Enhance -assume-single-threaded option (SR-3945)

CMakeLists.txt

@@ -270,6 +270,10 @@ option(SWIFT_STDLIB_ENABLE_RESILIENCE
     "Build the standard libraries and overlays with resilience enabled; see docs/LibraryEvolution.rst"
     FALSE)
 
+option(SWIFT_STDLIB_USE_NONATOMIC_RC
+    "Build the standard libraries and overlays with nonatomic reference count operations enabled"
+    FALSE)
+
 option(SWIFT_STDLIB_ENABLE_SIL_OWNERSHIP
   "Build the standard libraries and overlays with sil ownership enabled."
   FALSE)

cmake/modules/SwiftSource.cmake

@@ -239,6 +239,10 @@ function(_compile_swift_files
     list(APPEND swift_flags "-Xfrontend" "-enable-resilience")
   endif()
 
+  if(SWIFT_STDLIB_USE_NONATOMIC_RC)
+    list(APPEND swift_flags "-Xfrontend" "-assume-single-threaded")
+  endif()
+
   if(SWIFT_STDLIB_ENABLE_SIL_OWNERSHIP AND SWIFTFILE_IS_STDLIB)
     list(APPEND swift_flags "-Xfrontend" "-enable-sil-ownership")
   endif()

include/swift/Runtime/HeapObject.h

@@ -510,6 +510,16 @@ SWIFT_RT_ENTRY_VISIBILITY
 void swift_unownedRelease(HeapObject *value)
     SWIFT_CC(RegisterPreservingCC);
 
+/// Increment the unowned retain count.
+SWIFT_RT_ENTRY_VISIBILITY
+void swift_nonatomic_unownedRetain(HeapObject *value)
+    SWIFT_CC(RegisterPreservingCC);
+
+/// Decrement the unowned retain count.
+SWIFT_RT_ENTRY_VISIBILITY
+void swift_nonatomic_unownedRelease(HeapObject *value)
+    SWIFT_CC(RegisterPreservingCC);
+
 /// Increment the unowned retain count by n.
 SWIFT_RT_ENTRY_VISIBILITY
 void swift_unownedRetain_n(HeapObject *value, int n)
@@ -520,19 +530,42 @@ SWIFT_RT_ENTRY_VISIBILITY
 void swift_unownedRelease_n(HeapObject *value, int n)
     SWIFT_CC(RegisterPreservingCC);
 
+/// Increment the unowned retain count by n.
+SWIFT_RT_ENTRY_VISIBILITY
+void swift_nonatomic_unownedRetain_n(HeapObject *value, int n)
+    SWIFT_CC(RegisterPreservingCC);
+
+/// Decrement the unowned retain count by n.
+SWIFT_RT_ENTRY_VISIBILITY
+void swift_nonatomic_unownedRelease_n(HeapObject *value, int n)
+    SWIFT_CC(RegisterPreservingCC);
+
 /// Increment the strong retain count of an object, aborting if it has
 /// been deallocated.
 SWIFT_RT_ENTRY_VISIBILITY
 void swift_unownedRetainStrong(HeapObject *value)
     SWIFT_CC(RegisterPreservingCC);
 
+/// Increment the strong retain count of an object, aborting if it has
+/// been deallocated.
+SWIFT_RT_ENTRY_VISIBILITY
+void swift_nonatomic_unownedRetainStrong(HeapObject *value)
+    SWIFT_CC(RegisterPreservingCC);
+
 /// Increment the strong retain count of an object which may have been
 /// deallocated, aborting if it has been deallocated, and decrement its
 /// unowned reference count.
 SWIFT_RT_ENTRY_VISIBILITY
 void swift_unownedRetainStrongAndRelease(HeapObject *value)
     SWIFT_CC(RegisterPreservingCC);
 
+/// Increment the strong retain count of an object which may have been
+/// deallocated, aborting if it has been deallocated, and decrement its
+/// unowned reference count.
+SWIFT_RT_ENTRY_VISIBILITY
+void swift_nonatomic_unownedRetainStrongAndRelease(HeapObject *value)
+    SWIFT_CC(RegisterPreservingCC);
+
 /// Aborts if the object has been deallocated.
 SWIFT_RUNTIME_EXPORT
 void swift_unownedCheck(HeapObject *value);

include/swift/Runtime/RuntimeFunctions.def

@@ -369,6 +369,20 @@ FUNCTION(NativeUnownedRelease, swift_unownedRelease, RegisterPreservingCC,
          ARGS(RefCountedPtrTy),
          ATTRS(NoUnwind))
 
