build & link with luajit instead of lua5.1

1 files changed, 2838 insertions, 0 deletions

diff --git a/libs/luajit-cmake/luajit/src/lj_record.c b/libs/luajit-cmake/luajit/src/lj_record.c
new file mode 100644
index 0000000..bfd4123
--- /dev/null
+++ b/libs/luajit-cmake/luajit/src/lj_record.c
@@ -0,0 +1,2838 @@
+/*
+** Trace recorder (bytecode -> SSA IR).
+** Copyright (C) 2005-2022 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+#define lj_record_c
+#define LUA_CORE
+
+#include "lj_obj.h"
+
+#if LJ_HASJIT
+
+#include "lj_err.h"
+#include "lj_str.h"
+#include "lj_tab.h"
+#include "lj_meta.h"
+#include "lj_frame.h"
+#if LJ_HASFFI
+#include "lj_ctype.h"
+#endif
+#include "lj_bc.h"
+#include "lj_ff.h"
+#if LJ_HASPROFILE
+#include "lj_debug.h"
+#endif
+#include "lj_ir.h"
+#include "lj_jit.h"
+#include "lj_ircall.h"
+#include "lj_iropt.h"
+#include "lj_trace.h"
+#include "lj_record.h"
+#include "lj_ffrecord.h"
+#include "lj_snap.h"
+#include "lj_dispatch.h"
+#include "lj_vm.h"
+#include "lj_prng.h"
+
+/* Some local macros to save typing. Undef'd at the end. */
+#define IR(ref)			(&J->cur.ir[(ref)])
+
+/* Pass IR on to next optimization in chain (FOLD). */
+#define emitir(ot, a, b)	(lj_ir_set(J, (ot), (a), (b)), lj_opt_fold(J))
+
+/* Emit raw IR without passing through optimizations. */
+#define emitir_raw(ot, a, b)	(lj_ir_set(J, (ot), (a), (b)), lj_ir_emit(J))
+
+/* -- Sanity checks ------------------------------------------------------- */
+
+#ifdef LUA_USE_ASSERT
+/* Sanity check the whole IR -- sloooow. */
+static void rec_check_ir(jit_State *J)
+{
+  IRRef i, nins = J->cur.nins, nk = J->cur.nk;
+  lj_assertJ(nk <= REF_BIAS && nins >= REF_BIAS && nins < 65536,
+	     "inconsistent IR layout");
+  for (i = nk; i < nins; i++) {
+    IRIns *ir = IR(i);
+    uint32_t mode = lj_ir_mode[ir->o];
+    IRRef op1 = ir->op1;
+    IRRef op2 = ir->op2;
+    const char *err = NULL;
+    switch (irm_op1(mode)) {
+    case IRMnone:
+      if (op1 != 0) err = "IRMnone op1 used";
+      break;
+    case IRMref:
+      if (op1 < nk || (i >= REF_BIAS ? op1 >= i : op1 <= i))
+	err = "IRMref op1 out of range";
+      break;
+    case IRMlit: break;
+    case IRMcst:
+      if (i >= REF_BIAS) { err = "constant in IR range"; break; }
+      if (irt_is64(ir->t) && ir->o != IR_KNULL)
+	i++;
+      continue;
+    }
+    switch (irm_op2(mode)) {
+    case IRMnone:
+      if (op2) err = "IRMnone op2 used";
+      break;
+    case IRMref:
+      if (op2 < nk || (i >= REF_BIAS ? op2 >= i : op2 <= i))
+	err = "IRMref op2 out of range";
+      break;
+    case IRMlit: break;
+    case IRMcst: err = "IRMcst op2"; break;
+    }
+    if (!err && ir->prev) {
+      if (ir->prev < nk || (i >= REF_BIAS ? ir->prev >= i : ir->prev <= i))
+	err = "chain out of range";
+      else if (ir->o != IR_NOP && IR(ir->prev)->o != ir->o)
+	err = "chain to different op";
+    }
+    lj_assertJ(!err, "bad IR %04d op %d(%04d,%04d): %s",
+	       i-REF_BIAS,
+	       ir->o,
+	       irm_op1(mode) == IRMref ? op1-REF_BIAS : op1,
+	       irm_op2(mode) == IRMref ? op2-REF_BIAS : op2,
+	       err);
+  }
+}
+
+/* Compare stack slots and frames of the recorder and the VM. */
+static void rec_check_slots(jit_State *J)
+{
+  BCReg s, nslots = J->baseslot + J->maxslot;
+  int32_t depth = 0;
+  cTValue *base = J->L->base - J->baseslot;
+  lj_assertJ(J->baseslot >= 1+LJ_FR2, "bad baseslot");
+  lj_assertJ(J->baseslot == 1+LJ_FR2 || (J->slot[J->baseslot-1] & TREF_FRAME),
+	     "baseslot does not point to frame");
+  lj_assertJ(nslots <= LJ_MAX_JSLOTS, "slot overflow");
+  for (s = 0; s < nslots; s++) {
+    TRef tr = J->slot[s];
+    if (tr) {
+      cTValue *tv = &base[s];
+      IRRef ref = tref_ref(tr);
+      IRIns *ir = NULL;  /* Silence compiler. */
+      if (!LJ_FR2 || ref || !(tr & (TREF_FRAME | TREF_CONT))) {
+	lj_assertJ(ref >= J->cur.nk && ref < J->cur.nins,
+		   "slot %d ref %04d out of range", s, ref - REF_BIAS);
+	ir = IR(ref);
+	lj_assertJ(irt_t(ir->t) == tref_t(tr), "slot %d IR type mismatch", s);
+      }
+      if (s == 0) {
+	lj_assertJ(tref_isfunc(tr), "frame slot 0 is not a function");
+#if LJ_FR2
+      } else if (s == 1) {
+	lj_assertJ((tr & ~TREF_FRAME) == 0, "bad frame slot 1");
+#endif
+      } else if ((tr & TREF_FRAME)) {
+	GCfunc *fn = gco2func(frame_gc(tv));
+	BCReg delta = (BCReg)(tv - frame_prev(tv));
+#if LJ_FR2
+	lj_assertJ(!ref || ir_knum(ir)->u64 == tv->u64,
+		   "frame slot %d PC mismatch", s);
+	tr = J->slot[s-1];
+	ir = IR(tref_ref(tr));
+#endif
+	lj_assertJ(tref_isfunc(tr),
+		   "frame slot %d is not a function", s-LJ_FR2);
+	lj_assertJ(!tref_isk(tr) || fn == ir_kfunc(ir),
+		   "frame slot %d function mismatch", s-LJ_FR2);
+	lj_assertJ(s > delta + LJ_FR2 ? (J->slot[s-delta] & TREF_FRAME)
+				      : (s == delta + LJ_FR2),
+		   "frame slot %d broken chain", s-LJ_FR2);
+	depth++;
+      } else if ((tr & TREF_CONT)) {
+#if LJ_FR2
+	lj_assertJ(!ref || ir_knum(ir)->u64 == tv->u64,
+		   "cont slot %d continuation mismatch", s);
+#else
+	lj_assertJ(ir_kptr(ir) == gcrefp(tv->gcr, void),
+		   "cont slot %d continuation mismatch", s);
+#endif
+	lj_assertJ((J->slot[s+1+LJ_FR2] & TREF_FRAME),
+		   "cont slot %d not followed by frame", s);
+	depth++;
+      } else if ((tr & TREF_KEYINDEX)) {
+	lj_assertJ(tref_isint(tr), "keyindex slot %d bad type %d",
+				   s, tref_type(tr));
+      } else {
+	/* Number repr. may differ, but other types must be the same. */
+	lj_assertJ(tvisnumber(tv) ? tref_isnumber(tr) :
+				    itype2irt(tv) == tref_type(tr),
+		   "slot %d type mismatch: stack type %d vs IR type %d",
+		   s, itypemap(tv), tref_type(tr));
+	if (tref_isk(tr)) {  /* Compare constants. */
+	  TValue tvk;
+	  lj_ir_kvalue(J->L, &tvk, ir);
+	  lj_assertJ((tvisnum(&tvk) && tvisnan(&tvk)) ?
+		     (tvisnum(tv) && tvisnan(tv)) :
+		     lj_obj_equal(tv, &tvk),
+		     "slot %d const mismatch: stack %016llx vs IR %016llx",
+		     s, tv->u64, tvk.u64);
+	}
+      }
+    }
+  }
+  lj_assertJ(J->framedepth == depth,
+	     "frame depth mismatch %d vs %d", J->framedepth, depth);
+}
+#endif
+
+/* -- Type handling and specialization ------------------------------------ */
+
+/* Note: these functions return tagged references (TRef). */
+
+/* Specialize a slot to a specific type. Note: slot can be negative! */
+static TRef sloadt(jit_State *J, int32_t slot, IRType t, int mode)
+{
+  /* Caller may set IRT_GUARD in t. */
+  TRef ref = emitir_raw(IRT(IR_SLOAD, t), (int32_t)J->baseslot+slot, mode);
+  J->base[slot] = ref;
+  return ref;
+}
+
+/* Specialize a slot to the runtime type. Note: slot can be negative! */
+static TRef sload(jit_State *J, int32_t slot)
+{
+  IRType t = itype2irt(&J->L->base[slot]);
+  TRef ref = emitir_raw(IRTG(IR_SLOAD, t), (int32_t)J->baseslot+slot,
+			IRSLOAD_TYPECHECK);
+  if (irtype_ispri(t)) ref = TREF_PRI(t);  /* Canonicalize primitive refs. */
+  J->base[slot] = ref;
+  return ref;
+}
+
+/* Get TRef from slot. Load slot and specialize if not done already. */
+#define getslot(J, s)	(J->base[(s)] ? J->base[(s)] : sload(J, (int32_t)(s)))
+
+/* Get TRef for current function. */
+static TRef getcurrf(jit_State *J)
+{
+  if (J->base[-1-LJ_FR2])
+    return J->base[-1-LJ_FR2];
+  /* Non-base frame functions ought to be loaded already. */
+  lj_assertJ(J->baseslot == 1+LJ_FR2, "bad baseslot");
+  return sloadt(J, -1-LJ_FR2, IRT_FUNC, IRSLOAD_READONLY);
+}
+
+/* Compare for raw object equality.
