Merge pull request #19540 from mikeash/reserved-bits-refinement

[IRGen][Runtime] Adjust the ObjC reserved bits on x86-64 to exactly match what the target uses.

Author: mikeash

docs/Testing.md

@@ -311,6 +311,9 @@ code for the target that is not the build machine:
 * ``%target-os``: the target operating system (``macosx``, ``darwin``,
   ``linux``, ``freebsd``, ``windows-cygnus``, ``windows-gnu``).
 
+* ``%target-is-simulator``: ``true`` if the target is a simulator (iOS,
+  watchOS, tvOS), otherwise ``false``.
+
 * ``%target-object-format``: the platform's object format (``elf``, ``macho``,
   ``coff``).
 

lib/IRGen/SwiftTargetInfo.cpp

@@ -22,6 +22,7 @@
 #include "swift/ABI/System.h"
 #include "swift/AST/ASTContext.h"
 #include "swift/AST/IRGenOptions.h"
+#include "swift/Basic/Platform.h"
 
 using namespace swift;
 using namespace irgen;
@@ -66,10 +67,16 @@ static void configureX86_64(IRGenModule &IGM, const llvm::Triple &triple,
                             SwiftTargetInfo &target) {
   setToMask(target.PointerSpareBits, 64,
             SWIFT_ABI_X86_64_SWIFT_SPARE_BITS_MASK);
-  setToMask(target.ObjCPointerReservedBits, 64,
-            SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK);
   setToMask(target.IsObjCPointerBit, 64, SWIFT_ABI_X86_64_IS_OBJC_BIT);
 
+  if (tripleIsAnySimulator(triple)) {
+    setToMask(target.ObjCPointerReservedBits, 64,
+              SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK);
+  } else {
+    setToMask(target.ObjCPointerReservedBits, 64,
+              SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK);
+  }
+
   if (triple.isOSDarwin()) {
     target.LeastValidPointerValue =
       SWIFT_ABI_DARWIN_X86_64_LEAST_VALID_POINTER;

stdlib/public/SwiftShims/CMakeLists.txt

@@ -13,6 +13,7 @@ set(sources
   SwiftStddef.h
   SwiftStdint.h
   System.h
+  Target.h
   ThreadLocalStorage.h
   UnicodeShims.h
   Visibility.h

stdlib/public/SwiftShims/HeapObject.h

@@ -15,6 +15,7 @@
 #include "RefCount.h"
 #include "SwiftStddef.h"
 #include "System.h"
+#include "Target.h"
 
 #define SWIFT_ABI_HEAP_OBJECT_HEADER_SIZE_64 16
 #define SWIFT_ABI_HEAP_OBJECT_HEADER_SIZE_32 8
@@ -117,10 +118,20 @@ static_assert(alignof(HeapObject) == alignof(void*),
 #endif
 #define _swift_abi_SwiftSpareBitsMask                                          \
   (__swift_uintptr_t) SWIFT_ABI_X86_64_SWIFT_SPARE_BITS_MASK
+#if SWIFT_TARGET_OS_SIMULATOR
+#define _swift_abi_ObjCReservedBitsMask                                        \
+  (__swift_uintptr_t) SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK
+#define _swift_abi_ObjCReservedLowBits                                         \
+  (unsigned) SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS
+#else
 #define _swift_abi_ObjCReservedBitsMask                                        \
   (__swift_uintptr_t) SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK
 #define _swift_abi_ObjCReservedLowBits                                         \
   (unsigned) SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS
+#endif
+
+#define _swift_BridgeObject_TaggedPointerBits                                  \
+  (__swift_uintptr_t) SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_64
 
 #elif defined(__arm64__) || defined(__aarch64__) || defined(_M_ARM64)
 
@@ -137,6 +148,8 @@ static_assert(alignof(HeapObject) == alignof(void*),
   (__swift_uintptr_t) SWIFT_ABI_ARM64_OBJC_RESERVED_BITS_MASK
 #define _swift_abi_ObjCReservedLowBits                                         \
   (unsigned) SWIFT_ABI_ARM64_OBJC_NUM_RESERVED_LOW_BITS
+#define _swift_BridgeObject_TaggedPointerBits                                  \
+  (__swift_uintptr_t) SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_64
 
 #elif defined(__powerpc64__)
 
