Teach the compiler the 'no_dead' option

To facilitate debugging of compiler bugs, teach the compiler the
'no_dead' option. Since the beam_dead pass used to do the necessary
splitting of basic blocks to expose all labels, we must move that
splitting into a separate pass that is always run.

1 files changed, 3 insertions, 62 deletions

diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl
index 9f81a6ab43..5f12a98f09 100644
--- a/lib/compiler/src/beam_dead.erl
+++ b/lib/compiler/src/beam_dead.erl
@@ -131,10 +131,9 @@
 -import(lists, [mapfoldl/3,reverse/1]).
 
 module({Mod,Exp,Attr,Fs0,_}, _Opts) ->
-    Fs1 = [split_blocks(F) || F <- Fs0],
-    {Fs2,Lc1} = beam_clean:clean_labels(Fs1),
-    {Fs,Lc} = mapfoldl(fun function/2, Lc1, Fs2),
-    %%{Fs,Lc} = {Fs2,Lc1},
+    {Fs1,Lc1} = beam_clean:clean_labels(Fs0),
+    {Fs,Lc} = mapfoldl(fun function/2, Lc1, Fs1),
+    %%{Fs,Lc} = {Fs1,Lc1},
     {ok,{Mod,Exp,Attr,Fs,Lc}}.
 
 function({function,Name,Arity,CLabel,Is0}, Lc0) ->
@@ -160,64 +159,6 @@ function({function,Name,Arity,CLabel,Is0}, Lc0) ->
 	    erlang:raise(Class, Error, Stack)
     end.
 
-%% We must split the basic block when we encounter instructions with labels,
-%% such as catches and BIFs. All labels must be visible outside the blocks.
-
-split_blocks({function,Name,Arity,CLabel,Is0}) ->
-    Is = split_blocks(Is0, []),
-    {function,Name,Arity,CLabel,Is}.
-
-split_blocks([{block,Bl}|Is], Acc0) ->
-    Acc = split_block(Bl, [], Acc0),
-    split_blocks(Is, Acc);
-split_blocks([I|Is], Acc) ->
-    split_blocks(Is, [I|Acc]);
-split_blocks([], Acc) -> reverse(Acc).
-
-split_block([{set,[R],[_,_,_]=As,{bif,is_record,{f,Lbl}}}|Is], Bl, Acc) ->
-    %% is_record/3 must be translated by beam_clean; therefore,
-    %% it must be outside of any block.
-    split_block(Is, [], [{bif,is_record,{f,Lbl},As,R}|make_block(Bl, Acc)]);
-split_block([{set,[R],As,{bif,N,{f,Lbl}=Fail}}|Is], Bl, Acc) when Lbl =/= 0 ->
-    split_block(Is, [], [{bif,N,Fail,As,R}|make_block(Bl, Acc)]);
-split_block([{set,[R],As,{alloc,Live,{gc_bif,N,{f,Lbl}=Fail}}}|Is], Bl, Acc)
-  when Lbl =/= 0 ->
-    split_block(Is, [], [{gc_bif,N,Fail,Live,As,R}|make_block(Bl, Acc)]);
-split_block([{set,[R],[],{'catch',L}}|Is], Bl, Acc) ->
-    split_block(Is, [], [{'catch',R,L}|make_block(Bl, Acc)]);
-split_block([{set,[],[],{line,_}=Line}|Is], Bl, Acc) ->
-    split_block(Is, [], [Line|make_block(Bl, Acc)]);
-split_block([I|Is], Bl, Acc) ->
-    split_block(Is, [I|Bl], Acc);
-split_block([], Bl, Acc) -> make_block(Bl, Acc).
-
-make_block([], Acc) -> Acc;
-make_block([{set,[D],Ss,{bif,Op,Fail}}|Bl]=Bl0, Acc) ->
-    %% If the last instruction in the block is a comparison or boolean operator
-    %% (such as '=:='), move it out of the block to facilitate further
-    %% optimizations.
-    Arity = length(Ss),
-    case erl_internal:comp_op(Op, Arity) orelse
-	erl_internal:new_type_test(Op, Arity) orelse
-	erl_internal:bool_op(Op, Arity) of
-	false ->
-	    [{block,reverse(Bl0)}|Acc];
-	true ->
-	    I = {bif,Op,Fail,Ss,D},
-	    case Bl =:= [] of
-		true -> [I|Acc];
-		false -> [I,{block,reverse(Bl)}|Acc]
-	    end
-    end;
-make_block([{set,[Dst],[Src],move}|Bl], Acc) ->
-    %% Make optimization of {move,Src,Dst}, {jump,...} possible.
-    I = {move,Src,Dst},
-    case Bl =:= [] of
-	true -> [I|Acc];
-	false -> [I,{block,reverse(Bl)}|Acc]
-    end;
-make_block(Bl, Acc) -> [{block,reverse(Bl)}|Acc].
-
 %% 'move' instructions outside of blocks may thwart the jump optimizer.
 %% Move them back into the block.