Merge pull request #23462 from aschwaighofer/dynamic_replaceable_thunk_is_tail

IRGen: The call to the dynamic implementation is a tail call

Author: aschwaighofer

lib/IRGen/GenDecl.cpp

@@ -2057,6 +2057,7 @@ static void emitDynamicallyReplaceableThunk(IRGenModule &IGM,
     forwardedArgs.push_back(&arg);
   auto *Res =
       B.CreateCall(FunctionPointer(typeFnPtr, signature), forwardedArgs);
+  Res->setTailCall();
   if (implFn->getReturnType()->isVoidTy())
     B.CreateRetVoid();
   else

test/IRGen/dynamic_replaceable.sil

@@ -25,7 +25,7 @@
 // CHECK-NEXT: entry:
 // CHECK-NEXT:   [[FUN_PTR:%.*]] = load i8*, i8** getelementptr inbounds (%swift.dyn_repl_link_entry, %swift.dyn_repl_link_entry* @test_dynamically_replaceableTX, i32 0, i32 0)
 // CHECK-NEXT:   [[TYPED_PTR:%.*]] = bitcast i8* [[FUN_PTR]] to void ()*
-// CHECK-NEXT:   call swiftcc void [[TYPED_PTR]]()
+// CHECK-NEXT:   tail call swiftcc void [[TYPED_PTR]]()
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }