
return false;
} else {
return remaining_->Contains(value);
}
}
// Destructively set a value in this set.
void Set(unsigned value, Zone* zone) {
if (value < kFirstLimit) {
first_ |= (1 << value);
} else {
if (remaining_ == nullptr)
remaining_ = zone->New<ZoneList<unsigned>>(1, zone);
if (remaining_->is_empty() || !remaining_->Contains(value))
remaining_->Add(value, zone);
}
}
private:
static constexpr unsigned kFirstLimit = 32;
uint32_t first_ = 0;
ZoneList<unsigned>* remaining_ = nullptr;
};
int Trace::FindAffectedRegisters(DynamicBitSet* affected_registers,
Zone* zone) {
int max_register = RegExpCompiler::kNoRegister;
for (DeferredAction* action = actions_; action != nullptr;
action = action->next()) {
if (action->action_type() == ActionNode::CLEAR_CAPTURES) {
Interval range = static_cast<DeferredClearCaptures*>(action)->range();
for (int i = range.from(); i <= range.to(); i++)
affected_registers->Set(i, zone);
if (range.to() > max_register) max_register = range.to();
} else {
affected_registers->Set(action->reg(), zone);
if (action->reg() > max_register) max_register = action->reg();
}
}
return max_register;
}
void Trace::RestoreAffectedRegisters(RegExpMacroAssembler* assembler,
int max_register,
const DynamicBitSet& registers_to_pop,
const DynamicBitSet& registers_to_clear) {
for (int reg = max_register; reg >= 0; reg--) {
if (registers_to_pop.Get(reg)) {
assembler->PopRegister(reg);
} else if (registers_to_clear.Get(reg)) {
int clear_to = reg;
while (reg > 0 && registers_to_clear.Get(reg - 1)) {
reg--;
}
assembler->ClearRegisters(reg, clear_to);
}
}
}
void Trace::PerformDeferredActions(RegExpMacroAssembler* assembler,
int max_register,
const DynamicBitSet& affected_registers,
DynamicBitSet* registers_to_pop,
DynamicBitSet* registers_to_clear,
Zone* zone) {
// The "+1" is to avoid a push_limit of zero if stack_limit_slack() is 1.
const int push_limit = (assembler->stack_limit_slack() + 1) / 2;
// Count pushes performed to force a stack limit check occasionally.
int pushes = 0;
for (int reg = 0; reg <= max_register; reg++) {
if (!affected_registers.Get(reg)) continue;
// The chronologically first deferred action in the trace
// is used to infer the action needed to restore a register
// to its previous state (or not, if it's safe to ignore it).
enum DeferredActionUndoType { IGNORE, RESTORE, CLEAR };
DeferredActionUndoType undo_action = IGNORE;
int value = 0;
bool absolute = false;
bool clear = false;
static const int kNoStore = kMinInt;
int store_position = kNoStore;
// This is a little tricky because we are scanning the actions in reverse
// historical order (newest first).
for (DeferredAction* action = actions_; action != nullptr;
action = action->next()) {
if (action->Mentions(reg)) {
switch (action->action_type()) {
case ActionNode::SET_REGISTER_FOR_LOOP: {
Trace::DeferredSetRegisterForLoop* psr =
static_cast<Trace::DeferredSetRegisterForLoop*>(action);
if (!absolute) {
value += psr->value();
absolute = true;
}
// SET_REGISTER_FOR_LOOP is only used for newly introduced loop
// counters. They can have a significant previous value if they
// occur in a loop. TODO(lrn): Propagate this information, so
// we can set undo_action to IGNORE if we know there is no value to
// restore.
undo_action = RESTORE;
DCHECK_EQ(store_position, kNoStore);
DCHECK(!clear);
break;
}
case ActionNode::INCREMENT_REGISTER:
if (!absolute) {
value++;
}
DCHECK_EQ(store_position, kNoStore);
DCHECK(!clear);
undo_action = RESTORE;
break;
case ActionNode::STORE_POSITION: {
Trace::DeferredCapture* pc =
static_cast<Trace::DeferredCapture*>(action);
if (!clear && store_position == kNoStore) {
store_position = pc->cp_offset();
}
// For captures we know that stores and clears alternate.
// Other register, are never cleared, and if the occur
// inside a loop, they might be assigned more than once.
if (reg <= 1) {
// Registers zero and one, aka "capture zero", is
// always set correctly if we succeed. There is no
// need to undo a setting on backtrack, because we
// will set it again or fail.
undo_action = IGNORE;
} else {
undo_action = pc->is_capture() ? CLEAR : RESTORE;
}
DCHECK(!absolute);
DCHECK_EQ(value, 0);
break;
}
case ActionNode::CLEAR_CAPTURES: {
// Since we're scanning in reverse order, if we've already
// set the position we have to ignore historically earlier
// clearing operations.
if (store_position == kNoStore) {
clear = true;
}
undo_action = RESTORE;
DCHECK(!absolute);
DCHECK_EQ(value, 0);
break;
}
default:
UNREACHABLE();
}
}
}
// Prepare for the undo-action (e.g., push if it's going to be popped).
if (undo_action == RESTORE) {
pushes++;
RegExpMacroAssembler::StackCheckFlag stack_check =
RegExpMacroAssembler::kNoStackLimitCheck;
if (pushes == push_limit) {
stack_check = RegExpMacroAssembler::kCheckStackLimit;
pushes = 0;
}
assembler->PushRegister(reg, stack_check);
registers_to_pop->Set(reg, zone);
} else if (undo_action == CLEAR) {
registers_to_clear->Set(reg, zone);
}
// Perform the chronologically last action (or accumulated increment)
// for the register.
if (store_position != kNoStore) {
assembler->WriteCurrentPositionToRegister(reg, store_position);
} else if (clear) {
assembler->ClearRegisters(reg, reg);
} else if (absolute) {
assembler->SetRegister(reg, value);
} else if (value != 0) {
assembler->AdvanceRegister(reg, value);
}
}
}
// This is called as we come into a loop choice node and some other tricky
// nodes. It normalizes the state of the code generator to ensure we can
// generate generic code.
void Trace::Flush(RegExpCompiler* compiler, RegExpNode* successor) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
DCHECK(!is_trivial());
if (actions_ == nullptr && backtrack() == nullptr) {
// Here we just have some deferred cp advances to fix and we are back to
// a normal situation. We may also have to forget some information gained
// through a quick check that was already performed.
if (cp_offset_ != 0) assembler->AdvanceCurrentPosition(cp_offset_);
// Create a new trivial state and generate the node with that.
Trace new_state;
successor->Emit(compiler, &new_state);
return;
}
// Generate deferred actions here along with code to undo them again.
DynamicBitSet affected_registers;
if (backtrack() != nullptr) {
// Here we have a concrete backtrack location. These are set up by choice
// nodes and so they indicate that we have a deferred save of the current
// position which we may need to emit here.
assembler->PushCurrentPosition();
}
int max_register =
FindAffectedRegisters(&affected_registers, compiler->zone());
DynamicBitSet registers_to_pop;
DynamicBitSet registers_to_clear;
PerformDeferredActions(assembler, max_register, affected_registers,
®isters_to_pop, ®isters_to_clear,
compiler->zone());
if (cp_offset_ != 0) {
assembler->AdvanceCurrentPosition(cp_offset_);
}
// Create a new trivial state and generate the node with that.
Label undo;
assembler->PushBacktrack(&undo);
if (successor->KeepRecursing(compiler)) {
Trace new_state;
successor->Emit(compiler, &new_state);
} else {
compiler->AddWork(successor);
assembler->GoTo(successor->label());
}
// On backtrack we need to restore state.
assembler->BindJumpTarget(&undo);
RestoreAffectedRegisters(assembler, max_register, registers_to_pop,
registers_to_clear);
if (backtrack() == nullptr) {
assembler->Backtrack();
} else {
assembler->PopCurrentPosition();
assembler->GoTo(backtrack());
}
}
void NegativeSubmatchSuccess::Emit(RegExpCompiler* compiler, Trace* trace) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
// Omit flushing the trace. We discard the entire stack frame anyway.
if (!label()->is_bound()) {
// We are completely independent of the trace, since we ignore it,
// so this code can be used as the generic version.
assembler->Bind(label());
}
// Throw away everything on the backtrack stack since the start
// of the negative submatch and restore the character position.
assembler->ReadCurrentPositionFromRegister(current_position_register_);
assembler->ReadStackPointerFromRegister(stack_pointer_register_);
if (clear_capture_count_ > 0) {
// Clear any captures that might have been performed during the success
// of the body of the negative look-ahead.
int clear_capture_end = clear_capture_start_ + clear_capture_count_ - 1;
assembler->ClearRegisters(clear_capture_start_, clear_capture_end);
}
// Now that we have unwound the stack we find at the top of the stack the
// backtrack that the BeginNegativeSubmatch node got.
assembler->Backtrack();
}
void EndNode::Emit(RegExpCompiler* compiler, Trace* trace) {
if (!trace->is_trivial()) {
trace->Flush(compiler, this);
return;
}
RegExpMacroAssembler* assembler = compiler->macro_assembler();
if (!label()->is_bound()) {
assembler->Bind(label());
}
switch (action_) {
case ACCEPT:
assembler->Succeed();
return;
case BACKTRACK:
assembler->GoTo(trace->backtrack());
return;
case NEGATIVE_SUBMATCH_SUCCESS:
// This case is handled in a different virtual method.
UNREACHABLE();
}
UNIMPLEMENTED();
}
void GuardedAlternative::AddGuard(Guard* guard, Zone* zone) {
if (guards_ == nullptr) guards_ = zone->New<ZoneList<Guard*>>(1, zone);
guards_->Add(guard, zone);
}
ActionNode* ActionNode::SetRegisterForLoop(int reg, int val,
RegExpNode* on_success) {
ActionNode* result =
on_success->zone()->New<ActionNode>(SET_REGISTER_FOR_LOOP, on_success);
result->data_.u_store_register.reg = reg;
result->data_.u_store_register.value = val;
return result;
}
ActionNode* ActionNode::IncrementRegister(int reg, RegExpNode* on_success) {
ActionNode* result =
on_success->zone()->New<ActionNode>(INCREMENT_REGISTER, on_success);
result->data_.u_increment_register.reg = reg;
return result;
}
ActionNode* ActionNode::StorePosition(int reg, bool is_capture,
RegExpNode* on_success) {
ActionNode* result =
on_success->zone()->New<ActionNode>(STORE_POSITION, on_success);
result->data_.u_position_register.reg = reg;
result->data_.u_position_register.is_capture = is_capture;
return result;
}
ActionNode* ActionNode::ClearCaptures(Interval range, RegExpNode* on_success) {
ActionNode* result =
on_success->zone()->New<ActionNode>(CLEAR_CAPTURES, on_success);
result->data_.u_clear_captures.range_from = range.from();
result->data_.u_clear_captures.range_to = range.to();
return result;
}
ActionNode* ActionNode::BeginPositiveSubmatch(int stack_reg, int position_reg,
RegExpNode* on_success) {
ActionNode* result =
on_success->zone()->New<ActionNode>(BEGIN_POSITIVE_SUBMATCH, on_success);
result->data_.u_submatch.stack_pointer_register = stack_reg;
result->data_.u_submatch.current_position_register = position_reg;
return result;
}
ActionNode* ActionNode::BeginNegativeSubmatch(int stack_reg, int position_reg,
RegExpNode* on_success) {
ActionNode* result =
on_success->zone()->New<ActionNode>(BEGIN_NEGATIVE_SUBMATCH, on_success);
result->data_.u_submatch.stack_pointer_register = stack_reg;
result->data_.u_submatch.current_position_register = position_reg;
return result;
}
ActionNode* ActionNode::PositiveSubmatchSuccess(int stack_reg, int position_reg,
int clear_register_count,
int clear_register_from,
RegExpNode* on_success) {
ActionNode* result = on_success->zone()->New<ActionNode>(
POSITIVE_SUBMATCH_SUCCESS, on_success);
result->data_.u_submatch.stack_pointer_register = stack_reg;
result->data_.u_submatch.current_position_register = position_reg;
result->data_.u_submatch.clear_register_count = clear_register_count;
result->data_.u_submatch.clear_register_from = clear_register_from;
return result;
}
ActionNode* ActionNode::EmptyMatchCheck(int start_register,
int repetition_register,
int repetition_limit,
RegExpNode* on_success) {
ActionNode* result =
on_success->zone()->New<ActionNode>(EMPTY_MATCH_CHECK, on_success);
result->data_.u_empty_match_check.start_register = start_register;
result->data_.u_empty_match_check.repetition_register = repetition_register;
result->data_.u_empty_match_check.repetition_limit = repetition_limit;
return result;
}
#define DEFINE_ACCEPT(Type) \
void Type##Node::Accept(NodeVisitor* visitor) { visitor->Visit##Type(this); }
FOR_EACH_NODE_TYPE(DEFINE_ACCEPT)
#undef DEFINE_ACCEPT
// -------------------------------------------------------------------
// Emit code.
void ChoiceNode::GenerateGuard(RegExpMacroAssembler* macro_assembler,
Guard* guard, Trace* trace) {
switch (guard->op()) {
case Guard::LT:
DCHECK(!trace->mentions_reg(guard->reg()));
macro_assembler->IfRegisterGE(guard->reg(), guard->value(),
trace->backtrack());
break;
case Guard::GEQ:
DCHECK(!trace->mentions_reg(guard->reg()));
macro_assembler->IfRegisterLT(guard->reg(), guard->value(),
trace->backtrack());
break;
}
}
namespace {
#ifdef DEBUG
bool ContainsOnlyUtf16CodeUnits(unibrow::uchar* chars, int length) {
static_assert(sizeof(unibrow::uchar) == 4);
for (int i = 0; i < length; i++) {
if (chars[i] > String::kMaxUtf16CodeUnit) return false;
}
return true;
}
#endif // DEBUG
// Returns the number of characters in the equivalence class, omitting those
// that cannot occur in the source string because it is Latin1.
int GetCaseIndependentLetters(Isolate* isolate, base::uc16 character,
bool one_byte_subject, unibrow::uchar* letters,
int letter_length) {
#ifdef V8_INTL_SUPPORT
if (RegExpCaseFolding::IgnoreSet().contains(character)) {
letters[0] = character;
DCHECK(ContainsOnlyUtf16CodeUnits(letters, 1));
return 1;
}
bool in_special_add_set =
RegExpCaseFolding::SpecialAddSet().contains(character);
icu::UnicodeSet set;
set.add(character);
set = set.closeOver(USET_CASE_INSENSITIVE);
UChar32 canon = 0;
if (in_special_add_set) {
canon = RegExpCaseFolding::Canonicalize(character);
}
int32_t range_count = set.getRangeCount();
int items = 0;
for (int32_t i = 0; i < range_count; i++) {
UChar32 start = set.getRangeStart(i);
UChar32 end = set.getRangeEnd(i);
CHECK(end - start + items <= letter_length);
for (UChar32 cu = start; cu <= end; cu++) {
if (one_byte_subject && cu > String::kMaxOneByteCharCode) break;
if (in_special_add_set && RegExpCaseFolding::Canonicalize(cu) != canon) {
continue;
}
letters[items++] = static_cast<unibrow::uchar>(cu);
}
}
DCHECK(ContainsOnlyUtf16CodeUnits(letters, items));
return items;
#else
int length =
isolate->jsregexp_uncanonicalize()->get(character, '\0', letters);
// Unibrow returns 0 or 1 for characters where case independence is
// trivial.
if (length == 0) {
letters[0] = character;
length = 1;
}
if (one_byte_subject) {
int new_length = 0;
for (int i = 0; i < length; i++) {
if (letters[i] <= String::kMaxOneByteCharCode) {
letters[new_length++] = letters[i];
}
}
length = new_length;
}
DCHECK(ContainsOnlyUtf16CodeUnits(letters, length));
return length;
#endif // V8_INTL_SUPPORT
}
inline bool EmitSimpleCharacter(Isolate* isolate, RegExpCompiler* compiler,
base::uc16 c, Label* on_failure, int cp_offset,
bool check, bool preloaded) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
bool bound_checked = false;
if (!preloaded) {
assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
bound_checked = true;
}
assembler->CheckNotCharacter(c, on_failure);
return bound_checked;
}
// Only emits non-letters (things that don't have case). Only used for case
// independent matches.
inline bool EmitAtomNonLetter(Isolate* isolate, RegExpCompiler* compiler,
base::uc16 c, Label* on_failure, int cp_offset,
bool check, bool preloaded) {
RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
bool one_byte = compiler->one_byte();
unibrow::uchar chars[4];
int length = GetCaseIndependentLetters(isolate, c, one_byte, chars, 4);
if (length < 1) {
// This can't match. Must be an one-byte subject and a non-one-byte
// character. We do not need to do anything since the one-byte pass
// already handled this.
return false; // Bounds not checked.
