compiler: Avoid reuse hint for update_record with > 1 update

Take care to not produce a reuse hint when more than one update
exists. There is no point in attempting the reuse optimization when
more than one element is updated, as checking more than one element at
runtime is known to be slower than just copying the tuple in most
cases. Additionally, using a copy hint occasionally allows the alias
analysis pass to do a better job.

lib/compiler/src/beam_ssa_type.erl

@@ -1561,12 +1561,26 @@ will_succeed_1(#b_set{op=wait_timeout}, _Src, _Ts) ->
 will_succeed_1(#b_set{}, _Src, _Ts) ->
     'maybe'.
 
+%% Take care to not produce a reuse hint when more than one update
+%% exists. There is no point in attempting the reuse optimization when
+%% more than one element is updated, as checking more than one element
+%% at runtime is known to be slower than just copying the tuple in
+%% most cases. Additionally, using a copy hint occasionally allows the
+%% alias analysis pass to do a better job.
 simplify_update_record(Src, Hint0, Updates, Ts) ->
     case sur_1(Updates, concrete_type(Src, Ts), Ts, Hint0, []) of
+        {#b_literal{val=reuse}, []} when length(Updates) > 2 ->
+            {changed, #b_literal{val=copy}, Updates};
         {Hint0, []} ->
             unchanged;
-        {Hint, Skipped} ->
-            {changed, Hint, sur_skip(Updates, Skipped)}
+        {Hint1, Skipped} ->
+            Updates1 = sur_skip(Updates, Skipped),
+            Hint = if length(Updates1) > 2 ->
+                           #b_literal{val=copy};
+                      true ->
+                           Hint1
+                   end,
+            {changed, Hint, Updates1}
     end.
 
 sur_1([Index, Arg | Updates], RecordType, Ts, Hint, Skipped) ->

lib/compiler/test/beam_ssa_check_SUITE_data/alias.erl

@@ -1077,7 +1077,7 @@ update_record0() ->
 
 update_record0([Val|Ls], Acc=#r0{not_aliased=N}) ->
 %ssa% (_, Rec) when post_ssa_opt ->
-%ssa% _ = update_record(reuse, 3, Rec, 3, A, 2, NA) {unique => [Rec, NA], aliased => [A]}.
+%ssa% _ = update_record(copy, 3, Rec, 3, A, 2, NA) {unique => [Rec, NA], aliased => [A]}.
     R = Acc#r0{not_aliased=N+1,aliased=Val},
     update_record0(Ls, R);
 update_record0([], Acc) ->
@@ -1090,7 +1090,7 @@ update_record1() ->
 
 update_record1([Val|Ls], Acc=#r1{not_aliased0=N0,not_aliased1=N1}) ->
 %ssa% (_, Rec) when post_ssa_opt ->
-%ssa% _ = update_record(reuse, 3, Rec, 3, NA0, 2, NA1) {unique => [Rec, NA1, NA0], source_dies => true}.
+%ssa% _ = update_record(copy, 3, Rec, 3, NA0, 2, NA1) {unique => [Rec, NA1, NA0], source_dies => true}.
     R = Acc#r1{not_aliased0=N0+1,not_aliased1=[Val|N1]},
     update_record1(Ls, R);
 update_record1([], Acc) ->