[benchmark] half Array.removeAll bench size

Author: oxy

benchmark/single-source/ArrayRemoveAll.swift

@@ -26,8 +26,8 @@ class Slow {
   }
 }
 
-let inputArray_Int: [Int] = Array(0..<1_000_000)
-let inputArray_Class: [Slow] = (0..<100_000).map(Slow.init(num:))
+let inputArray_Int: [Int] = Array(0..<500_000)
+let inputArray_Class: [Slow] = (0..<50_000).map(Slow.init(num:))
 
 @inline(never)
 func removeAll<T>(_ arr: [T]) -> [T] {

stdlib/public/core/ArrayBuffer.swift

@@ -17,6 +17,7 @@
 
 #if _runtime(_ObjC)
 import SwiftShims
+import Builtin
 
 @usableFromInline
 internal typealias _ArrayBridgeStorage
@@ -201,10 +202,12 @@ extension _ArrayBuffer {
     if bufferIsUnique {
       // As an optimization, if the original buffer is unique, we can just move
       // the elements instead of copying.
+      if 
       let dest = newBuffer.firstElementAddress
       dest.moveInitialize(from: mutableFirstElementAddress,
                           count: c)
       _native.mutableCount = 0
+      }
     } else {
       _copyContents(
         subRange: 0..<c,

stdlib/public/core/Builtin.swift

@@ -709,6 +709,9 @@ internal func _isUnique<T>(_ object: inout T) -> Bool {
   return Bool(Builtin.isUnique(&object))
 }
 
+@_silgen_name("_swift_reallocObject")
+internal func _reallocObject(_ object: UnsafeMutableRawPointer, _ newSizeInBytes: Int) -> UnsafeMutableRawPointer?
+
 /// Returns `true` if `object` is uniquely referenced.
 /// This provides sanity checks on top of the Builtin.
 @_transparent

stdlib/public/runtime/SwiftObject.h

@@ -97,4 +97,11 @@ const HashableWitnessTable *getNSStringHashableConformance();
 }
 }
 
+namespace swift {
+
+SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_SPI
+HeapObject *_swift_reallocObject(HeapObject *obj, size_t size);
+
+}
+
 #endif

stdlib/public/runtime/SwiftObject.mm

@@ -79,6 +79,24 @@ OBJC_EXPORT __attribute__((__weak_import__))
 #endif
 }
 
+bool isObjCPinned(HeapObject *obj) {
+  #if SWIFT_OBJC_INTEROP
+    /* future: implement checking the relevant objc runtime bits */
+    return true;
+  #else
+    return false;
+  #endif
+}
+
+// returns non-null if realloc was successful
+SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_SPI
+HeapObject *swift::_swift_reallocObject(HeapObject *obj, size_t size) {
+ if (isObjCPinned(obj) || obj->refCounts.hasSideTable()) {
+   return nullptr;
+ }
+ return (HeapObject *)realloc(obj, size);
+}
+
 #if SWIFT_OBJC_INTEROP
 /// Replacement for ObjC object_isClass(), which is unavailable on
 /// deployment targets macOS 10.9 and iOS 7.