Small performace optimizations

doc/new_release.md

@@ -1,25 +1,26 @@
 - update version in `phmap_config.h`
 - update version in `CITATION.cff`
 - update version in comment on top of `CMakeLists.txt`
+- update all versions # in `doc/new_release.md`.
 - git commit
 - git push
 - create the new release on github (tag `v2.0.0` - use semantic versioning)
-- download the tar.gz from github, and use `sha256sum parallel-hashmap-1.4.0.tar.gz` on linux to get the sha256
+- download the tar.gz from github, and use `sha256sum parallel-hashmap-2.0.0.tar.gz` on linux to get the sha256
 
 ## conan
 
 - use [forked repo](https://github.com/greg7mdp/conan-center-index)
 - sync fork in github
 - git checkout conan-io:master
-- git checkout -b phmap_1.4.0
+- git checkout -b phmap_2.0.0
 - update: `recipes/parallel-hashmap/all/conandata.yml` and `recipes/parallel-hashmap/config.yml`
 - sudo pip install conan -U 
 - cd recipes/parallel-hashmap/all
-- *does not work* conan create conanfile.py parallel-hashmap/1.4.0@ -pr:b=default -pr:h=default 
-  update version in `recipes/parallel-hashmap/all/conanfile.py`
+- *does not work* conan create conanfile.py parallel-hashmap/2.0.0@ -pr:b=default -pr:h=default 
+  *no version??* update version in `recipes/parallel-hashmap/all/conanfile.py`
 - git diff
-- git commit -am "[parallel-hashmap] Bump version to 1.4.0"
-- git push origin phmap_1.4.0 
+- git commit -am "[parallel-hashmap] Bump version to 2.0.0"
+- git push origin phmap_2.0.0 
 - create PR like [this](https://github.com/conan-io/conan-center-index/pull/13161)
 
 
@@ -27,10 +28,11 @@
 
 - use [forked repo](https://github.com/greg7mdp/vcpkg)
 - sync fork in github
-- git checkout -b phmap_1.4.0
-- update ports/gtl/portfile.cmake (the sha512)  and ports/gtl/vcpkg.json
+- `git checkout -b phmap_2.0.0`
+- update ports/parallel-hashmap/portfile.cmake (the sha512)  and ports/parallel-hashmap/vcpkg.json (the version #)
 - commit
-- vcpkg x-add-version --all --overwrite-version ## (or ./vcpkg.exe --no-dry-run upgrade )
+- `./bootstrap-vcpkg.sh`
+- `vcpkg x-add-version --all --overwrite-version` ## (or `./vcpkg.exe --no-dry-run upgrade` )
 - commit
 - push
 - create PR

parallel_hashmap/phmap.h

@@ -555,7 +555,7 @@ inline bool IsValidCapacity(size_t n) { return ((n + 1) & n) == 0 && n > 0; }
 //   FULL -> DELETED
 // --------------------------------------------------------------------------
 inline void ConvertDeletedToEmptyAndFullToDeleted(
-    ctrl_t* ctrl, size_t capacity) 
+    ctrl_t* PHMAP_RESTRICT ctrl, size_t capacity) 
 {
     assert(ctrl[capacity] == kSentinel);
     assert(IsValidCapacity(capacity));
@@ -1857,20 +1857,22 @@ private:
     friend struct phmap::priv::hashtable_debug_internal::HashtableDebugAccess;
 