+// void swift_nonatomic_unownedRetain(void *ptr);
+FUNCTION(NonAtomicNativeUnownedRetain, swift_nonatomic_unownedRetain,
+         RegisterPreservingCC,
+         RETURNS(VoidTy),
+         ARGS(RefCountedPtrTy),
+         ATTRS(NoUnwind))
+
+// void swift_nonatomic_unownedRelease(void *ptr);
+FUNCTION(NonAtomicNativeUnownedRelease, swift_nonatomic_unownedRelease,
+         RegisterPreservingCC,
+         RETURNS(VoidTy),
+         ARGS(RefCountedPtrTy),
+         ATTRS(NoUnwind))
+
 // void swift_unownedRetain_n(void *ptr, int32_t n);
 FUNCTION(UnownedRetainN, swift_unownedRetain_n,
          RegisterPreservingCC,
@@ -383,19 +397,47 @@ FUNCTION(UnownedReleaseN, swift_unownedRelease_n,
          ARGS(RefCountedPtrTy, Int32Ty),
          ATTRS(NoUnwind))
 
+// void swift_nonatomic_unownedRetain_n(void *ptr, int32_t n);
+FUNCTION(NonAtomicUnownedRetainN, swift_nonatomic_unownedRetain_n,
+         RegisterPreservingCC,
+         RETURNS(VoidTy),
+         ARGS(RefCountedPtrTy, Int32Ty),
+         ATTRS(NoUnwind))
+
+// void swift_nonatomic_unownedRelease_n(void *ptr, int32_t n);
+FUNCTION(NonAtomicUnownedReleaseN, swift_nonatomic_unownedRelease_n,
+         RegisterPreservingCC,
+         RETURNS(VoidTy),
+         ARGS(RefCountedPtrTy, Int32Ty),
+         ATTRS(NoUnwind))
+
 // void swift_unownedRetainStrong(void *ptr);
 FUNCTION(NativeStrongRetainUnowned, swift_unownedRetainStrong, RegisterPreservingCC,
          RETURNS(VoidTy),
          ARGS(RefCountedPtrTy),
          ATTRS(NoUnwind))
 
+// void swift_nonatomic_unownedRetainStrong(void *ptr);
+FUNCTION(NonAtomicNativeStrongRetainUnowned, swift_nonatomic_unownedRetainStrong,
+         RegisterPreservingCC,
+         RETURNS(VoidTy),
+         ARGS(RefCountedPtrTy),
+         ATTRS(NoUnwind))
+
 // void swift_unownedRetainStrongAndRelease(void *ptr);
 FUNCTION(NativeStrongRetainAndUnownedRelease,
          swift_unownedRetainStrongAndRelease, RegisterPreservingCC,
          RETURNS(VoidTy),
          ARGS(RefCountedPtrTy),
          ATTRS(NoUnwind))
 
+// void swift_nonatomic_unownedRetainStrongAndRelease(void *ptr);
+FUNCTION(NonAtomicNativeStrongRetainAndUnownedRelease,
+         swift_nonatomic_unownedRetainStrongAndRelease, RegisterPreservingCC,
+         RETURNS(VoidTy),
+         ARGS(RefCountedPtrTy),
+         ATTRS(NoUnwind))
+
 // void swift_weakDestroy(WeakReference *object);
 FUNCTION(NativeWeakDestroy, swift_weakDestroy, DefaultCC,
          RETURNS(VoidTy),

include/swift/SIL/SILBuilder.h

@@ -819,17 +819,19 @@ class SILBuilder {
   }
 
   UnmanagedRetainValueInst *createUnmanagedRetainValue(SILLocation Loc,
-                                                       SILValue operand) {
+                                                       SILValue operand,
+                                                       Atomicity atomicity) {
     assert(F.hasQualifiedOwnership());
     return insert(new (F.getModule()) UnmanagedRetainValueInst(
-        getSILDebugLocation(Loc), operand));
+        getSILDebugLocation(Loc), operand, atomicity));
   }
 
   UnmanagedReleaseValueInst *createUnmanagedReleaseValue(SILLocation Loc,
-                                                         SILValue operand) {
+                                                         SILValue operand,
+                                                         Atomicity atomicity) {
     assert(F.hasQualifiedOwnership());
     return insert(new (F.getModule()) UnmanagedReleaseValueInst(
-        getSILDebugLocation(Loc), operand));
+        getSILDebugLocation(Loc), operand, atomicity));
   }
 
   CopyValueInst *createCopyValue(SILLocation Loc, SILValue operand) {
@@ -856,9 +858,10 @@ class SILBuilder {
   }
 
   UnmanagedAutoreleaseValueInst *
-  createUnmanagedAutoreleaseValue(SILLocation Loc, SILValue operand) {
+  createUnmanagedAutoreleaseValue(SILLocation Loc, SILValue operand,
+                                  Atomicity atomicity) {
     return insert(new (F.getModule()) UnmanagedAutoreleaseValueInst(
-                      getSILDebugLocation(Loc), operand));
+                      getSILDebugLocation(Loc), operand, atomicity));
   }
 
   SetDeallocatingInst *createSetDeallocating(SILLocation Loc,
@@ -1529,6 +1532,11 @@ class SILBuilder {
   // Memory management helpers
   //===--------------------------------------------------------------------===//
 
