1 files changed, 13 insertions, 3 deletions

diff --git a/src/lj_jit.h b/src/lj_jit.h
index 36e60113..1a1e407a 100644
--- a/src/lj_jit.h
+++ b/src/lj_jit.h
@@ -112,17 +112,27 @@ typedef uint8_t MCode;
 typedef struct SnapShot {
   uint16_t mapofs;      /* Offset into snapshot map. */
   IRRef1 ref;           /* First IR ref for this snapshot. */
-  uint8_t nslots;       /* Number of stack slots. */
+  uint8_t nslots;       /* Number of valid slots. */
+  uint8_t nent;         /* Number of compressed entries. */
   uint8_t nframelinks;  /* Number of frame links. */
   uint8_t count;        /* Count of taken exits for this snapshot. */
-  uint8_t unused1;
 } SnapShot;
 
 #define SNAPCOUNT_DONE  255     /* Already compiled and linked a side trace. */
 
-/* Snapshot entry. */
+/* Compressed snapshot entry. */
 typedef uint32_t SnapEntry;
+
+#define SNAP_FRAME              0x010000        /* Slot has frame link. */
+
+#define SNAP(slot, flags, ref)  ((SnapEntry)((slot) << 24) + (flags) + (ref))
+#define SNAP_MKPC(pc)           ((SnapEntry)u32ptr(pc))
+#define SNAP_MKFTSZ(ftsz)       ((SnapEntry)(ftsz))
 #define snap_ref(sn)            ((sn) & 0xffff)
+#define snap_slot(sn)           ((BCReg)((sn) >> 24))
+#define snap_isframe(sn)        ((sn) & SNAP_FRAME)
+#define snap_pc(sn)             ((const BCIns *)(uintptr_t)(sn))
+#define snap_setref(sn, ref)    (((sn) & 0xffff0000) | (ref))
 
 /* Snapshot and exit numbers. */
 typedef uint32_t SnapNo;