}
bool checked = false;
// We handle the length > 1 case in a later pass.
if (length == 1) {
if (one_byte && c > String::kMaxOneByteCharCodeU) {
// Can't match - see above.
return false; // Bounds not checked.
}
if (!preloaded) {
macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
checked = check;
}
macro_assembler->CheckNotCharacter(c, on_failure);
}
return checked;
}
bool ShortCutEmitCharacterPair(RegExpMacroAssembler* macro_assembler,
bool one_byte, base::uc16 c1, base::uc16 c2,
Label* on_failure) {
const uint32_t char_mask = CharMask(one_byte);
base::uc16 exor = c1 ^ c2;
// Check whether exor has only one bit set.
if (((exor - 1) & exor) == 0) {
// If c1 and c2 differ only by one bit.
// Ecma262UnCanonicalize always gives the highest number last.
DCHECK(c2 > c1);
base::uc16 mask = char_mask ^ exor;
macro_assembler->CheckNotCharacterAfterAnd(c1, mask, on_failure);
return true;
}
DCHECK(c2 > c1);
base::uc16 diff = c2 - c1;
if (((diff - 1) & diff) == 0 && c1 >= diff) {
// If the characters differ by 2^n but don't differ by one bit then
// subtract the difference from the found character, then do the or
// trick. We avoid the theoretical case where negative numbers are
// involved in order to simplify code generation.
base::uc16 mask = char_mask ^ diff;
macro_assembler->CheckNotCharacterAfterMinusAnd(c1 - diff, diff, mask,
on_failure);
return true;
}
return false;
}
// Only emits letters (things that have case). Only used for case independent
// matches.
inline bool EmitAtomLetter(Isolate* isolate, RegExpCompiler* compiler,
base::uc16 c, Label* on_failure, int cp_offset,
bool check, bool preloaded) {
RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
bool one_byte = compiler->one_byte();
unibrow::uchar chars[4];
int length = GetCaseIndependentLetters(isolate, c, one_byte, chars, 4);
if (length <= 1) return false;
// We may not need to check against the end of the input string
// if this character lies before a character that matched.
if (!preloaded) {
macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
}
Label ok;
switch (length) {
case 2: {
if (ShortCutEmitCharacterPair(macro_assembler, one_byte, chars[0],
chars[1], on_failure)) {
} else {
macro_assembler->CheckCharacter(chars[0], &ok);
macro_assembler->CheckNotCharacter(chars[1], on_failure);
macro_assembler->Bind(&ok);
}
break;
}
case 4:
macro_assembler->CheckCharacter(chars[3], &ok);
V8_FALLTHROUGH;
case 3:
macro_assembler->CheckCharacter(chars[0], &ok);
macro_assembler->CheckCharacter(chars[1], &ok);
macro_assembler->CheckNotCharacter(chars[2], on_failure);
macro_assembler->Bind(&ok);
break;
default:
UNREACHABLE();
}
return true;
}
void EmitBoundaryTest(RegExpMacroAssembler* masm, int border,
Label* fall_through, Label* above_or_equal,
Label* below) {
if (below != fall_through) {
masm->CheckCharacterLT(border, below);
if (above_or_equal != fall_through) masm->GoTo(above_or_equal);
} else {
masm->CheckCharacterGT(border - 1, above_or_equal);
}
}
void EmitDoubleBoundaryTest(RegExpMacroAssembler* masm, int first, int last,
Label* fall_through, Label* in_range,
Label* out_of_range) {
if (in_range == fall_through) {
if (first == last) {
masm->CheckNotCharacter(first, out_of_range);
} else {
masm->CheckCharacterNotInRange(first, last, out_of_range);
}
} else {
if (first == last) {
masm->CheckCharacter(first, in_range);
} else {
masm->CheckCharacterInRange(first, last, in_range);
}
if (out_of_range != fall_through) masm->GoTo(out_of_range);
}
}
// even_label is for ranges[i] to ranges[i + 1] where i - start_index is even.
// odd_label is for ranges[i] to ranges[i + 1] where i - start_index is odd.
void EmitUseLookupTable(RegExpMacroAssembler* masm,
ZoneList<base::uc32>* ranges, uint32_t start_index,
uint32_t end_index, base::uc32 min_char,
Label* fall_through, Label* even_label,
Label* odd_label) {
static const uint32_t kSize = RegExpMacroAssembler::kTableSize;
static const uint32_t kMask = RegExpMacroAssembler::kTableMask;
base::uc32 base = (min_char & ~kMask);
USE(base);
// Assert that everything is on one kTableSize page.
for (uint32_t i = start_index; i <= end_index; i++) {
DCHECK_EQ(ranges->at(i) & ~kMask, base);
}
DCHECK(start_index == 0 || (ranges->at(start_index - 1) & ~kMask) <= base);
char templ[kSize];
Label* on_bit_set;
Label* on_bit_clear;
int bit;
if (even_label == fall_through) {
on_bit_set = odd_label;
on_bit_clear = even_label;
bit = 1;
} else {
on_bit_set = even_label;
on_bit_clear = odd_label;
bit = 0;
}
for (uint32_t i = 0; i < (ranges->at(start_index) & kMask) && i < kSize;
i++) {
templ[i] = bit;
}
uint32_t j = 0;
bit ^= 1;
for (uint32_t i = start_index; i < end_index; i++) {
for (j = (ranges->at(i) & kMask); j < (ranges->at(i + 1) & kMask); j++) {
templ[j] = bit;
}
bit ^= 1;
}
for (uint32_t i = j; i < kSize; i++) {
templ[i] = bit;
}
Factory* factory = masm->isolate()->factory();
// TODO(erikcorry): Cache these.
Handle<ByteArray> ba = factory->NewByteArray(kSize, AllocationType::kOld);
for (uint32_t i = 0; i < kSize; i++) {
ba->set(i, templ[i]);
}
masm->CheckBitInTable(ba, on_bit_set);
if (on_bit_clear != fall_through) masm->GoTo(on_bit_clear);
}
void CutOutRange(RegExpMacroAssembler* masm, ZoneList<base::uc32>* ranges,
uint32_t start_index, uint32_t end_index, uint32_t cut_index,
Label* even_label, Label* odd_label) {
bool odd = (((cut_index - start_index) & 1) == 1);
Label* in_range_label = odd ? odd_label : even_label;
Label dummy;
EmitDoubleBoundaryTest(masm, ranges->at(cut_index),
ranges->at(cut_index + 1) - 1, &dummy, in_range_label,
&dummy);
DCHECK(!dummy.is_linked());
// Cut out the single range by rewriting the array. This creates a new
// range that is a merger of the two ranges on either side of the one we
// are cutting out. The oddity of the labels is preserved.
for (uint32_t j = cut_index; j > start_index; j--) {
ranges->at(j) = ranges->at(j - 1);
}
for (uint32_t j = cut_index + 1; j < end_index; j++) {
ranges->at(j) = ranges->at(j + 1);
}
}
// Unicode case. Split the search space into kSize spaces that are handled
// with recursion.
void SplitSearchSpace(ZoneList<base::uc32>* ranges, uint32_t start_index,
uint32_t end_index, uint32_t* new_start_index,
uint32_t* new_end_index, base::uc32* border) {
static const uint32_t kSize = RegExpMacroAssembler::kTableSize;
static const uint32_t kMask = RegExpMacroAssembler::kTableMask;
base::uc32 first = ranges->at(start_index);
base::uc32 last = ranges->at(end_index) - 1;
*new_start_index = start_index;
*border = (ranges->at(start_index) & ~kMask) + kSize;
while (*new_start_index < end_index) {
if (ranges->at(*new_start_index) > *border) break;
(*new_start_index)++;
}
// new_start_index is the index of the first edge that is beyond the
// current kSize space.
// For very large search spaces we do a binary chop search of the non-Latin1
// space instead of just going to the end of the current kSize space. The
// heuristics are complicated a little by the fact that any 128-character
// encoding space can be quickly tested with a table lookup, so we don't
// wish to do binary chop search at a smaller granularity than that. A
// 128-character space can take up a lot of space in the ranges array if,
// for example, we only want to match every second character (eg. the lower
// case characters on some Unicode pages).
uint32_t binary_chop_index = (end_index + start_index) / 2;
// The first test ensures that we get to the code that handles the Latin1
// range with a single not-taken branch, speeding up this important
// character range (even non-Latin1 charset-based text has spaces and
// punctuation).
if (*border - 1 > String::kMaxOneByteCharCode && // Latin1 case.
end_index - start_index > (*new_start_index - start_index) * 2 &&
last - first > kSize * 2 && binary_chop_index > *new_start_index &&
ranges->at(binary_chop_index) >= first + 2 * kSize) {
uint32_t scan_forward_for_section_border = binary_chop_index;
uint32_t new_border = (ranges->at(binary_chop_index) | kMask) + 1;
while (scan_forward_for_section_border < end_index) {
if (ranges->at(scan_forward_for_section_border) > new_border) {
*new_start_index = scan_forward_for_section_border;
*border = new_border;
break;
}
scan_forward_for_section_border++;
}
}
DCHECK(*new_start_index > start_index);
*new_end_index = *new_start_index - 1;
if (ranges->at(*new_end_index) == *border) {
(*new_end_index)--;
}
if (*border >= ranges->at(end_index)) {
*border = ranges->at(end_index);
*new_start_index = end_index; // Won't be used.
*new_end_index = end_index - 1;
}
}
// Gets a series of segment boundaries representing a character class. If the
// character is in the range between an even and an odd boundary (counting from
// start_index) then go to even_label, otherwise go to odd_label. We already
// know that the character is in the range of min_char to max_char inclusive.
// Either label can be nullptr indicating backtracking. Either label can also
// be equal to the fall_through label.
void GenerateBranches(RegExpMacroAssembler* masm, ZoneList<base::uc32>* ranges,
uint32_t start_index, uint32_t end_index,
base::uc32 min_char, base::uc32 max_char,
Label* fall_through, Label* even_label,
Label* odd_label) {
DCHECK_LE(min_char, String::kMaxUtf16CodeUnit);
DCHECK_LE(max_char, String::kMaxUtf16CodeUnit);
base::uc32 first = ranges->at(start_index);
base::uc32 last = ranges->at(end_index) - 1;
DCHECK_LT(min_char, first);
// Just need to test if the character is before or on-or-after
// a particular character.
if (start_index == end_index) {
EmitBoundaryTest(masm, first, fall_through, even_label, odd_label);
return;
}
// Another almost trivial case: There is one interval in the middle that is
// different from the end intervals.
if (start_index + 1 == end_index) {
EmitDoubleBoundaryTest(masm, first, last, fall_through, even_label,
odd_label);
return;
}
// It's not worth using table lookup if there are very few intervals in the
// character class.
if (end_index - start_index <= 6) {
// It is faster to test for individual characters, so we look for those
// first, then try arbitrary ranges in the second round.
static uint32_t kNoCutIndex = -1;
uint32_t cut = kNoCutIndex;
for (uint32_t i = start_index; i < end_index; i++) {
if (ranges->at(i) == ranges->at(i + 1) - 1) {
cut = i;
break;
}
}
if (cut == kNoCutIndex) cut = start_index;
CutOutRange(masm, ranges, start_index, end_index, cut, even_label,
odd_label);
DCHECK_GE(end_index - start_index, 2);
GenerateBranches(masm, ranges, start_index + 1, end_index - 1, min_char,
max_char, fall_through, even_label, odd_label);
return;
}
// If there are a lot of intervals in the regexp, then we will use tables to
// determine whether the character is inside or outside the character class.
static const int kBits = RegExpMacroAssembler::kTableSizeBits;
if ((max_char >> kBits) == (min_char >> kBits)) {
EmitUseLookupTable(masm, ranges, start_index, end_index, min_char,
fall_through, even_label, odd_label);
return;
}
if ((min_char >> kBits) != first >> kBits) {
masm->CheckCharacterLT(first, odd_label);
GenerateBranches(masm, ranges, start_index + 1, end_index, first, max_char,
fall_through, odd_label, even_label);
return;
}
uint32_t new_start_index = 0;
uint32_t new_end_index = 0;
base::uc32 border = 0;
SplitSearchSpace(ranges, start_index, end_index, &new_start_index,
&new_end_index, &border);
Label handle_rest;
Label* above = &handle_rest;
if (border == last + 1) {
// We didn't find any section that started after the limit, so everything
// above the border is one of the terminal labels.
above = (end_index & 1) != (start_index & 1) ? odd_label : even_label;
DCHECK(new_end_index == end_index - 1);
}
DCHECK_LE(start_index, new_end_index);
DCHECK_LE(new_start_index, end_index);
DCHECK_LT(start_index, new_start_index);
DCHECK_LT(new_end_index, end_index);
DCHECK(new_end_index + 1 == new_start_index ||
(new_end_index + 2 == new_start_index &&
border == ranges->at(new_end_index + 1)));
DCHECK_LT(min_char, border - 1);
DCHECK_LT(border, max_char);
DCHECK_LT(ranges->at(new_end_index), border);
DCHECK(border < ranges->at(new_start_index) ||
(border == ranges->at(new_start_index) &&
new_start_index == end_index && new_end_index == end_index - 1 &&
border == last + 1));
DCHECK(new_start_index == 0 || border >= ranges->at(new_start_index - 1));
masm->CheckCharacterGT(border - 1, above);
Label dummy;
GenerateBranches(masm, ranges, start_index, new_end_index, min_char,
border - 1, &dummy, even_label, odd_label);
if (handle_rest.is_linked()) {
masm->Bind(&handle_rest);
bool flip = (new_start_index & 1) != (start_index & 1);
GenerateBranches(masm, ranges, new_start_index, end_index, border, max_char,
&dummy, flip ? odd_label : even_label,
flip ? even_label : odd_label);
}
}
void EmitClassRanges(RegExpMacroAssembler* macro_assembler,
RegExpClassRanges* cr, bool one_byte, Label* on_failure,
int cp_offset, bool check_offset, bool preloaded,
Zone* zone) {
ZoneList<CharacterRange>* ranges = cr->ranges(zone);
CharacterRange::Canonicalize(ranges);
// Now that all processing (like case-insensitivity) is done, clamp the
// ranges to the set of ranges that may actually occur in the subject string.
if (one_byte) CharacterRange::ClampToOneByte(ranges);
const int ranges_length = ranges->length();
if (ranges_length == 0) {
if (!cr->is_negated()) {
macro_assembler->GoTo(on_failure);
}
if (check_offset) {
macro_assembler->CheckPosition(cp_offset, on_failure);
}
return;
}
const base::uc32 max_char = MaxCodeUnit(one_byte);
if (ranges_length == 1 && ranges->at(0).IsEverything(max_char)) {
if (cr->is_negated()) {
macro_assembler->GoTo(on_failure);
} else {
// This is a common case hit by non-anchored expressions.
if (check_offset) {
macro_assembler->CheckPosition(cp_offset, on_failure);
}
}
return;
}
if (!preloaded) {
macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check_offset);
}
if (cr->is_standard(zone) && macro_assembler->CheckSpecialClassRanges(
cr->standard_type(), on_failure)) {
return;
}
static constexpr int kMaxRangesForInlineBranchGeneration = 16;
if (ranges_length > kMaxRangesForInlineBranchGeneration) {
// For large range sets, emit a more compact instruction sequence to avoid
// a potentially problematic increase in code size.
// Note the flipped logic below (we check InRange if negated, NotInRange if
// not negated); this is necessary since the method falls through on
// failure whereas we want to fall through on success.
if (cr->is_negated()) {
if (macro_assembler->CheckCharacterInRangeArray(ranges, on_failure)) {
return;
}
} else {
if (macro_assembler->CheckCharacterNotInRangeArray(ranges, on_failure)) {
return;
}
}
}
// Generate a flat list of range boundaries for consumption by
// GenerateBranches. See the comment on that function for how the list should
// be structured
ZoneList<base::uc32>* range_boundaries =
zone->New<ZoneList<base::uc32>>(ranges_length * 2, zone);
bool zeroth_entry_is_failure = !cr->is_negated();
for (int i = 0; i < ranges_length; i++) {
CharacterRange& range = ranges->at(i);
if (range.from() == 0) {
DCHECK_EQ(i, 0);
zeroth_entry_is_failure = !zeroth_entry_is_failure;
} else {
range_boundaries->Add(range.from(), zone);
}
// `+ 1` to convert from inclusive to exclusive `to`.
