wingo pushed a commit to branch wip-whippet
in repository guile.
commit a8214af467142b45729355daf97528515f19ea77
Author: Andy Wingo <wi...@igalia.com>
AuthorDate: Mon Jun 6 16:58:53 2022 +0200
Whippet reserves a bit in object kind for forwarding
Tags without the bit are forwarding addresses.
---
whippet.h | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/whippet.h b/whippet.h
index 3314397d5..ab358faee 100644
--- a/whippet.h
+++ b/whippet.h
@@ -251,14 +251,20 @@ static inline size_t size_to_granules(size_t size) {
return (size + GRANULE_SIZE - 1) >> GRANULE_SIZE_LOG_2;
}
-// Alloc kind is in bits 0-7, for live objects.
-static const uintptr_t gcobj_alloc_kind_mask = 0xff;
-static const uintptr_t gcobj_alloc_kind_shift = 0;
+// Alloc kind is in bits 1-7, for live objects.
+static const uintptr_t gcobj_alloc_kind_mask = 0x7f;
+static const uintptr_t gcobj_alloc_kind_shift = 1;
+static const uintptr_t gcobj_forwarded_mask = 0x1;
+static const uintptr_t gcobj_not_forwarded_bit = 0x1;
static inline uint8_t tag_live_alloc_kind(uintptr_t tag) {
return (tag >> gcobj_alloc_kind_shift) & gcobj_alloc_kind_mask;
}
static inline uintptr_t tag_live(uint8_t alloc_kind) {
- return ((uintptr_t)alloc_kind << gcobj_alloc_kind_shift);
+ return ((uintptr_t)alloc_kind << gcobj_alloc_kind_shift)
+ | gcobj_not_forwarded_bit;
+}
+static inline uintptr_t tag_forwarded(struct gcobj *new_addr) {
+ return (uintptr_t)new_addr;
}
struct gcobj {
