[cast-opt] Eliminate some unneeded type checks in favor of just asserting the instructions we handle.

This code today only handles the following two instructions:

1. checked_cast_addr_br
2. unconditional_checked_cast_addr

We were asserting that the source/dest of these values were addresses... but
they are obviously are!

Author: gottesmm

lib/SILOptimizer/Utils/CastOptimizer.cpp

@@ -72,6 +72,12 @@ getObjCToSwiftBridgingFunction(SILOptFunctionBuilder &funcBuilder,
 /// _ObjectiveCBridgeable.
 SILInstruction *
 CastOptimizer::optimizeBridgedObjCToSwiftCast(SILDynamicCastInst dynamicCast) {
+  auto kind = dynamicCast.getKind();
+  (void)kind;
+  assert(((kind == SILDynamicCastKind::CheckedCastAddrBranchInst) ||
+          (kind == SILDynamicCastKind::UnconditionalCheckedCastAddrInst)) &&
+         "Unsupported dynamic cast kind");
+
   CanType target = dynamicCast.getTargetType();
   auto &mod = dynamicCast.getModule();
 
@@ -108,9 +114,6 @@ CastOptimizer::optimizeBridgedObjCToSwiftCast(SILDynamicCastInst dynamicCast) {
   SILValue SrcOp;
   SILInstruction *NewI = nullptr;
 
-  assert(Src->getType().isAddress() && "Source should have an address type");
-  assert(Dest->getType().isAddress() && "Source should have an address type");
-
   // If this is a conditional cast:
   // We need a new fail BB in order to add a dealloc_stack to it
   SILBasicBlock *ConvFailBB = nullptr;
@@ -121,10 +124,6 @@ CastOptimizer::optimizeBridgedObjCToSwiftCast(SILDynamicCastInst dynamicCast) {
     Builder.setInsertionPoint(CurrInsPoint);
   }
 
-  // We know this is always true since SILBridgedTy is an object and Src is an
-  // address.
-  assert(SILBridgedTy != Src->getType());
-
   // Check if we can simplify a cast into:
   // - ObjCTy to _ObjectiveCBridgeable._ObjectiveCType.
   // - then convert _ObjectiveCBridgeable._ObjectiveCType to