From c0a93fe2b9e36e00e9e3ebdec7840889ac571f6a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 24 May 2016 16:56:10 +0200
Subject: beam_jump: Clean up handling of labels before func_info

In complicated code with many indirect jumps to the func_info label,
a label could get lost.
---
 lib/compiler/src/beam_jump.erl        | 50 ++++++++++++++---------------
 lib/compiler/test/Makefile            |  2 ++
 lib/compiler/test/beam_jump_SUITE.erl | 59 +++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 26 deletions(-)
 create mode 100644 lib/compiler/test/beam_jump_SUITE.erl

(limited to 'lib/compiler')

diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl
index 359248c6af..09cd3aa2d4 100644
--- a/lib/compiler/src/beam_jump.erl
+++ b/lib/compiler/src/beam_jump.erl
@@ -266,17 +266,17 @@ extract_seq_1(_, _) -> no.
 %%% (3) (4) (5) (6) Jump and unreachable code optimizations.
 %%%
 
--record(st, {fc,				%Label for function class errors.
-	     entry,				%Entry label (must not be moved).
-	     mlbl,				%Moved labels.
-             labels :: cerl_sets:set()          %Set of referenced labels.
-	    }).
-
-opt([{label,Fc}|_]=Is0, CLabel) ->
-    Lbls = initial_labels(Is0),
+-record(st,
+	{
+	  entry,		     %Entry label (must not be moved).
+	  mlbl,			     %Moved labels.
+	  labels :: cerl_sets:set()  %Set of referenced labels.
+	}).
+
+opt(Is0, CLabel) ->
     find_fixpoint(fun(Is) ->
-			  St = #st{fc=Fc,entry=CLabel,mlbl=#{},
-				   labels=Lbls},
+			  Lbls = initial_labels(Is),
+			  St = #st{entry=CLabel,mlbl=#{},labels=Lbls},
 			  opt(Is, [], St)
 		  end, Is0).
 
@@ -327,7 +327,8 @@ opt([{label,Lbl}=I|Is], Acc, #st{mlbl=Mlbl}=St0) ->
 	    %% since we will rescan the inserted labels.  We MUST rescan.
 	    St = St0#st{mlbl=maps:remove(Lbl, Mlbl)},
 	    insert_labels([Lbl|Lbls], Is, Acc, St);
-	error -> opt(Is, [I|Acc], St0)
+	error ->
+	    opt(Is, [I|Acc], St0)
     end;
 opt([{jump,{f,_}=X}|[{label,_},{jump,X}|_]=Is], Acc, St) ->
     opt(Is, Acc, St);
@@ -362,12 +363,19 @@ opt([I|Is], Acc, #st{labels=Used0}=St0) ->
 	true  -> skip_unreachable(Is, [I|Acc], St);
 	false -> opt(Is, [I|Acc], St)
     end;
-opt([], Acc, #st{fc=Fc,mlbl=Mlbl}) ->
+opt([], Acc, #st{mlbl=Mlbl}) ->
     Code = reverse(Acc),
-    case maps:find(Fc, Mlbl) of
- 	{ok,Lbls} -> insert_fc_labels(Lbls, Mlbl, Code);
- 	error -> Code
-    end.
+    insert_fc_labels(Code, Mlbl).
+
+insert_fc_labels([{label,L}=I|Is0], Mlbl) ->
+    case maps:find(L, Mlbl) of
+	error ->
+	    [I|insert_fc_labels(Is0, Mlbl)];
+	{ok,Lbls} ->
+	    Is = [{label,Lb} || Lb <- Lbls] ++ Is0,
+	    [I|insert_fc_labels(Is, maps:remove(L, Mlbl))]
+    end;
+insert_fc_labels([_|_]=Is, _) -> Is.
 
 maps_append_list(K,Vs,M) ->
     case M of
@@ -375,16 +383,6 @@ maps_append_list(K,Vs,M) ->
         _ -> M#{K => Vs}
     end.
 
-insert_fc_labels([L|Ls], Mlbl, Acc0) ->
-    Acc = [{label,L}|Acc0],
-    case maps:find(L, Mlbl) of
-	error ->
-	    insert_fc_labels(Ls, Mlbl, Acc);
-	{ok,Lbls} ->
-	    insert_fc_labels(Lbls++Ls, Mlbl, Acc)
-    end;
-insert_fc_labels([], _, Acc) -> Acc.
-
 collect_labels(Is, #st{entry=Entry}) ->
     collect_labels_1(Is, Entry, []).
 
diff --git a/lib/compiler/test/Makefile b/lib/compiler/test/Makefile
index 203a50db55..da4ea548fd 100644
--- a/lib/compiler/test/Makefile
+++ b/lib/compiler/test/Makefile
@@ -13,6 +13,7 @@ MODULES= \
 	beam_validator_SUITE \
 	beam_disasm_SUITE \
 	beam_except_SUITE \
+	beam_jump_SUITE \
 	beam_reorder_SUITE \
 	beam_type_SUITE \
 	beam_utils_SUITE \
@@ -49,6 +50,7 @@ NO_OPT= \
 	beam_block \
 	beam_bool \
 	beam_except \
+	beam_jump \
 	beam_reorder \
 	beam_type \
 	beam_utils \
diff --git a/lib/compiler/test/beam_jump_SUITE.erl b/lib/compiler/test/beam_jump_SUITE.erl
new file mode 100644
index 0000000000..0b13adaff2
--- /dev/null
+++ b/lib/compiler/test/beam_jump_SUITE.erl
@@ -0,0 +1,59 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2016. 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%
+%%
+-module(beam_jump_SUITE).
+
+-export([all/0,suite/0,groups/0,init_per_suite/1,end_per_suite/1,
+	 init_per_group/2,end_per_group/2,
+	 undefined_label/1]).
+
+suite() ->
+    [{ct_hooks,[ts_install_cth]}].
+
+all() ->
+    test_lib:recompile(?MODULE),
+    [{group,p}].
+
+groups() ->
+    [{p,[parallel],
+      [undefined_label
+      ]}].
+
+init_per_suite(Config) ->
+    Config.
+
+end_per_suite(_Config) ->
+    ok.
+
+init_per_group(_GroupName, Config) ->
+    Config.
+
+end_per_group(_GroupName, Config) ->
+    Config.
+
+undefined_label(_Config) ->
+    {'EXIT',{function_clause,_}} = (catch flights(0, [], [])),
+    ok.
+
+%% Would lose a label when compiled with no_copt.
+
+flights(0, [], []) when [], 0; 0.0, [], false ->
+    clark;
+flights(_, Reproduction, introduction) when false, Reproduction ->
+    responsible.
-- 
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