File 4721-Optimize-comparison-of-equal-terms.patch of Package erlang

From ba77daa4dd35041c7c381ae9f19ac7cdf25798cc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Wed, 27 Jul 2022 09:26:32 +0200
Subject: [PATCH] Optimize comparison of equal terms

When doing comparisons, be sure to avoid calling the quite expensive
generic comparison routine for equal tagged values.  In particular,
the generic comparison function for atoms, `erts_cmp_atoms()`, will
always call `memcmp()` for equal atoms longer than 4 characters, so we
want to avoid that.
---
 erts/emulator/beam/beam_common.c            | 2 +-
 erts/emulator/beam/erl_map.c                | 2 +-
 erts/emulator/beam/jit/arm/instr_common.cpp | 8 ++++++++
 erts/emulator/beam/jit/x86/instr_common.cpp | 8 ++++++++
 4 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/erts/emulator/beam/beam_common.c b/erts/emulator/beam/beam_common.c
index 2055f60e91..6194644869 100644
--- a/erts/emulator/beam/beam_common.c
+++ b/erts/emulator/beam/beam_common.c
@@ -2174,7 +2174,7 @@ erts_gc_update_map_assoc(Process* p, Eterm* reg, Uint live,
 
 	ASSERT(kp < (Eterm *)mp);
 	key = *old_keys;
-	if ((c = CMP_TERM(key, new_key)) < 0) {
+	if ((c = (key == new_key) ? 0 : CMP_TERM(key, new_key)) < 0) {
 	    /* Copy old key and value */
 	    *kp++ = key;
 	    *hp++ = *old_vals;
diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index e0b881db0a..cb78bfe0f2 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -1378,7 +1378,7 @@ static Eterm flatmap_merge(Process *p, Eterm nodeA, Eterm nodeB) {
     vs2 = flatmap_get_values(mp2);
 
     while(i1 < n1 && i2 < n2) {
-	c = CMP_TERM(ks1[i1],ks2[i2]);
+	c = (ks1[i1] == ks2[i2]) ? 0 : CMP_TERM(ks1[i1],ks2[i2]);
 	if (c == 0) {
 	    /* use righthand side arguments map value,
 	     * but advance both maps */
-- 
2.35.3