@@ -148,6 +161,8 @@ static_assert(alignof(HeapObject) == alignof(void*),
   (__swift_uintptr_t) SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK
 #define _swift_abi_ObjCReservedLowBits                                         \
   (unsigned) SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS
+#define _swift_BridgeObject_TaggedPointerBits                                  \
+  (__swift_uintptr_t) SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_64
 
 #elif defined(__s390x__)
 
@@ -159,6 +174,8 @@ static_assert(alignof(HeapObject) == alignof(void*),
   (__swift_uintptr_t) SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK
 #define _swift_abi_ObjCReservedLowBits                                         \
   (unsigned) SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS
+#define _swift_BridgeObject_TaggedPointerBits                                  \
+  (__swift_uintptr_t) SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_64
 
 #else
 
@@ -180,6 +197,15 @@ static_assert(alignof(HeapObject) == alignof(void*),
   (__swift_uintptr_t) SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK
 #define _swift_abi_ObjCReservedLowBits                                         \
   (unsigned) SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS
+
+#if __POINTER_WIDTH__ == 64
+#define _swift_BridgeObject_TaggedPointerBits                                  \
+  (__swift_uintptr_t) SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_64
+#else
+#define _swift_BridgeObject_TaggedPointerBits                                  \
+  (__swift_uintptr_t) SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_32
+#endif
+
 #endif
 
 /// Corresponding namespaced decls
@@ -191,13 +217,11 @@ static const __swift_uintptr_t SwiftSpareBitsMask =
     _swift_abi_SwiftSpareBitsMask;
 static const __swift_uintptr_t ObjCReservedBitsMask =
     _swift_abi_ObjCReservedBitsMask;
-static const unsigned ObjCReservedLowBits = _swift_abi_ObjCReservedLowBits;
+static const unsigned ObjCReservedLowBits =
+    _swift_abi_ObjCReservedLowBits;
+static const __swift_uintptr_t BridgeObjectTagBitsMask =
+    _swift_BridgeObject_TaggedPointerBits;
 } // heap_object_abi
 #endif // __cplusplus
 
-/// BridgeObject masks
-
-#define _swift_BridgeObject_TaggedPointerBits _swift_abi_ObjCReservedBitsMask
-
-
 #endif // SWIFT_STDLIB_SHIMS_HEAPOBJECT_H

stdlib/public/SwiftShims/System.h

@@ -62,6 +62,10 @@
 #define SWIFT_ABI_DEFAULT_OBJC_WEAK_REFERENCE_MARKER_MASK 0
 #define SWIFT_ABI_DEFAULT_OBJC_WEAK_REFERENCE_MARKER_VALUE 0
 
+// BridgeObject uses this bit to indicate a tagged value.
+#define SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_32 0U
+#define SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_64 0x8000000000000000ULL
+
 /*********************************** i386 *************************************/
 
 // Heap objects are pointer-aligned, so the low two bits are unused.
@@ -102,22 +106,30 @@
 // Only the bottom 56 bits are used, and heap objects are eight-byte-aligned.
 #define SWIFT_ABI_X86_64_SWIFT_SPARE_BITS_MASK 0xFF00000000000007ULL
 
-// Objective-C reserves the high and low bits for tagged pointers.
-// Systems exist which use either bit.
-#define SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK 0x8000000000000001ULL
+// Objective-C reserves the low bit for tagged pointers on macOS, but
+// reserves the high bit on simulators.
+#define SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK 0x0000000000000001ULL
 #define SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS 1
+#define SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
+#define SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS 0
+
 
 // BridgeObject uses this bit to indicate whether it holds an ObjC object or
 // not.
 #define SWIFT_ABI_X86_64_IS_OBJC_BIT 0x4000000000000000ULL
 
-// ObjC weak reference discriminator is the two bits
-// reserved for ObjC tagged pointers plus one more low bit.
+// ObjC weak reference discriminator is the bit reserved for ObjC tagged
+// pointers plus one more low bit.
 #define SWIFT_ABI_X86_64_OBJC_WEAK_REFERENCE_MARKER_MASK  \
   (SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK |          \
    1<<SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS)
 #define SWIFT_ABI_X86_64_OBJC_WEAK_REFERENCE_MARKER_VALUE \
   (1<<SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS)
+#define SWIFT_ABI_X86_64_SIMULATOR_OBJC_WEAK_REFERENCE_MARKER_MASK  \
+  (SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK |          \
+   1<<SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS)
+#define SWIFT_ABI_X86_64_SIMULATOR_OBJC_WEAK_REFERENCE_MARKER_VALUE \
+  (1<<SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS)
 