+  /// Returns the default atomicity of the module.
+  Atomicity getDefaultAtomicity() {
+    return getModule().isDefaultAtomic() ? Atomicity::Atomic : Atomicity::NonAtomic;
+  }
+
   /// Try to fold a destroy_addr operation into the previous instructions, or
   /// generate an explicit one if that fails.  If this inserts a new
   /// instruction, it returns it, otherwise it returns null.

include/swift/SIL/SILCloner.h

@@ -1176,7 +1176,8 @@ void SILCloner<ImplClass>::visitUnmanagedRetainValueInst(
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   doPostProcess(
       Inst, getBuilder().createUnmanagedRetainValue(
-                getOpLocation(Inst->getLoc()), getOpValue(Inst->getOperand())));
+                getOpLocation(Inst->getLoc()), getOpValue(Inst->getOperand()),
+                  Inst->getAtomicity()));
 }
 
 template <typename ImplClass>
@@ -1211,7 +1212,8 @@ void SILCloner<ImplClass>::visitUnmanagedReleaseValueInst(
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   doPostProcess(
       Inst, getBuilder().createUnmanagedReleaseValue(
-                getOpLocation(Inst->getLoc()), getOpValue(Inst->getOperand())));
+                getOpLocation(Inst->getLoc()), getOpValue(Inst->getOperand()),
+                  Inst->getAtomicity()));
 }
 
 template <typename ImplClass>
@@ -1238,7 +1240,8 @@ void SILCloner<ImplClass>::visitUnmanagedAutoreleaseValueInst(
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   doPostProcess(
       Inst, getBuilder().createUnmanagedAutoreleaseValue(
-                getOpLocation(Inst->getLoc()), getOpValue(Inst->getOperand())));
+                getOpLocation(Inst->getLoc()), getOpValue(Inst->getOperand()),
+                  Inst->getAtomicity()));
 }
 
 template<typename ImplClass>

include/swift/SIL/SILInstruction.h

@@ -3021,8 +3021,11 @@ class UnmanagedRetainValueInst
                                   /*HasValue*/ false> {
   friend SILBuilder;
 
-  UnmanagedRetainValueInst(SILDebugLocation DebugLoc, SILValue operand)
-      : UnaryInstructionBase(DebugLoc, operand) {}
+  UnmanagedRetainValueInst(SILDebugLocation DebugLoc, SILValue operand,
+                           Atomicity atomicity)
+      : UnaryInstructionBase(DebugLoc, operand) {
+    setAtomicity(atomicity);
+  }
 };
 
 /// Destroys a loadable value in an unmanaged, unbalanced way. Only meant for
@@ -3034,8 +3037,11 @@ class UnmanagedReleaseValueInst
                                   /*HasValue*/ false> {
   friend SILBuilder;
 
-  UnmanagedReleaseValueInst(SILDebugLocation DebugLoc, SILValue operand)
-      : UnaryInstructionBase(DebugLoc, operand) {}
+  UnmanagedReleaseValueInst(SILDebugLocation DebugLoc, SILValue operand,
+                            Atomicity atomicity)
+      : UnaryInstructionBase(DebugLoc, operand) {
+    setAtomicity(atomicity);
+  }
 };
 
 /// Transfers ownership of a loadable value to the current autorelease
@@ -3046,8 +3052,11 @@ class UnmanagedAutoreleaseValueInst
                                                 /*HasValue*/ false> {
   friend SILBuilder;
 
-  UnmanagedAutoreleaseValueInst(SILDebugLocation DebugLoc, SILValue operand)
-      : UnaryInstructionBase(DebugLoc, operand) {}
+  UnmanagedAutoreleaseValueInst(SILDebugLocation DebugLoc, SILValue operand,
+                                Atomicity atomicity)
+      : UnaryInstructionBase(DebugLoc, operand) {
+    setAtomicity(atomicity);
+  }
 };
 
 /// Transfers ownership of a loadable value to the current autorelease pool.

include/swift/SIL/SILModule.h

@@ -642,6 +642,11 @@ class SILModule {
 
   /// Returns true if the builtin or intrinsic is no-return.
   bool isNoReturnBuiltinOrIntrinsic(Identifier Name);
+
+  /// Returns true if the default atomicity of the module is Atomic.
+  bool isDefaultAtomic() const {
+    return ! getOptions().AssumeSingleThreaded;
+  }
 };
 
 inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const SILModule &M){

lib/IRGen/GenClass.cpp

@@ -795,7 +795,7 @@ static bool getInstanceSizeByMethod(IRGenFunction &IGF,
 
   // Retain 'self' if necessary.
   if (fnType->getParameters()[0].isConsumed()) {
-    IGF.emitNativeStrongRetain(selfValue);
+    IGF.emitNativeStrongRetain(selfValue, IGF.getDefaultAtomicity());
   }
 
   // Adjust down to the defining subclass type if necessary.