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+// 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 "irregexp/imported/regexp-compiler.h"
+
+#include "irregexp/imported/regexp-macro-assembler-arch.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "irregexp/imported/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,
+ &registers_to_pop, &registers_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