From e7b3dcde36969be9442e05b18919ecb5b61bf6a4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Thu, 1 Nov 2018 06:19:52 +0100
Subject: beam_trim, beam_jump: Print Name/Arity if there is a crash

This will help investigation of compiler bugs.
---
 lib/compiler/src/beam_jump.erl   | 20 +++++++++++++-------
 lib/compiler/src/beam_trim.erl   | 13 +++++++++----
 lib/compiler/test/misc_SUITE.erl |  8 ++++++++
 3 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl
index edc4522cc7..40a2211325 100644
--- a/lib/compiler/src/beam_jump.erl
+++ b/lib/compiler/src/beam_jump.erl
@@ -144,13 +144,19 @@ module({Mod,Exp,Attr,Fs0,Lc0}, _Opt) ->
 %%
 %%  NOTE: This function assumes that there are no labels inside blocks.
 function({function,Name,Arity,CLabel,Asm0}, Lc0) ->
-    Asm1 = eliminate_moves(Asm0),
-    {Asm2,Lc} = insert_labels(Asm1, Lc0, []),
-    Asm3 = share(Asm2),
-    Asm4 = move(Asm3),
-    Asm5 = opt(Asm4, CLabel),
-    Asm = remove_unused_labels(Asm5),
-    {{function,Name,Arity,CLabel,Asm},Lc}.
+    try
+        Asm1 = eliminate_moves(Asm0),
+        {Asm2,Lc} = insert_labels(Asm1, Lc0, []),
+        Asm3 = share(Asm2),
+        Asm4 = move(Asm3),
+        Asm5 = opt(Asm4, CLabel),
+        Asm = remove_unused_labels(Asm5),
+        {{function,Name,Arity,CLabel,Asm},Lc}
+    catch
+        Class:Error:Stack ->
+	    io:fwrite("Function: ~w/~w\n", [Name,Arity]),
+	    erlang:raise(Class, Error, Stack)
+    end.
 
 %%%
 %%% Scan instructions in execution order and remove redundant 'move'
diff --git a/lib/compiler/src/beam_trim.erl b/lib/compiler/src/beam_trim.erl
index 61dd94d456..13cbedf3c0 100644
--- a/lib/compiler/src/beam_trim.erl
+++ b/lib/compiler/src/beam_trim.erl
@@ -36,10 +36,15 @@ module({Mod,Exp,Attr,Fs0,Lc}, _Opts) ->
     {ok,{Mod,Exp,Attr,Fs,Lc}}.
 
 function({function,Name,Arity,CLabel,Is0}) ->
-    %%ok = io:fwrite("~w: ~p\n", [?LINE,{Name,Arity}]),
-    St = #st{safe=safe_labels(Is0, []),lbl=beam_utils:index_labels(Is0)},
-    Is = trim(Is0, St, []),
-    {function,Name,Arity,CLabel,Is}.
+    try
+        St = #st{safe=safe_labels(Is0, []),lbl=beam_utils:index_labels(Is0)},
+        Is = trim(Is0, St, []),
+        {function,Name,Arity,CLabel,Is}
+    catch
+        Class:Error:Stack ->
+	    io:fwrite("Function: ~w/~w\n", [Name,Arity]),
+	    erlang:raise(Class, Error, Stack)
+    end.
 
 trim([{kill,_}|_]=Is0, St, Acc) ->
     {Kills0,Is1} = splitwith(fun({kill,_}) -> true;
diff --git a/lib/compiler/test/misc_SUITE.erl b/lib/compiler/test/misc_SUITE.erl
index c9acda2b6d..d6fc51448f 100644
--- a/lib/compiler/test/misc_SUITE.erl
+++ b/lib/compiler/test/misc_SUITE.erl
@@ -234,6 +234,10 @@ silly_coverage(Config) when is_list(Config) ->
 		      {label,2}|non_proper_list]}],99},
     expect_error(fun() -> beam_except:module(ExceptInput, []) end),
 
+    %% beam_jump
+    JumpInput = BlockInput,
+    expect_error(fun() -> beam_jump:module(JumpInput, []) end),
+
     %% beam_clean
     CleanInput = {?MODULE,[{foo,0}],[],
 		  [{function,foo,0,2,
@@ -243,6 +247,10 @@ silly_coverage(Config) when is_list(Config) ->
 		     {jump,{f,42}}]}],99},
     expect_error(fun() -> beam_clean:module(CleanInput, []) end),
 
+    %% beam_jump
+    TrimInput = BlockInput,
+    expect_error(fun() -> beam_trim:module(TrimInput, []) end),
+
     %% beam_peep. This is tricky. Use a select instruction with
     %% an odd number of elements in the list to crash
     %% prune_redundant_values/2 but not beam_clean:clean_labels/1.
-- 
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