Optimizer: support the new array literal initialization pattern in the COWOpts pass

Author: eeckstein

lib/SILOptimizer/Transforms/COWOpts.cpp

@@ -146,6 +146,8 @@ bool COWOptsPass::optimizeBeginCOW(BeginCOWMutationInst *BCM) {
       } else if (auto *ECM = dyn_cast<EndCOWMutationInst>(v)) {
         if (endCOWMutationsFound.insert(ECM))
           endCOWMutationInsts.push_back(ECM);
+      } else if (auto *urc = dyn_cast<UncheckedRefCastInst>(v)) {
+        workList.push_back(urc->getOperand());
       } else {
         return false;
       }

test/SILOptimizer/cow_opts.sil

@@ -39,6 +39,24 @@ bb0(%0 : $Buffer):
   return %t : $(Int, Builtin.Int1, Buffer)
 }
 
+// CHECK-LABEL: sil @test_cast
+// CHECK:   [[I:%[0-9]+]] = integer_literal $Builtin.Int1, -1
+// CHECK:   ({{.*}}, [[B:%[0-9]+]]) = begin_cow_mutation
+// CHECK:   [[T:%[0-9]+]] = tuple ({{.*}}, [[I]] : $Builtin.Int1, [[B]] : $Buffer)
+// CHECK:   return [[T]]
+// CHECK: } // end sil function 'test_cast'
+sil @test_cast : $@convention(thin) (@owned Builtin.BridgeObject) -> (Int, Builtin.Int1, @owned Buffer) {
+bb0(%0 : $Builtin.BridgeObject):
+  %1 = end_cow_mutation %0
+  %e = unchecked_ref_cast %1 to $Buffer
+  %addr = ref_element_addr [immutable] %e : $Buffer, #Buffer.i
+  debug_value %e : $Buffer, var, name "x"
+  %i = load %addr : $*Int
+  (%u, %b) = begin_cow_mutation %e : $Buffer
+  %t = tuple (%i : $Int, %u : $Builtin.Int1, %b : $Buffer)
+  return %t : $(Int, Builtin.Int1, Buffer)
+}
+
 // CHECK-LABEL: sil @test_store
 // CHECK:   end_cow_mutation
 // CHECK:   [[I:%[0-9]+]] = integer_literal $Builtin.Int1, -1