revert work on the Syncrhonization library for a separate PR

Author: Carl Peto

stdlib/public/Synchronization/Atomics/AtomicIntegers.swift.gyb

@@ -39,9 +39,6 @@ extension ${intType}: AtomicRepresentable {
 #elseif _pointerBitWidth(_32)
   @available(SwiftStdlib 6.0, *)
   public typealias AtomicRepresentation = _Atomic32BitStorage
-#elseif _pointerBitWidth(_16)
-  @available(SwiftStdlib 6.0, *)
-  public typealias AtomicRepresentation = _Atomic16BitStorage
 #else
 #error("Unsupported platform")
 #endif
@@ -131,11 +128,6 @@ extension Atomic where Value == ${intType} {
         _rawAddress,
         operand._value
       )
-#elseif _pointerBitWidth(_16)
-      Builtin.atomicrmw_${atomicOperationName(intType, builtinName)}_${llvmOrder}_Int16(
-        _rawAddress,
-        operand._value
-      )
 #else
 #error("Unsupported platform")
 #endif

stdlib/public/Synchronization/Atomics/AtomicPointers.swift

@@ -771,7 +771,7 @@ extension ObjectIdentifier: AtomicOptionalRepresentable {
 // UnsafeBufferPointer AtomicRepresentable conformance
 //===----------------------------------------------------------------------===//
 
-#if ((_pointerBitWidth(_32) || _pointerBitWidth(_16)) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
+#if (_pointerBitWidth(_32) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
 
 @available(SwiftStdlib 6.0, *)
 extension UnsafeBufferPointer: AtomicRepresentable where Element: ~Copyable {
@@ -837,7 +837,7 @@ extension UnsafeBufferPointer: AtomicRepresentable where Element: ~Copyable {
 // UnsafeMutableBufferPointer AtomicRepresentable conformance
 //===----------------------------------------------------------------------===//
 
-#if ((_pointerBitWidth(_32) || _pointerBitWidth(_16)) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
+#if (_pointerBitWidth(_32) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
 
 @available(SwiftStdlib 6.0, *)
 extension UnsafeMutableBufferPointer: AtomicRepresentable
@@ -905,7 +905,7 @@ where Element: ~Copyable
 // UnsafeRawBufferPointer AtomicRepresentable conformance
 //===----------------------------------------------------------------------===//
 
-#if ((_pointerBitWidth(_32) || _pointerBitWidth(_16)) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
+#if (_pointerBitWidth(_32) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
 
 @available(SwiftStdlib 6.0, *)
 extension UnsafeRawBufferPointer: AtomicRepresentable {
@@ -971,7 +971,7 @@ extension UnsafeRawBufferPointer: AtomicRepresentable {
 // UnsafeMutableRawBufferPointer AtomicRepresentable conformance
 //===----------------------------------------------------------------------===//
 
-#if ((_pointerBitWidth(_32) || _pointerBitWidth(_16)) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
+#if (_pointerBitWidth(_32) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
 
 @available(SwiftStdlib 6.0, *)
 extension UnsafeMutableRawBufferPointer: AtomicRepresentable {

stdlib/public/Synchronization/Atomics/WordPair.swift

@@ -62,7 +62,7 @@ public struct WordPair {
   }
 }
 
-#if ((_pointerBitWidth(_32) || _pointerBitWidth(_16)) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
+#if (_pointerBitWidth(_32) && _hasAtomicBitWidth(_64)) || (_pointerBitWidth(_64) && _hasAtomicBitWidth(_128))
 
 @available(SwiftStdlib 6.0, *)
 extension WordPair: AtomicRepresentable {
@@ -74,10 +74,6 @@ extension WordPair: AtomicRepresentable {
   /// The storage representation type that `Self` encodes to and decodes from
   /// which is a suitable type when used in atomic operations.
   public typealias AtomicRepresentation = _Atomic64BitStorage
-#elseif _pointerBitWidth(_16)
-  /// The storage representation type that `Self` encodes to and decodes from
-  /// which is a suitable type when used in atomic operations.
-  public typealias AtomicRepresentation = _Atomic32BitStorage
 #else
 #error("Unsupported platform")
 #endif
@@ -114,14 +110,6 @@ extension WordPair: AtomicRepresentable {
     i64 = Builtin.or_Int64(i64, high64)
 
     return AtomicRepresentation(i64)
-#elseif _pointerBitWidth(_16)
-    var i32 = Builtin.zext_Int16_Int32(value.first._value)
-    var high32 = Builtin.zext_Int16_Int32(value.second._value)
-    let highShift = Builtin.zext_Int16_Int32(UInt(16)._value)
-    high32 = Builtin.shl_Int32(high32, highShift)
-    i32 = Builtin.or_Int32(i32, high32)
-
-    return AtomicRepresentation(i32)
 #else
 #error("Unsupported platform")
 #endif
@@ -153,11 +141,6 @@ extension WordPair: AtomicRepresentable {
     let high64 = Builtin.lshr_Int64(representation._storage, highShift)
     let high = Builtin.trunc_Int64_Int32(high64)
     let low = Builtin.trunc_Int64_Int32(representation._storage)
-#elseif _pointerBitWidth(_16)
-    let highShift = Builtin.zext_Int16_Int32(UInt(16)._value)
-    let high32 = Builtin.lshr_Int32(representation._storage, highShift)
-    let high = Builtin.trunc_Int32_Int16(high32)
-    let low = Builtin.trunc_Int32_Int16(representation._storage)
 #else
 #error("Unsupported platform")
 #endif