Port and integrate the irregexp engine from V8

runtime/vm/regexp.h

Index: runtime/vm/regexp.h
diff --git a/runtime/vm/regexp.h b/runtime/vm/regexp.h
index 5a22c5f687e3b3fc44a3e3a709f8f2a829bcf26c..636d48fa7b7b9d3dbd5afd1056263642e233f7fa 100644
--- a/runtime/vm/regexp.h
+++ b/runtime/vm/regexp.h
@@ -6,7 +6,9 @@
 #define VM_REGEXP_H_
 
 #include "vm/assembler.h"
+#include "vm/intermediate_language.h"
 #include "vm/object.h"
+#include "vm/regexp_assembler.h"
 
 namespace dart {
 
@@ -239,7 +241,7 @@ class RegExpNode: public ZoneAllocated {
   bool EmitQuickCheck(RegExpCompiler* compiler,
                       Trace* trace,
                       bool preload_has_checked_bounds,
-                      Label* on_possible_success,
+                      BlockLabel* on_possible_success,
                       QuickCheckDetails* details_return,
                       bool fall_through_on_failure);
   // For a given number of characters this returns a mask and a value.  The
@@ -299,7 +301,7 @@ class RegExpNode: public ZoneAllocated {
     if (offset == 0) set_bm_info(not_at_start, bm);
   }
 
-  Label* label() { return &label_; }
+  BlockLabel* label() { return &label_; }
   // If non-generic code is generated for a node (i.e. the node is not at the
   // start of the trace) then it cannot be reused.  This variable sets a limit
   // on how often we allow that to happen before we insist on starting a new
@@ -319,13 +321,15 @@ class RegExpNode: public ZoneAllocated {
   enum LimitResult { DONE, CONTINUE };
   RegExpNode* replacement_;
 
+  LimitResult LimitVersions(RegExpCompiler* compiler, Trace* trace);
+
   void set_bm_info(bool not_at_start, BoyerMooreLookahead* bm) {
     bm_info_[not_at_start ? 1 : 0] = bm;
   }
 
  private:
   static const intptr_t kFirstCharBudget = 10;
-  Label label_;
+  BlockLabel label_;
   NodeInfo info_;
   // This variable keeps track of how many times code has been generated for
   // this node (in different traces).  We don't keep track of where the
@@ -535,7 +539,7 @@ class GuardedAlternative {
 class OutSet: public ZoneAllocated {
  public:
   OutSet() : first_(0), remaining_(NULL), successors_(NULL) { }
-  OutSet* Extend(unsigned value, Zone* zone);
+  OutSet* Extend(unsigned value, Isolate* isolate);
   bool Get(unsigned value) const;
   static const unsigned kFirstLimit = 32;
 
@@ -543,7 +547,7 @@ class OutSet: public ZoneAllocated {
   // Destructively set a value in this set.  In most cases you want
   // to use Extend instead to ensure that only one instance exists
   // that contains the same values.
-  void Set(unsigned value, Zone* zone);
+  void Set(unsigned value, Isolate* isolate);
 
   // The successors are a list of sets that contain the same values
   // as this set and the one more value that is not present in this
@@ -573,8 +577,8 @@ class DispatchTable : public ZoneAllocated {
     uint16_t from() { return from_; }
     uint16_t to() { return to_; }
     void set_to(uint16_t value) { to_ = value; }
-    void AddValue(intptr_t value, Zone* zone) {
-      out_set_ = out_set_->Extend(value, zone);
+    void AddValue(intptr_t value, Isolate* isolate) {
+      out_set_ = out_set_->Extend(value, isolate);
     }
     OutSet* out_set() { return out_set_; }
    private:
@@ -632,7 +636,6 @@ class ChoiceNode: public RegExpNode {
   ZoneGrowableArray<GuardedAlternative>* alternatives() {
     return alternatives_;
   }
-  DispatchTable* GetTable(bool ignore_case);
   virtual void Emit(RegExpCompiler* compiler, Trace* trace);
   virtual intptr_t EatsAtLeast(intptr_t still_to_find, intptr_t budget,
                                bool not_at_start);
@@ -986,6 +989,149 @@ class QuickCheckDetails {
 };
 
