Add shadow frame link stack for trace recorder.

Simplifies snapshots. Prerequisite for pre-call snapshots.
Increases consistency for fast function calls, too.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/lj_asm.c b/src/lj_asm.c
index 38bbb1c2..5e7ff7f5 100644
--- a/src/lj_asm.c
+++ b/src/lj_asm.c
@@ -3042,7 +3042,7 @@ static void asm_tail_sync(ASMState *as)
   SnapShot *snap = &as->T->snap[as->T->nsnap-1];  /* Last snapshot. */
   MSize n, nent = snap->nent;
   SnapEntry *map = &as->T->snapmap[snap->mapofs];
-  SnapEntry *flinks = map + nent + snap->nframelinks;
+  SnapEntry *flinks = map + nent + 1;
   BCReg newbase = 0;
   BCReg nslots, topslot = 0;
 
@@ -3116,11 +3116,11 @@ static void asm_tail_sync(ASMState *as)
       if (!(sn & (SNAP_CONT|SNAP_FRAME)))
         emit_movmroi(as, RID_BASE, ofs+4, irt_toitype(ir->t));
       else if (s != 0)  /* Do not overwrite link to previous frame. */
-        emit_movmroi(as, RID_BASE, ofs+4, (int32_t)(*--flinks));
+        emit_movmroi(as, RID_BASE, ofs+4, (int32_t)(*flinks++));
     }
     checkmclim(as);
   }
-  lua_assert(map + nent == flinks-1);
+  lua_assert(map + nent + 1 + snap->depth == flinks);
 }
 
 /* Fixup the tail code. */