// [from, to] == [from, to+1[.
range_boundaries->Add(range.to() + 1, zone);
}
int end_index = range_boundaries->length() - 1;
if (range_boundaries->at(end_index) > max_char) {
end_index--;
}
Label fall_through;
GenerateBranches(macro_assembler, range_boundaries,
0, // start_index.
end_index,
0, // min_char.
max_char, &fall_through,
zeroth_entry_is_failure ? &fall_through : on_failure,
zeroth_entry_is_failure ? on_failure : &fall_through);
macro_assembler->Bind(&fall_through);
}
} // namespace
RegExpNode::~RegExpNode() = default;
RegExpNode::LimitResult RegExpNode::LimitVersions(RegExpCompiler* compiler,
Trace* trace) {
// If we are generating a greedy loop then don't stop and don't reuse code.
if (trace->stop_node() != nullptr) {
return CONTINUE;
}
RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
if (trace->is_trivial()) {
if (label_.is_bound() || on_work_list() || !KeepRecursing(compiler)) {
// If a generic version is already scheduled to be generated or we have
// recursed too deeply then just generate a jump to that code.
macro_assembler->GoTo(&label_);
// This will queue it up for generation of a generic version if it hasn't
// already been queued.
compiler->AddWork(this);
return DONE;
}
// Generate generic version of the node and bind the label for later use.
macro_assembler->Bind(&label_);
return CONTINUE;
}
// We are being asked to make a non-generic version. Keep track of how many
// non-generic versions we generate so as not to overdo it.
trace_count_++;
if (KeepRecursing(compiler) && compiler->optimize() &&
trace_count_ < kMaxCopiesCodeGenerated) {
return CONTINUE;
}
// If we get here code has been generated for this node too many times or
// recursion is too deep. Time to switch to a generic version. The code for
// generic versions above can handle deep recursion properly.
bool was_limiting = compiler->limiting_recursion();
compiler->set_limiting_recursion(true);
trace->Flush(compiler, this);
compiler->set_limiting_recursion(was_limiting);
return DONE;
}
bool RegExpNode::KeepRecursing(RegExpCompiler* compiler) {
return !compiler->limiting_recursion() &&
compiler->recursion_depth() <= RegExpCompiler::kMaxRecursion;
}
void ActionNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
BoyerMooreLookahead* bm, bool not_at_start) {
if (action_type_ == POSITIVE_SUBMATCH_SUCCESS) {
// Anything may follow a positive submatch success, thus we need to accept
// all characters from this position onwards.
bm->SetRest(offset);
} else {
on_success()->FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
}
SaveBMInfo(bm, not_at_start, offset);
}
void ActionNode::GetQuickCheckDetails(QuickCheckDetails* details,
RegExpCompiler* compiler, int filled_in,
bool not_at_start) {
if (action_type_ == SET_REGISTER_FOR_LOOP) {
on_success()->GetQuickCheckDetailsFromLoopEntry(details, compiler,
filled_in, not_at_start);
} else {
on_success()->GetQuickCheckDetails(details, compiler, filled_in,
not_at_start);
}
}
void AssertionNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
BoyerMooreLookahead* bm, bool not_at_start) {
// Match the behaviour of EatsAtLeast on this node.
if (assertion_type() == AT_START && not_at_start) return;
on_success()->FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
SaveBMInfo(bm, not_at_start, offset);
}
void NegativeLookaroundChoiceNode::GetQuickCheckDetails(
QuickCheckDetails* details, RegExpCompiler* compiler, int filled_in,
bool not_at_start) {
RegExpNode* node = continue_node();
return node->GetQuickCheckDetails(details, compiler, filled_in, not_at_start);
}
namespace {
// Takes the left-most 1-bit and smears it out, setting all bits to its right.
inline uint32_t SmearBitsRight(uint32_t v) {
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
return v;
}
} // namespace
bool QuickCheckDetails::Rationalize(bool asc) {
bool found_useful_op = false;
const uint32_t char_mask = CharMask(asc);
mask_ = 0;
value_ = 0;
int char_shift = 0;
for (int i = 0; i < characters_; i++) {
Position* pos = &positions_[i];
if ((pos->mask & String::kMaxOneByteCharCode) != 0) {
found_useful_op = true;
}
mask_ |= (pos->mask & char_mask) << char_shift;
value_ |= (pos->value & char_mask) << char_shift;
char_shift += asc ? 8 : 16;
}
return found_useful_op;
}
int RegExpNode::EatsAtLeast(bool not_at_start) {
return not_at_start ? eats_at_least_.eats_at_least_from_not_start
: eats_at_least_.eats_at_least_from_possibly_start;
}
EatsAtLeastInfo RegExpNode::EatsAtLeastFromLoopEntry() {
// SET_REGISTER_FOR_LOOP is only used to initialize loop counters, and it
// implies that the following node must be a LoopChoiceNode. If we need to
// set registers to constant values for other reasons, we could introduce a
// new action type SET_REGISTER that doesn't imply anything about its
// successor.
UNREACHABLE();
}
void RegExpNode::GetQuickCheckDetailsFromLoopEntry(QuickCheckDetails* details,
RegExpCompiler* compiler,
int characters_filled_in,
bool not_at_start) {
// See comment in RegExpNode::EatsAtLeastFromLoopEntry.
UNREACHABLE();
}
EatsAtLeastInfo LoopChoiceNode::EatsAtLeastFromLoopEntry() {
DCHECK_EQ(alternatives_->length(), 2); // There's just loop and continue.
if (read_backward()) {
// The eats_at_least value is not used if reading backward. The
// EatsAtLeastPropagator should've zeroed it as well.
DCHECK_EQ(eats_at_least_info()->eats_at_least_from_possibly_start, 0);
DCHECK_EQ(eats_at_least_info()->eats_at_least_from_not_start, 0);
return {};
}
// Figure out how much the loop body itself eats, not including anything in
// the continuation case. In general, the nodes in the loop body should report
// that they eat at least the number eaten by the continuation node, since any
// successful match in the loop body must also include the continuation node.
// However, in some cases involving positive lookaround, the loop body under-
// reports its appetite, so use saturated math here to avoid negative numbers.
uint8_t loop_body_from_not_start = base::saturated_cast<uint8_t>(
loop_node_->EatsAtLeast(true) - continue_node_->EatsAtLeast(true));
uint8_t loop_body_from_possibly_start = base::saturated_cast<uint8_t>(
loop_node_->EatsAtLeast(false) - continue_node_->EatsAtLeast(true));
// Limit the number of loop iterations to avoid overflow in subsequent steps.
int loop_iterations = base::saturated_cast<uint8_t>(min_loop_iterations());
EatsAtLeastInfo result;
result.eats_at_least_from_not_start =
base::saturated_cast<uint8_t>(loop_iterations * loop_body_from_not_start +
continue_node_->EatsAtLeast(true));
if (loop_iterations > 0 && loop_body_from_possibly_start > 0) {
// First loop iteration eats at least one, so all subsequent iterations
// and the after-loop chunk are guaranteed to not be at the start.
result.eats_at_least_from_possibly_start = base::saturated_cast<uint8_t>(
loop_body_from_possibly_start +
(loop_iterations - 1) * loop_body_from_not_start +
continue_node_->EatsAtLeast(true));
} else {
// Loop body might eat nothing, so only continue node contributes.
result.eats_at_least_from_possibly_start =
continue_node_->EatsAtLeast(false);
}
return result;
}
bool RegExpNode::EmitQuickCheck(RegExpCompiler* compiler,
Trace* bounds_check_trace, Trace* trace,
bool preload_has_checked_bounds,
Label* on_possible_success,
QuickCheckDetails* details,
bool fall_through_on_failure,
ChoiceNode* predecessor) {
DCHECK_NOT_NULL(predecessor);
if (details->characters() == 0) return false;
GetQuickCheckDetails(details, compiler, 0,
trace->at_start() == Trace::FALSE_VALUE);
if (details->cannot_match()) return false;
if (!details->Rationalize(compiler->one_byte())) return false;
DCHECK(details->characters() == 1 ||
compiler->macro_assembler()->CanReadUnaligned());
uint32_t mask = details->mask();
uint32_t value = details->value();
RegExpMacroAssembler* assembler = compiler->macro_assembler();
if (trace->characters_preloaded() != details->characters()) {
DCHECK(trace->cp_offset() == bounds_check_trace->cp_offset());
// The bounds check is performed using the minimum number of characters
// any choice would eat, so if the bounds check fails, then none of the
// choices can succeed, so we can just immediately backtrack, rather
// than go to the next choice. The number of characters preloaded may be
// less than the number used for the bounds check.
int eats_at_least = predecessor->EatsAtLeast(
bounds_check_trace->at_start() == Trace::FALSE_VALUE);
DCHECK_GE(eats_at_least, details->characters());
assembler->LoadCurrentCharacter(
trace->cp_offset(), bounds_check_trace->backtrack(),
!preload_has_checked_bounds, details->characters(), eats_at_least);
}
bool need_mask = true;
if (details->characters() == 1) {
// If number of characters preloaded is 1 then we used a byte or 16 bit
// load so the value is already masked down.
const uint32_t char_mask = CharMask(compiler->one_byte());
if ((mask & char_mask) == char_mask) need_mask = false;
mask &= char_mask;
} else {
// For 2-character preloads in one-byte mode or 1-character preloads in
// two-byte mode we also use a 16 bit load with zero extend.
static const uint32_t kTwoByteMask = 0xFFFF;
static const uint32_t kFourByteMask = 0xFFFFFFFF;
if (details->characters() == 2 && compiler->one_byte()) {
if ((mask & kTwoByteMask) == kTwoByteMask) need_mask = false;
} else if (details->characters() == 1 && !compiler->one_byte()) {
if ((mask & kTwoByteMask) == kTwoByteMask) need_mask = false;
} else {
if (mask == kFourByteMask) need_mask = false;
}
}
if (fall_through_on_failure) {
if (need_mask) {
assembler->CheckCharacterAfterAnd(value, mask, on_possible_success);
} else {
assembler->CheckCharacter(value, on_possible_success);
}
} else {
if (need_mask) {
assembler->CheckNotCharacterAfterAnd(value, mask, trace->backtrack());
} else {
assembler->CheckNotCharacter(value, trace->backtrack());
}
}
return true;
}
// Here is the meat of GetQuickCheckDetails (see also the comment on the
// super-class in the .h file).
//
// We iterate along the text object, building up for each character a
// mask and value that can be used to test for a quick failure to match.
// The masks and values for the positions will be combined into a single
// machine word for the current character width in order to be used in
// generating a quick check.
void TextNode::GetQuickCheckDetails(QuickCheckDetails* details,
RegExpCompiler* compiler,
int characters_filled_in,
bool not_at_start) {
// Do not collect any quick check details if the text node reads backward,
// since it reads in the opposite direction than we use for quick checks.
if (read_backward()) return;
Isolate* isolate = compiler->macro_assembler()->isolate();
DCHECK(characters_filled_in < details->characters());
int characters = details->characters();
const uint32_t char_mask = CharMask(compiler->one_byte());
for (int k = 0; k < elements()->length(); k++) {
TextElement elm = elements()->at(k);
if (elm.text_type() == TextElement::ATOM) {
base::Vector<const base::uc16> quarks = elm.atom()->data();
for (int i = 0; i < characters && i < quarks.length(); i++) {
QuickCheckDetails::Position* pos =
details->positions(characters_filled_in);
base::uc16 c = quarks[i];
if (IsIgnoreCase(compiler->flags())) {
unibrow::uchar chars[4];
int length = GetCaseIndependentLetters(
isolate, c, compiler->one_byte(), chars, 4);
if (length == 0) {
// This can happen because all case variants are non-Latin1, but we
// know the input is Latin1.
details->set_cannot_match();
pos->determines_perfectly = false;
return;
}
if (length == 1) {
// This letter has no case equivalents, so it's nice and simple
// and the mask-compare will determine definitely whether we have
// a match at this character position.
pos->mask = char_mask;
pos->value = chars[0];
pos->determines_perfectly = true;
} else {
uint32_t common_bits = char_mask;
uint32_t bits = chars[0];
for (int j = 1; j < length; j++) {
uint32_t differing_bits = ((chars[j] & common_bits) ^ bits);
common_bits ^= differing_bits;
bits &= common_bits;
}
// If length is 2 and common bits has only one zero in it then
// our mask and compare instruction will determine definitely
// whether we have a match at this character position. Otherwise
// it can only be an approximate check.
uint32_t one_zero = (common_bits | ~char_mask);
if (length == 2 && ((~one_zero) & ((~one_zero) - 1)) == 0) {
pos->determines_perfectly = true;
}
pos->mask = common_bits;
pos->value = bits;
}
} else {
// Don't ignore case. Nice simple case where the mask-compare will
// determine definitely whether we have a match at this character
// position.
if (c > char_mask) {
details->set_cannot_match();
pos->determines_perfectly = false;
return;
}
pos->mask = char_mask;
pos->value = c;
pos->determines_perfectly = true;
}
characters_filled_in++;
DCHECK(characters_filled_in <= details->characters());
if (characters_filled_in == details->characters()) {
return;
}
}
} else {
QuickCheckDetails::Position* pos =
details->positions(characters_filled_in);
RegExpClassRanges* tree = elm.class_ranges();
ZoneList<CharacterRange>* ranges = tree->ranges(zone());
if (tree->is_negated() || ranges->is_empty()) {
// A quick check uses multi-character mask and compare. There is no
// useful way to incorporate a negative char class into this scheme
// so we just conservatively create a mask and value that will always
// succeed.
// Likewise for empty ranges (empty ranges can occur e.g. when
// compiling for one-byte subjects and impossible (non-one-byte) ranges
// have been removed).
pos->mask = 0;
pos->value = 0;
} else {
int first_range = 0;
while (ranges->at(first_range).from() > char_mask) {
first_range++;
if (first_range == ranges->length()) {
details->set_cannot_match();
pos->determines_perfectly = false;
return;
}
}
CharacterRange range = ranges->at(first_range);
const base::uc32 first_from = range.from();
const base::uc32 first_to =
(range.to() > char_mask) ? char_mask : range.to();
const uint32_t differing_bits = (first_from ^ first_to);
// A mask and compare is only perfect if the differing bits form a
// number like 00011111 with one single block of trailing 1s.
if ((differing_bits & (differing_bits + 1)) == 0 &&
first_from + differing_bits == first_to) {
pos->determines_perfectly = true;
}
uint32_t common_bits = ~SmearBitsRight(differing_bits);
uint32_t bits = (first_from & common_bits);
for (int i = first_range + 1; i < ranges->length(); i++) {
range = ranges->at(i);
const base::uc32 from = range.from();
if (from > char_mask) continue;
const base::uc32 to =
(range.to() > char_mask) ? char_mask : range.to();
// Here we are combining more ranges into the mask and compare
// value. With each new range the mask becomes more sparse and
// so the chances of a false positive rise. A character class
// with multiple ranges is assumed never to be equivalent to a
// mask and compare operation.
pos->determines_perfectly = false;
uint32_t new_common_bits = (from ^ to);
new_common_bits = ~SmearBitsRight(new_common_bits);
common_bits &= new_common_bits;
bits &= new_common_bits;
uint32_t new_differing_bits = (from & common_bits) ^ bits;
common_bits ^= new_differing_bits;
bits &= common_bits;
}
pos->mask = common_bits;
pos->value = bits;
}
characters_filled_in++;
DCHECK(characters_filled_in <= details->characters());
if (characters_filled_in == details->characters()) return;
}
}
DCHECK(characters_filled_in != details->characters());
if (!details->cannot_match()) {
on_success()->GetQuickCheckDetails(details, compiler, characters_filled_in,
true);
}
}
void QuickCheckDetails::Clear() {
for (int i = 0; i < characters_; i++) {
positions_[i].mask = 0;
positions_[i].value = 0;
positions_[i].determines_perfectly = false;
}
characters_ = 0;
}
void QuickCheckDetails::Advance(int by, bool one_byte) {
if (by >= characters_ || by < 0) {
DCHECK_IMPLIES(by < 0, characters_ == 0);
Clear();
return;
}
DCHECK_LE(characters_ - by, 4);
DCHECK_LE(characters_, 4);
for (int i = 0; i < characters_ - by; i++) {
positions_[i] = positions_[by + i];
}
for (int i = characters_ - by; i < characters_; i++) {
positions_[i].mask = 0;
positions_[i].value = 0;
positions_[i].determines_perfectly = false;
}
characters_ -= by;
// We could change mask_ and value_ here but we would never advance unless
// they had already been used in a check and they won't be used again because
// it would gain us nothing. So there's no point.