 /*********************************** arm64 ************************************/
 

stdlib/public/SwiftShims/Target.h

@@ -0,0 +1,32 @@
+//===--- Target.h - Info about the current compilation target ---*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// Info about the current compilation target.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_ABI_TARGET_H
+#define SWIFT_ABI_TARGET_H
+
+#if !defined(__has_builtin)
+#define __has_builtin(x) 0
+#endif
+
+// Is the target platform a simulator? We can't use TargetConditionals
+// when included from SwiftShims, so use the builtin.
+#if __has_builtin(__is_target_environment)
+# if __is_target_environment(simulator)
+#  define SWIFT_TARGET_OS_SIMULATOR 1
+# endif
+#endif
+
+#endif /* SWIFT_ABI_TARGET_H */

stdlib/public/core/BridgeStorage.swift

@@ -93,7 +93,8 @@ struct _BridgeStorage<
   public // @testable
   func isNativeWithClearedSpareBits(_ bits: Int) -> Bool {
     return (_bitPattern(rawValue) &
-            (_objCTaggedPointerBits | _objectPointerIsObjCBit |
+            (_bridgeObjectTaggedPointerBits | _objCTaggedPointerBits |
+             _objectPointerIsObjCBit |
              (UInt(bits)) << _objectPointerLowSpareBitShift)) == 0
   }
 

stdlib/public/core/Builtin.swift

@@ -340,13 +340,17 @@ internal func _isValidAddress(_ address: UInt) -> Bool {
 // TODO(<rdar://problem/34837023>): Get rid of superfluous UInt constructor
 // calls
 @inlinable
-internal var _objCTaggedPointerBits: UInt {
+internal var _bridgeObjectTaggedPointerBits: UInt {
   @inline(__always) get { return UInt(_swift_BridgeObject_TaggedPointerBits) }
 }
 @inlinable
+internal var _objCTaggedPointerBits: UInt {
+  @inline(__always) get { return UInt(_swift_abi_ObjCReservedBitsMask) }
+}
+@inlinable
 internal var _objectPointerSpareBits: UInt {
     @inline(__always) get {
-      return UInt(_swift_abi_SwiftSpareBitsMask) & ~_objCTaggedPointerBits
+      return UInt(_swift_abi_SwiftSpareBitsMask) & ~_bridgeObjectTaggedPointerBits
     }
 }
 @inlinable
@@ -400,12 +404,12 @@ internal func _isObjCTaggedPointer(_ x: UInt) -> Bool {
 
 @inlinable @inline(__always) public // FIXME
 func _isTaggedObject(_ x: Builtin.BridgeObject) -> Bool {
-  return _bitPattern(x) & _objCTaggedPointerBits != 0
+  return _bitPattern(x) & _bridgeObjectTaggedPointerBits != 0
 }
 @inlinable @inline(__always) public // FIXME
 func _isNativePointer(_ x: Builtin.BridgeObject) -> Bool {
   return (
-    _bitPattern(x) & (_objCTaggedPointerBits | _objectPointerIsObjCBit)
+    _bitPattern(x) & (_bridgeObjectTaggedPointerBits | _objectPointerIsObjCBit)
   ) == 0
 }
 @inlinable @inline(__always) public // FIXME
@@ -418,7 +422,7 @@ func _isNonTaggedObjCPointer(_ x: Builtin.BridgeObject) -> Bool {
 func _getNonTagBits(_ x: Builtin.BridgeObject) -> UInt {
   // Zero out the tag bits, and leave them all at the top.
   _sanityCheck(_isTaggedObject(x), "not tagged!")
-  return (_bitPattern(x) & ~_objCTaggedPointerBits)
+  return (_bitPattern(x) & ~_bridgeObjectTaggedPointerBits)
     >> _objectPointerLowSpareBitShift
 }
 
