Revision: 11696
Author:   [email protected]
Date:     Fri Jun  1 04:28:52 2012
Log:      Limit work done analyzing regexps with very large fanout.
BUG=128821
Review URL: https://chromiumcodereview.appspot.com/10448117
http://code.google.com/p/v8/source/detail?r=11696

Modified:
 /branches/bleeding_edge/src/jsregexp.cc
 /branches/bleeding_edge/src/jsregexp.h
 /branches/bleeding_edge/test/mjsunit/regexp-capture-3.js
 /branches/bleeding_edge/test/mjsunit/regexp-capture.js

=======================================
--- /branches/bleeding_edge/src/jsregexp.cc     Thu May 31 04:59:04 2012
+++ /branches/bleeding_edge/src/jsregexp.cc     Fri Jun  1 04:28:52 2012
@@ -2192,12 +2192,14 @@

 void ActionNode::FillInBMInfo(int offset,
                               int recursion_depth,
+                              int budget,
                               BoyerMooreLookahead* bm,
                               bool not_at_start) {
   if (type_ == BEGIN_SUBMATCH) {
     bm->SetRest(offset);
   } else if (type_ != POSITIVE_SUBMATCH_SUCCESS) {
- on_success()->FillInBMInfo(offset, recursion_depth + 1, bm, not_at_start);
+    on_success()->FillInBMInfo(
+        offset, recursion_depth + 1, budget - 1, bm, not_at_start);
   }
   SaveBMInfo(bm, not_at_start, offset);
 }
@@ -2221,11 +2223,13 @@

 void AssertionNode::FillInBMInfo(int offset,
                                  int recursion_depth,
+                                 int budget,
                                  BoyerMooreLookahead* bm,
                                  bool not_at_start) {
   // Match the behaviour of EatsAtLeast on this node.
   if (type() == AT_START && not_at_start) return;
- on_success()->FillInBMInfo(offset, recursion_depth + 1, bm, not_at_start);
+  on_success()->FillInBMInfo(
+      offset, recursion_depth + 1, budget - 1, bm, not_at_start);
   SaveBMInfo(bm, not_at_start, offset);
 }

@@ -2808,15 +2812,18 @@

 void LoopChoiceNode::FillInBMInfo(int offset,
                                   int recursion_depth,
+                                  int budget,
                                   BoyerMooreLookahead* bm,
                                   bool not_at_start) {
   if (body_can_be_zero_length_ ||
-      recursion_depth > RegExpCompiler::kMaxRecursion) {
+      recursion_depth > RegExpCompiler::kMaxRecursion ||
+      budget <= 0) {
     bm->SetRest(offset);
     SaveBMInfo(bm, not_at_start, offset);
     return;
   }
-  ChoiceNode::FillInBMInfo(offset, recursion_depth + 1, bm, not_at_start);
+  ChoiceNode::FillInBMInfo(
+      offset, recursion_depth + 1, budget - 1, bm, not_at_start);
   SaveBMInfo(bm, not_at_start, offset);
 }

@@ -2918,7 +2925,7 @@
     if (eats_at_least >= 1) {
       BoyerMooreLookahead* bm =
           new BoyerMooreLookahead(eats_at_least, compiler);
-      FillInBMInfo(0, 0, bm, not_at_start);
+      FillInBMInfo(0, 0, kFillInBMBudget, bm, not_at_start);
       if (bm->at(0)->is_non_word()) next_is_word_character = Trace::FALSE;
       if (bm->at(0)->is_word()) next_is_word_character = Trace::TRUE;
     }
@@ -3856,7 +3863,7 @@
             BoyerMooreLookahead* bm =
                 new BoyerMooreLookahead(eats_at_least, compiler);
             GuardedAlternative alt0 = alternatives_->at(0);
-            alt0.node()->FillInBMInfo(0, 0, bm, not_at_start);
+ alt0.node()->FillInBMInfo(0, 0, kFillInBMBudget, bm, not_at_start);
             skip_was_emitted = bm->EmitSkipInstructions(macro_assembler);
           }
         } else {
@@ -5597,6 +5604,7 @@

 void BackReferenceNode::FillInBMInfo(int offset,
                                      int recursion_depth,
+                                     int budget,
                                      BoyerMooreLookahead* bm,
                                      bool not_at_start) {
// Working out the set of characters that a backreference can match is too
@@ -5612,9 +5620,11 @@

