hipe_beam_to_icode: Correct translation of get_map_elements

If one of the destination registers for get_map_elements is
the same as the map source, extract that element last.

1 files changed, 17 insertions, 1 deletions

diff --git a/lib/hipe/icode/hipe_beam_to_icode.erl b/lib/hipe/icode/hipe_beam_to_icode.erl
index f429d40272..4f099baab3 100644
--- a/lib/hipe/icode/hipe_beam_to_icode.erl
+++ b/lib/hipe/icode/hipe_beam_to_icode.erl
@@ -1139,9 +1139,10 @@ trans_fun([{test,has_map_fields,{f,Lbl},Map,{list,Keys}}|Instructions], Env) ->
 		    lists:flatten([[K, {r, 0}] || K <- Keys])),
   [MapMove, TestInstructions | trans_fun(Instructions, Env2)];
 trans_fun([{get_map_elements,{f,Lbl},Map,{list,KVPs}}|Instructions], Env) ->
+  KVPs1 = overwrite_map_last(Map, KVPs),
   {MapMove, MapVar, Env1} = mk_move_and_var(Map, Env),
   {TestInstructions, GetInstructions, Env2} =
-    trans_map_query(MapVar, map_label(Lbl), Env1, KVPs),
+    trans_map_query(MapVar, map_label(Lbl), Env1, KVPs1),
   [MapMove, TestInstructions, GetInstructions | trans_fun(Instructions, Env2)];
 %%--- put_map_assoc ---
 trans_fun([{put_map_assoc,{f,Lbl},Map,Dst,_N,{list,Pairs}}|Instructions], Env) ->
@@ -1563,6 +1564,21 @@ trans_type_test2(function2, Lbl, Arg, Arity, Env) ->
 			 hipe_icode:label_name(True), map_label(Lbl)),
   {[Move1,Move2,I,True],Env2}.
 
+
+%%
+%% Makes sure that if a get_map_elements instruction will overwrite
+%% the map source, it will be done last.
+%%
+overwrite_map_last(Map, KVPs) ->
+  overwrite_map_last2(Map, KVPs, []).
+
+overwrite_map_last2(Map, [Key,Map|KVPs], _Last) ->
+  overwrite_map_last2(Map, KVPs, [Key,Map]);
+overwrite_map_last2(Map, [Key,Val|KVPs], Last) ->
+  [Key,Val|overwrite_map_last2(Map, KVPs, Last)];
+overwrite_map_last2(_Map, [], Last) ->
+  Last.
+
 %%
 %% Handles the get_map_elements instruction and the has_map_fields
 %% test instruction.