     template <class K = key_type>
-    bool find_impl(const key_arg<K>& key, size_t hashval, size_t& offset) {
+    bool find_impl(const key_arg<K>& PHMAP_RESTRICT key, size_t hashval, size_t& PHMAP_RESTRICT offset) {
+        auto ctrl_ptr = ctrl_;
         PHMAP_IF_CONSTEXPR (!std_alloc_t::value) {
             // ctrl_ could be nullptr
-            if (!ctrl_)
+            if (!ctrl_ptr)
                 return false;
         }
         auto seq = probe(hashval);
+        auto slots_ptr = slots_;
         while (true) {
-            Group g{ ctrl_ + seq.offset() };
+            Group g{ ctrl_ptr + seq.offset() };
             for (uint32_t i : g.Match((h2_t)H2(hashval))) {
                 offset = seq.offset((size_t)i);
                 if (PHMAP_PREDICT_TRUE(PolicyTraits::apply(
                     EqualElement<K>{key, eq_ref()},
-                    PolicyTraits::element(slots_ + offset))))
+                    PolicyTraits::element(slots_ptr + offset))))
                     return true;
             }
             if (PHMAP_PREDICT_TRUE(g.MatchEmpty()))
@@ -2034,9 +2036,11 @@ private:
                             std::is_same<typename Policy::is_flat, std::false_type>::value)) {
             // node map, or not trivially destructible... we  need to iterate and destroy values one by one
             // std::cout << "either this is a node map or " << type_name<typename PolicyTraits::value_type>()  << " is not trivially_destructible\n";
-            for (size_t i = 0; i != capacity_; ++i) {
-                if (IsFull(ctrl_[i])) {
-                    PolicyTraits::destroy(&alloc_ref(), slots_ + i);
+            auto slots_ptr = slots_;
+            auto ctrl_ptr  = ctrl_;
+            for (size_t i = 0, cnt = capacity_; i != cnt; ++i) {
+                if (IsFull(ctrl_ptr[i])) {
+                    PolicyTraits::destroy(&alloc_ref(), slots_ptr + i);
                 }
             }
         } 
@@ -2153,7 +2157,7 @@ private:
         }
     }
 
-    bool has_element(const value_type& elem, size_t hashval) const {
+    bool has_element(const value_type& PHMAP_RESTRICT elem, size_t hashval) const {
         PHMAP_IF_CONSTEXPR (!std_alloc_t::value) {
             // ctrl_ could be nullptr
             if (!ctrl_)
@@ -2220,19 +2224,21 @@ private:
 
 protected:
     template <class K>
-    size_t _find_key(const K& key, size_t hashval) {
+    size_t _find_key(const K& PHMAP_RESTRICT key, size_t hashval) {
+        auto ctrl_ptr = ctrl_;
         PHMAP_IF_CONSTEXPR (!std_alloc_t::value) {
             // ctrl_ could be nullptr
-            if (!ctrl_)
+            if (!ctrl_ptr)
                 return (size_t)-1;
         }
         auto seq = probe(hashval);
+        auto slots_ptr = slots_;
         while (true) {
-            Group g{ctrl_ + seq.offset()};
+            Group g{ctrl_ptr + seq.offset()};
             for (uint32_t i : g.Match((h2_t)H2(hashval))) {
                 if (PHMAP_PREDICT_TRUE(PolicyTraits::apply(
                                           EqualElement<K>{key, eq_ref()},
-                                          PolicyTraits::element(slots_ + seq.offset((size_t)i)))))
+                                          PolicyTraits::element(slots_ptr + seq.offset((size_t)i)))))
                     return seq.offset((size_t)i);
             }
             if (PHMAP_PREDICT_TRUE(g.MatchEmpty())) break;

parallel_hashmap/phmap_config.h

@@ -661,6 +661,17 @@
     #define PHMAP_BUILTIN_UNREACHABLE() (void)0
 #endif
 
+// ----------------------------------------------------------------------
+// RESTRICT
+// ----------------------------------------------------------------------
+#if (defined(__GNUC__) && (__GNUC__ > 3)) || defined(__clang__)
+    #define PHMAP_RESTRICT __restrict__
+#elif defined(_MSC_VER) && _MSC_VER >= 1400
+    #define PHMAP_RESTRICT __restrict
+#else
+    #define PHMAP_RESTRICT
+#endif
+
 // ----------------------------------------------------------------------
 // base/macros.h
 // ----------------------------------------------------------------------