v3_life: Eliminate special handling of guards

Remove the special handling #k_try{} in guards in v3_life. If we
introduce a new #k_protected{} record in v3_kernel, v3_life no longer
needs to know whether it is processing guards or bodies.

4 files changed, 22 insertions, 21 deletions

diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl
index b4bbc5e739..e3103e040e 100644
--- a/lib/compiler/src/v3_kernel.erl
+++ b/lib/compiler/src/v3_kernel.erl
@@ -1734,15 +1734,15 @@ uexpr(#k_receive_accept{anno=A}, _, St) ->
     {#k_receive_accept{anno=#k{us=[],ns=[],a=A}},[],St};
 uexpr(#k_receive_next{anno=A}, _, St) ->
     {#k_receive_next{anno=#k{us=[],ns=[],a=A}},[],St};
-uexpr(#k_try{anno=A,arg=A0,vars=Vs,body=B0,evars=Evs,handler=H0}=Try,
+uexpr(#k_try{anno=A,arg=A0,vars=Vs,body=B0,evars=Evs,handler=H0},
       {break,Rs0}=Br, St0) ->
     case is_in_guard(St0) of
 	true ->
 	    {[#k_var{name=X}],#k_var{name=X}} = {Vs,B0}, %Assertion.
 	    #k_atom{val=false} = H0,		%Assertion.
 	    {A1,Bu,St1} = uexpr(A0, Br, St0),
-	    {Try#k_try{anno=#k{us=Bu,ns=lit_list_vars(Rs0),a=A},
-		       arg=A1,ret=Rs0},Bu,St1};
+	    {#k_protected{anno=#k{us=Bu,ns=lit_list_vars(Rs0),a=A},
+			  arg=A1,ret=Rs0},Bu,St1};
 	false ->
 	    {Avs,St1} = new_vars(length(Vs), St0),
 	    {A1,Au,St2} = ubody(A0, {break,Avs}, St1),
diff --git a/lib/compiler/src/v3_kernel.hrl b/lib/compiler/src/v3_kernel.hrl
index 5216a1a620..1169a69117 100644
--- a/lib/compiler/src/v3_kernel.hrl
+++ b/lib/compiler/src/v3_kernel.hrl
@@ -66,6 +66,7 @@
 -record(k_receive_next, {anno=[]}).
 -record(k_try, {anno=[],arg,vars,body,evars,handler,ret=[]}).
 -record(k_try_enter, {anno=[],arg,vars,body,evars,handler}).
+-record(k_protected, {anno=[],arg,ret=[]}).
 -record(k_catch, {anno=[],body,ret=[]}).
 
 -record(k_guard_match, {anno=[],vars,body,ret=[]}).
diff --git a/lib/compiler/src/v3_kernel_pp.erl b/lib/compiler/src/v3_kernel_pp.erl
index 0b90f0a1e0..45065b7e11 100644
--- a/lib/compiler/src/v3_kernel_pp.erl
+++ b/lib/compiler/src/v3_kernel_pp.erl
@@ -279,6 +279,15 @@ format_1(#k_try_enter{arg=A,vars=Vs,body=B,evars=Evs,handler=H}, Ctxt) ->
      nl_indent(Ctxt),
      "end"
     ];
+format_1(#k_protected{arg=A,ret=Rs}, Ctxt) ->
+    Ctxt1 = ctxt_bump_indent(Ctxt, Ctxt#ctxt.body_indent),
+    ["protected",
+     nl_indent(Ctxt1),
+     format(A, Ctxt1),
+     nl_indent(Ctxt),
+     "end",
+     format_ret(Rs, ctxt_bump_indent(Ctxt, 1))
+    ];
 format_1(#k_catch{body=B,ret=Rs}, Ctxt) ->
     Ctxt1 = ctxt_bump_indent(Ctxt, Ctxt#ctxt.body_indent),
     ["catch",
diff --git a/lib/compiler/src/v3_life.erl b/lib/compiler/src/v3_life.erl
index 1452b78d1d..65c2735a4c 100644
--- a/lib/compiler/src/v3_life.erl
+++ b/lib/compiler/src/v3_life.erl
@@ -78,9 +78,7 @@ function(#k_fdef{anno=#k{a=Anno},func=F,arity=Ar,vars=Vs,body=Kb}) ->
 		     #k_match{anno=#k{us=Ka#k.us,ns=[],a=Ka#k.a},
 			      vars=Vs,body=Kb,ret=[]}
 	     end,
-	put(guard_refc, 0),
 	{B1,_,Vdb1} = body(B0, 1, Vdb0),
-	erase(guard_refc),
 	{function,F,Ar,As,B1,Vdb1,Anno}
     catch
 	Class:Error ->
@@ -106,12 +104,13 @@ body(Ke, I, Vdb0) ->
     E = expr(Ke, I, Vdb1),
     {[E],I,Vdb1}.
 
