allow some prefixes that may squash the literal match to run eagerly

src/nfagraph/ng_execute.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2016, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -324,4 +324,49 @@ flat_set<NFAVertex> execute_graph(const NGHolder &running_g,
                          initial_states);
 }
 
+static
+bool can_die_early(const NGHolder &g, const vector<StateInfo> &info,
+                   const dynamic_bitset<> &s,
+                   map<dynamic_bitset<>, u32> &visited, u32 age_limit) {
+    if (contains(visited, s) && visited[s] >= age_limit) {
+        /* we have already (or are in the process) of visiting here with a
+         * looser limit. */
+        return false;
+    }
+    visited[s] = age_limit;
+
+    if (s.none()) {
+        DEBUG_PRINTF("dead\n");
+        return true;
+    }
+
+    if (age_limit == 0) {
+        return false;
+    }
+
+    dynamic_bitset<> all_succ(s.size());
+    step(g, info, s, &all_succ);
+    all_succ.reset(NODE_START_DOTSTAR);
+
+    for (u32 i = 0; i < N_CHARS; i++) {
+        dynamic_bitset<> next = all_succ;
+        filter_by_reach(info, &next, CharReach(i));
+        if (can_die_early(g, info, next, visited, age_limit - 1)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+bool can_die_early(const NGHolder &g, u32 age_limit) {
+    if (proper_out_degree(g.startDs, g)) {
+        return false;
+    }
+    const vector<StateInfo> &info = makeInfoTable(g);
+    map<dynamic_bitset<>, u32> visited;
+    return can_die_early(g, info, makeStateBitset(g, {g.start}), visited,
+                         age_limit);
+}
+
 } // namespace ue2

src/nfagraph/ng_execute.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2016, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -64,6 +64,9 @@ flat_set<NFAVertex> execute_graph(const NGHolder &g, const NGHolder &input_dag,
                                   const flat_set<NFAVertex> &input_start_states,
                                   const flat_set<NFAVertex> &initial);
 
+/* returns true if it is possible for the nfa to die within age_limit bytes */
+bool can_die_early(const NGHolder &g, u32 age_limit);
+
 } // namespace ue2
 
 #endif

src/nfagraph/ng_holder.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2016, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -315,15 +315,26 @@ void remove_edges(const Container &c, NGHolder &h, bool renumber = true) {
     remove_edges(c.begin(), c.end(), h, renumber);
 }
 
-static UNUSED
+inline
 bool is_triggered(const NGHolder &g) {
     return is_triggered(g.kind);
 }
 
-static UNUSED
+inline
 bool generates_callbacks(const NGHolder &g) {
     return generates_callbacks(g.kind);
 }
+
+inline
+bool has_managed_reports(const NGHolder &g) {
+    return has_managed_reports(g.kind);
+}
+
+inline
+bool inspects_states_for_accepts(const NGHolder &g) {
+    return inspects_states_for_accepts(g.kind);
+}
+
 } // namespace ue2
 
 #endif

src/nfagraph/ng_limex.cpp

@@ -373,7 +373,7 @@ constructNFA(const NGHolder &h_in, const ReportManager *rm,
              const map<u32, vector<vector<CharReach>>> &triggers,
              bool compress_state, bool do_accel, bool impl_test_only, u32 hint,
              const CompileContext &cc) {
-    if (!generates_callbacks(h_in)) {
+    if (!has_managed_reports(h_in)) {
         rm = nullptr;
     } else {
         assert(rm);
@@ -413,7 +413,7 @@ constructNFA(const NGHolder &h_in, const ReportManager *rm,
 
     set<NFAVertex> zombies = findZombies(*h, br_cyclic, state_ids, cc);
 
-    if (generates_callbacks(*h)) {
+    if (has_managed_reports(*h)) {
         assert(rm);
         remapReportsToPrograms(*h, *rm);
     }
@@ -508,7 +508,7 @@ u32 isImplementableNFA(const NGHolder &g, const ReportManager *rm,
         return true;
     }
 
-    if (!generates_callbacks(g)) {
+    if (!has_managed_reports(g)) {
         rm = nullptr;
     } else {
         assert(rm);
@@ -547,7 +547,7 @@ void reduceImplementableGraph(NGHolder &g, som_type som, const ReportManager *rm
 
     removeRedundancy(g, som);
 
-    if (rm && generates_callbacks(g)) {
+    if (rm && has_managed_reports(g)) {
         pruneHighlanderDominated(g, *rm);
     }
 
@@ -560,7 +560,7 @@ void reduceImplementableGraph(NGHolder &g, som_type som, const ReportManager *rm
 
 u32 countAccelStates(const NGHolder &g, const ReportManager *rm,
                      const CompileContext &cc) {
-    if (!generates_callbacks(g)) {
+    if (!has_managed_reports(g)) {
         rm = nullptr;
     } else {
         assert(rm);

src/nfagraph/ng_mcclellan.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2016, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -531,9 +531,9 @@ unique_ptr<raw_dfa> buildMcClellan(const NGHolder &graph,
     DEBUG_PRINTF("attempting to build ?%d? mcclellan\n", (int)graph.kind);
     assert(allMatchStatesHaveReports(graph));
 
-    bool prunable = grey.highlanderPruneDFA && generates_callbacks(graph);
-    assert(rm || !generates_callbacks(graph));
-    if (!generates_callbacks(graph)) {
+    bool prunable = grey.highlanderPruneDFA && has_managed_reports(graph);
+    assert(rm || !has_managed_reports(graph));
+    if (!has_managed_reports(graph)) {
         rm = nullptr;
     }
 

src/nfagraph/ng_split.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2016, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -112,6 +112,12 @@ void splitLHS(const NGHolder &base, const vector<NFAVertex> &pivots,
     case NFA_SUFFIX:
         lhs->kind = NFA_INFIX;
         break;
+    case NFA_EAGER_PREFIX:
+        /* Current code should not be assigning eager until well after all the
+         * splitting is done. */
+        assert(0);
+        lhs->kind = NFA_EAGER_PREFIX;
+        break;
     case NFA_REV_PREFIX:
     case NFA_OUTFIX_RAW:
         assert(0);
@@ -154,6 +160,12 @@ void splitRHS(const NGHolder &base, const vector<NFAVertex> &pivots,
     case NFA_OUTFIX:
         rhs->kind = NFA_SUFFIX;
         break;
+    case NFA_EAGER_PREFIX:
+        /* Current code should not be assigning eager until well after all the
+         * splitting is done. */
+        assert(0);
+        rhs->kind = NFA_INFIX;
+        break;
     case NFA_REV_PREFIX:
     case NFA_OUTFIX_RAW:
         assert(0);