}
void QuickCheckDetails::Merge(QuickCheckDetails* other, int from_index) {
DCHECK(characters_ == other->characters_);
if (other->cannot_match_) {
return;
}
if (cannot_match_) {
*this = *other;
return;
}
for (int i = from_index; i < characters_; i++) {
QuickCheckDetails::Position* pos = positions(i);
QuickCheckDetails::Position* other_pos = other->positions(i);
if (pos->mask != other_pos->mask || pos->value != other_pos->value ||
!other_pos->determines_perfectly) {
// Our mask-compare operation will be approximate unless we have the
// exact same operation on both sides of the alternation.
pos->determines_perfectly = false;
}
pos->mask &= other_pos->mask;
pos->value &= pos->mask;
other_pos->value &= pos->mask;
uint32_t differing_bits = (pos->value ^ other_pos->value);
pos->mask &= ~differing_bits;
pos->value &= pos->mask;
}
}
class VisitMarker {
public:
explicit VisitMarker(NodeInfo* info) : info_(info) {
DCHECK(!info->visited);
info->visited = true;
}
~VisitMarker() { info_->visited = false; }
private:
NodeInfo* info_;
};
// Temporarily sets traversed_loop_initialization_node_.
class LoopInitializationMarker {
public:
explicit LoopInitializationMarker(LoopChoiceNode* node) : node_(node) {
DCHECK(!node_->traversed_loop_initialization_node_);
node_->traversed_loop_initialization_node_ = true;
}
~LoopInitializationMarker() {
DCHECK(node_->traversed_loop_initialization_node_);
node_->traversed_loop_initialization_node_ = false;
}
LoopInitializationMarker(const LoopInitializationMarker&) = delete;
LoopInitializationMarker& operator=(const LoopInitializationMarker&) = delete;
private:
LoopChoiceNode* node_;
};
// Temporarily decrements min_loop_iterations_.
class IterationDecrementer {
public:
explicit IterationDecrementer(LoopChoiceNode* node) : node_(node) {
DCHECK_GT(node_->min_loop_iterations_, 0);
--node_->min_loop_iterations_;
}
~IterationDecrementer() { ++node_->min_loop_iterations_; }
IterationDecrementer(const IterationDecrementer&) = delete;
IterationDecrementer& operator=(const IterationDecrementer&) = delete;
private:
LoopChoiceNode* node_;
};
RegExpNode* SeqRegExpNode::FilterOneByte(int depth, RegExpFlags flags) {
if (info()->replacement_calculated) return replacement();
if (depth < 0) return this;
DCHECK(!info()->visited);
VisitMarker marker(info());
return FilterSuccessor(depth - 1, flags);
}
RegExpNode* SeqRegExpNode::FilterSuccessor(int depth, RegExpFlags flags) {
RegExpNode* next = on_success_->FilterOneByte(depth - 1, flags);
if (next == nullptr) return set_replacement(nullptr);
on_success_ = next;
return set_replacement(this);
}
// We need to check for the following characters: 0x39C 0x3BC 0x178.
bool RangeContainsLatin1Equivalents(CharacterRange range) {
// TODO(dcarney): this could be a lot more efficient.
return range.Contains(0x039C) || range.Contains(0x03BC) ||
range.Contains(0x0178);
}
namespace {
bool RangesContainLatin1Equivalents(ZoneList<CharacterRange>* ranges) {
for (int i = 0; i < ranges->length(); i++) {
// TODO(dcarney): this could be a lot more efficient.
if (RangeContainsLatin1Equivalents(ranges->at(i))) return true;
}
return false;
}
} // namespace
RegExpNode* TextNode::FilterOneByte(int depth, RegExpFlags flags) {
if (info()->replacement_calculated) return replacement();
if (depth < 0) return this;
DCHECK(!info()->visited);
VisitMarker marker(info());
int element_count = elements()->length();
for (int i = 0; i < element_count; i++) {
TextElement elm = elements()->at(i);
if (elm.text_type() == TextElement::ATOM) {
base::Vector<const base::uc16> quarks = elm.atom()->data();
for (int j = 0; j < quarks.length(); j++) {
base::uc16 c = quarks[j];
if (IsIgnoreCase(flags)) {
c = unibrow::Latin1::TryConvertToLatin1(c);
}
if (c > unibrow::Latin1::kMaxChar) return set_replacement(nullptr);
// Replace quark in case we converted to Latin-1.
base::uc16* writable_quarks = const_cast<base::uc16*>(quarks.begin());
writable_quarks[j] = c;
}
} else {
DCHECK(elm.text_type() == TextElement::CLASS_RANGES);
RegExpClassRanges* cr = elm.class_ranges();
ZoneList<CharacterRange>* ranges = cr->ranges(zone());
CharacterRange::Canonicalize(ranges);
// Now they are in order so we only need to look at the first.
int range_count = ranges->length();
if (cr->is_negated()) {
if (range_count != 0 && ranges->at(0).from() == 0 &&
ranges->at(0).to() >= String::kMaxOneByteCharCode) {
// This will be handled in a later filter.
if (IsIgnoreCase(flags) && RangesContainLatin1Equivalents(ranges)) {
continue;
}
return set_replacement(nullptr);
}
} else {
if (range_count == 0 ||
ranges->at(0).from() > String::kMaxOneByteCharCode) {
// This will be handled in a later filter.
if (IsIgnoreCase(flags) && RangesContainLatin1Equivalents(ranges)) {
continue;
}
return set_replacement(nullptr);
}
}
}
}
return FilterSuccessor(depth - 1, flags);
}
RegExpNode* LoopChoiceNode::FilterOneByte(int depth, RegExpFlags flags) {
if (info()->replacement_calculated) return replacement();
if (depth < 0) return this;
if (info()->visited) return this;
{
VisitMarker marker(info());
RegExpNode* continue_replacement =
continue_node_->FilterOneByte(depth - 1, flags);
// If we can't continue after the loop then there is no sense in doing the
// loop.
if (continue_replacement == nullptr) return set_replacement(nullptr);
}
return ChoiceNode::FilterOneByte(depth - 1, flags);
}
RegExpNode* ChoiceNode::FilterOneByte(int depth, RegExpFlags flags) {
if (info()->replacement_calculated) return replacement();
if (depth < 0) return this;
if (info()->visited) return this;
VisitMarker marker(info());
int choice_count = alternatives_->length();
for (int i = 0; i < choice_count; i++) {
GuardedAlternative alternative = alternatives_->at(i);
if (alternative.guards() != nullptr &&
alternative.guards()->length() != 0) {
set_replacement(this);
return this;
}
}
int surviving = 0;
RegExpNode* survivor = nullptr;
for (int i = 0; i < choice_count; i++) {
GuardedAlternative alternative = alternatives_->at(i);
RegExpNode* replacement =
alternative.node()->FilterOneByte(depth - 1, flags);
DCHECK(replacement != this); // No missing EMPTY_MATCH_CHECK.
if (replacement != nullptr) {
alternatives_->at(i).set_node(replacement);
surviving++;
survivor = replacement;
}
}
if (surviving < 2) return set_replacement(survivor);
set_replacement(this);
if (surviving == choice_count) {
return this;
}
// Only some of the nodes survived the filtering. We need to rebuild the
// alternatives list.
ZoneList<GuardedAlternative>* new_alternatives =
zone()->New<ZoneList<GuardedAlternative>>(surviving, zone());
for (int i = 0; i < choice_count; i++) {
RegExpNode* replacement =
alternatives_->at(i).node()->FilterOneByte(depth - 1, flags);
if (replacement != nullptr) {
alternatives_->at(i).set_node(replacement);
new_alternatives->Add(alternatives_->at(i), zone());
}
}
alternatives_ = new_alternatives;
return this;
}
RegExpNode* NegativeLookaroundChoiceNode::FilterOneByte(int depth,
RegExpFlags flags) {
if (info()->replacement_calculated) return replacement();
if (depth < 0) return this;
if (info()->visited) return this;
VisitMarker marker(info());
// Alternative 0 is the negative lookahead, alternative 1 is what comes
// afterwards.
RegExpNode* node = continue_node();
RegExpNode* replacement = node->FilterOneByte(depth - 1, flags);
if (replacement == nullptr) return set_replacement(nullptr);
alternatives_->at(kContinueIndex).set_node(replacement);
RegExpNode* neg_node = lookaround_node();
RegExpNode* neg_replacement = neg_node->FilterOneByte(depth - 1, flags);
// If the negative lookahead is always going to fail then
// we don't need to check it.
if (neg_replacement == nullptr) return set_replacement(replacement);
alternatives_->at(kLookaroundIndex).set_node(neg_replacement);
return set_replacement(this);
}
void LoopChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details,
RegExpCompiler* compiler,
int characters_filled_in,
bool not_at_start) {
if (body_can_be_zero_length_ || info()->visited) return;
not_at_start = not_at_start || this->not_at_start();
DCHECK_EQ(alternatives_->length(), 2); // There's just loop and continue.
if (traversed_loop_initialization_node_ && min_loop_iterations_ > 0 &&
loop_node_->EatsAtLeast(not_at_start) >
continue_node_->EatsAtLeast(true)) {
// Loop body is guaranteed to execute at least once, and consume characters
// when it does, meaning the only possible quick checks from this point
// begin with the loop body. We may recursively visit this LoopChoiceNode,
// but we temporarily decrease its minimum iteration counter so we know when
// to check the continue case.
IterationDecrementer next_iteration(this);
loop_node_->GetQuickCheckDetails(details, compiler, characters_filled_in,
not_at_start);
} else {
// Might not consume anything in the loop body, so treat it like a normal
// ChoiceNode (and don't recursively visit this node again).
VisitMarker marker(info());
ChoiceNode::GetQuickCheckDetails(details, compiler, characters_filled_in,
not_at_start);
}
}
void LoopChoiceNode::GetQuickCheckDetailsFromLoopEntry(
QuickCheckDetails* details, RegExpCompiler* compiler,
int characters_filled_in, bool not_at_start) {
if (traversed_loop_initialization_node_) {
// We already entered this loop once, exited via its continuation node, and
// followed an outer loop's back-edge to before the loop entry point. We
// could try to reset the minimum iteration count to its starting value at
// this point, but that seems like more trouble than it's worth. It's safe
// to keep going with the current (possibly reduced) minimum iteration
// count.
GetQuickCheckDetails(details, compiler, characters_filled_in, not_at_start);
} else {
// We are entering a loop via its counter initialization action, meaning we
// are guaranteed to run the loop body at least some minimum number of times
// before running the continuation node. Set a flag so that this node knows
// (now and any times we visit it again recursively) that it was entered
// from the top.
LoopInitializationMarker marker(this);
GetQuickCheckDetails(details, compiler, characters_filled_in, not_at_start);
}
}
void LoopChoiceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
BoyerMooreLookahead* bm, bool not_at_start) {
if (body_can_be_zero_length_ || budget <= 0) {
bm->SetRest(offset);
SaveBMInfo(bm, not_at_start, offset);
return;
}
ChoiceNode::FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
SaveBMInfo(bm, not_at_start, offset);
}
void ChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details,
RegExpCompiler* compiler,
int characters_filled_in,
bool not_at_start) {
not_at_start = (not_at_start || not_at_start_);
int choice_count = alternatives_->length();
DCHECK_LT(0, choice_count);
alternatives_->at(0).node()->GetQuickCheckDetails(
details, compiler, characters_filled_in, not_at_start);
for (int i = 1; i < choice_count; i++) {
QuickCheckDetails new_details(details->characters());
RegExpNode* node = alternatives_->at(i).node();
node->GetQuickCheckDetails(&new_details, compiler, characters_filled_in,
not_at_start);
// Here we merge the quick match details of the two branches.
details->Merge(&new_details, characters_filled_in);
}
}
namespace {
// Check for [0-9A-Z_a-z].
void EmitWordCheck(RegExpMacroAssembler* assembler, Label* word,
Label* non_word, bool fall_through_on_word) {
if (assembler->CheckSpecialClassRanges(
fall_through_on_word ? StandardCharacterSet::kWord
: StandardCharacterSet::kNotWord,
fall_through_on_word ? non_word : word)) {
// Optimized implementation available.
return;
}
assembler->CheckCharacterGT('z', non_word);
assembler->CheckCharacterLT('0', non_word);
assembler->CheckCharacterGT('a' - 1, word);
assembler->CheckCharacterLT('9' + 1, word);
assembler->CheckCharacterLT('A', non_word);
assembler->CheckCharacterLT('Z' + 1, word);
if (fall_through_on_word) {
assembler->CheckNotCharacter('_', non_word);
} else {
assembler->CheckCharacter('_', word);
}
}
// Emit the code to check for a ^ in multiline mode (1-character lookbehind
// that matches newline or the start of input).
void EmitHat(RegExpCompiler* compiler, RegExpNode* on_success, Trace* trace) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
// We will load the previous character into the current character register.
Trace new_trace(*trace);
new_trace.InvalidateCurrentCharacter();
// A positive (> 0) cp_offset means we've already successfully matched a
// non-empty-width part of the pattern, and thus cannot be at or before the
// start of the subject string. We can thus skip both at-start and
// bounds-checks when loading the one-character lookbehind.
const bool may_be_at_or_before_subject_string_start =
new_trace.cp_offset() <= 0;
Label ok;
if (may_be_at_or_before_subject_string_start) {
// The start of input counts as a newline in this context, so skip to ok if
// we are at the start.
assembler->CheckAtStart(new_trace.cp_offset(), &ok);
}
// If we've already checked that we are not at the start of input, it's okay
// to load the previous character without bounds checks.
const bool can_skip_bounds_check = !may_be_at_or_before_subject_string_start;
assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1,
new_trace.backtrack(), can_skip_bounds_check);
if (!assembler->CheckSpecialClassRanges(StandardCharacterSet::kLineTerminator,
new_trace.backtrack())) {
// Newline means \n, \r, 0x2028 or 0x2029.
if (!compiler->one_byte()) {
assembler->CheckCharacterAfterAnd(0x2028, 0xFFFE, &ok);
}
assembler->CheckCharacter('\n', &ok);
assembler->CheckNotCharacter('\r', new_trace.backtrack());
}
assembler->Bind(&ok);
on_success->Emit(compiler, &new_trace);
}
} // namespace
// Emit the code to handle \b and \B (word-boundary or non-word-boundary).
void AssertionNode::EmitBoundaryCheck(RegExpCompiler* compiler, Trace* trace) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
Isolate* isolate = assembler->isolate();
Trace::TriBool next_is_word_character = Trace::UNKNOWN;
bool not_at_start = (trace->at_start() == Trace::FALSE_VALUE);
BoyerMooreLookahead* lookahead = bm_info(not_at_start);
if (lookahead == nullptr) {
int eats_at_least =
std::min(kMaxLookaheadForBoyerMoore, EatsAtLeast(not_at_start));
if (eats_at_least >= 1) {
BoyerMooreLookahead* bm =
zone()->New<BoyerMooreLookahead>(eats_at_least, compiler, zone());
FillInBMInfo(isolate, 0, kRecursionBudget, bm, not_at_start);
if (bm->at(0)->is_non_word()) next_is_word_character = Trace::FALSE_VALUE;
if (bm->at(0)->is_word()) next_is_word_character = Trace::TRUE_VALUE;
}
} else {
if (lookahead->at(0)->is_non_word())
next_is_word_character = Trace::FALSE_VALUE;
if (lookahead->at(0)->is_word()) next_is_word_character = Trace::TRUE_VALUE;
}
bool at_boundary = (assertion_type_ == AssertionNode::AT_BOUNDARY);
if (next_is_word_character == Trace::UNKNOWN) {
Label before_non_word;
Label before_word;
if (trace->characters_preloaded() != 1) {
assembler->LoadCurrentCharacter(trace->cp_offset(), &before_non_word);
}
// Fall through on non-word.
