From 5d75a3b453b64ae1b10c8980ec5c146d7b2d5d1a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn-Egil=20Dahlberg?= <egil@erlang.org>
Date: Thu, 6 Mar 2014 18:00:52 +0100
Subject: compiler: Constant fold Maps that are safe

For updates of Map literals which may cause an error will be
determined in runtime, i.e. instructions are emitted for those
updates.

The changes in cerl now requires compiler-5.0 to compile because of
is_map/1 guard.
---
 lib/compiler/src/cerl.erl          | 32 ++++++++++++++++++++++++++++++--
 lib/compiler/src/sys_core_fold.erl |  4 +++-
 2 files changed, 33 insertions(+), 3 deletions(-)

(limited to 'lib/compiler')

diff --git a/lib/compiler/src/cerl.erl b/lib/compiler/src/cerl.erl
index 9024999d7f..61b47ed468 100644
--- a/lib/compiler/src/cerl.erl
+++ b/lib/compiler/src/cerl.erl
@@ -1588,7 +1588,7 @@ ann_c_map(As,Es) ->
     ann_c_map(As, #c_literal{val=#{}}, Es).
 
 ann_c_map(As,#c_literal{val=Mval}=M,Es) when is_map(Mval), map_size(Mval) =:= 0 ->
-    Pairs = [[K,V]||#c_map_pair{key=K,val=V}<-Es],
+    Pairs = [[Ck,Cv]||#c_map_pair{key=Ck,val=Cv}<-Es],
     IsLit = lists:foldl(fun(Pair,Res) ->
 		Res andalso is_lit_list(Pair)
 	end, true, Pairs),
@@ -1599,8 +1599,36 @@ ann_c_map(As,#c_literal{val=Mval}=M,Es) when is_map(Mval), map_size(Mval) =:= 0
 	true ->
 	    #c_literal{anno=As, val=maps:from_list(lists:map(Fun, Pairs))}
 	end;
+ann_c_map(As,#c_literal{val=M},Es) when is_map(M) ->
+    fold_map_pairs(As,Es,M);
 ann_c_map(As,M,Es) ->
-    #c_map{var=M, es = Es, anno = As }.
+    #c_map{var=M, es=Es, anno=As }.
+
+fold_map_pairs(As,[],M) -> #c_literal{anno=As,val=M};
+%% M#{ K => V}
+fold_map_pairs(As,[#c_map_pair{op=#c_literal{val=assoc},key=Ck,val=Cv}=E|Es],M) ->
+    case is_lit_list([Ck,Cv]) of
+	true ->
+	    [K,V] = lit_list_vals([Ck,Cv]),
+	    fold_map_pairs(As,Es,maps:put(K,V,M));
+	false ->
+	    #c_map{var=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
+    end;
+%% M#{ K := V}
+fold_map_pairs(As,[#c_map_pair{op=#c_literal{val=exact},key=Ck,val=Cv}=E|Es],M) ->
+    case is_lit_list([Ck,Cv]) of
+	true ->
+	    [K,V] = lit_list_vals([Ck,Cv]),
+	    case maps:is_key(K,M) of
+		true -> fold_map_pairs(As,Es,maps:put(K,V,M));
+		false ->
+		    #c_map{var=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
+	    end;
+	false ->
+	    #c_map{var=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
+    end;
+fold_map_pairs(As,Es,M) ->
+    #c_map{var=#c_literal{val=M,anno=As}, es=Es, anno=As }.
 
 
 update_c_map(Old,M,Es) ->
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index 90cc3b9051..bf1be6d773 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -72,7 +72,7 @@
 -import(lists, [map/2,foldl/3,foldr/3,mapfoldl/3,all/2,any/2,
 		reverse/1,reverse/2,member/2,nth/2,flatten/1,unzip/1]).
 
--import(cerl, [ann_c_cons/3,ann_c_tuple/2,ann_c_map/3]).
+-import(cerl, [ann_c_cons/3,ann_c_map/3,ann_c_tuple/2]).
 
 -include("core_parse.hrl").
 
@@ -1378,6 +1378,7 @@ eval_is_record(Call, _, _, _, _) -> Call.
 is_not_integer(#c_literal{val=Val}) when not is_integer(Val) -> true;
 is_not_integer(#c_tuple{}) -> true;
 is_not_integer(#c_cons{}) -> true;
+is_not_integer(#c_map{}) -> true;
 is_not_integer(_) -> false.
 
 %% is_not_tuple(Core) -> true | false.
@@ -1385,6 +1386,7 @@ is_not_integer(_) -> false.
 
 is_not_tuple(#c_literal{val=Val}) when not is_tuple(Val) -> true;
 is_not_tuple(#c_cons{}) -> true;
+is_not_tuple(#c_map{}) -> true;
 is_not_tuple(_) -> false.
 
 %% eval_setelement(Call, Pos, Tuple, NewVal) -> Core.
-- 
cgit v1.2.3