@@ -446,7 +450,7 @@ public func _bridgeObject(
 @inline(__always)
 @inlinable
 public func _bridgeObject(fromTagged x: UInt) -> Builtin.BridgeObject {
-  _sanityCheck(x & _objCTaggedPointerBits != 0)
+  _sanityCheck(x & _bridgeObjectTaggedPointerBits != 0)
   let object: Builtin.BridgeObject = Builtin.valueToBridgeObject(x)
   _sanityCheck(_isTaggedObject(object))
   return object
@@ -458,9 +462,9 @@ public func _bridgeObject(taggingPayload x: UInt) -> Builtin.BridgeObject {
   let shifted = x &<< _objectPointerLowSpareBitShift
   _sanityCheck(x == (shifted &>> _objectPointerLowSpareBitShift),
     "out-of-range: limited bit range requires some zero top bits")
-  _sanityCheck(shifted & _objCTaggedPointerBits == 0,
+  _sanityCheck(shifted & _bridgeObjectTaggedPointerBits == 0,
     "out-of-range: post-shift use of tag bits")
-  return _bridgeObject(fromTagged: shifted | _objCTaggedPointerBits)
+  return _bridgeObject(fromTagged: shifted | _bridgeObjectTaggedPointerBits)
 }
 
 // BridgeObject -> Values
@@ -485,7 +489,7 @@ public func _bridgeObject(
 public func _bridgeObject(toTagged x: Builtin.BridgeObject) -> UInt {
   _sanityCheck(_isTaggedObject(x))
   let bits = _bitPattern(x)
-  _sanityCheck(bits & _objCTaggedPointerBits != 0)
+  _sanityCheck(bits & _bridgeObjectTaggedPointerBits != 0)
   return bits
 }
 @inline(__always)

stdlib/public/runtime/SwiftObject.mm

@@ -489,10 +489,11 @@ - (BOOL)isNSValue__      { return NO; }
 #endif
 }
 
-// The non-pointer bits, excluding the ObjC tag bits.
+// The non-pointer bits, excluding the tag bits.
 static auto const unTaggedNonNativeBridgeObjectBits
   = heap_object_abi::SwiftSpareBitsMask
-  & ~heap_object_abi::ObjCReservedBitsMask;
+  & ~heap_object_abi::ObjCReservedBitsMask
+  & ~heap_object_abi::BridgeObjectTagBitsMask;
 
 #if SWIFT_OBJC_INTEROP
 
@@ -579,7 +580,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
   static_assert((heap_object_abi::SwiftSpareBitsMask & objectPointerIsObjCBit) ==
                 objectPointerIsObjCBit,
                 "isObjC bit not within spare bits");
-  return (uintptr_t(object) & objectPointerIsObjCBit) != 0;
+  return (uintptr_t(object) & objectPointerIsObjCBit) != 0 && (uintptr_t(object) & heap_object_abi::BridgeObjectTagBitsMask) == 0;
 }
 #endif
 

stdlib/public/runtime/WeakReference.h

@@ -20,6 +20,7 @@
 #include "swift/Runtime/Config.h"
 #include "swift/Runtime/HeapObject.h"
 #include "swift/Runtime/Metadata.h"
+#include "../../../stdlib/public/SwiftShims/Target.h"
 
 #if SWIFT_OBJC_INTEROP
 #include "swift/Runtime/ObjCBridge.h"
@@ -78,6 +79,9 @@ class WeakReferenceBits {
 #if !SWIFT_OBJC_INTEROP
     NativeMarkerMask  = 0,
     NativeMarkerValue = 0
+#elif defined(__x86_64__) && SWIFT_TARGET_OS_SIMULATOR
+    NativeMarkerMask  = SWIFT_ABI_X86_64_SIMULATOR_OBJC_WEAK_REFERENCE_MARKER_MASK,
+    NativeMarkerValue = SWIFT_ABI_X86_64_SIMULATOR_OBJC_WEAK_REFERENCE_MARKER_VALUE
 #elif defined(__x86_64__)
     NativeMarkerMask  = SWIFT_ABI_X86_64_OBJC_WEAK_REFERENCE_MARKER_MASK,
     NativeMarkerValue = SWIFT_ABI_X86_64_OBJC_WEAK_REFERENCE_MARKER_VALUE

