From 6e87e37bdd01401aa340a0f47e2d10fd8fe472ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 19 Mar 2019 12:24:26 +0100
Subject: Optimize map updating instructions

---
 erts/emulator/beam/beam_debug.c   |  7 +++++--
 erts/emulator/beam/map_instrs.tab | 28 ++++++++++++++++++++++++----
 erts/emulator/beam/ops.tab        | 19 +++++++++----------
 3 files changed, 38 insertions(+), 16 deletions(-)

(limited to 'erts')

diff --git a/erts/emulator/beam/beam_debug.c b/erts/emulator/beam/beam_debug.c
index 96cbe33090..762c5da9be 100644
--- a/erts/emulator/beam/beam_debug.c
+++ b/erts/emulator/beam/beam_debug.c
@@ -780,8 +780,11 @@ print_op(fmtfn_t to, void *to_arg, int op, int size, BeamInstr* addr)
     case op_put_tuple2_xI:
     case op_put_tuple2_yI:
     case op_new_map_dtI:
-    case op_update_map_assoc_sdtI:
-    case op_update_map_exact_jsdtI:
+    case op_update_map_assoc_xdtI:
+    case op_update_map_assoc_ydtI:
+    case op_update_map_assoc_cdtI:
+    case op_update_map_exact_xjdtI:
+    case op_update_map_exact_yjdtI:
 	{
 	    int n = unpacked[-1];
 
diff --git a/erts/emulator/beam/map_instrs.tab b/erts/emulator/beam/map_instrs.tab
index c594a87298..5620d5a2d1 100644
--- a/erts/emulator/beam/map_instrs.tab
+++ b/erts/emulator/beam/map_instrs.tab
@@ -127,11 +127,21 @@ i_get_map_elements(Fail, Src, N) {
     }
 }
 
-update_map_assoc(Src, Dst, Live, N) {
+update_map_assoc := update_map_assoc.fetch.execute;
+
+update_map_assoc.head() {
+    Eterm map;
+}
+
+update_map_assoc.fetch(Src) {
+    map = $Src;
+}
+
+update_map_assoc.execute(Dst, Live, N) {
     Eterm res;
     Uint live = $Live;
 
-    reg[live] = $Src;
+    reg[live] = map;
     HEAVY_SWAPOUT;
     res = erts_gc_update_map_assoc(c_p, reg, live, $N, $NEXT_INSTRUCTION);
     HEAVY_SWAPIN;
@@ -141,11 +151,21 @@ update_map_assoc(Src, Dst, Live, N) {
     $NEXT($NEXT_INSTRUCTION+$N);
 }
 
-update_map_exact(Fail, Src, Dst, Live, N) {
+update_map_exact := update_map_exact.fetch.execute;
+
+update_map_exact.head() {
+    Eterm map;
+}
+
+update_map_exact.fetch(Src) {
+    map = $Src;
+}
+
+update_map_exact.execute(Fail, Dst, Live, N) {
     Eterm res;
     Uint live = $Live;
 
-    reg[live] = $Src;
+    reg[live] = map;
     HEAVY_SWAPOUT;
     res = erts_gc_update_map_exact(c_p, reg, live, $N, $NEXT_INSTRUCTION);
     HEAVY_SWAPIN;
diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab
index 485703101f..067f81930d 100644
--- a/erts/emulator/beam/ops.tab
+++ b/erts/emulator/beam/ops.tab
@@ -1546,23 +1546,22 @@ put_map_exact F Map Dst Live Size Rest=* | map_key_sort(Size, Rest) => \
 
 sorted_put_map_assoc Map Dst Live Size Rest=* | is_empty_map(Map) => \
    new_map Dst Live Size Rest
-sorted_put_map_assoc Src=s Dst Live Size Rest=* => \
-	       update_map_assoc Src Dst Live Size Rest
-sorted_put_map_assoc Src Dst Live Size Rest=* => \
-	       move Src x | update_map_assoc x Dst Live Size Rest
+sorted_put_map_assoc Src=xyc Dst Live Size Rest=* => \
+   update_map_assoc Src Dst Live Size Rest
 
-sorted_put_map_exact F Src=s Dst Live Size Rest=* => \
-	      update_map_exact F Src Dst Live Size Rest
-sorted_put_map_exact F Src Dst Live Size Rest=* => \
-	      move Src x | update_map_exact F x Dst Live Size Rest
+sorted_put_map_exact Fail Src=xy Dst Live Size Rest=* => \
+   update_map_exact Src Fail Dst Live Size Rest
+# Literal map arguments for an exact update operation are extremely rare.
+sorted_put_map_exact Fail Src Dst Live Size Rest=* => \
+   move Src x | update_map_exact x Fail Dst Live Size Rest
 
 new_map Dst Live Size Rest=* | is_small_map_literal_keys(Size, Rest) => \
    gen_new_small_map_lit(Dst, Live, Size, Rest)
 
 new_map d t I
 i_new_small_map_lit d t q
-update_map_assoc s d t I
-update_map_exact j? s d t I
+update_map_assoc xyc d t I
+update_map_exact xy j? d t I
 
 is_map Fail Lit=q | literal_is_map(Lit) =>
 is_map Fail cq => jump Fail
-- 
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