+** Returns 0 if the objects are the same.
+** Returns 1 if they are different, but the same type.
+** Returns 2 for two different types.
+** Comparisons between primitives always return 1 -- no caller cares about it.
+*/
+int lj_record_objcmp(jit_State *J, TRef a, TRef b, cTValue *av, cTValue *bv)
+{
+  int diff = !lj_obj_equal(av, bv);
+  if (!tref_isk2(a, b)) {  /* Shortcut, also handles primitives. */
+    IRType ta = tref_isinteger(a) ? IRT_INT : tref_type(a);
+    IRType tb = tref_isinteger(b) ? IRT_INT : tref_type(b);
+    if (ta != tb) {
+      /* Widen mixed number/int comparisons to number/number comparison. */
+      if (ta == IRT_INT && tb == IRT_NUM) {
+	a = emitir(IRTN(IR_CONV), a, IRCONV_NUM_INT);
+	ta = IRT_NUM;
+      } else if (ta == IRT_NUM && tb == IRT_INT) {
+	b = emitir(IRTN(IR_CONV), b, IRCONV_NUM_INT);
+      } else {
+	return 2;  /* Two different types are never equal. */
+      }
+    }
+    emitir(IRTG(diff ? IR_NE : IR_EQ, ta), a, b);
+  }
+  return diff;
+}
+
+/* Constify a value. Returns 0 for non-representable object types. */
+TRef lj_record_constify(jit_State *J, cTValue *o)
+{
+  if (tvisgcv(o))
+    return lj_ir_kgc(J, gcV(o), itype2irt(o));
+  else if (tvisint(o))
+    return lj_ir_kint(J, intV(o));
+  else if (tvisnum(o))
+    return lj_ir_knumint(J, numV(o));
+  else if (tvisbool(o))
+    return TREF_PRI(itype2irt(o));
+  else
+    return 0;  /* Can't represent lightuserdata (pointless). */
+}
+
+/* Emit a VLOAD with the correct type. */
+TRef lj_record_vload(jit_State *J, TRef ref, MSize idx, IRType t)
+{
+  TRef tr = emitir(IRTG(IR_VLOAD, t), ref, idx);
+  if (irtype_ispri(t)) tr = TREF_PRI(t);  /* Canonicalize primitives. */
+  return tr;
+}
+
+/* -- Record loop ops ----------------------------------------------------- */
+
+/* Loop event. */
+typedef enum {
+  LOOPEV_LEAVE,		/* Loop is left or not entered. */
+  LOOPEV_ENTERLO,	/* Loop is entered with a low iteration count left. */
+  LOOPEV_ENTER		/* Loop is entered. */
+} LoopEvent;
+
+/* Canonicalize slots: convert integers to numbers. */
+static void canonicalize_slots(jit_State *J)
+{
+  BCReg s;
+  if (LJ_DUALNUM) return;
+  for (s = J->baseslot+J->maxslot-1; s >= 1; s--) {
+    TRef tr = J->slot[s];
+    if (tref_isinteger(tr) && !(tr & TREF_KEYINDEX)) {
+      IRIns *ir = IR(tref_ref(tr));
+      if (!(ir->o == IR_SLOAD && (ir->op2 & (IRSLOAD_READONLY))))
+	J->slot[s] = emitir(IRTN(IR_CONV), tr, IRCONV_NUM_INT);
+    }
+  }
+}
+
+/* Stop recording. */
+void lj_record_stop(jit_State *J, TraceLink linktype, TraceNo lnk)
+{
+#ifdef LUAJIT_ENABLE_TABLE_BUMP
+  if (J->retryrec)
+    lj_trace_err(J, LJ_TRERR_RETRY);
+#endif
+  lj_trace_end(J);
+  J->cur.linktype = (uint8_t)linktype;
+  J->cur.link = (uint16_t)lnk;
+  /* Looping back at the same stack level? */
+  if (lnk == J->cur.traceno && J->framedepth + J->retdepth == 0) {
+    if ((J->flags & JIT_F_OPT_LOOP))  /* Shall we try to create a loop? */
+      goto nocanon;  /* Do not canonicalize or we lose the narrowing. */
+    if (J->cur.root)  /* Otherwise ensure we always link to the root trace. */
+      J->cur.link = J->cur.root;
+  }
+  canonicalize_slots(J);
+nocanon:
+  /* Note: all loop ops must set J->pc to the following instruction! */
+  lj_snap_add(J);  /* Add loop snapshot. */
+  J->needsnap = 0;
+  J->mergesnap = 1;  /* In case recording continues. */
+}
+
+/* Search bytecode backwards for a int/num constant slot initializer. */
+static TRef find_kinit(jit_State *J, const BCIns *endpc, BCReg slot, IRType t)
+{
+  /* This algorithm is rather simplistic and assumes quite a bit about
+  ** how the bytecode is generated. It works fine for FORI initializers,
+  ** but it won't necessarily work in other cases (e.g. iterator arguments).
+  ** It doesn't do anything fancy, either (like backpropagating MOVs).
+  */
+  const BCIns *pc, *startpc = proto_bc(J->pt);
+  for (pc = endpc-1; pc > startpc; pc--) {
+    BCIns ins = *pc;
+    BCOp op = bc_op(ins);
+    /* First try to find the last instruction that stores to this slot. */
+    if (bcmode_a(op) == BCMbase && bc_a(ins) <= slot) {
+      return 0;  /* Multiple results, e.g. from a CALL or KNIL. */
+    } else if (bcmode_a(op) == BCMdst && bc_a(ins) == slot) {
+      if (op == BC_KSHORT || op == BC_KNUM) {  /* Found const. initializer. */
+	/* Now try to verify there's no forward jump across it. */
+	const BCIns *kpc = pc;
+	for (; pc > startpc; pc--)
+	  if (bc_op(*pc) == BC_JMP) {
+	    const BCIns *target = pc+bc_j(*pc)+1;
+	    if (target > kpc && target <= endpc)
+	      return 0;  /* Conditional assignment. */
+	  }
+	if (op == BC_KSHORT) {
+	  int32_t k = (int32_t)(int16_t)bc_d(ins);
+	  return t == IRT_INT ? lj_ir_kint(J, k) : lj_ir_knum(J, (lua_Number)k);
+	} else {
+	  cTValue *tv = proto_knumtv(J->pt, bc_d(ins));
+	  if (t == IRT_INT) {
+	    int32_t k = numberVint(tv);
+	    if (tvisint(tv) || numV(tv) == (lua_Number)k)  /* -0 is ok here. */
+	      return lj_ir_kint(J, k);
+	    return 0;  /* Type mismatch. */
+	  } else {
+	    return lj_ir_knum(J, numberVnum(tv));
+	  }
+	}
+      }
+      return 0;  /* Non-constant initializer. */
+    }
+  }
+  return 0;  /* No assignment to this slot found? */
+}
+
+/* Load and optionally convert a FORI argument from a slot. */
+static TRef fori_load(jit_State *J, BCReg slot, IRType t, int mode)
+{
+  int conv = (tvisint(&J->L->base[slot]) != (t==IRT_INT)) ? IRSLOAD_CONVERT : 0;
+  return sloadt(J, (int32_t)slot,
+		t + (((mode & IRSLOAD_TYPECHECK) ||
+		      (conv && t == IRT_INT && !(mode >> 16))) ?
+		     IRT_GUARD : 0),
+		mode + conv);
+}
+
+/* Peek before FORI to find a const initializer. Otherwise load from slot. */
+static TRef fori_arg(jit_State *J, const BCIns *fori, BCReg slot,
+		     IRType t, int mode)
+{
+  TRef tr = J->base[slot];
+  if (!tr) {
+    tr = find_kinit(J, fori, slot, t);
+    if (!tr)
+      tr = fori_load(J, slot, t, mode);
+  }
+  return tr;
+}
+
+/* Return the direction of the FOR loop iterator.
+** It's important to exactly reproduce the semantics of the interpreter.
