wip

lib/compiler/src/beam_asm.erl

@@ -380,7 +380,7 @@ build_beam_debug_info_1(ExtraChunks0, Dict0) ->
     DebugTab1 = [{Index,Info} ||
                     Index := Info <- maps:iterator(DebugTab0, ordered)],
     DebugTab = build_bdi_fill_holes(DebugTab1),
-    NumVars = lists:sum([length(Vs) || {_,Vs} <- DebugTab]),
+    NumVars = lists:sum([length(Vs) || {_,_,Vs} <- DebugTab]),
     {Contents0,Dict} = build_bdi(DebugTab, Dict0),
     NumItems = length(Contents0),
     Contents1 = iolist_to_binary(Contents0),
@@ -402,11 +402,11 @@ build_bdi_fill_holes([{I0,Item}|[{I1,_}|_]=T]) ->
         I1 ->
             [Item|build_bdi_fill_holes(T)];
         Next ->
-            NewPair = {Next,{none,[]}},
+            NewPair = {Next,{none,0,[]}},
             [Item|build_bdi_fill_holes([NewPair|T])]
     end.
 
-build_bdi([{FrameSize0,Vars0}|Items], Dict0) ->
+build_bdi([{FrameSize0,_,Vars0}|Items], Dict0) ->
     %% The debug information utilizes the encoding machinery for BEAM
     %% instructions. The debug information for `executable_line`
     %% instruction is translated to:

lib/compiler/src/beam_block.erl

@@ -179,7 +179,7 @@ collect({swap,D1,D2})        ->
 collect({make_fun3,F,I,U,D,{list,Ss}}) -> {set,[D],Ss,{make_fun3,F,I,U}};
 collect(_)                   -> error.
 
-collect_executable_line({executable_line,_Loc,_Index,{_,Vars}}=I) ->
+collect_executable_line({executable_line,_Loc,_Index,{_,_,Vars}}=I) ->
     Ss = flatmap(fun({_Name,Regs}) -> Regs end, Vars),
     {set,[],Ss,I}.
 

lib/compiler/src/beam_ssa_codegen.erl

@@ -698,6 +698,7 @@ need_live_anno(Op) ->
         bs_start_match -> true;
         bs_skip -> true;
         call -> true;
+        executable_line -> true;
         put_map -> true;
         update_record -> true;
         _ -> false
@@ -825,6 +826,10 @@ need_y_init(#cg_set{op=bs_skip,args=[#b_literal{val=Type}|_]}) ->
         _ -> false
     end;
 need_y_init(#cg_set{op=bs_start_match}) -> true;
+need_y_init(#cg_set{op=executable_line,anno=Anno}) ->
+    %% If this instruction is used for debugging (as opposed to code coverage),
+    %% all Y registers must be initialized.
+    is_map_key(alias, Anno);
 need_y_init(#cg_set{op=put_map}) -> true;
 need_y_init(#cg_set{op=update_record}) -> true;
 need_y_init(#cg_set{}) -> false.
@@ -993,9 +998,13 @@ add_debug_info_blk([], _Regs, _FrameSzMap, _VarMap) ->
     [].
 
