From f0be7ca7e42915779175a9332c6baba18a2a840c Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Sat, 7 Jan 2012 13:12:07 +0000
Subject: [PATCH] Port the trick to skip the check for empty buckets from
 StringMap to DenseMap.

This should fix the odd behavior that find() is slower than lookup().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147731 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/ADT/DenseMap.h | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index e70cacf3ca5..2ba6db78cc4 100644
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -86,13 +86,13 @@ public:
     return empty() ? end() : iterator(Buckets, Buckets+NumBuckets);
   }
   inline iterator end() {
-    return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
+    return iterator(Buckets+NumBuckets, Buckets+NumBuckets, true);
   }
   inline const_iterator begin() const {
     return empty() ? end() : const_iterator(Buckets, Buckets+NumBuckets);
   }
   inline const_iterator end() const {
-    return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
+    return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets, true);
   }
 
   bool empty() const { return NumEntries == 0; }
@@ -137,13 +137,13 @@ public:
   iterator find(const KeyT &Val) {
     BucketT *TheBucket;
     if (LookupBucketFor(Val, TheBucket))
-      return iterator(TheBucket, Buckets+NumBuckets);
+      return iterator(TheBucket, Buckets+NumBuckets, true);
     return end();
   }
   const_iterator find(const KeyT &Val) const {
     BucketT *TheBucket;
     if (LookupBucketFor(Val, TheBucket))
-      return const_iterator(TheBucket, Buckets+NumBuckets);
+      return const_iterator(TheBucket, Buckets+NumBuckets, true);
     return end();
   }
 
@@ -162,13 +162,12 @@ public:
   std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
     BucketT *TheBucket;
     if (LookupBucketFor(KV.first, TheBucket))
-      return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
+      return std::make_pair(iterator(TheBucket, Buckets+NumBuckets, true),
                             false); // Already in map.
 
     // Otherwise, insert the new element.
     TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
-    return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
-                          true);
+    return std::make_pair(iterator(TheBucket, Buckets+NumBuckets, true), true);
   }
 
   /// insert - Range insertion of pairs.
@@ -495,8 +494,9 @@ private:
 public:
   DenseMapIterator() : Ptr(0), End(0) {}
 
-  DenseMapIterator(pointer Pos, pointer E) : Ptr(Pos), End(E) {
-    AdvancePastEmptyBuckets();
+  DenseMapIterator(pointer Pos, pointer E, bool NoAdvance = false)
+    : Ptr(Pos), End(E) {
+    if (!NoAdvance) AdvancePastEmptyBuckets();
   }
 
   // If IsConst is true this is a converting constructor from iterator to