From f71aaa0be84a7b401bc6494488880f3b17b5bca9 Mon Sep 17 00:00:00 2001
From: Paul Wankadia <junyer@google.com>
Date: Sun, 29 Dec 2019 23:22:22 -0800
Subject: [PATCH] Make DFA use hints.

Change-Id: I7b7b338a019ea19c4a99072c961dc6aa35c15915
Reviewed-on: https://code-review.googlesource.com/c/re2/+/49950
Reviewed-by: Paul Wankadia <junyer@google.com>
---
 re2/dfa.cc | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/re2/dfa.cc b/re2/dfa.cc
index 816080a02..b3b5eca02 100644
--- a/re2/dfa.cc
+++ b/re2/dfa.cc
@@ -971,8 +971,21 @@ void DFA::RunWorkqOnByte(Workq* oldq, Workq* newq,
         break;
 
       case kInstByteRange:   // can follow if c is in range
-        if (ip->Matches(c))
-          AddToQueue(newq, ip->out(), flag);
+        if (!ip->Matches(c))
+          break;
+        AddToQueue(newq, ip->out(), flag);
+        if (ip->hint() != 0) {
+          // We have a hint, but we must cancel out the
+          // increment that will occur after the break.
+          i += ip->hint() - 1;
+        } else {
+          // We have no hint, so we must find the end
+          // of the current list and then skip to it.
+          Prog::Inst* ip0 = ip;
+          while (!ip->last())
+            ++ip;
+          i += ip - ip0;
+        }
         break;
 
       case kInstMatch: