From 2f0f43a8692aab8a24a0d6386ba751024ca4c3be Mon Sep 17 00:00:00 2001
From: Karoy Lorentey <klorentey@apple.com>
Date: Tue, 2 Oct 2018 20:26:03 +0100
Subject: [PATCH 1/2] [stdlib] Dictionary, Set: Force-inline hidden
 Sequence/Collection customization points

This should eliminate a branch, which should probably lead to a tiny overall code size improvement, as well as a tiny performance boost.
---
 stdlib/public/core/Dictionary.swift | 3 +++
 stdlib/public/core/Set.swift        | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/stdlib/public/core/Dictionary.swift b/stdlib/public/core/Dictionary.swift
index 8169357875226..52715dd841083 100644
--- a/stdlib/public/core/Dictionary.swift
+++ b/stdlib/public/core/Dictionary.swift
@@ -1383,16 +1383,19 @@ extension Dictionary {
     }
 
     @inlinable
+    @inline(__always)
     public func _customContainsEquatableElement(_ element: Element) -> Bool? {
       return _variant.contains(element)
     }
 
     @inlinable
+    @inline(__always)
     public func _customIndexOfEquatableElement(_ element: Element) -> Index?? {
       return Optional(_variant.index(forKey: element))
     }
 
     @inlinable
+    @inline(__always)
     public func _customLastIndexOfEquatableElement(_ element: Element) -> Index?? {
       // The first and last elements are the same because each element is unique.
       return _customIndexOfEquatableElement(element)
diff --git a/stdlib/public/core/Set.swift b/stdlib/public/core/Set.swift
index 2dadaabf386a7..6541ba75d28f0 100644
--- a/stdlib/public/core/Set.swift
+++ b/stdlib/public/core/Set.swift
@@ -266,6 +266,7 @@ extension Set: Sequence {
   }
 
   @inlinable
+  @inline(__always)
   public func _customContainsEquatableElement(_ member: Element) -> Bool? {
     return contains(member)
   }
@@ -361,6 +362,7 @@ extension Set: Collection {
   }
 
   @inlinable
+  @inline(__always)
   public func _customIndexOfEquatableElement(
      _ member: Element
     ) -> Index?? {
@@ -368,6 +370,7 @@ extension Set: Collection {
   }
 
   @inlinable
+  @inline(__always)
   public func _customLastIndexOfEquatableElement(
      _ member: Element
     ) -> Index?? {

From 4615e18366d58abc8aefe3ad4ec4be39fae7cd84 Mon Sep 17 00:00:00 2001
From: Karoy Lorentey <klorentey@apple.com>
Date: Tue, 2 Oct 2018 20:27:42 +0100
Subject: [PATCH 2/2] [stdlib] Force-inline trivial default implementations for
 hidden Sequence/Collection customization points

This is usually a code size pessimization, but in this case the bodies are trivial, so inlining them eliminates a call + a conditional branch.
---
 stdlib/public/core/Collection.swift | 3 +++
 stdlib/public/core/Sequence.swift   | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/stdlib/public/core/Collection.swift b/stdlib/public/core/Collection.swift
index f9dac4df4c9cc..ef8c14669f679 100644
--- a/stdlib/public/core/Collection.swift
+++ b/stdlib/public/core/Collection.swift
@@ -1267,6 +1267,7 @@ extension Collection {
   ///
   /// - Complexity: Hopefully less than O(`count`).
   @inlinable
+  @inline(__always)
   public // dispatching
   func _customIndexOfEquatableElement(_: Element) -> Index?? {
     return nil
@@ -1283,6 +1284,7 @@ extension Collection {
   ///
   /// - Complexity: Hopefully less than O(`count`).
   @inlinable
+  @inline(__always)
   public // dispatching
   func _customLastIndexOfEquatableElement(_ element: Element) -> Index?? {
     return nil
@@ -1802,6 +1804,7 @@ extension Collection where SubSequence == Self {
 
 extension Collection {
   @inlinable
+  @inline(__always)
   public func _preprocessingPass<R>(
     _ preprocess: () throws -> R
   ) rethrows -> R? {
diff --git a/stdlib/public/core/Sequence.swift b/stdlib/public/core/Sequence.swift
index 6cd5ff0253005..85d154b181d93 100644
--- a/stdlib/public/core/Sequence.swift
+++ b/stdlib/public/core/Sequence.swift
@@ -905,6 +905,7 @@ extension Sequence {
   }
 
   @inlinable
+  @inline(__always)
   public func _preprocessingPass<R>(
     _ preprocess: () throws -> R
   ) rethrows -> R? {
@@ -912,6 +913,7 @@ extension Sequence {
   }
 
   @inlinable
+  @inline(__always)
   public func _customContainsEquatableElement(
     _ element: Iterator.Element
   ) -> Bool? {