Optimize a catch whose return value is ignored

Rewrite a catch expression like this:

   catch side_effect(),
   ...

to:

   try
      side_effect()
   catch
      _:_ ->
       ok
   end,
   ...

A try/catch is more efficient since no stack trace will be built
when an exception occurs.

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index f3f315935a..df880ff784 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -418,6 +418,15 @@ expr(#c_call{module=M0,name=N0}=Call0, Ctxt, Sub) ->
 expr(#c_primop{args=As0}=Prim, _, Sub) ->
     As1 = expr_list(As0, value, Sub),
     Prim#c_primop{args=As1};
+expr(#c_catch{anno=Anno,body=B}, effect, Sub) ->
+    %% When the return value of the 'catch' is ignored, we can replace it
+    %% with a try/catch to avoid building a stack trace when an exception
+    %% occurs.
+    Var = #c_var{name='catch_value'},
+    Evs = [#c_var{name='Class'},#c_var{name='Reason'},#c_var{name='Stk'}],
+    Try = #c_try{anno=Anno,arg=B,vars=[Var],body=Var,
+                 evars=Evs,handler=void()},
+    expr(Try, effect, Sub);
 expr(#c_catch{body=B0}=Catch, _, Sub) ->
     %% We can remove catch if the value is simple
     B1 = body(B0, value, Sub),