+*/
+static int rec_for_direction(cTValue *o)
+{
+  return (tvisint(o) ? intV(o) : (int32_t)o->u32.hi) >= 0;
+}
+
+/* Simulate the runtime behavior of the FOR loop iterator. */
+static LoopEvent rec_for_iter(IROp *op, cTValue *o, int isforl)
+{
+  lua_Number stopv = numberVnum(&o[FORL_STOP]);
+  lua_Number idxv = numberVnum(&o[FORL_IDX]);
+  lua_Number stepv = numberVnum(&o[FORL_STEP]);
+  if (isforl)
+    idxv += stepv;
+  if (rec_for_direction(&o[FORL_STEP])) {
+    if (idxv <= stopv) {
+      *op = IR_LE;
+      return idxv + 2*stepv > stopv ? LOOPEV_ENTERLO : LOOPEV_ENTER;
+    }
+    *op = IR_GT; return LOOPEV_LEAVE;
+  } else {
+    if (stopv <= idxv) {
+      *op = IR_GE;
+      return idxv + 2*stepv < stopv ? LOOPEV_ENTERLO : LOOPEV_ENTER;
+    }
+    *op = IR_LT; return LOOPEV_LEAVE;
+  }
+}
+
+/* Record checks for FOR loop overflow and step direction. */
+static void rec_for_check(jit_State *J, IRType t, int dir,
+			  TRef stop, TRef step, int init)
+{
+  if (!tref_isk(step)) {
+    /* Non-constant step: need a guard for the direction. */
+    TRef zero = (t == IRT_INT) ? lj_ir_kint(J, 0) : lj_ir_knum_zero(J);
+    emitir(IRTG(dir ? IR_GE : IR_LT, t), step, zero);
+    /* Add hoistable overflow checks for a narrowed FORL index. */
+    if (init && t == IRT_INT) {
+      if (tref_isk(stop)) {
+	/* Constant stop: optimize check away or to a range check for step. */
+	int32_t k = IR(tref_ref(stop))->i;
+	if (dir) {
+	  if (k > 0)
+	    emitir(IRTGI(IR_LE), step, lj_ir_kint(J, (int32_t)0x7fffffff-k));
+	} else {
+	  if (k < 0)
+	    emitir(IRTGI(IR_GE), step, lj_ir_kint(J, (int32_t)0x80000000-k));
+	}
+      } else {
+	/* Stop+step variable: need full overflow check. */
+	TRef tr = emitir(IRTGI(IR_ADDOV), step, stop);
+	emitir(IRTI(IR_USE), tr, 0);  /* ADDOV is weak. Avoid dead result. */
+      }
+    }
+  } else if (init && t == IRT_INT && !tref_isk(stop)) {
+    /* Constant step: optimize overflow check to a range check for stop. */
+    int32_t k = IR(tref_ref(step))->i;
+    k = (int32_t)(dir ? 0x7fffffff : 0x80000000) - k;
+    emitir(IRTGI(dir ? IR_LE : IR_GE), stop, lj_ir_kint(J, k));
+  }
+}
+
+/* Record a FORL instruction. */
+static void rec_for_loop(jit_State *J, const BCIns *fori, ScEvEntry *scev,
+			 int init)
+{
+  BCReg ra = bc_a(*fori);
+  cTValue *tv = &J->L->base[ra];
+  TRef idx = J->base[ra+FORL_IDX];
+  IRType t = idx ? tref_type(idx) :
+	     (init || LJ_DUALNUM) ? lj_opt_narrow_forl(J, tv) : IRT_NUM;
+  int mode = IRSLOAD_INHERIT +
+    ((!LJ_DUALNUM || tvisint(tv) == (t == IRT_INT)) ? IRSLOAD_READONLY : 0);
+  TRef stop = fori_arg(J, fori, ra+FORL_STOP, t, mode);
+  TRef step = fori_arg(J, fori, ra+FORL_STEP, t, mode);
+  int tc, dir = rec_for_direction(&tv[FORL_STEP]);
+  lj_assertJ(bc_op(*fori) == BC_FORI || bc_op(*fori) == BC_JFORI,
+	     "bad bytecode %d instead of FORI/JFORI", bc_op(*fori));
+  scev->t.irt = t;
+  scev->dir = dir;
+  scev->stop = tref_ref(stop);
+  scev->step = tref_ref(step);
+  rec_for_check(J, t, dir, stop, step, init);
+  scev->start = tref_ref(find_kinit(J, fori, ra+FORL_IDX, IRT_INT));
+  tc = (LJ_DUALNUM &&
+	!(scev->start && irref_isk(scev->stop) && irref_isk(scev->step) &&
+	  tvisint(&tv[FORL_IDX]) == (t == IRT_INT))) ?
+	IRSLOAD_TYPECHECK : 0;
+  if (tc) {
+    J->base[ra+FORL_STOP] = stop;
+    J->base[ra+FORL_STEP] = step;
+  }
+  if (!idx)
+    idx = fori_load(J, ra+FORL_IDX, t,
+		    IRSLOAD_INHERIT + tc + (J->scev.start << 16));
+  if (!init)
+    J->base[ra+FORL_IDX] = idx = emitir(IRT(IR_ADD, t), idx, step);
+  J->base[ra+FORL_EXT] = idx;
+  scev->idx = tref_ref(idx);
+  setmref(scev->pc, fori);
+  J->maxslot = ra+FORL_EXT+1;
+}
+
+/* Record FORL/JFORL or FORI/JFORI. */
+static LoopEvent rec_for(jit_State *J, const BCIns *fori, int isforl)
+{
+  BCReg ra = bc_a(*fori);
+  TValue *tv = &J->L->base[ra];
+  TRef *tr = &J->base[ra];
+  IROp op;
+  LoopEvent ev;
+  TRef stop;
+  IRType t;
+  if (isforl) {  /* Handle FORL/JFORL opcodes. */
+    TRef idx = tr[FORL_IDX];
+    if (mref(J->scev.pc, const BCIns) == fori && tref_ref(idx) == J->scev.idx) {
+      t = J->scev.t.irt;
+      stop = J->scev.stop;
+      idx = emitir(IRT(IR_ADD, t), idx, J->scev.step);
+      tr[FORL_EXT] = tr[FORL_IDX] = idx;
+    } else {
+      ScEvEntry scev;
+      rec_for_loop(J, fori, &scev, 0);
+      t = scev.t.irt;
+      stop = scev.stop;
+    }
+  } else {  /* Handle FORI/JFORI opcodes. */
+    BCReg i;
+    lj_meta_for(J->L, tv);
+    t = (LJ_DUALNUM || tref_isint(tr[FORL_IDX])) ? lj_opt_narrow_forl(J, tv) :
+						   IRT_NUM;
+    for (i = FORL_IDX; i <= FORL_STEP; i++) {
+      if (!tr[i]) sload(J, ra+i);
+      lj_assertJ(tref_isnumber_str(tr[i]), "bad FORI argument type");
+      if (tref_isstr(tr[i]))
+	tr[i] = emitir(IRTG(IR_STRTO, IRT_NUM), tr[i], 0);
+      if (t == IRT_INT) {
+	if (!tref_isinteger(tr[i]))
+	  tr[i] = emitir(IRTGI(IR_CONV), tr[i], IRCONV_INT_NUM|IRCONV_CHECK);
+      } else {
+	if (!tref_isnum(tr[i]))
+	  tr[i] = emitir(IRTN(IR_CONV), tr[i], IRCONV_NUM_INT);
+      }
+    }
+    tr[FORL_EXT] = tr[FORL_IDX];
+    stop = tr[FORL_STOP];
+    rec_for_check(J, t, rec_for_direction(&tv[FORL_STEP]),
+		  stop, tr[FORL_STEP], 1);
+  }
+
+  ev = rec_for_iter(&op, tv, isforl);
+  if (ev == LOOPEV_LEAVE) {
+    J->maxslot = ra+FORL_EXT+1;
+    J->pc = fori+1;
+  } else {
+    J->maxslot = ra;
+    J->pc = fori+bc_j(*fori)+1;
+  }
+  lj_snap_add(J);
+
+  emitir(IRTG(op, t), tr[FORL_IDX], stop);
+
+  if (ev == LOOPEV_LEAVE) {
+    J->maxslot = ra;
+    J->pc = fori+bc_j(*fori)+1;
+  } else {
+    J->maxslot = ra+FORL_EXT+1;
+    J->pc = fori+1;
+  }
+  J->needsnap = 1;
+  return ev;
+}
+
+/* Record ITERL/JITERL. */
+static LoopEvent rec_iterl(jit_State *J, const BCIns iterins)
+{
+  BCReg ra = bc_a(iterins);
+  if (!tref_isnil(getslot(J, ra))) {  /* Looping back? */
+    J->base[ra-1] = J->base[ra];  /* Copy result of ITERC to control var. */
+    J->maxslot = ra-1+bc_b(J->pc[-1]);
+    J->pc += bc_j(iterins)+1;
+    return LOOPEV_ENTER;
+  } else {
+    J->maxslot = ra-3;
+    J->pc++;
+    return LOOPEV_LEAVE;
+  }
+}
+
+/* Record LOOP/JLOOP. Now, that was easy. */
+static LoopEvent rec_loop(jit_State *J, BCReg ra, int skip)
+{
+  if (ra < J->maxslot) J->maxslot = ra;
+  J->pc += skip;
+  return LOOPEV_ENTER;
+}
+
+/* Check if a loop repeatedly failed to trace because it didn't loop back. */
+static int innerloopleft(jit_State *J, const BCIns *pc)
+{
+  ptrdiff_t i;
+  for (i = 0; i < PENALTY_SLOTS; i++)
+    if (mref(J->penalty[i].pc, const BCIns) == pc) {
+      if ((J->penalty[i].reason == LJ_TRERR_LLEAVE ||
+	   J->penalty[i].reason == LJ_TRERR_LINNER) &&
+	  J->penalty[i].val >= 2*PENALTY_MIN)
+	return 1;
+      break;
+    }
+  return 0;
+}
+
+/* Handle the case when an interpreted loop op is hit. */
+static void rec_loop_interp(jit_State *J, const BCIns *pc, LoopEvent ev)
+{
+  if (J->parent == 0 && J->exitno == 0) {
+    if (pc == J->startpc && J->framedepth + J->retdepth == 0) {
+      if (bc_op(J->cur.startins) == BC_ITERN) return;  /* See rec_itern(). */
+      /* Same loop? */
+      if (ev == LOOPEV_LEAVE)  /* Must loop back to form a root trace. */
+	lj_trace_err(J, LJ_TRERR_LLEAVE);
+      lj_record_stop(J, LJ_TRLINK_LOOP, J->cur.traceno);  /* Looping trace. */
+    } else if (ev != LOOPEV_LEAVE) {  /* Entering inner loop? */
+      /* It's usually better to abort here and wait until the inner loop
+      ** is traced. But if the inner loop repeatedly didn't loop back,
+      ** this indicates a low trip count. In this case try unrolling
+      ** an inner loop even in a root trace. But it's better to be a bit
+      ** more conservative here and only do it for very short loops.
