Refactor to make it clear that H2 computation is not repeated in each iteration of the probe loop.

This is a no-op for generated code.

PiperOrigin-RevId: 737024397
Change-Id: I81bdeee8d6a1b64b86d12747d9866d450c55b2a6

Author: ezbr

absl/container/internal/raw_hash_set.cc

@@ -320,13 +320,14 @@ size_t DropDeletesWithoutResizeAndPrepareInsert(CommonFields& common,
     // If they do, we don't need to move the object as it falls already in the
     // best probe we can.
     const size_t probe_offset = probe(common, hash).offset();
+    const h2_t h2 = H2(hash);
     const auto probe_index = [probe_offset, capacity](size_t pos) {
       return ((pos - probe_offset) & capacity) / Group::kWidth;
     };
 
     // Element doesn't move.
     if (ABSL_PREDICT_TRUE(probe_index(new_i) == probe_index(i))) {
-      SetCtrlInLargeTable(common, i, H2(hash), slot_size);
+      SetCtrlInLargeTable(common, i, h2, slot_size);
       continue;
     }
 
@@ -335,14 +336,14 @@ size_t DropDeletesWithoutResizeAndPrepareInsert(CommonFields& common,
       // Transfer element to the empty spot.
       // SetCtrl poisons/unpoisons the slots so we have to call it at the
       // right time.
-      SetCtrlInLargeTable(common, new_i, H2(hash), slot_size);
+      SetCtrlInLargeTable(common, new_i, h2, slot_size);
       (*transfer)(set, new_slot_ptr, slot_ptr, 1);
       SetCtrlInLargeTable(common, i, ctrl_t::kEmpty, slot_size);
       // Initialize or change empty space id.
       tmp_space_id = i;
     } else {
       assert(IsDeleted(ctrl[new_i]));
-      SetCtrlInLargeTable(common, new_i, H2(hash), slot_size);
+      SetCtrlInLargeTable(common, new_i, h2, slot_size);
       // Until we are done rehashing, DELETED marks previously FULL slots.
 
       if (tmp_space_id == kUnknownId) {

absl/container/internal/raw_hash_set.h

@@ -3110,10 +3110,11 @@ class raw_hash_set {
   iterator find_non_soo(const key_arg<K>& key, size_t hash) {
     ABSL_SWISSTABLE_ASSERT(!is_soo());
     auto seq = probe(common(), hash);
+    const h2_t h2 = H2(hash);
     const ctrl_t* ctrl = control();
     while (true) {
       Group g{ctrl + seq.offset()};
-      for (uint32_t i : g.Match(H2(hash))) {
+      for (uint32_t i : g.Match(h2)) {
         if (ABSL_PREDICT_TRUE(PolicyTraits::apply(
                 EqualElement<K>{key, eq_ref()},
                 PolicyTraits::element(slot_array() + seq.offset(i)))))
@@ -3345,12 +3346,13 @@ class raw_hash_set {
   std::pair<iterator, bool> find_or_prepare_insert_non_soo(const K& key) {
     ABSL_SWISSTABLE_ASSERT(!is_soo());
     prefetch_heap_block();
-    auto hash = hash_ref()(key);
+    const size_t hash = hash_ref()(key);
     auto seq = probe(common(), hash);
+    const h2_t h2 = H2(hash);
     const ctrl_t* ctrl = control();
     while (true) {
       Group g{ctrl + seq.offset()};
-      for (uint32_t i : g.Match(H2(hash))) {
+      for (uint32_t i : g.Match(h2)) {
         if (ABSL_PREDICT_TRUE(PolicyTraits::apply(
                 EqualElement<K>{key, eq_ref()},
                 PolicyTraits::element(slot_array() + seq.offset(i)))))
@@ -3740,12 +3742,13 @@ struct HashtableDebugAccess<Set, absl::void_t<typename Set::raw_hash_set>> {
                              const typename Set::key_type& key) {
     if (set.is_soo()) return 0;
     size_t num_probes = 0;
-    size_t hash = set.hash_ref()(key);
+    const size_t hash = set.hash_ref()(key);
     auto seq = probe(set.common(), hash);
+    const h2_t h2 = H2(hash);
     const ctrl_t* ctrl = set.control();
     while (true) {
       container_internal::Group g{ctrl + seq.offset()};
-      for (uint32_t i : g.Match(container_internal::H2(hash))) {
+      for (uint32_t i : g.Match(h2)) {
         if (Traits::apply(
                 typename Set::template EqualElement<typename Set::key_type>{
                     key, set.eq_ref()},