beam_except: Eliminate compiler crash

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

1 files changed, 7 insertions, 3 deletions

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