+      */
+      if (bc_j(*pc) != -1 && !innerloopleft(J, pc))
+	lj_trace_err(J, LJ_TRERR_LINNER);  /* Root trace hit an inner loop. */
+      if ((ev != LOOPEV_ENTERLO &&
+	   J->loopref && J->cur.nins - J->loopref > 24) || --J->loopunroll < 0)
+	lj_trace_err(J, LJ_TRERR_LUNROLL);  /* Limit loop unrolling. */
+      J->loopref = J->cur.nins;
+    }
+  } else if (ev != LOOPEV_LEAVE) {  /* Side trace enters an inner loop. */
+    J->loopref = J->cur.nins;
+    if (--J->loopunroll < 0)
+      lj_trace_err(J, LJ_TRERR_LUNROLL);  /* Limit loop unrolling. */
+  }  /* Side trace continues across a loop that's left or not entered. */
+}
+
+/* Handle the case when an already compiled loop op is hit. */
+static void rec_loop_jit(jit_State *J, TraceNo lnk, LoopEvent ev)
+{
+  if (J->parent == 0 && J->exitno == 0) {  /* Root trace hit an inner loop. */
+    /* Better let the inner loop spawn a side trace back here. */
+    lj_trace_err(J, LJ_TRERR_LINNER);
+  } else if (ev != LOOPEV_LEAVE) {  /* Side trace enters a compiled loop. */
+    J->instunroll = 0;  /* Cannot continue across a compiled loop op. */
+    if (J->pc == J->startpc && J->framedepth + J->retdepth == 0)
+      lj_record_stop(J, LJ_TRLINK_LOOP, J->cur.traceno);  /* Form extra loop. */
+    else
+      lj_record_stop(J, LJ_TRLINK_ROOT, lnk);  /* Link to the loop. */
+  }  /* Side trace continues across a loop that's left or not entered. */
+}
+
+/* Record ITERN. */
+static LoopEvent rec_itern(jit_State *J, BCReg ra, BCReg rb)
+{
+#if LJ_BE
+  /* YAGNI: Disabled on big-endian due to issues with lj_vm_next,
+  ** IR_HIOP, RID_RETLO/RID_RETHI and ra_destpair.
+  */
+  UNUSED(ra); UNUSED(rb);
+  setintV(&J->errinfo, (int32_t)BC_ITERN);
+  lj_trace_err_info(J, LJ_TRERR_NYIBC);
+#else
+  RecordIndex ix;
+  /* Since ITERN is recorded at the start, we need our own loop detection. */
+  if (J->pc == J->startpc &&
+      J->framedepth + J->retdepth == 0 && J->parent == 0 && J->exitno == 0) {
+    IRRef ref = REF_FIRST + LJ_HASPROFILE;
+#ifdef LUAJIT_ENABLE_CHECKHOOK
+    ref += 3;
+#endif
+    if (J->cur.nins > ref ||
+       (LJ_HASPROFILE && J->cur.nins == ref && J->cur.ir[ref-1].o != IR_PROF)) {
+      J->instunroll = 0;  /* Cannot continue unrolling across an ITERN. */
+      lj_record_stop(J, LJ_TRLINK_LOOP, J->cur.traceno);  /* Looping trace. */
+      return LOOPEV_ENTER;
+    }
+  }
+  J->maxslot = ra;
+  lj_snap_add(J);  /* Required to make JLOOP the first ins in a side-trace. */
+  ix.tab = getslot(J, ra-2);
+  ix.key = J->base[ra-1] ? J->base[ra-1] :
+	   sloadt(J, (int32_t)(ra-1), IRT_GUARD|IRT_INT,
+		  IRSLOAD_TYPECHECK|IRSLOAD_KEYINDEX);
+  copyTV(J->L, &ix.tabv, &J->L->base[ra-2]);
+  copyTV(J->L, &ix.keyv, &J->L->base[ra-1]);
+  ix.idxchain = (rb < 3);  /* Omit value type check, if unused. */
+  ix.mobj = 1;  /* We need the next index, too. */
+  J->maxslot = ra + lj_record_next(J, &ix);
+  J->needsnap = 1;
+  if (!tref_isnil(ix.key)) {  /* Looping back? */
+    J->base[ra-1] = ix.mobj | TREF_KEYINDEX;  /* Control var has next index. */
+    J->base[ra] = ix.key;
+    J->base[ra+1] = ix.val;
+    J->pc += bc_j(J->pc[1])+2;
+    return LOOPEV_ENTER;
+  } else {
+    J->maxslot = ra-3;
+    J->pc += 2;
+    return LOOPEV_LEAVE;
+  }
+#endif
+}
+
+/* Record ISNEXT. */
+static void rec_isnext(jit_State *J, BCReg ra)
+{
+  cTValue *b = &J->L->base[ra-3];
+  if (tvisfunc(b) && funcV(b)->c.ffid == FF_next &&
+      tvistab(b+1) && tvisnil(b+2)) {
+    /* These checks are folded away for a compiled pairs(). */
+    TRef func = getslot(J, ra-3);
+    TRef trid = emitir(IRT(IR_FLOAD, IRT_U8), func, IRFL_FUNC_FFID);
+    emitir(IRTGI(IR_EQ), trid, lj_ir_kint(J, FF_next));
+    (void)getslot(J, ra-2); /* Type check for table. */
+    (void)getslot(J, ra-1); /* Type check for nil key. */
+    J->base[ra-1] = lj_ir_kint(J, 0) | TREF_KEYINDEX;
+    J->maxslot = ra;
+  } else {  /* Abort trace. Interpreter will despecialize bytecode. */
+    lj_trace_err(J, LJ_TRERR_RECERR);
+  }
+}
+
+/* -- Record profiler hook checks ----------------------------------------- */
+
+#if LJ_HASPROFILE
+
+/* Need to insert profiler hook check? */
+static int rec_profile_need(jit_State *J, GCproto *pt, const BCIns *pc)
+{
+  GCproto *ppt;
+  lj_assertJ(J->prof_mode == 'f' || J->prof_mode == 'l',
+	     "bad profiler mode %c", J->prof_mode);
+  if (!pt)
+    return 0;
+  ppt = J->prev_pt;
+  J->prev_pt = pt;
+  if (pt != ppt && ppt) {
+    J->prev_line = -1;
+    return 1;
+  }
+  if (J->prof_mode == 'l') {
+    BCLine line = lj_debug_line(pt, proto_bcpos(pt, pc));
+    BCLine pline = J->prev_line;
+    J->prev_line = line;
+    if (pline != line)
+      return 1;
+  }
+  return 0;
+}
+
+static void rec_profile_ins(jit_State *J, const BCIns *pc)
+{
+  if (J->prof_mode && rec_profile_need(J, J->pt, pc)) {
+    emitir(IRTG(IR_PROF, IRT_NIL), 0, 0);
+    lj_snap_add(J);
+  }
+}
+
+static void rec_profile_ret(jit_State *J)
+{
+  if (J->prof_mode == 'f') {
+    emitir(IRTG(IR_PROF, IRT_NIL), 0, 0);
+    J->prev_pt = NULL;
+    lj_snap_add(J);
+  }
+}
+
+#endif
+
+/* -- Record calls and returns -------------------------------------------- */
+
+/* Specialize to the runtime value of the called function or its prototype. */
+static TRef rec_call_specialize(jit_State *J, GCfunc *fn, TRef tr)
+{
+  TRef kfunc;
+  if (isluafunc(fn)) {
+    GCproto *pt = funcproto(fn);
+    /* Too many closures created? Probably not a monomorphic function. */
+    if (pt->flags >= PROTO_CLC_POLY) {  /* Specialize to prototype instead. */
+      TRef trpt = emitir(IRT(IR_FLOAD, IRT_PGC), tr, IRFL_FUNC_PC);
+      emitir(IRTG(IR_EQ, IRT_PGC), trpt, lj_ir_kptr(J, proto_bc(pt)));
+      (void)lj_ir_kgc(J, obj2gco(pt), IRT_PROTO);  /* Prevent GC of proto. */
+      return tr;
+    }
+  } else {
+    /* Don't specialize to non-monomorphic builtins. */
+    switch (fn->c.ffid) {
+    case FF_coroutine_wrap_aux:
+    case FF_string_gmatch_aux:
+      /* NYI: io_file_iter doesn't have an ffid, yet. */
+      {  /* Specialize to the ffid. */
+	TRef trid = emitir(IRT(IR_FLOAD, IRT_U8), tr, IRFL_FUNC_FFID);
+	emitir(IRTGI(IR_EQ), trid, lj_ir_kint(J, fn->c.ffid));
+      }
+      return tr;
+    default:
+      /* NYI: don't specialize to non-monomorphic C functions. */
+      break;
+    }
+  }
+  /* Otherwise specialize to the function (closure) value itself. */
+  kfunc = lj_ir_kfunc(J, fn);
+  emitir(IRTG(IR_EQ, IRT_FUNC), tr, kfunc);
+  return kfunc;
+}
+
+/* Record call setup. */
+static void rec_call_setup(jit_State *J, BCReg func, ptrdiff_t nargs)
+{
+  RecordIndex ix;
+  TValue *functv = &J->L->base[func];
+  TRef kfunc, *fbase = &J->base[func];
+  ptrdiff_t i;
+  (void)getslot(J, func); /* Ensure func has a reference. */
+  for (i = 1; i <= nargs; i++)
+    (void)getslot(J, func+LJ_FR2+i);  /* Ensure all args have a reference. */
+  if (!tref_isfunc(fbase[0])) {  /* Resolve __call metamethod. */
+    ix.tab = fbase[0];
+    copyTV(J->L, &ix.tabv, functv);
+    if (!lj_record_mm_lookup(J, &ix, MM_call) || !tref_isfunc(ix.mobj))
+      lj_trace_err(J, LJ_TRERR_NOMM);
+    for (i = ++nargs; i > LJ_FR2; i--)  /* Shift arguments up. */
+      fbase[i+LJ_FR2] = fbase[i+LJ_FR2-1];
+#if LJ_FR2
+    fbase[2] = fbase[0];
+#endif
+    fbase[0] = ix.mobj;  /* Replace function. */
+    functv = &ix.mobjv;
+  }
+  kfunc = rec_call_specialize(J, funcV(functv), fbase[0]);
+#if LJ_FR2
