Merge branch 'john/compiler/fix-fail-path-exceptions-bsm/OTP-15946' into maint-22

* john/compiler/fix-fail-path-exceptions-bsm/OTP-15946:
  beam_ssa_bsm: Leave ?BADARG_BLOCK alone when cloning fail path

2 files changed, 22 insertions, 3 deletions

diff --git a/lib/compiler/src/beam_ssa_bsm.erl b/lib/compiler/src/beam_ssa_bsm.erl
index 382e6f635e..1ac9e6a3bb 100644
--- a/lib/compiler/src/beam_ssa_bsm.erl
+++ b/lib/compiler/src/beam_ssa_bsm.erl
@@ -683,8 +683,12 @@ aca_copy_successors(Lbl0, Blocks0, Counter0) ->
     Lbl = maps:get(Lbl0, BRs),
     {Lbl, Blocks, Counter}.
 
+aca_cs_build_brs([?BADARG_BLOCK=Lbl | Path], Counter, Acc) ->
+    %% ?BADARG_BLOCK is a marker and not an actual block, so renaming it will
+    %% break exception handling.
+    aca_cs_build_brs(Path, Counter, Acc#{ Lbl => Lbl });
 aca_cs_build_brs([Lbl | Path], Counter0, Acc) ->
-    aca_cs_build_brs(Path, Counter0 + 1, maps:put(Lbl, Counter0, Acc));
+    aca_cs_build_brs(Path, Counter0 + 1, Acc#{ Lbl => Counter0 });
 aca_cs_build_brs([], Counter, Acc) ->
     {Acc, Counter}.
 
diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index d97f49c56e..145a50f4ad 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -44,7 +44,8 @@
          beam_bsm/1,guard/1,is_ascii/1,non_opt_eq/1,
          expression_before_match/1,erl_689/1,restore_on_call/1,
          restore_after_catch/1,matches_on_parameter/1,big_positions/1,
-         matching_meets_apply/1,bs_start_match2_defs/1]).
+         matching_meets_apply/1,bs_start_match2_defs/1,
+         exceptions_after_match_failure/1]).
 
 -export([coverage_id/1,coverage_external_ignore/2]).
 
@@ -80,7 +81,8 @@ groups() ->
        beam_bsm,guard,is_ascii,non_opt_eq,
        expression_before_match,erl_689,restore_on_call,
        matches_on_parameter,big_positions,
-       matching_meets_apply,bs_start_match2_defs]}].
+       matching_meets_apply,bs_start_match2_defs,
+       exceptions_after_match_failure]}].
 
 
 init_per_suite(Config) ->
@@ -2005,4 +2007,17 @@ do_matching_meets_apply(_Bin, {Handler, State}) ->
     %% Another case of the above.
     Handler:abs(State).
 
+%% Exception handling was broken on the failure path of bs_start_match as
+%% beam_ssa_bsm accidentally cloned and renamed the ?BADARG_BLOCK.
+exceptions_after_match_failure(_Config) ->
+    {'EXIT', {badarith, _}} = (catch do_exceptions_after_match_failure(atom)),
+    ok = do_exceptions_after_match_failure(<<0, 1, "gurka">>),
+    ok = do_exceptions_after_match_failure(2.0).
+
+do_exceptions_after_match_failure(<<_A, _B, "gurka">>) ->
+    ok;
+do_exceptions_after_match_failure(Other) ->
+    Other / 2.0,
+    ok.
+
 id(I) -> I.