SimplifyCheckedCast: only simplify if source and destination address types match

Fixes a crash when creating a copy_addr with mismtaching types.
rdar://128195403

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyCheckedCast.swift

@@ -18,7 +18,10 @@ extension CheckedCastAddrBranchInst : OnoneSimplifyable {
       return
     }
     if castWillSucceed {
-      replaceSuccess(context)
+      // TODO: handle cases where the operand address types are different.
+      if source.type == destination.type {
+        replaceSuccess(context)
+      }
     } else {
       replaceFailure(context)
     }

test/SILOptimizer/simplify_checked_cast_addr_br.sil

@@ -129,3 +129,14 @@ bb2:
   unreachable
 }
 
+// Check that we don't crash on this
+sil @success_but_different_operand_type : $@convention(thin) (@in D) -> @out X {
+bb0(%0 : $*X, %1 : $*D):
+  checked_cast_addr_br copy_on_success D in %1 : $*D to X in %0 : $*X, bb1, bb2
+bb1:
+  %r = tuple()
+  return %r : $()
+bb2:
+  unreachable
+}
+