+  fbase[0] = kfunc;
+  fbase[1] = TREF_FRAME;
+#else
+  fbase[0] = kfunc | TREF_FRAME;
+#endif
+  J->maxslot = (BCReg)nargs;
+}
+
+/* Record call. */
+void lj_record_call(jit_State *J, BCReg func, ptrdiff_t nargs)
+{
+  rec_call_setup(J, func, nargs);
+  /* Bump frame. */
+  J->framedepth++;
+  J->base += func+1+LJ_FR2;
+  J->baseslot += func+1+LJ_FR2;
+  if (J->baseslot + J->maxslot >= LJ_MAX_JSLOTS)
+    lj_trace_err(J, LJ_TRERR_STACKOV);
+}
+
+/* Record tail call. */
+void lj_record_tailcall(jit_State *J, BCReg func, ptrdiff_t nargs)
+{
+  rec_call_setup(J, func, nargs);
+  if (frame_isvarg(J->L->base - 1)) {
+    BCReg cbase = (BCReg)frame_delta(J->L->base - 1);
+    if (--J->framedepth < 0)
+      lj_trace_err(J, LJ_TRERR_NYIRETL);
+    J->baseslot -= (BCReg)cbase;
+    J->base -= cbase;
+    func += cbase;
+  }
+  /* Move func + args down. */
+  if (LJ_FR2 && J->baseslot == 2)
+    J->base[func+1] = TREF_FRAME;
+  memmove(&J->base[-1-LJ_FR2], &J->base[func], sizeof(TRef)*(J->maxslot+1+LJ_FR2));
+  /* Note: the new TREF_FRAME is now at J->base[-1] (even for slot #0). */
+  /* Tailcalls can form a loop, so count towards the loop unroll limit. */
+  if (++J->tailcalled > J->loopunroll)
+    lj_trace_err(J, LJ_TRERR_LUNROLL);
+}
+
+/* Check unroll limits for down-recursion. */
+static int check_downrec_unroll(jit_State *J, GCproto *pt)
+{
+  IRRef ptref;
+  for (ptref = J->chain[IR_KGC]; ptref; ptref = IR(ptref)->prev)
+    if (ir_kgc(IR(ptref)) == obj2gco(pt)) {
+      int count = 0;
+      IRRef ref;
+      for (ref = J->chain[IR_RETF]; ref; ref = IR(ref)->prev)
+	if (IR(ref)->op1 == ptref)
+	  count++;
+      if (count) {
+	if (J->pc == J->startpc) {
+	  if (count + J->tailcalled > J->param[JIT_P_recunroll])
+	    return 1;
+	} else {
+	  lj_trace_err(J, LJ_TRERR_DOWNREC);
+	}
+      }
+    }
+  return 0;
+}
+
+static TRef rec_cat(jit_State *J, BCReg baseslot, BCReg topslot);
+
+/* Record return. */
+void lj_record_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
+{
+  TValue *frame = J->L->base - 1;
+  ptrdiff_t i;
+  for (i = 0; i < gotresults; i++)
+    (void)getslot(J, rbase+i);  /* Ensure all results have a reference. */
+  while (frame_ispcall(frame)) {  /* Immediately resolve pcall() returns. */
+    BCReg cbase = (BCReg)frame_delta(frame);
+    if (--J->framedepth <= 0)
+      lj_trace_err(J, LJ_TRERR_NYIRETL);
+    lj_assertJ(J->baseslot > 1+LJ_FR2, "bad baseslot for return");
+    gotresults++;
+    rbase += cbase;
+    J->baseslot -= (BCReg)cbase;
+    J->base -= cbase;
+    J->base[--rbase] = TREF_TRUE;  /* Prepend true to results. */
+    frame = frame_prevd(frame);
+    J->needsnap = 1;  /* Stop catching on-trace errors. */
+  }
+  /* Return to lower frame via interpreter for unhandled cases. */
+  if (J->framedepth == 0 && J->pt && bc_isret(bc_op(*J->pc)) &&
+       (!frame_islua(frame) ||
+	(J->parent == 0 && J->exitno == 0 &&
+	 !bc_isret(bc_op(J->cur.startins))))) {
+    /* NYI: specialize to frame type and return directly, not via RET*. */
+    for (i = 0; i < (ptrdiff_t)rbase; i++)
+      J->base[i] = 0;  /* Purge dead slots. */
+    J->maxslot = rbase + (BCReg)gotresults;
+    lj_record_stop(J, LJ_TRLINK_RETURN, 0);  /* Return to interpreter. */
+    return;
+  }
+  if (frame_isvarg(frame)) {
+    BCReg cbase = (BCReg)frame_delta(frame);
+    if (--J->framedepth < 0)  /* NYI: return of vararg func to lower frame. */
+      lj_trace_err(J, LJ_TRERR_NYIRETL);
+    lj_assertJ(J->baseslot > 1+LJ_FR2, "bad baseslot for return");
+    rbase += cbase;
+    J->baseslot -= (BCReg)cbase;
+    J->base -= cbase;
+    frame = frame_prevd(frame);
+  }
+  if (frame_islua(frame)) {  /* Return to Lua frame. */
+    BCIns callins = *(frame_pc(frame)-1);
+    ptrdiff_t nresults = bc_b(callins) ? (ptrdiff_t)bc_b(callins)-1 :gotresults;
+    BCReg cbase = bc_a(callins);
+    GCproto *pt = funcproto(frame_func(frame - (cbase+1+LJ_FR2)));
+    if ((pt->flags & PROTO_NOJIT))
+      lj_trace_err(J, LJ_TRERR_CJITOFF);
+    if (J->framedepth == 0 && J->pt && frame == J->L->base - 1) {
+      if (check_downrec_unroll(J, pt)) {
+	J->maxslot = (BCReg)(rbase + gotresults);
+	lj_snap_purge(J);
+	lj_record_stop(J, LJ_TRLINK_DOWNREC, J->cur.traceno);  /* Down-rec. */
+	return;
+      }
+      lj_snap_add(J);
+    }
+    for (i = 0; i < nresults; i++)  /* Adjust results. */
+      J->base[i-1-LJ_FR2] = i < gotresults ? J->base[rbase+i] : TREF_NIL;
+    J->maxslot = cbase+(BCReg)nresults;
+    if (J->framedepth > 0) {  /* Return to a frame that is part of the trace. */
+      J->framedepth--;
+      lj_assertJ(J->baseslot > cbase+1+LJ_FR2, "bad baseslot for return");
+      J->baseslot -= cbase+1+LJ_FR2;
+      J->base -= cbase+1+LJ_FR2;
+    } else if (J->parent == 0 && J->exitno == 0 &&
+	       !bc_isret(bc_op(J->cur.startins))) {
+      /* Return to lower frame would leave the loop in a root trace. */
+      lj_trace_err(J, LJ_TRERR_LLEAVE);
+    } else if (J->needsnap) {  /* Tailcalled to ff with side-effects. */
+      lj_trace_err(J, LJ_TRERR_NYIRETL);  /* No way to insert snapshot here. */
+    } else {  /* Return to lower frame. Guard for the target we return to. */
+      TRef trpt = lj_ir_kgc(J, obj2gco(pt), IRT_PROTO);
+      TRef trpc = lj_ir_kptr(J, (void *)frame_pc(frame));
+      emitir(IRTG(IR_RETF, IRT_PGC), trpt, trpc);
+      J->retdepth++;
+      J->needsnap = 1;
+      lj_assertJ(J->baseslot == 1+LJ_FR2, "bad baseslot for return");
+      /* Shift result slots up and clear the slots of the new frame below. */
+      memmove(J->base + cbase, J->base-1-LJ_FR2, sizeof(TRef)*nresults);
+      memset(J->base-1-LJ_FR2, 0, sizeof(TRef)*(cbase+1+LJ_FR2));
+    }
+  } else if (frame_iscont(frame)) {  /* Return to continuation frame. */
+    ASMFunction cont = frame_contf(frame);
+    BCReg cbase = (BCReg)frame_delta(frame);
+    if ((J->framedepth -= 2) < 0)
+      lj_trace_err(J, LJ_TRERR_NYIRETL);
+    J->baseslot -= (BCReg)cbase;
+    J->base -= cbase;
+    J->maxslot = cbase-(2<<LJ_FR2);
+    if (cont == lj_cont_ra) {
+      /* Copy result to destination slot. */
+      BCReg dst = bc_a(*(frame_contpc(frame)-1));
+      J->base[dst] = gotresults ? J->base[cbase+rbase] : TREF_NIL;
+      if (dst >= J->maxslot) {
+	J->maxslot = dst+1;
+      }
+    } else if (cont == lj_cont_nop) {
+      /* Nothing to do here. */
+    } else if (cont == lj_cont_cat) {
+      BCReg bslot = bc_b(*(frame_contpc(frame)-1));
+      TRef tr = gotresults ? J->base[cbase+rbase] : TREF_NIL;
+      if (bslot != J->maxslot) {  /* Concatenate the remainder. */
+	TValue *b = J->L->base, save;  /* Simulate lower frame and result. */
+	/* Can't handle MM_concat + CALLT + fast func side-effects. */
+	if (J->postproc != LJ_POST_NONE)
+	  lj_trace_err(J, LJ_TRERR_NYIRETL);
+	J->base[J->maxslot] = tr;
+	copyTV(J->L, &save, b-(2<<LJ_FR2));
+	if (gotresults)
+	  copyTV(J->L, b-(2<<LJ_FR2), b+rbase);
+	else
+	  setnilV(b-(2<<LJ_FR2));
+	J->L->base = b - cbase;
+	tr = rec_cat(J, bslot, cbase-(2<<LJ_FR2));
+	b = J->L->base + cbase;  /* Undo. */
+	J->L->base = b;
+	copyTV(J->L, b-(2<<LJ_FR2), &save);
+      }
+      if (tr) {  /* Store final result. */
+	BCReg dst = bc_a(*(frame_contpc(frame)-1));
+	J->base[dst] = tr;
+	if (dst >= J->maxslot) {
+	  J->maxslot = dst+1;
+	}
+      }  /* Otherwise continue with another __concat call. */
+    } else {
+      /* Result type already specialized. */
