OP_APPLY_LAST: fix stacktrace on failure

Truncate stack only after checking module and function, thus generating a
more helpful stacktrace, following what BEAM does.

Signed-off-by: Paul Guyot <[email protected]>

Author: pguyot

src/libAtomVM/opcodesswitch.h

@@ -5384,13 +5384,13 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
                 READ_ANY_XREG(function, arity + 1);
                 TRACE("apply_last/1, module=%lu, function=%lu arity=%i deallocate=%i\n", module, function, arity, n_words);
 
-                ctx->cp = ctx->e[n_words];
-                ctx->e += (n_words + 1);
-
                 if (UNLIKELY(!term_is_atom(module) || !term_is_atom(function))) {
                     RAISE_ERROR(BADARG_ATOM);
                 }
 
+                ctx->cp = ctx->e[n_words];
+                ctx->e += (n_words + 1);
+
                 AtomString module_name = globalcontext_atomstring_from_term(glb, module);
                 AtomString function_name = globalcontext_atomstring_from_term(glb, function);
 

tests/erlang_tests/fail_apply_last.erl

@@ -53,11 +53,25 @@ try_apply_last(M, F) ->
     try
         ?MODULE:do_apply0(M, F)
     catch
-        _Class:_Reason -> 1
+        _Class:_Reason:Stack ->
+            test_stacktrace(Stack, false, false, 1)
     end.
 
 pad_some_calls() ->
     X = 1,
     Y = 2,
     Z = X + Y,
     Z.
+
+% if try_apply_last/2 is in stacktrace, we also want do_apply0/2
+test_stacktrace([], _, _, R) ->
+    R;
+test_stacktrace([{?MODULE, try_apply_last, 2, _} | T], false, DoApply0, R) ->
+    test_stacktrace(T, true, DoApply0, R - 1);
+test_stacktrace([{?MODULE, do_apply0, 2, _} | T], TryApplyLast, false, R) ->
+    test_stacktrace(T, TryApplyLast, true, R + 1);
+test_stacktrace([_ | T], TryApplyLast, DoApply0, R) ->
+    test_stacktrace(T, TryApplyLast, DoApply0, R);
+test_stacktrace(undefined, _, _, R) ->
+    % AVM_CREATE_STACKTRACES=off
+    R.