[region-isolation] Handle BeginCowMutation.

Author: gottesmm

lib/SILOptimizer/Analysis/RegionAnalysis.cpp

@@ -192,6 +192,7 @@ static bool isStaticallyLookThroughInst(SILInstruction *inst) {
     return false;
   case SILInstructionKind::BeginAccessInst:
   case SILInstructionKind::BeginBorrowInst:
+  case SILInstructionKind::BeginCOWMutationInst:
   case SILInstructionKind::BeginDeallocRefInst:
   case SILInstructionKind::BridgeObjectToRefInst:
   case SILInstructionKind::CopyValueInst:
@@ -2306,6 +2307,7 @@ CONSTANT_TRANSLATION(UnownedToRefInst, LookThrough)
 CONSTANT_TRANSLATION(UnownedCopyValueInst, LookThrough)
 CONSTANT_TRANSLATION(DropDeinitInst, LookThrough)
 CONSTANT_TRANSLATION(ValueToBridgeObjectInst, LookThrough)
+CONSTANT_TRANSLATION(BeginCOWMutationInst, LookThrough)
 
 //===---
 // Store
@@ -2452,7 +2454,6 @@ CONSTANT_TRANSLATION(DeinitExistentialValueInst, Unhandled)
 CONSTANT_TRANSLATION(UnconditionalCheckedCastAddrInst, Unhandled)
 CONSTANT_TRANSLATION(UncheckedRefCastAddrInst, Unhandled)
 CONSTANT_TRANSLATION(PackElementSetInst, Unhandled)
-CONSTANT_TRANSLATION(BeginCOWMutationInst, Unhandled)
 
 //===---
 // Apply

test/Concurrency/transfernonsendable_instruction_matching.sil

@@ -1188,3 +1188,25 @@ bb0:
   %9999 = tuple ()
   return %9999 : $()
 }
+
+sil [ossa] @begin_cow_mutation : $@async @convention(thin) () -> () {
+bb0:
+  %0 = function_ref @constructNonSendableKlass : $@convention(thin) () -> @owned NonSendableKlass
+  %1 = apply %0() : $@convention(thin) () -> @owned NonSendableKlass
+  %2a = copy_value %1 : $NonSendableKlass
+  (%uniq, %2) = begin_cow_mutation %2a : $NonSendableKlass
+  %f = function_ref @transferNonSendableKlass : $@convention(thin) @async (@guaranteed NonSendableKlass) -> ()
+  apply [caller_isolation=nonisolated] [callee_isolation=global_actor] %f(%1) : $@convention(thin) @async (@guaranteed NonSendableKlass) -> () // expected-warning {{transferring value of non-Sendable type 'NonSendableKlass' from nonisolated context to global actor '<null>'-isolated context; later accesses could race}}
+  destroy_value %2 : $NonSendableKlass
+
+  %3a = copy_value %1 : $NonSendableKlass
+  (%uniq2, %3) = begin_cow_mutation %3a : $NonSendableKlass
+  %f3 = function_ref @useNonSendableKlass : $@convention(thin) (@guaranteed NonSendableKlass) -> ()
+  apply %f3(%3) : $@convention(thin) (@guaranteed NonSendableKlass) -> () // expected-note {{access here could race}}
+  destroy_value %3 : $NonSendableKlass
+
+  destroy_value %1 : $NonSendableKlass
+  %9999 = tuple ()
+  return %9999 : $()
+}
+