SILOptimizer: remove some unused variables

to fix "unused variable" warnings

rdar://84035249

Author: eeckstein

lib/SILOptimizer/Utils/CanonicalOSSALifetime.cpp

@@ -80,7 +80,6 @@ llvm::Statistic swift::NumCopiesGenerated = {
 STATISTIC(NumDestroysEliminated,
           "number of destroy_value instructions removed");
 STATISTIC(NumDestroysGenerated, "number of destroy_value instructions created");
-STATISTIC(NumUnknownUsers, "number of functions with unknown users");
 
 //===----------------------------------------------------------------------===//
 //                           MARK: General utilities

lib/SILOptimizer/Utils/CanonicalizeBorrowScope.cpp

@@ -35,9 +35,6 @@
 
 using namespace swift;
 
-STATISTIC(NumOuterCopies, "number of copy_value instructions added for a "
-                          "borrow scope");
-
 //===----------------------------------------------------------------------===//
 //                           MARK: Local utilities
 //===----------------------------------------------------------------------===//

lib/SILOptimizer/Utils/CanonicalizeInstruction.cpp

@@ -33,12 +33,7 @@
 
 using namespace swift;
 
-// STATISTIC uses the default DEBUG_TYPE.
-#define DEBUG_TYPE CanonicalizeInstruction::defaultDebugType
-STATISTIC(NumSimplified, "Number of instructions simplified");
-
 // Tracing within the implementation can also be activiated by the pass.
-#undef DEBUG_TYPE
 #define DEBUG_TYPE pass.debugType
 
 // Vtable anchor.

lib/SILOptimizer/Utils/DistributedActor.cpp

@@ -68,15 +68,13 @@ void emitActorTransportWitnessCall(
   ProtocolConformanceRef transportConfRef;
 
   // If the transport is an existential open it.
-  bool openedExistential = false;
   if (transportASTType->isAnyExistentialType()) {
     OpenedArchetypeType *opened;
     transportASTType =
         transportASTType->openAnyExistentialType(opened)->getCanonicalType();
     transport = B.createOpenExistentialAddr(
         loc, transport, F.getLoweredType(transportASTType),
         OpenedExistentialAccess::Immutable);
-    openedExistential = true;
   }
 
   if (transportASTType->isTypeParameter() ||