 void ChoiceNode::FillInBMInfo(int offset,
                               int recursion_depth,
+                              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() != NULL && alt.guards()->length() != 0) {
@@ -5622,7 +5632,8 @@
       SaveBMInfo(bm, not_at_start, offset);
       return;
     }
- alt.node()->FillInBMInfo(offset, recursion_depth + 1, bm, not_at_start);
+    alt.node()->FillInBMInfo(
+        offset, recursion_depth + 1, budget, bm, not_at_start);
   }
   SaveBMInfo(bm, not_at_start, offset);
 }
@@ -5630,6 +5641,7 @@

 void TextNode::FillInBMInfo(int initial_offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start) {
   if (initial_offset >= bm->length()) return;
@@ -5686,6 +5698,7 @@
   }
   on_success()->FillInBMInfo(offset,
                              recursion_depth + 1,
+                             budget - 1,
                              bm,
                              true);  // Not at start after a text node.
   if (initial_offset == 0) set_bm_info(not_at_start, bm);
=======================================
--- /branches/bleeding_edge/src/jsregexp.h      Thu May 31 04:59:04 2012
+++ /branches/bleeding_edge/src/jsregexp.h      Fri Jun  1 04:28:52 2012
@@ -580,9 +580,12 @@
// Collects information on the possible code units (mod 128) that can match if
   // we look forward.  This is used for a Boyer-Moore-like string searching
   // implementation.  TODO(erikcorry):  This should share more code with
-  // EatsAtLeast, GetQuickCheckDetails.
+ // EatsAtLeast, GetQuickCheckDetails. The budget argument is used to limit + // the number of nodes we are willing to look at in order to create this data.
+  static const int kFillInBMBudget = 200;
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start) {
     UNREACHABLE();
@@ -685,9 +688,11 @@
   virtual RegExpNode* FilterASCII(int depth);
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start) {
- on_success_->FillInBMInfo(offset, recursion_depth + 1, bm, not_at_start);
+    on_success_->FillInBMInfo(
+        offset, recursion_depth + 1, budget - 1, bm, not_at_start);
     if (offset == 0) set_bm_info(not_at_start, bm);
   }

@@ -742,6 +747,7 @@
   }
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start);
   Type type() { return type_; }
@@ -813,6 +819,7 @@
       RegExpCompiler* compiler);
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start);
   void CalculateOffsets();
@@ -875,6 +882,7 @@
                                     bool not_at_start);
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start);
   AssertionNodeType type() { return type_; }
@@ -915,6 +923,7 @@
   }
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start);

@@ -942,6 +951,7 @@
   }
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start) {
     // Returning 0 from EatsAtLeast should ensure we never get here.
@@ -1034,6 +1044,7 @@
                                     bool not_at_start);
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start);

@@ -1086,10 +1097,11 @@
                                     bool not_at_start);
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start) {
     alternatives_->at(1).node()->FillInBMInfo(
-        offset, recursion_depth + 1, bm, not_at_start);
+        offset, recursion_depth + 1, budget - 1, bm, not_at_start);
     if (offset == 0) set_bm_info(not_at_start, bm);
   }
   // For a negative lookahead we don't emit the quick check for the
@@ -1121,6 +1133,7 @@
                                     bool not_at_start);
   virtual void FillInBMInfo(int offset,
                             int recursion_depth,
+                            int budget,
                             BoyerMooreLookahead* bm,
                             bool not_at_start);
   RegExpNode* loop_node() { return loop_node_; }
=======================================
--- /branches/bleeding_edge/test/mjsunit/regexp-capture-3.js Thu May 31 04:59:04 2012 +++ /branches/bleeding_edge/test/mjsunit/regexp-capture-3.js Fri Jun 1 04:28:52 2012
@@ -162,7 +162,6 @@
 // string we can test that the relevant node is removed by verifying that
 // there is no hang.
 function NoHang(re) {
-  print(re);
   "This is an ASCII string that could take forever".match(re);
 }

=======================================
--- /branches/bleeding_edge/test/mjsunit/regexp-capture.js Fri Apr 15 04:35:36 2011 +++ /branches/bleeding_edge/test/mjsunit/regexp-capture.js Fri Jun 1 04:28:52 2012
@@ -56,3 +56,5 @@
 assertEquals(["bbaa", "a", "", "a"],
              /((\3|b)\2(a)){2,}/.exec("bbaababbabaaaaabbaaaabba"));

+// From crbug.com/128821 - don't hang:
+"".match(/((a|i|A|I|u|o|U|O)(s|c|b|c|d|f|g|h|j|k|l|m|n|p|q|r|s|t|v|w|x|y|z| B|C|D|F|G|H|J|K|L|M|N|P|Q|R|S|T|V|W|X|Y|Z)*) de\/da([.,!?\s]|$)/);

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