+      lj_assertJ(cont == lj_cont_condf || cont == lj_cont_condt,
+		 "bad continuation type");
+    }
+  } else {
+    lj_trace_err(J, LJ_TRERR_NYIRETL);  /* NYI: handle return to C frame. */
+  }
+  lj_assertJ(J->baseslot >= 1+LJ_FR2, "bad baseslot for return");
+}
+
+/* -- Metamethod handling ------------------------------------------------- */
+
+/* Prepare to record call to metamethod. */
+static BCReg rec_mm_prep(jit_State *J, ASMFunction cont)
+{
+  BCReg s, top = cont == lj_cont_cat ? J->maxslot : curr_proto(J->L)->framesize;
+#if LJ_FR2
+  J->base[top] = lj_ir_k64(J, IR_KNUM, u64ptr(contptr(cont)));
+  J->base[top+1] = TREF_CONT;
+#else
+  J->base[top] = lj_ir_kptr(J, contptr(cont)) | TREF_CONT;
+#endif
+  J->framedepth++;
+  for (s = J->maxslot; s < top; s++)
+    J->base[s] = 0;  /* Clear frame gap to avoid resurrecting previous refs. */
+  return top+1+LJ_FR2;
+}
+
+/* Record metamethod lookup. */
+int lj_record_mm_lookup(jit_State *J, RecordIndex *ix, MMS mm)
+{
+  RecordIndex mix;
+  GCtab *mt;
+  if (tref_istab(ix->tab)) {
+    mt = tabref(tabV(&ix->tabv)->metatable);
+    mix.tab = emitir(IRT(IR_FLOAD, IRT_TAB), ix->tab, IRFL_TAB_META);
+  } else if (tref_isudata(ix->tab)) {
+    int udtype = udataV(&ix->tabv)->udtype;
+    mt = tabref(udataV(&ix->tabv)->metatable);
+    /* The metatables of special userdata objects are treated as immutable. */
+    if (udtype != UDTYPE_USERDATA) {
+      cTValue *mo;
+      if (LJ_HASFFI && udtype == UDTYPE_FFI_CLIB) {
+	/* Specialize to the C library namespace object. */
+	emitir(IRTG(IR_EQ, IRT_PGC), ix->tab, lj_ir_kptr(J, udataV(&ix->tabv)));
+      } else {
+	/* Specialize to the type of userdata. */
+	TRef tr = emitir(IRT(IR_FLOAD, IRT_U8), ix->tab, IRFL_UDATA_UDTYPE);
+	emitir(IRTGI(IR_EQ), tr, lj_ir_kint(J, udtype));
+      }
+  immutable_mt:
+      mo = lj_tab_getstr(mt, mmname_str(J2G(J), mm));
+      if (!mo || tvisnil(mo))
+	return 0;  /* No metamethod. */
+      /* Treat metamethod or index table as immutable, too. */
+      if (!(tvisfunc(mo) || tvistab(mo)))
+	lj_trace_err(J, LJ_TRERR_BADTYPE);
+      copyTV(J->L, &ix->mobjv, mo);
+      ix->mobj = lj_ir_kgc(J, gcV(mo), tvisfunc(mo) ? IRT_FUNC : IRT_TAB);
+      ix->mtv = mt;
+      ix->mt = TREF_NIL;  /* Dummy value for comparison semantics. */
+      return 1;  /* Got metamethod or index table. */
+    }
+    mix.tab = emitir(IRT(IR_FLOAD, IRT_TAB), ix->tab, IRFL_UDATA_META);
+  } else {
+    /* Specialize to base metatable. Must flush mcode in lua_setmetatable(). */
+    mt = tabref(basemt_obj(J2G(J), &ix->tabv));
+    if (mt == NULL) {
+      ix->mt = TREF_NIL;
+      return 0;  /* No metamethod. */
+    }
+    /* The cdata metatable is treated as immutable. */
+    if (LJ_HASFFI && tref_iscdata(ix->tab)) goto immutable_mt;
+    ix->mt = mix.tab = lj_ir_ggfload(J, IRT_TAB,
+      GG_OFS(g.gcroot[GCROOT_BASEMT+itypemap(&ix->tabv)]));
+    goto nocheck;
+  }
+  ix->mt = mt ? mix.tab : TREF_NIL;
+  emitir(IRTG(mt ? IR_NE : IR_EQ, IRT_TAB), mix.tab, lj_ir_knull(J, IRT_TAB));
+nocheck:
+  if (mt) {
+    GCstr *mmstr = mmname_str(J2G(J), mm);
+    cTValue *mo = lj_tab_getstr(mt, mmstr);
+    if (mo && !tvisnil(mo))
+      copyTV(J->L, &ix->mobjv, mo);
+    ix->mtv = mt;
+    settabV(J->L, &mix.tabv, mt);
+    setstrV(J->L, &mix.keyv, mmstr);
+    mix.key = lj_ir_kstr(J, mmstr);
+    mix.val = 0;
+    mix.idxchain = 0;
+    ix->mobj = lj_record_idx(J, &mix);
+    return !tref_isnil(ix->mobj);  /* 1 if metamethod found, 0 if not. */
+  }
+  return 0;  /* No metamethod. */
+}
+
+/* Record call to arithmetic metamethod. */
+static TRef rec_mm_arith(jit_State *J, RecordIndex *ix, MMS mm)
+{
+  /* Set up metamethod call first to save ix->tab and ix->tabv. */
+  BCReg func = rec_mm_prep(J, mm == MM_concat ? lj_cont_cat : lj_cont_ra);
+  TRef *base = J->base + func;
+  TValue *basev = J->L->base + func;
+  base[1+LJ_FR2] = ix->tab; base[2+LJ_FR2] = ix->key;
+  copyTV(J->L, basev+1+LJ_FR2, &ix->tabv);
+  copyTV(J->L, basev+2+LJ_FR2, &ix->keyv);
+  if (!lj_record_mm_lookup(J, ix, mm)) {  /* Lookup mm on 1st operand. */
+    if (mm != MM_unm) {
+      ix->tab = ix->key;
+      copyTV(J->L, &ix->tabv, &ix->keyv);
+      if (lj_record_mm_lookup(J, ix, mm))  /* Lookup mm on 2nd operand. */
+	goto ok;
+    }
+    lj_trace_err(J, LJ_TRERR_NOMM);
+  }
+ok:
+  base[0] = ix->mobj;
+#if LJ_FR2
+  base[1] = 0;
+#endif
+  copyTV(J->L, basev+0, &ix->mobjv);
+  lj_record_call(J, func, 2);
+  return 0;  /* No result yet. */
+}
+
+/* Record call to __len metamethod. */
+static TRef rec_mm_len(jit_State *J, TRef tr, TValue *tv)
+{
+  RecordIndex ix;
+  ix.tab = tr;
+  copyTV(J->L, &ix.tabv, tv);
+  if (lj_record_mm_lookup(J, &ix, MM_len)) {
+    BCReg func = rec_mm_prep(J, lj_cont_ra);
+    TRef *base = J->base + func;
+    TValue *basev = J->L->base + func;
+    base[0] = ix.mobj; copyTV(J->L, basev+0, &ix.mobjv);
+    base += LJ_FR2;
+    basev += LJ_FR2;
+    base[1] = tr; copyTV(J->L, basev+1, tv);
+#if LJ_52
+    base[2] = tr; copyTV(J->L, basev+2, tv);
+#else
+    base[2] = TREF_NIL; setnilV(basev+2);
+#endif
+    lj_record_call(J, func, 2);
+  } else {
+    if (LJ_52 && tref_istab(tr))
+      return emitir(IRTI(IR_ALEN), tr, TREF_NIL);
+    lj_trace_err(J, LJ_TRERR_NOMM);
+  }
+  return 0;  /* No result yet. */
+}
+
+/* Call a comparison metamethod. */
+static void rec_mm_callcomp(jit_State *J, RecordIndex *ix, int op)
+{
+  BCReg func = rec_mm_prep(J, (op&1) ? lj_cont_condf : lj_cont_condt);
+  TRef *base = J->base + func + LJ_FR2;
+  TValue *tv = J->L->base + func + LJ_FR2;
+  base[-LJ_FR2] = ix->mobj; base[1] = ix->val; base[2] = ix->key;
+  copyTV(J->L, tv-LJ_FR2, &ix->mobjv);
+  copyTV(J->L, tv+1, &ix->valv);
+  copyTV(J->L, tv+2, &ix->keyv);
+  lj_record_call(J, func, 2);
+}
+
+/* Record call to equality comparison metamethod (for tab and udata only). */
+static void rec_mm_equal(jit_State *J, RecordIndex *ix, int op)
+{
+  ix->tab = ix->val;
+  copyTV(J->L, &ix->tabv, &ix->valv);
+  if (lj_record_mm_lookup(J, ix, MM_eq)) {  /* Lookup mm on 1st operand. */
+    cTValue *bv;
+    TRef mo1 = ix->mobj;
+    TValue mo1v;
+    copyTV(J->L, &mo1v, &ix->mobjv);
+    /* Avoid the 2nd lookup and the objcmp if the metatables are equal. */
+    bv = &ix->keyv;
+    if (tvistab(bv) && tabref(tabV(bv)->metatable) == ix->mtv) {
+      TRef mt2 = emitir(IRT(IR_FLOAD, IRT_TAB), ix->key, IRFL_TAB_META);
+      emitir(IRTG(IR_EQ, IRT_TAB), mt2, ix->mt);
+    } else if (tvisudata(bv) && tabref(udataV(bv)->metatable) == ix->mtv) {
+      TRef mt2 = emitir(IRT(IR_FLOAD, IRT_TAB), ix->key, IRFL_UDATA_META);
+      emitir(IRTG(IR_EQ, IRT_TAB), mt2, ix->mt);
+    } else {  /* Lookup metamethod on 2nd operand and compare both. */
+      ix->tab = ix->key;
+      copyTV(J->L, &ix->tabv, bv);
+      if (!lj_record_mm_lookup(J, ix, MM_eq) ||
+	  lj_record_objcmp(J, mo1, ix->mobj, &mo1v, &ix->mobjv))
+	return;
+    }
+    rec_mm_callcomp(J, ix, op);
+  }
+}
+
+/* Record call to ordered comparison metamethods (for arbitrary objects). */
+static void rec_mm_comp(jit_State *J, RecordIndex *ix, int op)
+{
+  ix->tab = ix->val;
+  copyTV(J->L, &ix->tabv, &ix->valv);
+  while (1) {
+    MMS mm = (op & 2) ? MM_le : MM_lt;  /* Try __le + __lt or only __lt. */
+#if LJ_52
+    if (!lj_record_mm_lookup(J, ix, mm)) {  /* Lookup mm on 1st operand. */
+      ix->tab = ix->key;
+      copyTV(J->L, &ix->tabv, &ix->keyv);
