Teach the ownership model eliminator how to lower explicit-copy-addr.

Later parts of the pipeline do not know about the instruction, so we need to
lower it there. This is additionally safe since we will not be performing move
only checking later in the pipeline.

Author: gottesmm

lib/SILOptimizer/Mandatory/OwnershipModelEliminator.cpp

@@ -134,6 +134,7 @@ struct OwnershipModelEliminatorVisitor
   bool visitStoreBorrowInst(StoreBorrowInst *si);
   bool visitCopyValueInst(CopyValueInst *cvi);
   bool visitExplicitCopyValueInst(ExplicitCopyValueInst *cvi);
+  bool visitExplicitCopyAddrInst(ExplicitCopyAddrInst *cai);
   bool visitDestroyValueInst(DestroyValueInst *dvi);
   bool visitLoadBorrowInst(LoadBorrowInst *lbi);
   bool visitMoveValueInst(MoveValueInst *mvi) {
@@ -334,6 +335,18 @@ bool OwnershipModelEliminatorVisitor::visitExplicitCopyValueInst(
   return true;
 }
 
+bool OwnershipModelEliminatorVisitor::visitExplicitCopyAddrInst(
+    ExplicitCopyAddrInst *ecai) {
+  // Now that we have set the unqualified ownership flag, destroy value
+  // operation will delegate to the appropriate strong_release, etc.
+  withBuilder<void>(ecai, [&](SILBuilder &b, SILLocation loc) {
+    b.createCopyAddr(loc, ecai->getSrc(), ecai->getDest(), ecai->isTakeOfSrc(),
+                     ecai->isInitializationOfDest());
+  });
+  eraseInstruction(ecai);
+  return true;
+}
+
 bool OwnershipModelEliminatorVisitor::visitUnmanagedRetainValueInst(
     UnmanagedRetainValueInst *urvi) {
   // Now that we have set the unqualified ownership flag, destroy value

test/SILOptimizer/ownership_model_eliminator.sil

@@ -381,3 +381,16 @@ bb0(%0 : @guaranteed $Builtin.NativeObject):
   %9999 = tuple()
   return %9999 : $()
 }
+
+// CHECK-LABEL: sil @lower_explicit_copy_addr : $@convention(thin) (@in_guaranteed C) -> () {
+// CHECK: {{[^_]copy_addr}}
+// CHECK: } // end sil function 'lower_explicit_copy_addr'
+sil [ossa] @lower_explicit_copy_addr : $@convention(thin) (@in_guaranteed C) -> () {
+bb0(%0 : $*C):
+  %1 = alloc_stack $C
+  explicit_copy_addr %0 to [init] %1 : $*C
+  destroy_addr %1 : $*C
+  dealloc_stack %1 : $*C
+  %9999 = tuple()
+  return %9999 : $()
+}