EmitWordCheck(assembler, &before_word, &before_non_word, false);
// Next character is not a word character.
assembler->Bind(&before_non_word);
Label ok;
BacktrackIfPrevious(compiler, trace, at_boundary ? kIsNonWord : kIsWord);
assembler->GoTo(&ok);
assembler->Bind(&before_word);
BacktrackIfPrevious(compiler, trace, at_boundary ? kIsWord : kIsNonWord);
assembler->Bind(&ok);
} else if (next_is_word_character == Trace::TRUE_VALUE) {
BacktrackIfPrevious(compiler, trace, at_boundary ? kIsWord : kIsNonWord);
} else {
DCHECK(next_is_word_character == Trace::FALSE_VALUE);
BacktrackIfPrevious(compiler, trace, at_boundary ? kIsNonWord : kIsWord);
}
}
void AssertionNode::BacktrackIfPrevious(
RegExpCompiler* compiler, Trace* trace,
AssertionNode::IfPrevious backtrack_if_previous) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
Trace new_trace(*trace);
new_trace.InvalidateCurrentCharacter();
Label fall_through;
Label* non_word = backtrack_if_previous == kIsNonWord ? new_trace.backtrack()
: &fall_through;
Label* word = backtrack_if_previous == kIsNonWord ? &fall_through
: new_trace.backtrack();
// A positive (> 0) cp_offset means we've already successfully matched a
// non-empty-width part of the pattern, and thus cannot be at or before the
// start of the subject string. We can thus skip both at-start and
// bounds-checks when loading the one-character lookbehind.
const bool may_be_at_or_before_subject_string_start =
new_trace.cp_offset() <= 0;
if (may_be_at_or_before_subject_string_start) {
// The start of input counts as a non-word character, so the question is
// decided if we are at the start.
assembler->CheckAtStart(new_trace.cp_offset(), non_word);
}
// If we've already checked that we are not at the start of input, it's okay
// to load the previous character without bounds checks.
const bool can_skip_bounds_check = !may_be_at_or_before_subject_string_start;
assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1, non_word,
can_skip_bounds_check);
EmitWordCheck(assembler, word, non_word, backtrack_if_previous == kIsNonWord);
assembler->Bind(&fall_through);
on_success()->Emit(compiler, &new_trace);
}
void AssertionNode::GetQuickCheckDetails(QuickCheckDetails* details,
RegExpCompiler* compiler,
int filled_in, bool not_at_start) {
if (assertion_type_ == AT_START && not_at_start) {
details->set_cannot_match();
return;
}
return on_success()->GetQuickCheckDetails(details, compiler, filled_in,
not_at_start);
}
void AssertionNode::Emit(RegExpCompiler* compiler, Trace* trace) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
switch (assertion_type_) {
case AT_END: {
Label ok;
assembler->CheckPosition(trace->cp_offset(), &ok);
assembler->GoTo(trace->backtrack());
assembler->Bind(&ok);
break;
}
case AT_START: {
if (trace->at_start() == Trace::FALSE_VALUE) {
assembler->GoTo(trace->backtrack());
return;
}
if (trace->at_start() == Trace::UNKNOWN) {
assembler->CheckNotAtStart(trace->cp_offset(), trace->backtrack());
Trace at_start_trace = *trace;
at_start_trace.set_at_start(Trace::TRUE_VALUE);
on_success()->Emit(compiler, &at_start_trace);
return;
}
} break;
case AFTER_NEWLINE:
EmitHat(compiler, on_success(), trace);
return;
case AT_BOUNDARY:
case AT_NON_BOUNDARY: {
EmitBoundaryCheck(compiler, trace);
return;
}
}
on_success()->Emit(compiler, trace);
}
namespace {
bool DeterminedAlready(QuickCheckDetails* quick_check, int offset) {
if (quick_check == nullptr) return false;
if (offset >= quick_check->characters()) return false;
return quick_check->positions(offset)->determines_perfectly;
}
void UpdateBoundsCheck(int index, int* checked_up_to) {
if (index > *checked_up_to) {
*checked_up_to = index;
}
}
} // namespace
// We call this repeatedly to generate code for each pass over the text node.
// The passes are in increasing order of difficulty because we hope one
// of the first passes will fail in which case we are saved the work of the
// later passes. for example for the case independent regexp /%[asdfghjkl]a/
// we will check the '%' in the first pass, the case independent 'a' in the
// second pass and the character class in the last pass.
//
// The passes are done from right to left, so for example to test for /bar/
// we will first test for an 'r' with offset 2, then an 'a' with offset 1
// and then a 'b' with offset 0. This means we can avoid the end-of-input
// bounds check most of the time. In the example we only need to check for
// end-of-input when loading the putative 'r'.
//
// A slight complication involves the fact that the first character may already
// be fetched into a register by the previous node. In this case we want to
// do the test for that character first. We do this in separate passes. The
// 'preloaded' argument indicates that we are doing such a 'pass'. If such a
// pass has been performed then subsequent passes will have true in
// first_element_checked to indicate that that character does not need to be
// checked again.
//
// In addition to all this we are passed a Trace, which can
// contain an AlternativeGeneration object. In this AlternativeGeneration
// object we can see details of any quick check that was already passed in
// order to get to the code we are now generating. The quick check can involve
// loading characters, which means we do not need to recheck the bounds
// up to the limit the quick check already checked. In addition the quick
// check can have involved a mask and compare operation which may simplify
// or obviate the need for further checks at some character positions.
void TextNode::TextEmitPass(RegExpCompiler* compiler, TextEmitPassType pass,
bool preloaded, Trace* trace,
bool first_element_checked, int* checked_up_to) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
Isolate* isolate = assembler->isolate();
bool one_byte = compiler->one_byte();
Label* backtrack = trace->backtrack();
QuickCheckDetails* quick_check = trace->quick_check_performed();
int element_count = elements()->length();
int backward_offset = read_backward() ? -Length() : 0;
for (int i = preloaded ? 0 : element_count - 1; i >= 0; i--) {
TextElement elm = elements()->at(i);
int cp_offset = trace->cp_offset() + elm.cp_offset() + backward_offset;
if (elm.text_type() == TextElement::ATOM) {
if (SkipPass(pass, IsIgnoreCase(compiler->flags()))) continue;
base::Vector<const base::uc16> quarks = elm.atom()->data();
for (int j = preloaded ? 0 : quarks.length() - 1; j >= 0; j--) {
if (first_element_checked && i == 0 && j == 0) continue;
if (DeterminedAlready(quick_check, elm.cp_offset() + j)) continue;
base::uc16 quark = quarks[j];
if (IsIgnoreCase(compiler->flags())) {
// Everywhere else we assume that a non-Latin-1 character cannot match
// a Latin-1 character. Avoid the cases where this is assumption is
// invalid by using the Latin1 equivalent instead.
quark = unibrow::Latin1::TryConvertToLatin1(quark);
}
bool needs_bounds_check =
*checked_up_to < cp_offset + j || read_backward();
bool bounds_checked = false;
switch (pass) {
case NON_LATIN1_MATCH:
DCHECK(one_byte);
if (quark > String::kMaxOneByteCharCode) {
assembler->GoTo(backtrack);
return;
}
break;
case NON_LETTER_CHARACTER_MATCH:
bounds_checked =
EmitAtomNonLetter(isolate, compiler, quark, backtrack,
cp_offset + j, needs_bounds_check, preloaded);
break;
case SIMPLE_CHARACTER_MATCH:
bounds_checked = EmitSimpleCharacter(isolate, compiler, quark,
backtrack, cp_offset + j,
needs_bounds_check, preloaded);
break;
case CASE_CHARACTER_MATCH:
bounds_checked =
EmitAtomLetter(isolate, compiler, quark, backtrack,
cp_offset + j, needs_bounds_check, preloaded);
break;
default:
break;
}
if (bounds_checked) UpdateBoundsCheck(cp_offset + j, checked_up_to);
}
} else {
DCHECK_EQ(TextElement::CLASS_RANGES, elm.text_type());
if (pass == CHARACTER_CLASS_MATCH) {
if (first_element_checked && i == 0) continue;
if (DeterminedAlready(quick_check, elm.cp_offset())) continue;
RegExpClassRanges* cr = elm.class_ranges();
bool bounds_check = *checked_up_to < cp_offset || read_backward();
EmitClassRanges(assembler, cr, one_byte, backtrack, cp_offset,
bounds_check, preloaded, zone());
UpdateBoundsCheck(cp_offset, checked_up_to);
}
}
}
}
int TextNode::Length() {
TextElement elm = elements()->last();
DCHECK_LE(0, elm.cp_offset());
return elm.cp_offset() + elm.length();
}
bool TextNode::SkipPass(TextEmitPassType pass, bool ignore_case) {
if (ignore_case) {
return pass == SIMPLE_CHARACTER_MATCH;
} else {
return pass == NON_LETTER_CHARACTER_MATCH || pass == CASE_CHARACTER_MATCH;
}
}
TextNode* TextNode::CreateForCharacterRanges(Zone* zone,
ZoneList<CharacterRange>* ranges,
bool read_backward,
RegExpNode* on_success) {
DCHECK_NOT_NULL(ranges);
// TODO(jgruber): There's no fundamental need to create this
// RegExpClassRanges; we could refactor to avoid the allocation.
return zone->New<TextNode>(zone->New<RegExpClassRanges>(zone, ranges),
read_backward, on_success);
}
TextNode* TextNode::CreateForSurrogatePair(
Zone* zone, CharacterRange lead, ZoneList<CharacterRange>* trail_ranges,
bool read_backward, RegExpNode* on_success) {
ZoneList<CharacterRange>* lead_ranges = CharacterRange::List(zone, lead);
ZoneList<TextElement>* elms = zone->New<ZoneList<TextElement>>(2, zone);
elms->Add(
TextElement::ClassRanges(zone->New<RegExpClassRanges>(zone, lead_ranges)),
zone);
elms->Add(TextElement::ClassRanges(
zone->New<RegExpClassRanges>(zone, trail_ranges)),
zone);
return zone->New<TextNode>(elms, read_backward, on_success);
}
TextNode* TextNode::CreateForSurrogatePair(
Zone* zone, ZoneList<CharacterRange>* lead_ranges, CharacterRange trail,
bool read_backward, RegExpNode* on_success) {
ZoneList<CharacterRange>* trail_ranges = CharacterRange::List(zone, trail);
ZoneList<TextElement>* elms = zone->New<ZoneList<TextElement>>(2, zone);
elms->Add(
TextElement::ClassRanges(zone->New<RegExpClassRanges>(zone, lead_ranges)),
zone);
elms->Add(TextElement::ClassRanges(
zone->New<RegExpClassRanges>(zone, trail_ranges)),
zone);
return zone->New<TextNode>(elms, read_backward, on_success);
}
// This generates the code to match a text node. A text node can contain
// straight character sequences (possibly to be matched in a case-independent
// way) and character classes. For efficiency we do not do this in a single
// pass from left to right. Instead we pass over the text node several times,
// emitting code for some character positions every time. See the comment on
// TextEmitPass for details.
void TextNode::Emit(RegExpCompiler* compiler, Trace* trace) {
LimitResult limit_result = LimitVersions(compiler, trace);
if (limit_result == DONE) return;
DCHECK(limit_result == CONTINUE);
if (trace->cp_offset() + Length() > RegExpMacroAssembler::kMaxCPOffset) {
compiler->SetRegExpTooBig();
return;
}
if (compiler->one_byte()) {
int dummy = 0;
TextEmitPass(compiler, NON_LATIN1_MATCH, false, trace, false, &dummy);
}
bool first_elt_done = false;
int bound_checked_to = trace->cp_offset() - 1;
bound_checked_to += trace->bound_checked_up_to();
// If a character is preloaded into the current character register then
// check that now.
if (trace->characters_preloaded() == 1) {
for (int pass = kFirstRealPass; pass <= kLastPass; pass++) {
TextEmitPass(compiler, static_cast<TextEmitPassType>(pass), true, trace,
false, &bound_checked_to);
}
first_elt_done = true;
}
for (int pass = kFirstRealPass; pass <= kLastPass; pass++) {
TextEmitPass(compiler, static_cast<TextEmitPassType>(pass), false, trace,
first_elt_done, &bound_checked_to);
}
Trace successor_trace(*trace);
// If we advance backward, we may end up at the start.
successor_trace.AdvanceCurrentPositionInTrace(
read_backward() ? -Length() : Length(), compiler);
successor_trace.set_at_start(read_backward() ? Trace::UNKNOWN
: Trace::FALSE_VALUE);
RecursionCheck rc(compiler);
on_success()->Emit(compiler, &successor_trace);
}
void Trace::InvalidateCurrentCharacter() { characters_preloaded_ = 0; }
void Trace::AdvanceCurrentPositionInTrace(int by, RegExpCompiler* compiler) {
// We don't have an instruction for shifting the current character register
// down or for using a shifted value for anything so lets just forget that
// we preloaded any characters into it.
characters_preloaded_ = 0;
// Adjust the offsets of the quick check performed information. This
// information is used to find out what we already determined about the
// characters by means of mask and compare.
quick_check_performed_.Advance(by, compiler->one_byte());
cp_offset_ += by;
if (cp_offset_ > RegExpMacroAssembler::kMaxCPOffset) {
compiler->SetRegExpTooBig();
cp_offset_ = 0;
}
bound_checked_up_to_ = std::max(0, bound_checked_up_to_ - by);
}
void TextNode::MakeCaseIndependent(Isolate* isolate, bool is_one_byte,
RegExpFlags flags) {
if (!IsIgnoreCase(flags)) return;
#ifdef V8_INTL_SUPPORT
if (NeedsUnicodeCaseEquivalents(flags)) return;
#endif
int element_count = elements()->length();
for (int i = 0; i < element_count; i++) {
TextElement elm = elements()->at(i);
if (elm.text_type() == TextElement::CLASS_RANGES) {
RegExpClassRanges* cr = elm.class_ranges();
// None of the standard character classes is different in the case
// independent case and it slows us down if we don't know that.
if (cr->is_standard(zone())) continue;
ZoneList<CharacterRange>* ranges = cr->ranges(zone());
CharacterRange::AddCaseEquivalents(isolate, zone(), ranges, is_one_byte);
}
}
}
int TextNode::GreedyLoopTextLength() { return Length(); }
RegExpNode* TextNode::GetSuccessorOfOmnivorousTextNode(
RegExpCompiler* compiler) {
if (read_backward()) return nullptr;
if (elements()->length() != 1) return nullptr;
TextElement elm = elements()->at(0);
if (elm.text_type() != TextElement::CLASS_RANGES) return nullptr;
RegExpClassRanges* node = elm.class_ranges();
ZoneList<CharacterRange>* ranges = node->ranges(zone());
CharacterRange::Canonicalize(ranges);
if (node->is_negated()) {
return ranges->length() == 0 ? on_success() : nullptr;
}
if (ranges->length() != 1) return nullptr;
const base::uc32 max_char = MaxCodeUnit(compiler->one_byte());
return ranges->at(0).IsEverything(max_char) ? on_success() : nullptr;
}
// Finds the fixed match length of a sequence of nodes that goes from
// this alternative and back to this choice node. If there are variable
// length nodes or other complications in the way then return a sentinel
// value indicating that a greedy loop cannot be constructed.
int ChoiceNode::GreedyLoopTextLengthForAlternative(
GuardedAlternative* alternative) {
int length = 0;
RegExpNode* node = alternative->node();
// Later we will generate code for all these text nodes using recursion
// so we have to limit the max number.
int recursion_depth = 0;
while (node != this) {
if (recursion_depth++ > RegExpCompiler::kMaxRecursion) {
return kNodeIsTooComplexForGreedyLoops;
}
int node_length = node->GreedyLoopTextLength();
if (node_length == kNodeIsTooComplexForGreedyLoops) {
return kNodeIsTooComplexForGreedyLoops;
}
length += node_length;
SeqRegExpNode* seq_node = static_cast<SeqRegExpNode*>(node);
node = seq_node->on_success();
}
if (read_backward()) {
length = -length;
}
// Check that we can jump by the whole text length. If not, return sentinel
// to indicate the we can't construct a greedy loop.
if (length < RegExpMacroAssembler::kMinCPOffset ||
length > RegExpMacroAssembler::kMaxCPOffset) {
return kNodeIsTooComplexForGreedyLoops;
}
return length;
}
void LoopChoiceNode::AddLoopAlternative(GuardedAlternative alt) {
DCHECK_NULL(loop_node_);
AddAlternative(alt);
loop_node_ = alt.node();
}
void LoopChoiceNode::AddContinueAlternative(GuardedAlternative alt) {
DCHECK_NULL(continue_node_);
AddAlternative(alt);
continue_node_ = alt.node();
}
void LoopChoiceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
if (trace->stop_node() == this) {
// Back edge of greedy optimized loop node graph.
int text_length =
GreedyLoopTextLengthForAlternative(&(alternatives_->at(0)));
DCHECK_NE(kNodeIsTooComplexForGreedyLoops, text_length);
// Update the counter-based backtracking info on the stack. This is an
// optimization for greedy loops (see below).