+      if (!lj_record_mm_lookup(J, ix, mm))  /* Lookup mm on 2nd operand. */
+	goto nomatch;
+    }
+    rec_mm_callcomp(J, ix, op);
+    return;
+#else
+    if (lj_record_mm_lookup(J, ix, mm)) {  /* Lookup mm on 1st operand. */
+      cTValue *bv;
+      TRef mo1 = ix->mobj;
+      TValue mo1v;
+      copyTV(J->L, &mo1v, &ix->mobjv);
+      /* Avoid the 2nd lookup and the objcmp if the metatables are equal. */
+      bv = &ix->keyv;
+      if (tvistab(bv) && tabref(tabV(bv)->metatable) == ix->mtv) {
+	TRef mt2 = emitir(IRT(IR_FLOAD, IRT_TAB), ix->key, IRFL_TAB_META);
+	emitir(IRTG(IR_EQ, IRT_TAB), mt2, ix->mt);
+      } else if (tvisudata(bv) && tabref(udataV(bv)->metatable) == ix->mtv) {
+	TRef mt2 = emitir(IRT(IR_FLOAD, IRT_TAB), ix->key, IRFL_UDATA_META);
+	emitir(IRTG(IR_EQ, IRT_TAB), mt2, ix->mt);
+      } else {  /* Lookup metamethod on 2nd operand and compare both. */
+	ix->tab = ix->key;
+	copyTV(J->L, &ix->tabv, bv);
+	if (!lj_record_mm_lookup(J, ix, mm) ||
+	    lj_record_objcmp(J, mo1, ix->mobj, &mo1v, &ix->mobjv))
+	  goto nomatch;
+      }
+      rec_mm_callcomp(J, ix, op);
+      return;
+    }
+#endif
+  nomatch:
+    /* Lookup failed. Retry with  __lt and swapped operands. */
+    if (!(op & 2)) break;  /* Already at __lt. Interpreter will throw. */
+    ix->tab = ix->key; ix->key = ix->val; ix->val = ix->tab;
+    copyTV(J->L, &ix->tabv, &ix->keyv);
+    copyTV(J->L, &ix->keyv, &ix->valv);
+    copyTV(J->L, &ix->valv, &ix->tabv);
+    op ^= 3;
+  }
+}
+
+#if LJ_HASFFI
+/* Setup call to cdata comparison metamethod. */
+static void rec_mm_comp_cdata(jit_State *J, RecordIndex *ix, int op, MMS mm)
+{
+  lj_snap_add(J);
+  if (tref_iscdata(ix->val)) {
+    ix->tab = ix->val;
+    copyTV(J->L, &ix->tabv, &ix->valv);
+  } else {
+    lj_assertJ(tref_iscdata(ix->key), "cdata expected");
+    ix->tab = ix->key;
+    copyTV(J->L, &ix->tabv, &ix->keyv);
+  }
+  lj_record_mm_lookup(J, ix, mm);
+  rec_mm_callcomp(J, ix, op);
+}
+#endif
+
+/* -- Indexed access ------------------------------------------------------ */
+
+#ifdef LUAJIT_ENABLE_TABLE_BUMP
+/* Bump table allocations in bytecode when they grow during recording. */
+static void rec_idx_bump(jit_State *J, RecordIndex *ix)
+{
+  RBCHashEntry *rbc = &J->rbchash[(ix->tab & (RBCHASH_SLOTS-1))];
+  if (tref_ref(ix->tab) == rbc->ref) {
+    const BCIns *pc = mref(rbc->pc, const BCIns);
+    GCtab *tb = tabV(&ix->tabv);
+    uint32_t nhbits;
+    IRIns *ir;
+    if (!tvisnil(&ix->keyv))
+      (void)lj_tab_set(J->L, tb, &ix->keyv);  /* Grow table right now. */
+    nhbits = tb->hmask > 0 ? lj_fls(tb->hmask)+1 : 0;
+    ir = IR(tref_ref(ix->tab));
+    if (ir->o == IR_TNEW) {
+      uint32_t ah = bc_d(*pc);
+      uint32_t asize = ah & 0x7ff, hbits = ah >> 11;
+      if (nhbits > hbits) hbits = nhbits;
+      if (tb->asize > asize) {
+	asize = tb->asize <= 0x7ff ? tb->asize : 0x7ff;
+      }
+      if ((asize | (hbits<<11)) != ah) {  /* Has the size changed? */
+	/* Patch bytecode, but continue recording (for more patching). */
+	setbc_d(pc, (asize | (hbits<<11)));
+	/* Patching TNEW operands is only safe if the trace is aborted. */
+	ir->op1 = asize; ir->op2 = hbits;
+	J->retryrec = 1;  /* Abort the trace at the end of recording. */
+      }
+    } else if (ir->o == IR_TDUP) {
+      GCtab *tpl = gco2tab(proto_kgc(&gcref(rbc->pt)->pt, ~(ptrdiff_t)bc_d(*pc)));
+      /* Grow template table, but preserve keys with nil values. */
+      if ((tb->asize > tpl->asize && (1u << nhbits)-1 == tpl->hmask) ||
+	  (tb->asize == tpl->asize && (1u << nhbits)-1 > tpl->hmask)) {
+	Node *node = noderef(tpl->node);
+	uint32_t i, hmask = tpl->hmask, asize;
+	TValue *array;
+	for (i = 0; i <= hmask; i++) {
+	  if (!tvisnil(&node[i].key) && tvisnil(&node[i].val))
+	    settabV(J->L, &node[i].val, tpl);
+	}
+	if (!tvisnil(&ix->keyv) && tref_isk(ix->key)) {
+	  TValue *o = lj_tab_set(J->L, tpl, &ix->keyv);
+	  if (tvisnil(o)) settabV(J->L, o, tpl);
+	}
+	lj_tab_resize(J->L, tpl, tb->asize, nhbits);
+	node = noderef(tpl->node);
+	hmask = tpl->hmask;
+	for (i = 0; i <= hmask; i++) {
+	  /* This is safe, since template tables only hold immutable values. */
+	  if (tvistab(&node[i].val))
+	    setnilV(&node[i].val);
+	}
+	/* The shape of the table may have changed. Clean up array part, too. */
+	asize = tpl->asize;
+	array = tvref(tpl->array);
+	for (i = 0; i < asize; i++) {
+	  if (tvistab(&array[i]))
+	    setnilV(&array[i]);
+	}
+	J->retryrec = 1;  /* Abort the trace at the end of recording. */
+      }
+    }
+  }
+}
+#endif
+
+/* Record bounds-check. */
+static void rec_idx_abc(jit_State *J, TRef asizeref, TRef ikey, uint32_t asize)
+{
+  /* Try to emit invariant bounds checks. */
+  if ((J->flags & (JIT_F_OPT_LOOP|JIT_F_OPT_ABC)) ==
+      (JIT_F_OPT_LOOP|JIT_F_OPT_ABC)) {
+    IRRef ref = tref_ref(ikey);
+    IRIns *ir = IR(ref);
+    int32_t ofs = 0;
+    IRRef ofsref = 0;
+    /* Handle constant offsets. */
+    if (ir->o == IR_ADD && irref_isk(ir->op2)) {
+      ofsref = ir->op2;
+      ofs = IR(ofsref)->i;
+      ref = ir->op1;
+      ir = IR(ref);
+    }
+    /* Got scalar evolution analysis results for this reference? */
+    if (ref == J->scev.idx) {
+      int32_t stop;
+      lj_assertJ(irt_isint(J->scev.t) && ir->o == IR_SLOAD,
+		 "only int SCEV supported");
+      stop = numberVint(&(J->L->base - J->baseslot)[ir->op1 + FORL_STOP]);
+      /* Runtime value for stop of loop is within bounds? */
+      if ((uint64_t)stop + ofs < (uint64_t)asize) {
+	/* Emit invariant bounds check for stop. */
+	emitir(IRTG(IR_ABC, IRT_P32), asizeref, ofs == 0 ? J->scev.stop :
+	       emitir(IRTI(IR_ADD), J->scev.stop, ofsref));
+	/* Emit invariant bounds check for start, if not const or negative. */
+	if (!(J->scev.dir && J->scev.start &&
+	      (int64_t)IR(J->scev.start)->i + ofs >= 0))
+	  emitir(IRTG(IR_ABC, IRT_P32), asizeref, ikey);
+	return;
+      }
+    }
+  }
+  emitir(IRTGI(IR_ABC), asizeref, ikey);  /* Emit regular bounds check. */
+}
+
+/* Record indexed key lookup. */
+static TRef rec_idx_key(jit_State *J, RecordIndex *ix, IRRef *rbref,
+			IRType1 *rbguard)
+{
+  TRef key;
+  GCtab *t = tabV(&ix->tabv);
+  ix->oldv = lj_tab_get(J->L, t, &ix->keyv);  /* Lookup previous value. */
+  *rbref = 0;
+  rbguard->irt = 0;
+
+  /* Integer keys are looked up in the array part first. */
+  key = ix->key;
+  if (tref_isnumber(key)) {
+    int32_t k = numberVint(&ix->keyv);
+    if (!tvisint(&ix->keyv) && numV(&ix->keyv) != (lua_Number)k)
+      k = LJ_MAX_ASIZE;
+    if ((MSize)k < LJ_MAX_ASIZE) {  /* Potential array key? */
+      TRef ikey = lj_opt_narrow_index(J, key);
+      TRef asizeref = emitir(IRTI(IR_FLOAD), ix->tab, IRFL_TAB_ASIZE);
+      if ((MSize)k < t->asize) {  /* Currently an array key? */
+	TRef arrayref;
+	rec_idx_abc(J, asizeref, ikey, t->asize);
+	arrayref = emitir(IRT(IR_FLOAD, IRT_PGC), ix->tab, IRFL_TAB_ARRAY);
+	return emitir(IRT(IR_AREF, IRT_PGC), arrayref, ikey);
+      } else {  /* Currently not in array (may be an array extension)? */
+	emitir(IRTGI(IR_ULE), asizeref, ikey);  /* Inv. bounds check. */
+	if (k == 0 && tref_isk(key))
+	  key = lj_ir_knum_zero(J);  /* Canonicalize 0 or +-0.0 to +0.0. */
+	/* And continue with the hash lookup. */
+      }
+    } else if (!tref_isk(key)) {
+      /* We can rule out const numbers which failed the integerness test
+      ** above. But all other numbers are potential array keys.