 
+// Improve the speed that we scan for an initial point where a non-anchored
+// regexp can match by using a Boyer-Moore-like table. This is done by
+// identifying non-greedy non-capturing loops in the nodes that eat any
+// character one at a time.  For example in the middle of the regexp
+// /foo[\s\S]*?bar/ we find such a loop.  There is also such a loop implicitly
+// inserted at the start of any non-anchored regexp.
+//
+// When we have found such a loop we look ahead in the nodes to find the set of
+// characters that can come at given distances. For example for the regexp
+// /.?foo/ we know that there are at least 3 characters ahead of us, and the
+// sets of characters that can occur are [any, [f, o], [o]]. We find a range in
+// the lookahead info where the set of characters is reasonably constrained. In
+// our example this is from index 1 to 2 (0 is not constrained). We can now
+// look 3 characters ahead and if we don't find one of [f, o] (the union of
+// [f, o] and [o]) then we can skip forwards by the range size (in this case 2).
+//
+// For Unicode input strings we do the same, but modulo 128.
+//
+// We also look at the first string fed to the regexp and use that to get a hint
+// of the character frequencies in the inputs. This affects the assessment of
+// whether the set of characters is 'reasonably constrained'.
+//
+// We also have another lookahead mechanism (called quick check in the code),
+// which uses a wide load of multiple characters followed by a mask and compare
+// to determine whether a match is possible at this point.
+enum ContainedInLattice {
+  kNotYet = 0,
+  kLatticeIn = 1,
+  kLatticeOut = 2,
+  kLatticeUnknown = 3  // Can also mean both in and out.
+};
+
+
+inline ContainedInLattice Combine(ContainedInLattice a, ContainedInLattice b) {
+  return static_cast<ContainedInLattice>(a | b);
+}
+
+
+ContainedInLattice AddRange(ContainedInLattice a,
+                            const int* ranges,
+                            intptr_t ranges_size,
+                            Interval new_range);
+
+
+class BoyerMoorePositionInfo : public ZoneAllocated {
+ public:
+  explicit BoyerMoorePositionInfo(Isolate* isolate)
+      : map_(new(isolate) ZoneGrowableArray<bool>(kMapSize)),
+        map_count_(0),
+        w_(kNotYet),
+        s_(kNotYet),
+        d_(kNotYet),
+        surrogate_(kNotYet) {
+     for (intptr_t i = 0; i < kMapSize; i++) {
+       map_->Add(false);
+     }
+  }
+
+  bool& at(intptr_t i) { return (*map_)[i]; }
+
+  static const intptr_t kMapSize = 128;
+  static const intptr_t kMask = kMapSize - 1;
+
+  intptr_t map_count() const { return map_count_; }
+
+  void Set(intptr_t character);
+  void SetInterval(const Interval& interval);
+  void SetAll();
+  bool is_non_word() { return w_ == kLatticeOut; }
+  bool is_word() { return w_ == kLatticeIn; }
+
+ private:
+  ZoneGrowableArray<bool>* map_;
+  intptr_t map_count_;  // Number of set bits in the map.
+  ContainedInLattice w_;  // The \w character class.
+  ContainedInLattice s_;  // The \s character class.
+  ContainedInLattice d_;  // The \d character class.
+  ContainedInLattice surrogate_;  // Surrogate UTF-16 code units.
+};
+
+
+class BoyerMooreLookahead : public ZoneAllocated{
+ public:
+  BoyerMooreLookahead(intptr_t length, RegExpCompiler* compiler,
+                      Isolate* Isolate);
+
+  intptr_t length() { return length_; }
+  intptr_t max_char() { return max_char_; }
+  RegExpCompiler* compiler() { return compiler_; }
+
+  intptr_t Count(intptr_t map_number) {
+    return bitmaps_->At(map_number)->map_count();
+  }
+
+  BoyerMoorePositionInfo* at(intptr_t i) { return bitmaps_->At(i); }
+
+  void Set(intptr_t map_number, intptr_t character) {
+    if (character > max_char_) return;
+    BoyerMoorePositionInfo* info = bitmaps_->At(map_number);
+    info->Set(character);
+  }
+
+  void SetInterval(intptr_t map_number, const Interval& interval) {
+    if (interval.from() > max_char_) return;
+    BoyerMoorePositionInfo* info = bitmaps_->At(map_number);
+    if (interval.to() > max_char_) {
+      info->SetInterval(Interval(interval.from(), max_char_));
+    } else {
+      info->SetInterval(interval);
+    }
+  }
+
+  void SetAll(intptr_t map_number) {
+    bitmaps_->At(map_number)->SetAll();
+  }
+
+  void SetRest(intptr_t from_map) {
+    for (intptr_t i = from_map; i < length_; i++) SetAll(i);
+  }
+  bool EmitSkipInstructions(RegExpMacroAssembler* masm);
+
+ private:
+  // This is the value obtained by EatsAtLeast.  If we do not have at least this
+  // many characters left in the sample string then the match is bound to fail.
+  // Therefore it is OK to read a character this far ahead of the current match
+  // point.
+  intptr_t length_;
+  RegExpCompiler* compiler_;
+  // 0x7f for ASCII, 0xffff for UTF-16.
+  intptr_t max_char_;
+  ZoneGrowableArray<BoyerMoorePositionInfo*>* bitmaps_;
+
+  intptr_t GetSkipTable(intptr_t min_lookahead,
+                        intptr_t max_lookahead,
+                        TypedData* boolean_skip_table);
+  bool FindWorthwhileInterval(intptr_t* from, intptr_t* to);
+  intptr_t FindBestInterval(
+      intptr_t max_number_of_chars,
+      intptr_t old_biggest_points,
+      intptr_t* from, intptr_t* to);
+};
+
+
 // There are many ways to generate code for a node.  This class encapsulates
 // the current way we should be generating.  In other words it encapsulates
 // the current state of the code generator.  The effect of this is that we
@@ -1101,8 +1247,8 @@ class Trace {
   void set_at_start(bool at_start) {
     at_start_ = at_start ? TRUE_VALUE : FALSE_VALUE;
   }
-  Label* backtrack() { return backtrack_; }
-  Label* loop_label() { return loop_label_; }
+  BlockLabel* backtrack() { return backtrack_; }
+  BlockLabel* loop_label() { return loop_label_; }
   RegExpNode* stop_node() { return stop_node_; }
   intptr_t characters_preloaded() { return characters_preloaded_; }
   intptr_t bound_checked_up_to() { return bound_checked_up_to_; }
@@ -1120,9 +1266,9 @@ class Trace {
     new_action->next_ = actions_;
     actions_ = new_action;
   }
-  void set_backtrack(Label* backtrack) { backtrack_ = backtrack; }
+  void set_backtrack(BlockLabel* backtrack) { backtrack_ = backtrack; }
   void set_stop_node(RegExpNode* node) { stop_node_ = node; }
-  void set_loop_label(Label* label) { loop_label_ = label; }
+  void set_loop_label(BlockLabel* label) { loop_label_ = label; }
   void set_characters_preloaded(intptr_t count) {
     characters_preloaded_ = count;
   }
@@ -1135,22 +1281,22 @@ class Trace {
   void AdvanceCurrentPositionInTrace(intptr_t by, RegExpCompiler* compiler);
 
