From 403f44ec2c5047367271f5ec7a07b0460631321b Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Tue, 16 Jul 2024 15:38:48 -0400
Subject: Make OBJ_ID_INCREMENT == RUBY_IMMEDIATE_MASK + 1

All the non-GC objects (i.e. immediates) have addresses such that
`obj % RUBY_IMMEDIATE_MASK != 0` (except for `Qfalse`, which is 0). We
can define `OBJ_ID_INCREMENT` as `RUBY_IMMEDIATE_MASK + 1` which should
guarantee that GC objects never have conflicting object IDs with
immediates.
---
 gc/default.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gc/default.c b/gc/default.c
index 67f1c7dde2..560da7388b 100644
--- a/gc/default.c
+++ b/gc/default.c
@@ -1629,7 +1629,7 @@ object_id_hash(st_data_t n)
     return FIX2LONG(rb_hash((VALUE)n));
 }
 
-#define OBJ_ID_INCREMENT (BASE_SLOT_SIZE)
+#define OBJ_ID_INCREMENT (RUBY_IMMEDIATE_MASK + 1)
 #define OBJ_ID_INITIAL (OBJ_ID_INCREMENT)
 
 static const struct st_hash_type object_id_hash_type = {
-- 
cgit v1.2.3