 add_debug_info_is([#cg_alloc{stack=FrameSize}=I|Is],
-                  Regs, _FrameSize, VarMap, Acc)
-  when is_integer(FrameSize) ->
-    add_debug_info_is(Is, Regs, FrameSize, VarMap, [I|Acc]);
+                  Regs, FrameSize0, VarMap, Acc) ->
+    if
+        is_integer(FrameSize) ->
+            add_debug_info_is(Is, Regs, FrameSize, VarMap, [I|Acc]);
+        true ->
+            add_debug_info_is(Is, Regs, FrameSize0, VarMap, [I|Acc])
+    end;
 add_debug_info_is([#cg_set{anno=#{was_phi := true},op=copy}=I|Is],
                   Regs, FrameSize, VarMap, Acc) ->
     %% This copy operation originates from a phi node. The source and
@@ -1011,27 +1020,29 @@ add_debug_info_is([#cg_set{anno=Anno,op=copy,dst=#b_var{name=Dst},
                      VarMap0#{Dst => Src}
              end,
     add_debug_info_is(Is, Regs, FrameSize, VarMap, [I|Acc]);
-add_debug_info_is([#cg_set{anno=Anno,op=executable_line,args=Args}=I0|Is],
+add_debug_info_is([#cg_set{anno=Anno0,op=executable_line,args=Args}=I0|Is],
                   Regs, FrameSize, VarMap, Acc) ->
     #{def_regs := DefRegs,
       alias := Alias,
-      literals := Literals0} = Anno,
+      literals := Literals0,
+      live := NumLive0} = Anno0,
     Literals1 = [{get_original_name(#b_var{name=Var}, VarMap, Alias),Val} ||
                     {Val,Var} <- Literals0],
     Literals = [{hd(Vars),[{literal,Val}]} ||
                    {Vars,Val} <- Literals1, Vars =/= []],
-    LiveRegs = [{map_get(V, Regs),get_original_name(V, VarMap, Alias)} ||
-                   V <- DefRegs,
-                   not is_beam_register(V)],
-    S0 = sofs:family(LiveRegs, [{reg,[variable]}]),
+    RegVarMap = [{map_get(V, Regs),get_original_name(V, VarMap, Alias)} ||
+                    V <- DefRegs,
+                    not is_beam_register(V)],
+    S0 = sofs:family(RegVarMap, [{reg,[variable]}]),
     S1 = sofs:family_to_relation(S0),
     S2 = sofs:converse(S1),
     S3 = sofs:relation_to_family(S2),
     S = Literals ++ sofs:to_external(S3),
-    Info = {FrameSize,S},
+    NumLive = max(NumLive0, num_live(DefRegs, Regs)),
+    Info = {FrameSize,NumLive,S},
     I = I0#cg_set{args=Args++[#b_literal{val=Info}]},
     add_debug_info_is(Is, Regs, FrameSize, VarMap, [I|Acc]);
-add_debug_info_is([I|Is], Regs, FrameSize, VarMap, Acc) ->
+add_debug_info_is([#cg_set{}=I|Is], Regs, FrameSize, VarMap, Acc) ->
     add_debug_info_is(Is, Regs, FrameSize, VarMap, [I|Acc]);
 add_debug_info_is([], _Regs, FrameSize, VarMap, Info) ->
     {reverse(Info),VarMap,FrameSize}.

lib/compiler/src/beam_ssa_pre_codegen.erl

@@ -2846,6 +2846,23 @@ res_place_gc_instrs([#b_set{op=call}=I|Is], Acc) ->
         [_|_] ->
             res_place_gc_instrs(Is, [I,gc|Acc])
     end;
+res_place_gc_instrs([#b_set{anno=Anno,op=executable_line}=I|Is], Acc0) ->
+    case is_map_key(alias, Anno) of
+        true ->
+            %% This instruction is for debugging. Treat it as an
+            %% instruction that can garbage collect to ensure that we
+            %% don't leave any uninitialized X registers in between
+            %% initialized X registers.
+            res_place_gc_instrs(Is, [gc,I|Acc0]);
+        false ->
+            %% Used for coverage. Treat it as a neutral instruction.
+            case Acc0 of
+                [test_heap|Acc] ->
+                    res_place_gc_instrs(Is, [test_heap,I|Acc]);
+                Acc ->
+                    res_place_gc_instrs(Is, [I|Acc])
+            end
+    end;
 res_place_gc_instrs([#b_set{op=Op,args=Args}=I|Is], Acc0) ->
     case beam_ssa_codegen:classify_heap_need(Op, Args) of
         neutral ->

lib/compiler/src/beam_trim.erl

@@ -319,11 +319,11 @@ remap_block([{set,Ds0,Ss0,Info}|Is], Remap) ->
     [{set,Ds,Ss,Info}|remap_block(Is, Remap)];
 remap_block([], _) -> [].
 
-remap_debug_info({FrameSize0,Vars0}, {Trim,Map}) ->
+remap_debug_info({FrameSize0,LiveRegs,Vars0}, {Trim,Map}) ->
     FrameSize = FrameSize0 - Trim,
     Vars = [{Name,[remap_arg(Arg, Trim, Map) || Arg <- Args]} ||
                {Name,Args} <- Vars0],
-    {FrameSize,Vars}.
+    {FrameSize,LiveRegs,Vars}.
 
 remap_args(Args, {Trim,Map}) ->
     [remap_arg(Arg, Trim, Map) || Arg <- Args].

lib/compiler/src/beam_validator.erl

@@ -2161,13 +2161,17 @@ validate_select_tuple_arity(Fail, [], _, #vst{}=Vst) ->
 %% Validate executable_line instructions in the presence of BEAM debug info.
 %%
 
-validate_executable_line({Stk,Vars}, #vst{current=St}=Vst) ->
+validate_executable_line({Stk,Live,Vars}, #vst{current=St}=Vst0) ->
     case St of
         #st{numy=Stk} ->
             ok;
         #st{numy=ActualStk} ->
             error({beam_debug_info,frame_size,Stk,actual,ActualStk})
     end,
+
+    verify_live(Live, Vst0),
+    verify_y_init(Vst0),
+    Vst = prune_x_regs(Live, Vst0),
     _ = [validate_el_vars(Regs, Name, Vst) || {Name,Regs} <- Vars],
     Vst.