test/IRGen/bridge_object_x86_64.sil

@@ -34,7 +34,7 @@ entry(%c : $C, %w : $Builtin.Word):
 // CHECK-LABEL: define{{( dllexport)?}}{{( protected)?}} swiftcc { %objc_object*, i64 } @convert_from_bridge_object
 // CHECK:         [[BOBITS:%.*]] = ptrtoint [[BRIDGE]] %0 to i64
 // --                                                     0x8000_0000_0000_0001
-// CHECK:         [[TAGBITS:%.*]] = and i64 [[BOBITS]], -9223372036854775807
+// CHECK:         [[TAGBITS:%.*]] = and i64 [[BOBITS]], 1
 // CHECK:         [[TAGGED:%.*]] = icmp eq i64 [[TAGBITS]], 0
 // CHECK:         br i1 [[TAGGED]], label %not-tagged-pointer, label %tagged-pointer
 // CHECK:       tagged-pointer:

test/IRGen/enum.sil

@@ -1,6 +1,6 @@
 // #if directives don't work with SIL keywords, therefore please put ObjC tests
 // in `enum_objc.sil`.
-// RUN: %target-swift-frontend -assume-parsing-unqualified-ownership-sil %s -gnone -emit-ir -enable-objc-interop  | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-ptrsize --check-prefix=CHECK-objc --check-prefix=CHECK-objc-%target-ptrsize
+// RUN: %target-swift-frontend -assume-parsing-unqualified-ownership-sil %s -gnone -emit-ir -enable-objc-interop  | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-ptrsize --check-prefix=CHECK-objc --check-prefix=CHECK-objc-%target-ptrsize --check-prefix=CHECK-objc-%target-ptrsize-simulator-%target-is-simulator
 // RUN: %target-swift-frontend -assume-parsing-unqualified-ownership-sil %s -gnone -emit-ir -disable-objc-interop | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-ptrsize --check-prefix=CHECK-native --check-prefix=CHECK-native-%target-ptrsize
 
 // REQUIRES: CPU=i386 || CPU=x86_64
@@ -1134,8 +1134,10 @@ enum SinglePayloadClass {
 // CHECK-64: entry:
 // CHECK-64:   switch i64 %0, label {{%.*}} [
 // CHECK-64:     i64 0, label {{%.*}}
-// CHECK-objc-64:   i64 2, label {{%.*}}
-// CHECK-objc-64:   i64 4, label {{%.*}}
+// CHECK-objc-64-simulator-false:   i64 2, label {{%.*}}
+// CHECK-objc-64-simulator-false:   i64 4, label {{%.*}}
+// CHECK-objc-64-simulator-true:   i64 1, label {{%.*}}
+// CHECK-objc-64-simulator-true:   i64 2, label {{%.*}}
 // CHECK-native-64: i64 1, label {{%.*}}
 // CHECK-native-64: i64 2, label {{%.*}}
 // CHECK-64:   ]
@@ -1179,8 +1181,10 @@ enum SinglePayloadClassProtocol {
 // CHECK-64: define{{( dllexport)?}}{{( protected)?}} swiftcc void @single_payload_class_protocol_switch(i64, i64) {{.*}} {
 // CHECK-64:   switch i64 %0, label {{%.*}} [
 // CHECK-64:     i64 0, label {{%.*}}
-// CHECK-objc-64:     i64 2, label {{%.*}}
-// CHECK-objc-64:     i64 4, label {{%.*}}
+// CHECK-objc-64-simulator-false:     i64 2, label {{%.*}}
+// CHECK-objc-64-simulator-false:     i64 4, label {{%.*}}
+// CHECK-objc-64-simulator-true:     i64 1, label {{%.*}}
+// CHECK-objc-64-simulator-true:     i64 2, label {{%.*}}
 // CHECK-native-64:   i64 1, label {{%.*}}
 // CHECK-native-64:   i64 2, label {{%.*}}
 // CHECK-64:   ]
@@ -2457,7 +2461,8 @@ entry(%0 : $DynamicSingleton<NoPayloads>):
 // Check that payloads get properly masked in nested single-payload enums.
 // rdar://problem/18841262
 // CHECK-64-LABEL: define{{( dllexport)?}}{{( protected)?}} swiftcc i1 @optional_optional_class_protocol(i64, i64)
-// CHECK-objc-64:       icmp eq i64 %0, 2
+// CHECK-objc-64-simulator-false:       icmp eq i64 %0, 2
+// CHECK-objc-64-simulator-true:       icmp eq i64 %0, 1
 // CHECK-native-64:     icmp eq i64 %0, 1
 // CHECK-32-LABEL: define{{( dllexport)?}}{{( protected)?}} swiftcc i1 @optional_optional_class_protocol(i32, i32)
 // CHECK-32:         icmp eq i32 %0, 1