From d6509e377db65f2afd7394db2a5154e420dfd4dc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20H=C3=B6gberg?= <john@erlang.org>
Date: Fri, 5 Oct 2018 14:33:01 +0200
Subject: beam_ssa_pre_codegen: Literal funs need stack frames too

Fixes a crash during code generation of the following code:

call_atom() ->
    fun({send = Send}) ->
            Send()
    end.
---
 lib/compiler/src/beam_ssa_pre_codegen.erl | 8 ++++----
 lib/compiler/test/fun_SUITE.erl           | 7 +++++++
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/lib/compiler/src/beam_ssa_pre_codegen.erl b/lib/compiler/src/beam_ssa_pre_codegen.erl
index 40742e441a..9175931375 100644
--- a/lib/compiler/src/beam_ssa_pre_codegen.erl
+++ b/lib/compiler/src/beam_ssa_pre_codegen.erl
@@ -1043,11 +1043,11 @@ need_frame_1([#b_set{op=call,args=[Func|_]}|Is], Context) ->
         #b_remote{} ->
             %% This is an apply(), which always needs a frame.
             true;
-        #b_var{} ->
-            %% A fun call always needs a frame.
-            true;
+        #b_local{} ->
+            Context =:= body orelse Is =/= [];
         _ ->
-            Context =:= body orelse Is =/= []
+             %% A fun call always needs a frame.
+            true
     end;
 need_frame_1([I|Is], Context) ->
     beam_ssa:clobbers_xregs(I) orelse need_frame_1(Is, Context);
diff --git a/lib/compiler/test/fun_SUITE.erl b/lib/compiler/test/fun_SUITE.erl
index e00885fcd6..1df0a05275 100644
--- a/lib/compiler/test/fun_SUITE.erl
+++ b/lib/compiler/test/fun_SUITE.erl
@@ -249,6 +249,13 @@ badfun(_Config) ->
     expect_badfun(X, catch X(put(?FUNCTION_NAME, of_course))),
     of_course = erase(?FUNCTION_NAME),
 
+    %% A literal as a Fun used to crash the code generator. This only happened
+    %% when type optimization had reduced `Fun` to a literal, hence the match.
+    Literal = fun(literal = Fun) ->
+                      Fun()
+              end,
+    expect_badfun(literal, catch Literal(literal)),
+
     ok.
 
 expect_badfun(Term, Exit) ->
-- 
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