From aad7d6fe4e1e9fe086d275ab3ea34c5285cc8edb Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Tue, 10 Feb 2015 21:58:45 +0100
Subject: erts: Change to total ordering of keys in small maps

---
 erts/emulator/beam/utils.c       | 26 +++++++++++++++++++++++---
 erts/emulator/test/map_SUITE.erl |  4 +++-
 2 files changed, 26 insertions(+), 4 deletions(-)

(limited to 'erts/emulator')

diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index 471bce8940..908116c64c 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -2686,8 +2686,22 @@ tailrecur_ne:
 		}
 		aa += 2;
 		bb += 2;
-		i  += 1; /* increment for tuple-keys */
-		goto term_array;
+		if (exact) {
+		    i  += 1; /* increment for tuple-keys */
+		    goto term_array;
+		}
+		else {
+		    /* Value array */
+		    WSTACK_PUSH3(stack, i, (UWord)(bb+1), (UWord)(aa+1) | TAG_PRIMARY_HEADER);
+		    /* Marker to switch back from 'exact' compare */
+		    WSTACK_PUSH(stack, (UWord)NULL | TAG_PRIMARY_HEADER);
+		    /* Now do 'exact' compare of key tuples */
+		    a = *aa;
+		    b = *bb;
+		    exact = 1;
+		    goto tailrecur;
+		}
+
 	    case (_TAG_HEADER_FLOAT >> _TAG_PRIMARY_SIZE):
 		if (!is_float_rel(b,b_base)) {
 		    a_tag = FLOAT_DEF;
@@ -3061,7 +3075,13 @@ pop_next:
     if (!WSTACK_ISEMPTY(stack)) {
 	UWord something = WSTACK_POP(stack);
 	if (primary_tag((Eterm) something) == TAG_PRIMARY_HEADER) { /* a term_array */
-	    aa = (Eterm*) something;
+	    if (something == ((UWord)NULL | TAG_PRIMARY_HEADER)) {
+		/* Done with exact compare of map keys, switch back */
+		ASSERT(exact);
+		exact = 0;
+		goto pop_next;
+	    }
+	    aa = (Eterm *)something;
 	    bb = (Eterm*) WSTACK_POP(stack);
 	    i = WSTACK_POP(stack);
 	    goto term_array;
diff --git a/erts/emulator/test/map_SUITE.erl b/erts/emulator/test/map_SUITE.erl
index 888ed8e272..1e989fbc4d 100644
--- a/erts/emulator/test/map_SUITE.erl
+++ b/erts/emulator/test/map_SUITE.erl
@@ -432,7 +432,7 @@ t_map_sort_literals(Config) when is_list(Config) ->
     true  = #{ c => 1, b => 1, a => 1 } < id(#{ b => 1, c => 1, d => 1}),
     true  = #{ "a" => 1 } < id(#{ <<"a">> => 1}),
     false = #{ <<"a">> => 1 } < id(#{ "a" => 1}),
-    false = #{ 1 => 1 } < id(#{ 1.0 => 1}),
+    true = #{ 1 => 1 } < id(#{ 1.0 => 1}),
     false = #{ 1.0 => 1 } < id(#{ 1 => 1}),
 
     %% value order
@@ -440,6 +440,8 @@ t_map_sort_literals(Config) when is_list(Config) ->
     false = #{ a => 2 } < id(#{ a => 1}),
     false = #{ a => 2, b => 1 } < id(#{ a => 1, b => 3}),
     true  = #{ a => 1, b => 1 } < id(#{ a => 1, b => 3}),
+    false = #{ a => 1 } < id(#{ a => 1.0}),
+    false = #{ a => 1.0 } < id(#{ a => 1}),
 
     true  = #{ "a" => "hi", b => 134 } == id(#{ b => 134,"a" => "hi"}),
 
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