-%% guard(Kguard, I, Vdb) -> Guard.
+%% protected(Kprotected, I, Vdb) -> Protected.
+%%  Only used in guards.
 
-guard(#k_try{anno=A,arg=Ts,vars=[#k_var{name=X}],body=#k_var{name=X},
-	     handler=#k_atom{val=false},ret=Rs}, I, Vdb) ->
+protected(#k_protected{anno=A,arg=Ts,ret=Rs}, I, Vdb) ->
     %% Lock variables that are alive before try and used afterwards.
-    %% Don't lock variables that are only used inside the try expression.
+    %% Don't lock variables that are only used inside the protected
+    %% expression.
     Pdb0 = vdb_sub(I, I+1, Vdb),
     {T,MaxI,Pdb1} = body(Ts, I+1, Pdb0),
     Pdb2 = use_vars(A#k.ns, MaxI+1, Pdb1),	%Save "return" values
@@ -139,10 +138,9 @@ expr(#k_guard_match{anno=A,body=Kb,ret=Rs}, I, Vdb) ->
     M = match(Kb, A#k.us, I+1, [], Mdb),
     #l{ke={guard_match,M,var_list(Rs)},i=I,vdb=use_vars(A#k.us, I+1, Mdb),a=A#k.a};
 expr(#k_try{}=Try, I, Vdb) ->
-    case is_in_guard() of
-	false -> body_try(Try, I, Vdb);
-	true -> guard(Try, I, Vdb)
-    end;
+    body_try(Try, I, Vdb);
+expr(#k_protected{}=Protected, I, Vdb) ->
+    protected(Protected, I, Vdb);
 expr(#k_try_enter{anno=A,arg=Ka,vars=Vs,body=Kb,evars=Evs,handler=Kh}, I, Vdb) ->
     %% Lock variables that are alive before the catch and used afterwards.
     %% Don't lock variables that are only used inside the try.
@@ -303,9 +301,7 @@ val_clause(#k_val_clause{anno=A,val=V,body=Kb}, Ls0, I, Ctxt0, Vdb0) ->
 guard_clause(#k_guard_clause{anno=A,guard=Kg,body=Kb}, Ls, I, Ctxt, Vdb0) ->
     Vdb1 = use_vars(union(A#k.us, Ls), I+2, Vdb0),
     Gdb = vdb_sub(I+1, I+2, Vdb1),
-    OldRefc = put(guard_refc, get(guard_refc)+1),
-    G = guard(Kg, I+1, Gdb),
-    put(guard_refc, OldRefc),
+    G = protected(Kg, I+1, Gdb),
     B = match(Kb, Ls, I+2, Ctxt, Vdb1),
     #l{ke={guard_clause,G,B},
        i=I,vdb=use_vars((get_kanno(Kg))#k.us, I+2, Vdb1),
@@ -431,11 +427,6 @@ use_vars(Vs, I, Vdb) -> vdb_update_vars(Vs, Vdb, I).
 add_var(V, F, L, Vdb) ->
     vdb_store_new(V, {V,F,L}, Vdb).
 
-%% is_in_guard() -> true|false.
-
-is_in_guard() ->
-    get(guard_refc) > 0.
-
 %% vdb
 
 vdb_new(Vs) ->