DCHECK(trace->cp_offset() == text_length);
macro_assembler->AdvanceCurrentPosition(text_length);
macro_assembler->GoTo(trace->loop_label());
return;
}
DCHECK_NULL(trace->stop_node());
if (!trace->is_trivial()) {
trace->Flush(compiler, this);
return;
}
ChoiceNode::Emit(compiler, trace);
}
int ChoiceNode::CalculatePreloadCharacters(RegExpCompiler* compiler,
int eats_at_least) {
int preload_characters = std::min(4, eats_at_least);
DCHECK_LE(preload_characters, 4);
if (compiler->macro_assembler()->CanReadUnaligned()) {
bool one_byte = compiler->one_byte();
if (one_byte) {
// We can't preload 3 characters because there is no machine instruction
// to do that. We can't just load 4 because we could be reading
// beyond the end of the string, which could cause a memory fault.
if (preload_characters == 3) preload_characters = 2;
} else {
if (preload_characters > 2) preload_characters = 2;
}
} else {
if (preload_characters > 1) preload_characters = 1;
}
return preload_characters;
}
// This class is used when generating the alternatives in a choice node. It
// records the way the alternative is being code generated.
class AlternativeGeneration : public Malloced {
public:
AlternativeGeneration()
: possible_success(),
expects_preload(false),
after(),
quick_check_details() {}
Label possible_success;
bool expects_preload;
Label after;
QuickCheckDetails quick_check_details;
};
// Creates a list of AlternativeGenerations. If the list has a reasonable
// size then it is on the stack, otherwise the excess is on the heap.
class AlternativeGenerationList {
public:
AlternativeGenerationList(int count, Zone* zone) : alt_gens_(count, zone) {
for (int i = 0; i < count && i < kAFew; i++) {
alt_gens_.Add(a_few_alt_gens_ + i, zone);
}
for (int i = kAFew; i < count; i++) {
alt_gens_.Add(new AlternativeGeneration(), zone);
}
}
~AlternativeGenerationList() {
for (int i = kAFew; i < alt_gens_.length(); i++) {
delete alt_gens_[i];
alt_gens_[i] = nullptr;
}
}
AlternativeGeneration* at(int i) { return alt_gens_[i]; }
private:
static const int kAFew = 10;
ZoneList<AlternativeGeneration*> alt_gens_;
AlternativeGeneration a_few_alt_gens_[kAFew];
};
void BoyerMoorePositionInfo::Set(int character) {
SetInterval(Interval(character, character));
}
namespace {
ContainedInLattice AddRange(ContainedInLattice containment, const int* ranges,
int ranges_length, Interval new_range) {
DCHECK_EQ(1, ranges_length & 1);
DCHECK_EQ(String::kMaxCodePoint + 1, ranges[ranges_length - 1]);
if (containment == kLatticeUnknown) return containment;
bool inside = false;
int last = 0;
for (int i = 0; i < ranges_length; inside = !inside, last = ranges[i], i++) {
// Consider the range from last to ranges[i].
// We haven't got to the new range yet.
if (ranges[i] <= new_range.from()) continue;
// New range is wholly inside last-ranges[i]. Note that new_range.to() is
// inclusive, but the values in ranges are not.
if (last <= new_range.from() && new_range.to() < ranges[i]) {
return Combine(containment, inside ? kLatticeIn : kLatticeOut);
}
return kLatticeUnknown;
}
return containment;
}
int BitsetFirstSetBit(BoyerMoorePositionInfo::Bitset bitset) {
static_assert(BoyerMoorePositionInfo::kMapSize ==
2 * kInt64Size * kBitsPerByte);
// Slight fiddling is needed here, since the bitset is of length 128 while
// CountTrailingZeros requires an integral type and std::bitset can only
// convert to unsigned long long. So we handle the most- and least-significant
// bits separately.
{
static constexpr BoyerMoorePositionInfo::Bitset mask(~uint64_t{0});
BoyerMoorePositionInfo::Bitset masked_bitset = bitset & mask;
static_assert(kInt64Size >= sizeof(decltype(masked_bitset.to_ullong())));
uint64_t lsb = masked_bitset.to_ullong();
if (lsb != 0) return base::bits::CountTrailingZeros(lsb);
}
{
BoyerMoorePositionInfo::Bitset masked_bitset = bitset >> 64;
uint64_t msb = masked_bitset.to_ullong();
if (msb != 0) return 64 + base::bits::CountTrailingZeros(msb);
}
return -1;
}
} // namespace
void BoyerMoorePositionInfo::SetInterval(const Interval& interval) {
w_ = AddRange(w_, kWordRanges, kWordRangeCount, interval);
if (interval.size() >= kMapSize) {
map_count_ = kMapSize;
map_.set();
return;
}
for (int i = interval.from(); i <= interval.to(); i++) {
int mod_character = (i & kMask);
if (!map_[mod_character]) {
map_count_++;
map_.set(mod_character);
}
if (map_count_ == kMapSize) return;
}
}
void BoyerMoorePositionInfo::SetAll() {
w_ = kLatticeUnknown;
if (map_count_ != kMapSize) {
map_count_ = kMapSize;
map_.set();
}
}
BoyerMooreLookahead::BoyerMooreLookahead(int length, RegExpCompiler* compiler,
Zone* zone)
: length_(length),
compiler_(compiler),
max_char_(MaxCodeUnit(compiler->one_byte())) {
bitmaps_ = zone->New<ZoneList<BoyerMoorePositionInfo*>>(length, zone);
for (int i = 0; i < length; i++) {
bitmaps_->Add(zone->New<BoyerMoorePositionInfo>(), zone);
}
}
// Find the longest range of lookahead that has the fewest number of different
// characters that can occur at a given position. Since we are optimizing two
// different parameters at once this is a tradeoff.
bool BoyerMooreLookahead::FindWorthwhileInterval(int* from, int* to) {
int biggest_points = 0;
// If more than 32 characters out of 128 can occur it is unlikely that we can
// be lucky enough to step forwards much of the time.
const int kMaxMax = 32;
for (int max_number_of_chars = 4; max_number_of_chars < kMaxMax;
max_number_of_chars *= 2) {
biggest_points =
FindBestInterval(max_number_of_chars, biggest_points, from, to);
}
if (biggest_points == 0) return false;
return true;
}
// Find the highest-points range between 0 and length_ where the character
// information is not too vague. 'Too vague' means that there are more than
// max_number_of_chars that can occur at this position. Calculates the number
// of points as the product of width-of-the-range and
// probability-of-finding-one-of-the-characters, where the probability is
// calculated using the frequency distribution of the sample subject string.
int BoyerMooreLookahead::FindBestInterval(int max_number_of_chars,
int old_biggest_points, int* from,
int* to) {
int biggest_points = old_biggest_points;
static const int kSize = RegExpMacroAssembler::kTableSize;
for (int i = 0; i < length_;) {
while (i < length_ && Count(i) > max_number_of_chars) i++;
if (i == length_) break;
int remembered_from = i;
BoyerMoorePositionInfo::Bitset union_bitset;
for (; i < length_ && Count(i) <= max_number_of_chars; i++) {
union_bitset |= bitmaps_->at(i)->raw_bitset();
}
int frequency = 0;
// Iterate only over set bits.
int j;
while ((j = BitsetFirstSetBit(union_bitset)) != -1) {
DCHECK(union_bitset[j]); // Sanity check.
// Add 1 to the frequency to give a small per-character boost for
// the cases where our sampling is not good enough and many
// characters have a frequency of zero. This means the frequency
// can theoretically be up to 2*kSize though we treat it mostly as
// a fraction of kSize.
frequency += compiler_->frequency_collator()->Frequency(j) + 1;
union_bitset.reset(j);
}
// We use the probability of skipping times the distance we are skipping to
// judge the effectiveness of this. Actually we have a cut-off: By
// dividing by 2 we switch off the skipping if the probability of skipping
// is less than 50%. This is because the multibyte mask-and-compare
// skipping in quickcheck is more likely to do well on this case.
bool in_quickcheck_range =
((i - remembered_from < 4) ||
(compiler_->one_byte() ? remembered_from <= 4 : remembered_from <= 2));
// Called 'probability' but it is only a rough estimate and can actually
// be outside the 0-kSize range.
int probability = (in_quickcheck_range ? kSize / 2 : kSize) - frequency;
int points = (i - remembered_from) * probability;
if (points > biggest_points) {
*from = remembered_from;
*to = i - 1;
biggest_points = points;
}
}
return biggest_points;
}
// Take all the characters that will not prevent a successful match if they
// occur in the subject string in the range between min_lookahead and
// max_lookahead (inclusive) measured from the current position. If the
// character at max_lookahead offset is not one of these characters, then we
// can safely skip forwards by the number of characters in the range.
int BoyerMooreLookahead::GetSkipTable(int min_lookahead, int max_lookahead,
Handle<ByteArray> boolean_skip_table) {
const int kSkipArrayEntry = 0;
const int kDontSkipArrayEntry = 1;
std::memset(boolean_skip_table->GetDataStartAddress(), kSkipArrayEntry,
boolean_skip_table->length());
for (int i = max_lookahead; i >= min_lookahead; i--) {
BoyerMoorePositionInfo::Bitset bitset = bitmaps_->at(i)->raw_bitset();
// Iterate only over set bits.
int j;
while ((j = BitsetFirstSetBit(bitset)) != -1) {
DCHECK(bitset[j]); // Sanity check.
boolean_skip_table->set(j, kDontSkipArrayEntry);
bitset.reset(j);
}
}
const int skip = max_lookahead + 1 - min_lookahead;
return skip;
}
// See comment above on the implementation of GetSkipTable.
void BoyerMooreLookahead::EmitSkipInstructions(RegExpMacroAssembler* masm) {
const int kSize = RegExpMacroAssembler::kTableSize;
int min_lookahead = 0;
int max_lookahead = 0;
if (!FindWorthwhileInterval(&min_lookahead, &max_lookahead)) return;
// Check if we only have a single non-empty position info, and that info
// contains precisely one character.
bool found_single_character = false;
int single_character = 0;
for (int i = max_lookahead; i >= min_lookahead; i--) {
BoyerMoorePositionInfo* map = bitmaps_->at(i);
if (map->map_count() == 0) continue;
if (found_single_character || map->map_count() > 1) {
found_single_character = false;
break;
}
DCHECK(!found_single_character);
DCHECK_EQ(map->map_count(), 1);
found_single_character = true;
single_character = BitsetFirstSetBit(map->raw_bitset());
DCHECK_NE(single_character, -1);
}
int lookahead_width = max_lookahead + 1 - min_lookahead;
if (found_single_character && lookahead_width == 1 && max_lookahead < 3) {
// The mask-compare can probably handle this better.
return;
}
if (found_single_character) {
Label cont, again;
masm->Bind(&again);
masm->LoadCurrentCharacter(max_lookahead, &cont, true);
if (max_char_ > kSize) {
masm->CheckCharacterAfterAnd(single_character,
RegExpMacroAssembler::kTableMask, &cont);
} else {
masm->CheckCharacter(single_character, &cont);
}
masm->AdvanceCurrentPosition(lookahead_width);
masm->GoTo(&again);
masm->Bind(&cont);
return;
}
Factory* factory = masm->isolate()->factory();
Handle<ByteArray> boolean_skip_table =
factory->NewByteArray(kSize, AllocationType::kOld);
int skip_distance =
GetSkipTable(min_lookahead, max_lookahead, boolean_skip_table);
DCHECK_NE(0, skip_distance);
Label cont, again;
masm->Bind(&again);
masm->LoadCurrentCharacter(max_lookahead, &cont, true);
masm->CheckBitInTable(boolean_skip_table, &cont);
masm->AdvanceCurrentPosition(skip_distance);
masm->GoTo(&again);
masm->Bind(&cont);
}
/* Code generation for choice nodes.
*
* We generate quick checks that do a mask and compare to eliminate a
* choice. If the quick check succeeds then it jumps to the continuation to
* do slow checks and check subsequent nodes. If it fails (the common case)
* it falls through to the next choice.
*
* Here is the desired flow graph. Nodes directly below each other imply
* fallthrough. Alternatives 1 and 2 have quick checks. Alternative
* 3 doesn't have a quick check so we have to call the slow check.
* Nodes are marked Qn for quick checks and Sn for slow checks. The entire
* regexp continuation is generated directly after the Sn node, up to the
* next GoTo if we decide to reuse some already generated code. Some
* nodes expect preload_characters to be preloaded into the current
* character register. R nodes do this preloading. Vertices are marked
* F for failures and S for success (possible success in the case of quick
* nodes). L, V, < and > are used as arrow heads.
*
* ----------> R
* |
* V
* Q1 -----> S1
* | S /
* F| /
* | F/
* | /
* | R
* | /
* V L
* Q2 -----> S2
* | S /
* F| /
* | F/
* | /
* | R
* | /
* V L
* S3
* |
* F|
* |
* R
* |
* backtrack V
* <----------Q4
* \ F |
* \ |S
* \ F V
* \-----S4
*
* For greedy loops we push the current position, then generate the code that
* eats the input specially in EmitGreedyLoop. The other choice (the
* continuation) is generated by the normal code in EmitChoices, and steps back
* in the input to the starting position when it fails to match. The loop code
* looks like this (U is the unwind code that steps back in the greedy loop).
*
* _____
* / \
* V |
* ----------> S1 |
* /| |
* / |S |
* F/ \_____/
* /
* |<-----
* | \
* V |S
* Q2 ---> U----->backtrack
* | F /
* S| /
* V F /
* S2--/
*/
GreedyLoopState::GreedyLoopState(bool not_at_start) {
counter_backtrack_trace_.set_backtrack(&label_);
if (not_at_start) counter_backtrack_trace_.set_at_start(Trace::FALSE_VALUE);
}
void ChoiceNode::AssertGuardsMentionRegisters(Trace* trace) {
#ifdef DEBUG
int choice_count = alternatives_->length();
for (int i = 0; i < choice_count - 1; i++) {
GuardedAlternative alternative = alternatives_->at(i);
ZoneList<Guard*>* guards = alternative.guards();
int guard_count = (guards == nullptr) ? 0 : guards->length();
for (int j = 0; j < guard_count; j++) {
DCHECK(!trace->mentions_reg(guards->at(j)->reg()));
}
}
#endif
}
void ChoiceNode::SetUpPreLoad(RegExpCompiler* compiler, Trace* current_trace,
PreloadState* state) {
if (state->eats_at_least_ == PreloadState::kEatsAtLeastNotYetInitialized) {
// Save some time by looking at most one machine word ahead.
state->eats_at_least_ =
EatsAtLeast(current_trace->at_start() == Trace::FALSE_VALUE);
}
state->preload_characters_ =
CalculatePreloadCharacters(compiler, state->eats_at_least_);
state->preload_is_current_ =
(current_trace->characters_preloaded() == state->preload_characters_);
state->preload_has_checked_bounds_ = state->preload_is_current_;
}
void ChoiceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
int choice_count = alternatives_->length();
if (choice_count == 1 && alternatives_->at(0).guards() == nullptr) {
alternatives_->at(0).node()->Emit(compiler, trace);
return;
}
AssertGuardsMentionRegisters(trace);
LimitResult limit_result = LimitVersions(compiler, trace);
if (limit_result == DONE) return;
DCHECK(limit_result == CONTINUE);
// For loop nodes we already flushed (see LoopChoiceNode::Emit), but for
// other choice nodes we only flush if we are out of code size budget.
if (trace->flush_budget() == 0 && trace->actions() != nullptr) {
trace->Flush(compiler, this);
return;
}
RecursionCheck rc(compiler);
PreloadState preload;
preload.init();
GreedyLoopState greedy_loop_state(not_at_start());
int text_length = GreedyLoopTextLengthForAlternative(&alternatives_->at(0));
AlternativeGenerationList alt_gens(choice_count, zone());
if (choice_count > 1 && text_length != kNodeIsTooComplexForGreedyLoops) {
trace = EmitGreedyLoop(compiler, trace, &alt_gens, &preload,
&greedy_loop_state, text_length);
} else {
// TODO(erikcorry): Delete this. We don't need this label, but it makes us
// match the traces produced pre-cleanup.