  private:
-  intptr_t FindAffectedRegisters(OutSet* affected_registers, Zone* zone);
+  intptr_t FindAffectedRegisters(OutSet* affected_registers, Isolate* isolate);
   void PerformDeferredActions(RegExpMacroAssembler* macro,
                               intptr_t max_register,
                               const OutSet& affected_registers,
                               OutSet* registers_to_pop,
                               OutSet* registers_to_clear,
-                              Zone* zone);
+                              Isolate* isolate);
   void RestoreAffectedRegisters(RegExpMacroAssembler* macro,
                                 intptr_t max_register,
                                 const OutSet& registers_to_pop,
                                 const OutSet& registers_to_clear);
   intptr_t cp_offset_;
   DeferredAction* actions_;
-  Label* backtrack_;
+  BlockLabel* backtrack_;
   RegExpNode* stop_node_;
-  Label* loop_label_;
+  BlockLabel* loop_label_;
   intptr_t characters_preloaded_;
   intptr_t bound_checked_up_to_;
   QuickCheckDetails quick_check_performed_;
@@ -1214,7 +1360,7 @@ FOR_EACH_NODE_TYPE(DECLARE_VISIT)
 };
 
 
-struct RegExpCompileData {
+struct RegExpCompileData : public ZoneAllocated {
   RegExpCompileData()
     : tree(NULL),
       node(NULL),
@@ -1235,22 +1381,38 @@ class RegExpEngine: public AllStatic {
  public:
   struct CompilationResult {
     explicit CompilationResult(const char* error_message)
-        : error_message(error_message),
-          num_registers(0) {}
-    CompilationResult(Object* code, intptr_t registers)
-      : error_message(NULL),
-        num_registers(registers) {}
+        : macro_assembler(NULL),
+          graph_entry(NULL),
+          num_blocks(-1),
+          num_stack_locals(-1),
+          error_message(error_message) {}
+    explicit CompilationResult(IRRegExpMacroAssembler* macro_assembler,
+                               GraphEntryInstr* graph_entry,
+                               intptr_t num_blocks,
+                               intptr_t num_stack_locals)
+      : macro_assembler(macro_assembler),
+        graph_entry(graph_entry),
+        num_blocks(num_blocks),
+        num_stack_locals(num_stack_locals),
+        error_message(NULL) {}
+
+    IRRegExpMacroAssembler* macro_assembler;
+    GraphEntryInstr* graph_entry;
+    const intptr_t num_blocks;
+    const intptr_t num_stack_locals;
+
     const char* error_message;
-    intptr_t num_registers;
   };
 
-  static CompilationResult Compile(RegExpCompileData* input,
-                                   bool ignore_case,
-                                   bool global,
-                                   bool multiline,
-                                   const String& pattern,
-                                   const String& sample_subject,
-                                   bool is_ascii);
+  static CompilationResult Compile(
+      RegExpCompileData* input,
+      const ParsedFunction* parsed_function,
+      ZoneGrowableArray<const ICData*>* ic_data_array);
+
+  static RawJSRegExp* New(Isolate* isolate,
+                          const String& pattern,
+                          bool multi_line,
+                          bool ignore_case);
 
   static void DotPrint(const char* label, RegExpNode* node, bool ignore_case);
 };