From 9b940b12210500e615ea05b447b0e1be34e70d39 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Wed, 25 Mar 2015 13:10:30 +0100
Subject: Pre-compute hash values for the general get_map_elements instruction

See the previous commit for justification and use cases.
---
 erts/emulator/beam/beam_emu.c  | 14 +++++++-------
 erts/emulator/beam/beam_load.c | 41 +++++++++++++++++++++++++++++++++++++++++
 erts/emulator/beam/ops.tab     |  2 +-
 3 files changed, 49 insertions(+), 8 deletions(-)

(limited to 'erts')

diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index 5f49032e23..6fde14bc8d 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -2427,7 +2427,7 @@ do {								\
      * i.e. that it follows a test is_map if needed.
      */
 
-    n  = (Uint)Arg(2) / 2;
+    n  = (Uint)Arg(2) / 3;
     fs = &Arg(3); /* pattern fields and target registers */
 
     if (is_flatmap(map)) {
@@ -2450,12 +2450,11 @@ do {								\
 	    if (EQ((Eterm)*fs,*ks)) {
 		PUT_TERM_REG(*vs, fs[1]);
 		n--;
-		fs += 2;
+		fs += 3;
 		/* no more values to fetch, we are done */
 		if (n == 0) break;
 	    }
-	    ks++; sz--;
-	    vs++;
+	    ks++, sz--, vs++;
 	}
 
 	if (n) {
@@ -2467,13 +2466,14 @@ do {								\
 	Uint32 hx;
 	ASSERT(is_hashmap(map));
 	while(n--) {
-	    hx = hashmap_make_hash((Eterm)*fs);
-	    if ((v = erts_hashmap_get(hx,(Eterm)*fs, map)) == NULL) {
+	    hx = fs[2];
+	    ASSERT(hx == hashmap_make_hash((Eterm)fs[0]));
+	    if ((v = erts_hashmap_get(hx, (Eterm)fs[0], map)) == NULL) {
 		SET_I((BeamInstr *) Arg(0));
 		goto get_map_elements_fail;
 	    }
 	    PUT_TERM_REG(*v, fs[1]);
-	    fs += 2;
+	    fs += 3;
 	}
     }
 
diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index ee319d0a78..8d7beb4eb4 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -4218,6 +4218,47 @@ gen_get_map_element(LoaderState* stp, GenOpArg Fail, GenOpArg Src,
     return op;
 }
 
+static GenOp*
+gen_get_map_elements(LoaderState* stp, GenOpArg Fail, GenOpArg Src,
+		     GenOpArg Size, GenOpArg* Rest)
+{
+    GenOp* op;
+    Uint32 hx;
+    Uint i;
+    GenOpArg* dst;
+#ifdef DEBUG
+    int good_hash;
+#endif
+
+    ASSERT(Size.type == TAG_u);
+
+    NEW_GENOP(stp, op);
+    op->op = genop_i_get_map_elements_3;
+    GENOP_ARITY(op, 3 + 3*(Size.val/2));
+    op->next = NULL;
+    op->a[0] = Fail;
+    op->a[1] = Src;
+    op->a[2].type = TAG_u;
+    op->a[2].val = 3*(Size.val/2);
+
+    dst = op->a+3;
+    for (i = 0; i < Size.val / 2; i++) {
+	dst[0] = Rest[2*i];
+	dst[1] = Rest[2*i+1];
+#ifdef DEBUG
+	good_hash =
+#endif
+	    hash_genop_arg(stp, dst[0], &hx);
+#ifdef DEBUG
+	ASSERT(good_hash);
+#endif
+	dst[2].type = TAG_u;
+	dst[2].val = (BeamInstr) hx;
+	dst += 3;
+    }
+    return op;
+}
+
 static GenOp*
 gen_has_map_fields(LoaderState* stp, GenOpArg Fail, GenOpArg Src,
 		   GenOpArg Size, GenOpArg* Rest)
diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab
index 456f879ab5..9bdc9cb88d 100644
--- a/erts/emulator/beam/ops.tab
+++ b/erts/emulator/beam/ops.tab
@@ -1515,7 +1515,7 @@ has_map_fields Fail Src Size Rest=* => \
 get_map_elements Fail Src=rxy Size=u==2 Rest=* => \
     gen_get_map_element(Fail, Src, Size, Rest)
 get_map_elements Fail Src Size Rest=* | map_key_sort(Size, Rest) => \
-   i_get_map_elements Fail Src Size Rest
+   gen_get_map_elements(Fail, Src, Size, Rest)
 
 i_get_map_elements f s I
 
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