Label second_choice;
compiler->macro_assembler()->Bind(&second_choice);
preload.eats_at_least_ = EmitOptimizedUnanchoredSearch(compiler, trace);
EmitChoices(compiler, &alt_gens, 0, trace, &preload);
}
// At this point we need to generate slow checks for the alternatives where
// the quick check was inlined. We can recognize these because the associated
// label was bound.
int new_flush_budget = trace->flush_budget() / choice_count;
for (int i = 0; i < choice_count; i++) {
AlternativeGeneration* alt_gen = alt_gens.at(i);
Trace new_trace(*trace);
// If there are actions to be flushed we have to limit how many times
// they are flushed. Take the budget of the parent trace and distribute
// it fairly amongst the children.
if (new_trace.actions() != nullptr) {
new_trace.set_flush_budget(new_flush_budget);
}
bool next_expects_preload =
i == choice_count - 1 ? false : alt_gens.at(i + 1)->expects_preload;
EmitOutOfLineContinuation(compiler, &new_trace, alternatives_->at(i),
alt_gen, preload.preload_characters_,
next_expects_preload);
}
}
Trace* ChoiceNode::EmitGreedyLoop(RegExpCompiler* compiler, Trace* trace,
AlternativeGenerationList* alt_gens,
PreloadState* preload,
GreedyLoopState* greedy_loop_state,
int text_length) {
RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
// Here we have special handling for greedy loops containing only text nodes
// and other simple nodes. These are handled by pushing the current
// position on the stack and then incrementing the current position each
// time around the switch. On backtrack we decrement the current position
// and check it against the pushed value. This avoids pushing backtrack
// information for each iteration of the loop, which could take up a lot of
// space.
DCHECK(trace->stop_node() == nullptr);
macro_assembler->PushCurrentPosition();
Label greedy_match_failed;
Trace greedy_match_trace;
if (not_at_start()) greedy_match_trace.set_at_start(Trace::FALSE_VALUE);
greedy_match_trace.set_backtrack(&greedy_match_failed);
Label loop_label;
macro_assembler->Bind(&loop_label);
greedy_match_trace.set_stop_node(this);
greedy_match_trace.set_loop_label(&loop_label);
alternatives_->at(0).node()->Emit(compiler, &greedy_match_trace);
macro_assembler->Bind(&greedy_match_failed);
Label second_choice; // For use in greedy matches.
macro_assembler->Bind(&second_choice);
Trace* new_trace = greedy_loop_state->counter_backtrack_trace();
EmitChoices(compiler, alt_gens, 1, new_trace, preload);
macro_assembler->Bind(greedy_loop_state->label());
// If we have unwound to the bottom then backtrack.
macro_assembler->CheckGreedyLoop(trace->backtrack());
// Otherwise try the second priority at an earlier position.
macro_assembler->AdvanceCurrentPosition(-text_length);
macro_assembler->GoTo(&second_choice);
return new_trace;
}
int ChoiceNode::EmitOptimizedUnanchoredSearch(RegExpCompiler* compiler,
Trace* trace) {
int eats_at_least = PreloadState::kEatsAtLeastNotYetInitialized;
if (alternatives_->length() != 2) return eats_at_least;
GuardedAlternative alt1 = alternatives_->at(1);
if (alt1.guards() != nullptr && alt1.guards()->length() != 0) {
return eats_at_least;
}
RegExpNode* eats_anything_node = alt1.node();
if (eats_anything_node->GetSuccessorOfOmnivorousTextNode(compiler) != this) {
return eats_at_least;
}
// Really we should be creating a new trace when we execute this function,
// but there is no need, because the code it generates cannot backtrack, and
// we always arrive here with a trivial trace (since it's the entry to a
// loop. That also implies that there are no preloaded characters, which is
// good, because it means we won't be violating any assumptions by
// overwriting those characters with new load instructions.
DCHECK(trace->is_trivial());
RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
Isolate* isolate = macro_assembler->isolate();
// At this point we know that we are at a non-greedy loop that will eat
// any character one at a time. Any non-anchored regexp has such a
// loop prepended to it in order to find where it starts. We look for
// a pattern of the form ...abc... where we can look 6 characters ahead
// and step forwards 3 if the character is not one of abc. Abc need
// not be atoms, they can be any reasonably limited character class or
// small alternation.
BoyerMooreLookahead* bm = bm_info(false);
if (bm == nullptr) {
eats_at_least = std::min(kMaxLookaheadForBoyerMoore, EatsAtLeast(false));
if (eats_at_least >= 1) {
bm = zone()->New<BoyerMooreLookahead>(eats_at_least, compiler, zone());
GuardedAlternative alt0 = alternatives_->at(0);
alt0.node()->FillInBMInfo(isolate, 0, kRecursionBudget, bm, false);
}
}
if (bm != nullptr) {
bm->EmitSkipInstructions(macro_assembler);
}
return eats_at_least;
}
void ChoiceNode::EmitChoices(RegExpCompiler* compiler,
AlternativeGenerationList* alt_gens,
int first_choice, Trace* trace,
PreloadState* preload) {
RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
SetUpPreLoad(compiler, trace, preload);
// For now we just call all choices one after the other. The idea ultimately
// is to use the Dispatch table to try only the relevant ones.
int choice_count = alternatives_->length();
int new_flush_budget = trace->flush_budget() / choice_count;
for (int i = first_choice; i < choice_count; i++) {
bool is_last = i == choice_count - 1;
bool fall_through_on_failure = !is_last;
GuardedAlternative alternative = alternatives_->at(i);
AlternativeGeneration* alt_gen = alt_gens->at(i);
alt_gen->quick_check_details.set_characters(preload->preload_characters_);
ZoneList<Guard*>* guards = alternative.guards();
int guard_count = (guards == nullptr) ? 0 : guards->length();
Trace new_trace(*trace);
new_trace.set_characters_preloaded(
preload->preload_is_current_ ? preload->preload_characters_ : 0);
if (preload->preload_has_checked_bounds_) {
new_trace.set_bound_checked_up_to(preload->preload_characters_);
}
new_trace.quick_check_performed()->Clear();
if (not_at_start_) new_trace.set_at_start(Trace::FALSE_VALUE);
if (!is_last) {
new_trace.set_backtrack(&alt_gen->after);
}
alt_gen->expects_preload = preload->preload_is_current_;
bool generate_full_check_inline = false;
if (compiler->optimize() &&
try_to_emit_quick_check_for_alternative(i == 0) &&
alternative.node()->EmitQuickCheck(
compiler, trace, &new_trace, preload->preload_has_checked_bounds_,
&alt_gen->possible_success, &alt_gen->quick_check_details,
fall_through_on_failure, this)) {
// Quick check was generated for this choice.
preload->preload_is_current_ = true;
preload->preload_has_checked_bounds_ = true;
// If we generated the quick check to fall through on possible success,
// we now need to generate the full check inline.
if (!fall_through_on_failure) {
macro_assembler->Bind(&alt_gen->possible_success);
new_trace.set_quick_check_performed(&alt_gen->quick_check_details);
new_trace.set_characters_preloaded(preload->preload_characters_);
new_trace.set_bound_checked_up_to(preload->preload_characters_);
generate_full_check_inline = true;
}
} else if (alt_gen->quick_check_details.cannot_match()) {
if (!fall_through_on_failure) {
macro_assembler->GoTo(trace->backtrack());
}
continue;
} else {
// No quick check was generated. Put the full code here.
// If this is not the first choice then there could be slow checks from
// previous cases that go here when they fail. There's no reason to
// insist that they preload characters since the slow check we are about
// to generate probably can't use it.
if (i != first_choice) {
alt_gen->expects_preload = false;
new_trace.InvalidateCurrentCharacter();
}
generate_full_check_inline = true;
}
if (generate_full_check_inline) {
if (new_trace.actions() != nullptr) {
new_trace.set_flush_budget(new_flush_budget);
}
for (int j = 0; j < guard_count; j++) {
GenerateGuard(macro_assembler, guards->at(j), &new_trace);
}
alternative.node()->Emit(compiler, &new_trace);
preload->preload_is_current_ = false;
}
macro_assembler->Bind(&alt_gen->after);
}
}
void ChoiceNode::EmitOutOfLineContinuation(RegExpCompiler* compiler,
Trace* trace,
GuardedAlternative alternative,
AlternativeGeneration* alt_gen,
int preload_characters,
bool next_expects_preload) {
if (!alt_gen->possible_success.is_linked()) return;
RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
macro_assembler->Bind(&alt_gen->possible_success);
Trace out_of_line_trace(*trace);
out_of_line_trace.set_characters_preloaded(preload_characters);
out_of_line_trace.set_quick_check_performed(&alt_gen->quick_check_details);
if (not_at_start_) out_of_line_trace.set_at_start(Trace::FALSE_VALUE);
ZoneList<Guard*>* guards = alternative.guards();
int guard_count = (guards == nullptr) ? 0 : guards->length();
if (next_expects_preload) {
Label reload_current_char;
out_of_line_trace.set_backtrack(&reload_current_char);
for (int j = 0; j < guard_count; j++) {
GenerateGuard(macro_assembler, guards->at(j), &out_of_line_trace);
}
alternative.node()->Emit(compiler, &out_of_line_trace);
macro_assembler->Bind(&reload_current_char);
// Reload the current character, since the next quick check expects that.
// We don't need to check bounds here because we only get into this
// code through a quick check which already did the checked load.
macro_assembler->LoadCurrentCharacter(trace->cp_offset(), nullptr, false,
preload_characters);
macro_assembler->GoTo(&(alt_gen->after));
} else {
out_of_line_trace.set_backtrack(&(alt_gen->after));
for (int j = 0; j < guard_count; j++) {
GenerateGuard(macro_assembler, guards->at(j), &out_of_line_trace);
}
alternative.node()->Emit(compiler, &out_of_line_trace);
}
}
void ActionNode::Emit(RegExpCompiler* compiler, Trace* trace) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
LimitResult limit_result = LimitVersions(compiler, trace);
if (limit_result == DONE) return;
DCHECK(limit_result == CONTINUE);
RecursionCheck rc(compiler);
switch (action_type_) {
case STORE_POSITION: {
Trace::DeferredCapture new_capture(data_.u_position_register.reg,
data_.u_position_register.is_capture,
trace);
Trace new_trace = *trace;
new_trace.add_action(&new_capture);
on_success()->Emit(compiler, &new_trace);
break;
}
case INCREMENT_REGISTER: {
Trace::DeferredIncrementRegister new_increment(
data_.u_increment_register.reg);
Trace new_trace = *trace;
new_trace.add_action(&new_increment);
on_success()->Emit(compiler, &new_trace);
break;
}
case SET_REGISTER_FOR_LOOP: {
Trace::DeferredSetRegisterForLoop new_set(data_.u_store_register.reg,
data_.u_store_register.value);
Trace new_trace = *trace;
new_trace.add_action(&new_set);
on_success()->Emit(compiler, &new_trace);
break;
}
case CLEAR_CAPTURES: {
Trace::DeferredClearCaptures new_capture(Interval(
data_.u_clear_captures.range_from, data_.u_clear_captures.range_to));
Trace new_trace = *trace;
new_trace.add_action(&new_capture);
on_success()->Emit(compiler, &new_trace);
break;
}
case BEGIN_POSITIVE_SUBMATCH:
case BEGIN_NEGATIVE_SUBMATCH:
if (!trace->is_trivial()) {
trace->Flush(compiler, this);
} else {
assembler->WriteCurrentPositionToRegister(
data_.u_submatch.current_position_register, 0);
assembler->WriteStackPointerToRegister(
data_.u_submatch.stack_pointer_register);
on_success()->Emit(compiler, trace);
}
break;
case EMPTY_MATCH_CHECK: {
int start_pos_reg = data_.u_empty_match_check.start_register;
int stored_pos = 0;
int rep_reg = data_.u_empty_match_check.repetition_register;
bool has_minimum = (rep_reg != RegExpCompiler::kNoRegister);
bool know_dist = trace->GetStoredPosition(start_pos_reg, &stored_pos);
if (know_dist && !has_minimum && stored_pos == trace->cp_offset()) {
// If we know we haven't advanced and there is no minimum we
// can just backtrack immediately.
assembler->GoTo(trace->backtrack());
} else if (know_dist && stored_pos < trace->cp_offset()) {
// If we know we've advanced we can generate the continuation
// immediately.
on_success()->Emit(compiler, trace);
} else if (!trace->is_trivial()) {
trace->Flush(compiler, this);
} else {
Label skip_empty_check;
// If we have a minimum number of repetitions we check the current
// number first and skip the empty check if it's not enough.
if (has_minimum) {
int limit = data_.u_empty_match_check.repetition_limit;
assembler->IfRegisterLT(rep_reg, limit, &skip_empty_check);
}
// If the match is empty we bail out, otherwise we fall through
// to the on-success continuation.
assembler->IfRegisterEqPos(data_.u_empty_match_check.start_register,
trace->backtrack());
assembler->Bind(&skip_empty_check);
on_success()->Emit(compiler, trace);
}
break;
}
case POSITIVE_SUBMATCH_SUCCESS: {
if (!trace->is_trivial()) {
trace->Flush(compiler, this);
return;
}
assembler->ReadCurrentPositionFromRegister(
data_.u_submatch.current_position_register);
assembler->ReadStackPointerFromRegister(
data_.u_submatch.stack_pointer_register);
int clear_register_count = data_.u_submatch.clear_register_count;
if (clear_register_count == 0) {
on_success()->Emit(compiler, trace);
return;
}
int clear_registers_from = data_.u_submatch.clear_register_from;
Label clear_registers_backtrack;
Trace new_trace = *trace;
new_trace.set_backtrack(&clear_registers_backtrack);
on_success()->Emit(compiler, &new_trace);
assembler->Bind(&clear_registers_backtrack);
int clear_registers_to = clear_registers_from + clear_register_count - 1;
assembler->ClearRegisters(clear_registers_from, clear_registers_to);
DCHECK(trace->backtrack() == nullptr);
assembler->Backtrack();
return;
}
default:
UNREACHABLE();
}
}
void BackReferenceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
RegExpMacroAssembler* assembler = compiler->macro_assembler();
if (!trace->is_trivial()) {
trace->Flush(compiler, this);
return;
}
LimitResult limit_result = LimitVersions(compiler, trace);
if (limit_result == DONE) return;
DCHECK(limit_result == CONTINUE);
RecursionCheck rc(compiler);
DCHECK_EQ(start_reg_ + 1, end_reg_);
if (IsIgnoreCase(flags_)) {
bool unicode = IsEitherUnicode(flags_);
assembler->CheckNotBackReferenceIgnoreCase(start_reg_, read_backward(),
unicode, trace->backtrack());
} else {
assembler->CheckNotBackReference(start_reg_, read_backward(),
trace->backtrack());
}
// We are going to advance backward, so we may end up at the start.
if (read_backward()) trace->set_at_start(Trace::UNKNOWN);
// Check that the back reference does not end inside a surrogate pair.
if (IsEitherUnicode(flags_) && !compiler->one_byte()) {
assembler->CheckNotInSurrogatePair(trace->cp_offset(), trace->backtrack());
}
on_success()->Emit(compiler, trace);
}
void TextNode::CalculateOffsets() {
int element_count = elements()->length();
// Set up the offsets of the elements relative to the start. This is a fixed
// quantity since a TextNode can only contain fixed-width things.
