From 37dfdbdc97fceface901c6bce7a34342989576f1 Mon Sep 17 00:00:00 2001
From: Martin Kustermann <kustermann@google.com>
Date: Thu, 1 Dec 2016 13:51:49 +0100
Subject: [PATCH] VM: Remove unused (and incomplete) HashMap::Remove() function

R=vegorov@google.com

Review URL: https://codereview.chromium.org/2542103002 .
---
 runtime/bin/hashmap_test.cc | 43 -------------------------------------
 runtime/platform/hashmap.cc | 17 ---------------
 runtime/platform/hashmap.h  | 17 ---------------
 3 files changed, 77 deletions(-)

diff --git a/runtime/bin/hashmap_test.cc b/runtime/bin/hashmap_test.cc
index 0a4ee31ed10..bad384b79a3 100644
--- a/runtime/bin/hashmap_test.cc
+++ b/runtime/bin/hashmap_test.cc
@@ -180,47 +180,4 @@ UNIT_TEST_CASE(HashMap_Basic) {
   TestSet(CollisionHash4, 50);
 }
 
-
-UNIT_TEST_CASE(HashMap_RemoveDuringIteration) {
-  class Utils {
-   public:
-    static bool MatchFun(void* key1, void* key2) { return key1 == key2; }
-    static void* Key(intptr_t i) { return reinterpret_cast<void*>(i); }
-    static void* Value(intptr_t i) { return reinterpret_cast<void*>(i); }
-    static uint32_t HashCode(intptr_t key) { return 1; }
-  };
-
-  HashMap map(Utils::MatchFun, 8);
-
-  // Add 6 (1, 1), ..., (6, 60) entries to the map all with a hashcode of 1
-  // (i.e. have all keys have collinding hashcode).
-  //
-  // This causes the probing position in the hashmap to be 1 and open-addressing
-  // with linear probing will fill in the slots towards the right
-  // (i.e. from 1..6).
-  for (intptr_t i = 1; i <= 6 /* avoid rehash at 7 */; i++) {
-    HashMap::Entry* entry = map.Lookup(Utils::Key(i), Utils::HashCode(i), true);
-    entry->value = Utils::Value(10 * i);
-  }
-
-  // Now we iterate over all elements and delete the current element. Since all
-  // our entries have a colliding hashcode of 1, each deletion will cause all
-  // following elements to be left-rotated by 1.
-  intptr_t i = 0;
-  HashMap::Entry* current = map.Start();
-  while (current != NULL) {
-    i++;
-    EXPECT_EQ(Utils::Key(i), current->key);
-    EXPECT_EQ(Utils::Value(10 * i), current->value);
-
-    // Every 2nd element we keep to hit the left-rotation case only sometimes.
-    if (i % 2 == 0) {
-      current = map.Remove(current);
-    } else {
-      current = map.Next(current);
-    }
-  }
-  EXPECT_EQ(6, i);
-}
-
 }  // namespace dart
diff --git a/runtime/platform/hashmap.cc b/runtime/platform/hashmap.cc
index 4d4b4774dd3..4a18cb211ca 100644
--- a/runtime/platform/hashmap.cc
+++ b/runtime/platform/hashmap.cc
@@ -110,23 +110,6 @@ void HashMap::Remove(void* key, uint32_t hash) {
 }
 
 
-HashMap::Entry* HashMap::Remove(Entry* entry) {
-  Remove(entry->key, entry->hash);
-
-  // A key can only exist once in the map and we just removed `key`. This means
-  // that either a left-rotation has happened (in which case `entry` points
-  // already to the next element (in terms of iteration order)) or alternatively
-  // we can use the normal `Next()` call to move in iteration order.
-  if (entry->key != NULL) {
-    // A left-rotation happened. `entry` points already to the next element in
-    // iteration order.
-    return entry;
-  } else {
-    return Next(entry);
-  }
-}
-
-
 void HashMap::Clear(ClearFun clear) {
   // Mark all entries as empty.
   const Entry* end = map_end();
diff --git a/runtime/platform/hashmap.h b/runtime/platform/hashmap.h
index 240e94d1a0f..be8278e909d 100644
--- a/runtime/platform/hashmap.h
+++ b/runtime/platform/hashmap.h
@@ -66,23 +66,6 @@ class HashMap {
   // otherwise the iteration might step over elements!
   void Remove(void* key, uint32_t hash);
 
-  // Removes the entry and returns the next entry (in iteration order) after
-  // this one.
-  //
-  // Usage instructions for removing elements during iteration:
-  //
-  //    HashMap::Entry* current = map.Start();
-  //    while (current != NULL) {
-  //       ...
-  //      if (condition) {
-  //        current = map.Remove(current);
-  //      } else {
-  //        current = map.Next(current);
-  //      }
-  //    }
-  //
-  Entry* Remove(Entry* entry);
-
   // Empties the hash map (occupancy() == 0), and calls the function 'clear' on
   // each of the values if given.
   void Clear(ClearFun clear = NULL);