From b454ab64848a9850ba87c310539338a3643f2aff Mon Sep 17 00:00:00 2001
From: Justin Viiret <justin.viiret@intel.com>
Date: Tue, 4 Jul 2017 13:22:09 +1000
Subject: [PATCH] ng_prefilter.cpp: remove interior edges first

This allows us to avoid looking them up while we're in copyOutEdges(),
halves time on large cases.
---
 src/nfagraph/ng_prefilter.cpp | 37 +++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/src/nfagraph/ng_prefilter.cpp b/src/nfagraph/ng_prefilter.cpp
index 3cd9d06d..64d4cf2f 100644
--- a/src/nfagraph/ng_prefilter.cpp
+++ b/src/nfagraph/ng_prefilter.cpp
@@ -213,27 +213,17 @@ map<u32, RegionInfo> findRegionInfo(const NGHolder &h,
 }
 
 static
-void copyInEdges(NGHolder &g, NFAVertex from, NFAVertex to,
-                 const ue2::unordered_set<NFAVertex> &rverts) {
+void copyInEdges(NGHolder &g, NFAVertex from, NFAVertex to) {
     for (const auto &e : in_edges_range(from, g)) {
         NFAVertex u = source(e, g);
-        if (contains(rverts, u)) {
-            continue;
-        }
-
         add_edge_if_not_present(u, to, g[e], g);
     }
 }
 
 static
-void copyOutEdges(NGHolder &g, NFAVertex from, NFAVertex to,
-                  const ue2::unordered_set<NFAVertex> &rverts) {
+void copyOutEdges(NGHolder &g, NFAVertex from, NFAVertex to) {
     for (const auto &e : out_edges_range(from, g)) {
         NFAVertex t = target(e, g);
-        if (contains(rverts, t)) {
-            continue;
-        }
-
         add_edge_if_not_present(to, t, g[e], g);
 
         if (is_any_accept(t, g)) {
@@ -243,6 +233,21 @@ void copyOutEdges(NGHolder &g, NFAVertex from, NFAVertex to,
     }
 }
 
+static
+void removeInteriorEdges(NGHolder &g, const RegionInfo &ri) {
+    // Set of vertices in region, for quick lookups.
+    const unordered_set<NFAVertex> rverts(ri.vertices.begin(),
+                                          ri.vertices.end());
+
+    auto is_interior_in_edge = [&](const NFAEdge &e) {
+        return contains(rverts, source(e, g));
+    };
+
+    for (auto v : ri.vertices) {
+        remove_in_edge_if(v, is_interior_in_edge, g);
+    }
+}
+
 static
 void replaceRegion(NGHolder &g, const RegionInfo &ri,
                    size_t *verticesAdded, size_t *verticesRemoved) {
@@ -284,19 +289,17 @@ void replaceRegion(NGHolder &g, const RegionInfo &ri,
         add_edge(verts.back(), verts.back(), g);
     }
 
-    // Set of vertices in region, for quick lookups.
-    const ue2::unordered_set<NFAVertex> rverts(ri.vertices.begin(),
-                                               ri.vertices.end());
+    removeInteriorEdges(g, ri);
 
     for (size_t i = 0; i < replacementSize; i++) {
         NFAVertex v_new = verts[i];
 
         for (auto v_old : ri.vertices) {
             if (i == 0) {
-                copyInEdges(g, v_old, v_new, rverts);
+                copyInEdges(g, v_old, v_new);
             }
             if (i + 1 >= ri.minWidth) {
-                copyOutEdges(g, v_old, v_new, rverts);
+                copyOutEdges(g, v_old, v_new);
             }
         }
     }