int cp_offset = 0;
for (int i = 0; i < element_count; i++) {
TextElement& elm = elements()->at(i);
elm.set_cp_offset(cp_offset);
cp_offset += elm.length();
}
}
namespace {
// Assertion propagation moves information about assertions such as
// \b to the affected nodes. For instance, in /.\b./ information must
// be propagated to the first '.' that whatever follows needs to know
// if it matched a word or a non-word, and to the second '.' that it
// has to check if it succeeds a word or non-word. In this case the
// result will be something like:
//
// +-------+ +------------+
// | . | | . |
// +-------+ ---> +------------+
// | word? | | check word |
// +-------+ +------------+
class AssertionPropagator : public AllStatic {
public:
static void VisitText(TextNode* that) {}
static void VisitAction(ActionNode* that) {
// If the next node is interested in what it follows then this node
// has to be interested too so it can pass the information on.
that->info()->AddFromFollowing(that->on_success()->info());
}
static void VisitChoice(ChoiceNode* that, int i) {
// Anything the following nodes need to know has to be known by
// this node also, so it can pass it on.
that->info()->AddFromFollowing(that->alternatives()->at(i).node()->info());
}
static void VisitLoopChoiceContinueNode(LoopChoiceNode* that) {
that->info()->AddFromFollowing(that->continue_node()->info());
}
static void VisitLoopChoiceLoopNode(LoopChoiceNode* that) {
that->info()->AddFromFollowing(that->loop_node()->info());
}
static void VisitNegativeLookaroundChoiceLookaroundNode(
NegativeLookaroundChoiceNode* that) {
VisitChoice(that, NegativeLookaroundChoiceNode::kLookaroundIndex);
}
static void VisitNegativeLookaroundChoiceContinueNode(
NegativeLookaroundChoiceNode* that) {
VisitChoice(that, NegativeLookaroundChoiceNode::kContinueIndex);
}
static void VisitBackReference(BackReferenceNode* that) {}
static void VisitAssertion(AssertionNode* that) {}
};
// Propagates information about the minimum size of successful matches from
// successor nodes to their predecessors. Note that all eats_at_least values
// are initialized to zero before analysis.
class EatsAtLeastPropagator : public AllStatic {
public:
static void VisitText(TextNode* that) {
// The eats_at_least value is not used if reading backward.
if (!that->read_backward()) {
// We are not at the start after this node, and thus we can use the
// successor's eats_at_least_from_not_start value.
uint8_t eats_at_least = base::saturated_cast<uint8_t>(
that->Length() + that->on_success()
->eats_at_least_info()
->eats_at_least_from_not_start);
that->set_eats_at_least_info(EatsAtLeastInfo(eats_at_least));
}
}
static void VisitAction(ActionNode* that) {
switch (that->action_type()) {
case ActionNode::BEGIN_POSITIVE_SUBMATCH:
case ActionNode::POSITIVE_SUBMATCH_SUCCESS:
// We do not propagate eats_at_least data through positive lookarounds,
// because they rewind input.
// TODO(v8:11859) Potential approaches for fixing this include:
// 1. Add a dedicated choice node for positive lookaround, similar to
// NegativeLookaroundChoiceNode.
// 2. Add an eats_at_least_inside_loop field to EatsAtLeastInfo, which
// is <= eats_at_least_from_possibly_start, and use that value in
// EatsAtLeastFromLoopEntry.
DCHECK(that->eats_at_least_info()->IsZero());
break;
case ActionNode::SET_REGISTER_FOR_LOOP:
// SET_REGISTER_FOR_LOOP indicates a loop entry point, which means the
// loop body will run at least the minimum number of times before the
// continuation case can run.
that->set_eats_at_least_info(
that->on_success()->EatsAtLeastFromLoopEntry());
break;
case ActionNode::BEGIN_NEGATIVE_SUBMATCH:
default:
// Otherwise, the current node eats at least as much as its successor.
// Note: we can propagate eats_at_least data for BEGIN_NEGATIVE_SUBMATCH
// because NegativeLookaroundChoiceNode ignores its lookaround successor
// when computing eats-at-least and quick check information.
that->set_eats_at_least_info(*that->on_success()->eats_at_least_info());
break;
}
}
static void VisitChoice(ChoiceNode* that, int i) {
// The minimum possible match from a choice node is the minimum of its
// successors.
EatsAtLeastInfo eats_at_least =
i == 0 ? EatsAtLeastInfo(UINT8_MAX) : *that->eats_at_least_info();
eats_at_least.SetMin(
*that->alternatives()->at(i).node()->eats_at_least_info());
that->set_eats_at_least_info(eats_at_least);
}
static void VisitLoopChoiceContinueNode(LoopChoiceNode* that) {
if (!that->read_backward()) {
that->set_eats_at_least_info(
*that->continue_node()->eats_at_least_info());
}
}
static void VisitLoopChoiceLoopNode(LoopChoiceNode* that) {}
static void VisitNegativeLookaroundChoiceLookaroundNode(
NegativeLookaroundChoiceNode* that) {}
static void VisitNegativeLookaroundChoiceContinueNode(
NegativeLookaroundChoiceNode* that) {
that->set_eats_at_least_info(*that->continue_node()->eats_at_least_info());
}
static void VisitBackReference(BackReferenceNode* that) {
if (!that->read_backward()) {
that->set_eats_at_least_info(*that->on_success()->eats_at_least_info());
}
}
static void VisitAssertion(AssertionNode* that) {
EatsAtLeastInfo eats_at_least = *that->on_success()->eats_at_least_info();
if (that->assertion_type() == AssertionNode::AT_START) {
// If we know we are not at the start and we are asked "how many
// characters will you match if you succeed?" then we can answer anything
// since false implies false. So let's just set the max answer
// (UINT8_MAX) since that won't prevent us from preloading a lot of
// characters for the other branches in the node graph.
eats_at_least.eats_at_least_from_not_start = UINT8_MAX;
}
that->set_eats_at_least_info(eats_at_least);
}
};
} // namespace
// -------------------------------------------------------------------
// Analysis
// Iterates the node graph and provides the opportunity for propagators to set
// values that depend on successor nodes.
template <typename... Propagators>
class Analysis : public NodeVisitor {
public:
Analysis(Isolate* isolate, bool is_one_byte, RegExpFlags flags)
: isolate_(isolate),
is_one_byte_(is_one_byte),
flags_(flags),
error_(RegExpError::kNone) {}
void EnsureAnalyzed(RegExpNode* that) {
StackLimitCheck check(isolate());
if (check.HasOverflowed()) {
if (v8_flags.correctness_fuzzer_suppressions) {
FATAL("Analysis: Aborting on stack overflow");
}
fail(RegExpError::kAnalysisStackOverflow);
return;
}
if (that->info()->been_analyzed || that->info()->being_analyzed) return;
that->info()->being_analyzed = true;
that->Accept(this);
that->info()->being_analyzed = false;
that->info()->been_analyzed = true;
}
bool has_failed() { return error_ != RegExpError::kNone; }
RegExpError error() {
DCHECK(error_ != RegExpError::kNone);
return error_;
}
void fail(RegExpError error) { error_ = error; }
Isolate* isolate() const { return isolate_; }
void VisitEnd(EndNode* that) override {
// nothing to do
}
// Used to call the given static function on each propagator / variadic template
// argument.
#define STATIC_FOR_EACH(expr) \
do { \
int dummy[] = {((expr), 0)...}; \
USE(dummy); \
} while (false)
void VisitText(TextNode* that) override {
that->MakeCaseIndependent(isolate(), is_one_byte_, flags_);
EnsureAnalyzed(that->on_success());
if (has_failed()) return;
that->CalculateOffsets();
STATIC_FOR_EACH(Propagators::VisitText(that));
}
void VisitAction(ActionNode* that) override {
EnsureAnalyzed(that->on_success());
if (has_failed()) return;
STATIC_FOR_EACH(Propagators::VisitAction(that));
}
void VisitChoice(ChoiceNode* that) override {
for (int i = 0; i < that->alternatives()->length(); i++) {
EnsureAnalyzed(that->alternatives()->at(i).node());
if (has_failed()) return;
STATIC_FOR_EACH(Propagators::VisitChoice(that, i));
}
}
void VisitLoopChoice(LoopChoiceNode* that) override {
DCHECK_EQ(that->alternatives()->length(), 2); // Just loop and continue.
// First propagate all information from the continuation node.
EnsureAnalyzed(that->continue_node());
if (has_failed()) return;
STATIC_FOR_EACH(Propagators::VisitLoopChoiceContinueNode(that));
// Check the loop last since it may need the value of this node
// to get a correct result.
EnsureAnalyzed(that->loop_node());
if (has_failed()) return;
STATIC_FOR_EACH(Propagators::VisitLoopChoiceLoopNode(that));
}
void VisitNegativeLookaroundChoice(
NegativeLookaroundChoiceNode* that) override {
DCHECK_EQ(that->alternatives()->length(), 2); // Lookaround and continue.
EnsureAnalyzed(that->lookaround_node());
if (has_failed()) return;
STATIC_FOR_EACH(
Propagators::VisitNegativeLookaroundChoiceLookaroundNode(that));
EnsureAnalyzed(that->continue_node());
if (has_failed()) return;
STATIC_FOR_EACH(
Propagators::VisitNegativeLookaroundChoiceContinueNode(that));
}
void VisitBackReference(BackReferenceNode* that) override {
EnsureAnalyzed(that->on_success());
if (has_failed()) return;
STATIC_FOR_EACH(Propagators::VisitBackReference(that));
}
void VisitAssertion(AssertionNode* that) override {
EnsureAnalyzed(that->on_success());
if (has_failed()) return;
STATIC_FOR_EACH(Propagators::VisitAssertion(that));
}
#undef STATIC_FOR_EACH
private:
Isolate* isolate_;
const bool is_one_byte_;
const RegExpFlags flags_;
RegExpError error_;
DISALLOW_IMPLICIT_CONSTRUCTORS(Analysis);
};
RegExpError AnalyzeRegExp(Isolate* isolate, bool is_one_byte, RegExpFlags flags,
RegExpNode* node) {
Analysis<AssertionPropagator, EatsAtLeastPropagator> analysis(
isolate, is_one_byte, flags);
DCHECK_EQ(node->info()->been_analyzed, false);
analysis.EnsureAnalyzed(node);
DCHECK_IMPLIES(analysis.has_failed(), analysis.error() != RegExpError::kNone);
return analysis.has_failed() ? analysis.error() : RegExpError::kNone;
}
void BackReferenceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
BoyerMooreLookahead* bm,
bool not_at_start) {
// Working out the set of characters that a backreference can match is too
// hard, so we just say that any character can match.
bm->SetRest(offset);
SaveBMInfo(bm, not_at_start, offset);
}
static_assert(BoyerMoorePositionInfo::kMapSize ==
RegExpMacroAssembler::kTableSize);
void ChoiceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
BoyerMooreLookahead* bm, bool not_at_start) {
ZoneList<GuardedAlternative>* alts = alternatives();
budget = (budget - 1) / alts->length();
for (int i = 0; i < alts->length(); i++) {
GuardedAlternative& alt = alts->at(i);
if (alt.guards() != nullptr && alt.guards()->length() != 0) {
bm->SetRest(offset); // Give up trying to fill in info.
SaveBMInfo(bm, not_at_start, offset);
return;
}
alt.node()->FillInBMInfo(isolate, offset, budget, bm, not_at_start);
}
SaveBMInfo(bm, not_at_start, offset);
}
void TextNode::FillInBMInfo(Isolate* isolate, int initial_offset, int budget,
BoyerMooreLookahead* bm, bool not_at_start) {
if (initial_offset >= bm->length()) return;
int offset = initial_offset;
int max_char = bm->max_char();
for (int i = 0; i < elements()->length(); i++) {
if (offset >= bm->length()) {
if (initial_offset == 0) set_bm_info(not_at_start, bm);
return;
}
TextElement text = elements()->at(i);
if (text.text_type() == TextElement::ATOM) {
RegExpAtom* atom = text.atom();
for (int j = 0; j < atom->length(); j++, offset++) {
if (offset >= bm->length()) {
if (initial_offset == 0) set_bm_info(not_at_start, bm);
return;
}
base::uc16 character = atom->data()[j];
if (IsIgnoreCase(bm->compiler()->flags())) {
unibrow::uchar chars[4];
int length = GetCaseIndependentLetters(
isolate, character, bm->max_char() == String::kMaxOneByteCharCode,
chars, 4);
for (int k = 0; k < length; k++) {
bm->Set(offset, chars[k]);
}
} else {
if (character <= max_char) bm->Set(offset, character);
}
}
} else {
DCHECK_EQ(TextElement::CLASS_RANGES, text.text_type());
RegExpClassRanges* class_ranges = text.class_ranges();
ZoneList<CharacterRange>* ranges = class_ranges->ranges(zone());
if (class_ranges->is_negated()) {
bm->SetAll(offset);
} else {
for (int k = 0; k < ranges->length(); k++) {
CharacterRange& range = ranges->at(k);
if (static_cast<int>(range.from()) > max_char) continue;
int to = std::min(max_char, static_cast<int>(range.to()));
bm->SetInterval(offset, Interval(range.from(), to));
}
}
offset++;
}
}
if (offset >= bm->length()) {
if (initial_offset == 0) set_bm_info(not_at_start, bm);
return;
}
on_success()->FillInBMInfo(isolate, offset, budget - 1, bm,
true); // Not at start after a text node.
if (initial_offset == 0) set_bm_info(not_at_start, bm);
}
RegExpNode* RegExpCompiler::OptionallyStepBackToLeadSurrogate(
RegExpNode* on_success) {
DCHECK(!read_backward());
ZoneList<CharacterRange>* lead_surrogates = CharacterRange::List(
zone(), CharacterRange::Range(kLeadSurrogateStart, kLeadSurrogateEnd));
ZoneList<CharacterRange>* trail_surrogates = CharacterRange::List(
zone(), CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd));
ChoiceNode* optional_step_back = zone()->New<ChoiceNode>(2, zone());
int stack_register = UnicodeLookaroundStackRegister();
int position_register = UnicodeLookaroundPositionRegister();
RegExpNode* step_back = TextNode::CreateForCharacterRanges(
zone(), lead_surrogates, true, on_success);
RegExpLookaround::Builder builder(true, step_back, stack_register,
position_register);
RegExpNode* match_trail = TextNode::CreateForCharacterRanges(
zone(), trail_surrogates, false, builder.on_match_success());
optional_step_back->AddAlternative(
GuardedAlternative(builder.ForMatch(match_trail)));
optional_step_back->AddAlternative(GuardedAlternative(on_success));
return optional_step_back;
}
RegExpNode* RegExpCompiler::PreprocessRegExp(RegExpCompileData* data,
RegExpFlags flags,
bool is_one_byte) {
// Wrap the body of the regexp in capture #0.
RegExpNode* captured_body =
RegExpCapture::ToNode(data->tree, 0, this, accept());
RegExpNode* node = captured_body;
if (!data->tree->IsAnchoredAtStart() && !IsSticky(flags)) {
// Add a .*? at the beginning, outside the body capture, unless
// this expression is anchored at the beginning or sticky.
RegExpNode* loop_node = RegExpQuantifier::ToNode(
0, RegExpTree::kInfinity, false,
zone()->New<RegExpClassRanges>(StandardCharacterSet::kEverything), this,
captured_body, data->contains_anchor);
if (data->contains_anchor) {
// Unroll loop once, to take care of the case that might start
// at the start of input.
ChoiceNode* first_step_node = zone()->New<ChoiceNode>(2, zone());
first_step_node->AddAlternative(GuardedAlternative(captured_body));
first_step_node->AddAlternative(GuardedAlternative(zone()->New<TextNode>(
zone()->New<RegExpClassRanges>(StandardCharacterSet::kEverything),
false, loop_node)));
node = first_step_node;
} else {
node = loop_node;
}
}
if (is_one_byte) {
node = node->FilterOneByte(RegExpCompiler::kMaxRecursion, flags);
// Do it again to propagate the new nodes to places where they were not
// put because they had not been calculated yet.
if (node != nullptr) {
node = node->FilterOneByte(RegExpCompiler::kMaxRecursion, flags);
}
} else if (IsEitherUnicode(flags) && (IsGlobal(flags) || IsSticky(flags))) {
node = OptionallyStepBackToLeadSurrogate(node);
}
if (node == nullptr) node = zone()->New<EndNode>(EndNode::BACKTRACK, zone());
return node;
}
void RegExpCompiler::ToNodeCheckForStackOverflow() {
if (StackLimitCheck{isolate()}.HasOverflowed()) {
V8::FatalProcessOutOfMemory(isolate(), "RegExpCompiler");
}
}
} // namespace internal
} // namespace v8
Mini Shell