Remove some workarounds

Author: Azoy

stdlib/public/core/KeyPath.swift

@@ -3661,16 +3661,7 @@ internal struct InstantiateKeyPathBuffer: KeyPathPatternVisitor {
     self.patternArgs = patternArgs
     self.base = root
 
-    // FIXME: This will not work on arm64e.
-    let metadataPtr = unsafeBitCast(root, to: UnsafeRawPointer.self)
-    let vwtPtr = metadataPtr.load(
-      fromByteOffset: 0 &- MemoryLayout<Int>.size,
-      as: UnsafeRawPointer.self
-    )
-    self.maxSize = vwtPtr.load(fromByteOffset: 0x40, as: Int.self)
-
-    // FIXME: The following doesn't work as it crashes the compiler in IRGen.
-    //self.maxSize = _openExistential(root, do: _getTypeSize(_:))
+    self.maxSize = _openExistential(root, do: _getTypeSize(_:))
   }
 
   // Track the triviality of the resulting object data.
@@ -3976,14 +3967,7 @@ internal struct InstantiateKeyPathBuffer: KeyPathPatternVisitor {
     pushDest(metadata)
     base = metadata
 
-    // FIXME: This will not work on arm64e.
-    let metadataPtr = unsafeBitCast(metadata, to: UnsafeRawPointer.self)
-    let vwtPtr = metadataPtr.load(
-      fromByteOffset: 0 &- MemoryLayout<Int>.size,
-      as: UnsafeRawPointer.self
-    )
-    let size = vwtPtr.load(fromByteOffset: 0x40, as: Int.self)
-    //let size = _openExistential(metadata, do: _getTypeSize(_:))
+    let size = _openExistential(metadata, do: _getTypeSize(_:))
 
     maxSize = Swift.max(maxSize, size)
   }

stdlib/public/core/TemporaryAllocation.swift

@@ -178,8 +178,7 @@ internal func _withUnprotectedUnsafeTemporaryAllocation<
   _ body: (Builtin.RawPointer) throws -> R
 ) rethrows -> R {
   // How many bytes do we need to allocate?
-  //let byteCount = _byteCountForTemporaryAllocation(of: type, capacity: capacity)
-  let byteCount = MemoryLayout<T>.stride &* capacity
+  let byteCount = _byteCountForTemporaryAllocation(of: type, capacity: capacity)
 
   guard _isStackAllocationSafe(byteCount: byteCount, alignment: alignment) else {
     return try _fallBackToHeapAllocation(byteCount: byteCount, alignment: alignment, body)
@@ -303,7 +302,7 @@ public func _withUnprotectedUnsafeTemporaryAllocation<R: ~Copyable>(
     alignment: alignment
   ) { pointer in
     let buffer = UnsafeMutableRawBufferPointer(
-      _uncheckedStart: .init(pointer),
+      start: .init(pointer),
       count: byteCount
     )
     return try body(buffer)
@@ -383,7 +382,7 @@ public func _withUnprotectedUnsafeTemporaryAllocation<
   ) { pointer in
     Builtin.bindMemory(pointer, capacity._builtinWordValue, type)
     let buffer = UnsafeMutableBufferPointer<T>(
-      _uncheckedStart: .init(pointer),
+      start: .init(pointer),
       count: capacity
     )
     return try body(buffer)

stdlib/public/core/UnsafeRawBufferPointer.swift.gyb

@@ -116,20 +116,6 @@ public struct Unsafe${Mutable}RawBufferPointer {
     _debugPrecondition(count == 0 || start != nil,
       "${Self} has a nil start and nonzero count")
 
-    self.init(_uncheckedStart: start, count: count)
-  }
-
-  @_alwaysEmitIntoClient
-  internal init(
-    _uncheckedStart start: Unsafe${Mutable}RawPointer?,
-    count: Int
-  ) {
-    _internalInvariant(count >= 0, "${Self} with negative count")
-    _internalInvariant(
-      count == 0 || start != nil,
-      "${Self} has a nil start and nonzero count"
-    )
-
     _position = start
     _end = start.map { $0 + _assumeNonNegative(count) }
   }
@@ -1408,10 +1394,7 @@ public func _withUnprotectedUnsafeBytes<
 #else
   let addr = UnsafeRawPointer(Builtin.addressOfBorrow(value))
 #endif
-  let buffer = UnsafeRawBufferPointer(
-    _uncheckedStart: addr,
-    count: MemoryLayout<T>.size
-  )
+  let buffer = UnsafeRawBufferPointer(start: addr, count: MemoryLayout<T>.size)
   return try body(buffer)
 }