get_index_of_hashed_raw_with_index

Summary:
`RawTable::get` function is relatively large, and it is often inlined into `get_index_of_hashed_raw`.

So `get_index_of_hashed_raw` is never inlined.

So the simple path of searching in `VecMap` is always behind a call.

When `get_index_of_hashed_raw_with_index` extracted, `RawTable::get` is inlined into `get_index_of_hashed_raw_with_index`, which is not inlined, but `get_index_of_hashed_raw` is now often inlined, so code path without index does not have calls.

Reviewed By: ndmitchell

Differential Revision: D40913232

fbshipit-source-id: 33e193ee562562a73776cbf849dfb6ce29578490

Author: stepancheg

starlark_map/src/small_map/mod.rs

@@ -261,18 +261,28 @@ impl<K, V> SmallMap<K, V> {
     }
 
     #[inline]
-    pub(crate) fn get_index_of_hashed_raw(
+    fn get_index_of_hashed_raw_with_index(
         &self,
         hash: StarlarkHashValue,
         mut eq: impl FnMut(&K) -> bool,
+        index: &RawTable<usize>,
+    ) -> Option<usize> {
+        index
+            .get(hash.promote(), |&index| unsafe {
+                eq(self.entries.get_unchecked(index).0.key())
+            })
+            .copied()
+    }
+
+    #[inline]
+    pub(crate) fn get_index_of_hashed_raw(
+        &self,
+        hash: StarlarkHashValue,
+        eq: impl FnMut(&K) -> bool,
     ) -> Option<usize> {
         match &self.index {
             None => self.entries.get_index_of_hashed_raw(hash, eq),
-            Some(index) => index
-                .get(hash.promote(), |&index| unsafe {
-                    eq(self.entries.get_unchecked(index).0.key())
-                })
-                .copied(),
+            Some(index) => self.get_index_of_hashed_raw_with_index(hash, eq, index),
         }
     }