From 3ec5e5594657db530072be69ba94e4e655e4a407 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 24 Jan 2014 16:21:10 +0100
Subject: beam_except: Eliminate compiler crash
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Code such as:

  bar(X) ->
    case {X+1} of
      1 -> ok
    end.

would crash the beam_except pass of the compiler.

The reason for the crash is that the '+' operator would add a line/1
instruction that the beam_except pass was not prepared to handle.

Reported-by: Erik Søe Sørensen
---
 lib/compiler/src/beam_except.erl        | 10 +++++++---
 lib/compiler/test/beam_except_SUITE.erl | 10 ++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

(limited to 'lib/compiler')

diff --git a/lib/compiler/src/beam_except.erl b/lib/compiler/src/beam_except.erl
index e5ec1bd904..d261809765 100644
--- a/lib/compiler/src/beam_except.erl
+++ b/lib/compiler/src/beam_except.erl
@@ -131,9 +131,13 @@ translate_exception(_, _, _, _) -> no.
 
 fix_block(Is, 0) ->
     reverse(Is);
-fix_block(Is0, Words) ->
-    [{set,[],[],{alloc,Live,{F1,F2,Needed,F3}}}|Is] = reverse(Is0),
-    [{set,[],[],{alloc,Live,{F1,F2,Needed-Words,F3}}}|Is].
+fix_block(Is, Words) ->
+    fix_block_1(reverse(Is), Words).
+
+fix_block_1([{set,[],[],{alloc,Live,{F1,F2,Needed,F3}}}|Is], Words) ->
+    [{set,[],[],{alloc,Live,{F1,F2,Needed-Words,F3}}}|Is];
+fix_block_1([I|Is], Words) ->
+    [I|fix_block_1(Is, Words)].
 
 dig_out_block_fc([{set,[],[],{alloc,Live,_}}|Bl]) ->
     case dig_out_fc(Bl, Live-1, nil) of
diff --git a/lib/compiler/test/beam_except_SUITE.erl b/lib/compiler/test/beam_except_SUITE.erl
index bf67eedd5f..d088863c5c 100644
--- a/lib/compiler/test/beam_except_SUITE.erl
+++ b/lib/compiler/test/beam_except_SUITE.erl
@@ -57,6 +57,11 @@ coverage(_) ->
 
     {'EXIT',{undef,[{erlang,error,[a,b,c],_}|_]}} =
 	(catch erlang:error(a, b, c)),
+
+    {'EXIT',{badarith,[{?MODULE,bar,1,[File,{line,9}]}|_]}} =
+	(catch bar(x)),
+    {'EXIT',{{case_clause,{1}},[{?MODULE,bar,1,[File,{line,9}]}|_]}} =
+	(catch bar(0)),
     ok.
 
 -file("fake.erl", 1).
@@ -65,3 +70,8 @@ fc(a) ->	                                %Line 2
 fc(L) when length(L) > 2 ->			%Line 4
     %% Not the same as a "real" function_clause error.
     error(function_clause, [L]).		%Line 6
+%% Would crash the compiler.
+bar(X) ->					%Line 8
+    case {X+1} of				%Line 9
+	1 -> ok					%Line 10
+    end.					%Line 11
-- 
cgit v1.2.3