fixup: compiler alias analysis: Avoid variable creation for plain values

Extracting from a plain value is not possible, but the alias analysis
pass can sometimes encounter it when no type information is
available. Don't crash when trying to add an edge when trying to add
an edge recording the extraction when the source doesn't
exist. Instead conservatively set the result to aliased and leave the
source unchanged.

lib/compiler/src/beam_ssa_ss.erl

@@ -213,7 +213,7 @@ add_embedding(Dst, Src, Element, State0) ->
 extract(Dst, Src, Element, State) ->
     ?DP("Extracting ~p[~p] into ~p~n", [Src,Element,Dst]),
     ?assert_state(State),
-    case beam_digraph:vertex(State, Src, unique) of
+    case beam_digraph:vertex(State, Src, plain) of
         aliased ->
             %% The pair/tuple is aliased, so what is extracted will be aliased.
             ?assert_state(set_status(Dst, aliased, State));
@@ -226,7 +226,13 @@ extract(Dst, Src, Element, State) ->
                 [Dst, Src, Element, OutEdges]),
             extract_element(Dst, Src, Element, OutEdges, State);
         no_info ->
-            ?assert_state(set_status(Dst, no_info, State))
+            ?assert_state(set_status(Dst, no_info, State));
+        plain ->
+            %% Extracting from a plain value is not possible, but the
+            %% alias analysis pass can sometimes encounter it when no
+            %% type information is available. Conservatively set the
+            %% result to aliased.
+            ?assert_state(set_status(Dst, aliased, State))
     end.
 
 %% Note that extract_element/5 will never be given an out edge with a

lib/compiler/test/beam_ssa_check_SUITE.erl

@@ -32,6 +32,7 @@
          annotation_checks/1,
          appendable_checks/1,
          bs_size_unit_checks/1,
+         no_type_info_checks/1,
          private_append_checks/1,
          ret_annotation_checks/1,
          sanity_checks/1,
@@ -47,6 +48,7 @@ groups() ->
       [alias_checks,
        annotation_checks,
        appendable_checks,
+       no_type_info_checks,
        private_append_checks,
        ret_annotation_checks,
        sanity_checks,
@@ -99,6 +101,9 @@ appendable_checks(Config) when is_list(Config) ->
 bs_size_unit_checks(Config) when is_list(Config) ->
     gen_and_run_post_ssa_opt(bs_size_unit_checks, Config).
 
+no_type_info_checks(Config) when is_list(Config) ->
+    run_post_ssa_opt(no_type_info, Config).
+
 private_append_checks(Config) when is_list(Config) ->
     run_post_ssa_opt(private_append, Config).
 

lib/compiler/test/beam_ssa_check_SUITE_data/no_type_info.erl

@@ -0,0 +1,48 @@
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2024. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+%% This module tests functions which have previously crashed the
+%% compiler when the `no_type_opt` option was used.
+%%
+
+-module(no_type_info).
+-export([bug/0]).
+
+-compile(no_type_opt).
+
+bug() ->
+    begin
+        + <<42 ||
+              $s <-
+                  try
+                      something
+                  catch
+                      error:false ->
+                          []
+                  end
+          >>
+    end:(hd(not girl))(
+      try home of
+          _ when 34 ->
+              8
+      catch
+          _:_ ->
+              whatever
+      after
+          ok
+      end).