+      */
+      if (t->asize == 0) {  /* True sparse tables have an empty array part. */
+	/* Guard that the array part stays empty. */
+	TRef tmp = emitir(IRTI(IR_FLOAD), ix->tab, IRFL_TAB_ASIZE);
+	emitir(IRTGI(IR_EQ), tmp, lj_ir_kint(J, 0));
+      } else {
+	lj_trace_err(J, LJ_TRERR_NYITMIX);
+      }
+    }
+  }
+
+  /* Otherwise the key is located in the hash part. */
+  if (t->hmask == 0) {  /* Shortcut for empty hash part. */
+    /* Guard that the hash part stays empty. */
+    TRef tmp = emitir(IRTI(IR_FLOAD), ix->tab, IRFL_TAB_HMASK);
+    emitir(IRTGI(IR_EQ), tmp, lj_ir_kint(J, 0));
+    return lj_ir_kkptr(J, niltvg(J2G(J)));
+  }
+  if (tref_isinteger(key))  /* Hash keys are based on numbers, not ints. */
+    key = emitir(IRTN(IR_CONV), key, IRCONV_NUM_INT);
+  if (tref_isk(key)) {
+    /* Optimize lookup of constant hash keys. */
+    GCSize hslot = (GCSize)((char *)ix->oldv-(char *)&noderef(t->node)[0].val);
+    if (hslot <= t->hmask*(GCSize)sizeof(Node) &&
+	hslot <= 65535*(GCSize)sizeof(Node)) {
+      TRef node, kslot, hm;
+      *rbref = J->cur.nins;  /* Mark possible rollback point. */
+      *rbguard = J->guardemit;
+      hm = emitir(IRTI(IR_FLOAD), ix->tab, IRFL_TAB_HMASK);
+      emitir(IRTGI(IR_EQ), hm, lj_ir_kint(J, (int32_t)t->hmask));
+      node = emitir(IRT(IR_FLOAD, IRT_PGC), ix->tab, IRFL_TAB_NODE);
+      kslot = lj_ir_kslot(J, key, (IRRef)(hslot / sizeof(Node)));
+      return emitir(IRTG(IR_HREFK, IRT_PGC), node, kslot);
+    }
+  }
+  /* Fall back to a regular hash lookup. */
+  return emitir(IRT(IR_HREF, IRT_PGC), ix->tab, key);
+}
+
+/* Determine whether a key is NOT one of the fast metamethod names. */
+static int nommstr(jit_State *J, TRef key)
+{
+  if (tref_isstr(key)) {
+    if (tref_isk(key)) {
+      GCstr *str = ir_kstr(IR(tref_ref(key)));
+      uint32_t mm;
+      for (mm = 0; mm <= MM_FAST; mm++)
+	if (mmname_str(J2G(J), mm) == str)
+	  return 0;  /* MUST be one the fast metamethod names. */
+    } else {
+      return 0;  /* Variable string key MAY be a metamethod name. */
+    }
+  }
+  return 1;  /* CANNOT be a metamethod name. */
+}
+
+/* Record indexed load/store. */
+TRef lj_record_idx(jit_State *J, RecordIndex *ix)
+{
+  TRef xref;
+  IROp xrefop, loadop;
+  IRRef rbref;
+  IRType1 rbguard;
+  cTValue *oldv;
+
+  while (!tref_istab(ix->tab)) { /* Handle non-table lookup. */
+    /* Never call raw lj_record_idx() on non-table. */
+    lj_assertJ(ix->idxchain != 0, "bad usage");
+    if (!lj_record_mm_lookup(J, ix, ix->val ? MM_newindex : MM_index))
+      lj_trace_err(J, LJ_TRERR_NOMM);
+  handlemm:
+    if (tref_isfunc(ix->mobj)) {  /* Handle metamethod call. */
+      BCReg func = rec_mm_prep(J, ix->val ? lj_cont_nop : lj_cont_ra);
+      TRef *base = J->base + func + LJ_FR2;
+      TValue *tv = J->L->base + func + LJ_FR2;
+      base[-LJ_FR2] = ix->mobj; base[1] = ix->tab; base[2] = ix->key;
+      setfuncV(J->L, tv-LJ_FR2, funcV(&ix->mobjv));
+      copyTV(J->L, tv+1, &ix->tabv);
+      copyTV(J->L, tv+2, &ix->keyv);
+      if (ix->val) {
+	base[3] = ix->val;
+	copyTV(J->L, tv+3, &ix->valv);
+	lj_record_call(J, func, 3);  /* mobj(tab, key, val) */
+	return 0;
+      } else {
+	lj_record_call(J, func, 2);  /* res = mobj(tab, key) */
+	return 0;  /* No result yet. */
+      }
+    }
+#if LJ_HASBUFFER
+    /* The index table of buffer objects is treated as immutable. */
+    if (ix->mt == TREF_NIL && !ix->val &&
+	tref_isudata(ix->tab) && udataV(&ix->tabv)->udtype == UDTYPE_BUFFER &&
+	tref_istab(ix->mobj) && tref_isstr(ix->key) && tref_isk(ix->key)) {
+      cTValue *val = lj_tab_getstr(tabV(&ix->mobjv), strV(&ix->keyv));
+      TRef tr = lj_record_constify(J, val);
+      if (tr) return tr;  /* Specialize to the value, i.e. a method. */
+    }
+#endif
+    /* Otherwise retry lookup with metaobject. */
+    ix->tab = ix->mobj;
+    copyTV(J->L, &ix->tabv, &ix->mobjv);
+    if (--ix->idxchain == 0)
+      lj_trace_err(J, LJ_TRERR_IDXLOOP);
+  }
+
+  /* First catch nil and NaN keys for tables. */
+  if (tvisnil(&ix->keyv) || (tvisnum(&ix->keyv) && tvisnan(&ix->keyv))) {
+    if (ix->val)  /* Better fail early. */
+      lj_trace_err(J, LJ_TRERR_STORENN);
+    if (tref_isk(ix->key)) {
+      if (ix->idxchain && lj_record_mm_lookup(J, ix, MM_index))
+	goto handlemm;
+      return TREF_NIL;
+    }
+  }
+
+  /* Record the key lookup. */
+  xref = rec_idx_key(J, ix, &rbref, &rbguard);
+  xrefop = IR(tref_ref(xref))->o;
+  loadop = xrefop == IR_AREF ? IR_ALOAD : IR_HLOAD;
+  /* The lj_meta_tset() inconsistency is gone, but better play safe. */
+  oldv = xrefop == IR_KKPTR ? (cTValue *)ir_kptr(IR(tref_ref(xref))) : ix->oldv;
+
+  if (ix->val == 0) {  /* Indexed load */
+    IRType t = itype2irt(oldv);
+    TRef res;
+    if (oldv == niltvg(J2G(J))) {
+      emitir(IRTG(IR_EQ, IRT_PGC), xref, lj_ir_kkptr(J, niltvg(J2G(J))));
+      res = TREF_NIL;
+    } else {
+      res = emitir(IRTG(loadop, t), xref, 0);
+    }
+    if (tref_ref(res) < rbref) {  /* HREFK + load forwarded? */
+      lj_ir_rollback(J, rbref);  /* Rollback to eliminate hmask guard. */
+      J->guardemit = rbguard;
+    }
+    if (t == IRT_NIL && ix->idxchain && lj_record_mm_lookup(J, ix, MM_index))
+      goto handlemm;
+    if (irtype_ispri(t)) res = TREF_PRI(t);  /* Canonicalize primitives. */
+    return res;
+  } else {  /* Indexed store. */
+    GCtab *mt = tabref(tabV(&ix->tabv)->metatable);
+    int keybarrier = tref_isgcv(ix->key) && !tref_isnil(ix->val);
+    if (tref_ref(xref) < rbref) {  /* HREFK forwarded? */
+      lj_ir_rollback(J, rbref);  /* Rollback to eliminate hmask guard. */
+      J->guardemit = rbguard;
+    }
+    if (tvisnil(oldv)) {  /* Previous value was nil? */
+      /* Need to duplicate the hasmm check for the early guards. */
+      int hasmm = 0;
+      if (ix->idxchain && mt) {
+	cTValue *mo = lj_tab_getstr(mt, mmname_str(J2G(J), MM_newindex));
+	hasmm = mo && !tvisnil(mo);
+      }
+      if (hasmm)
+	emitir(IRTG(loadop, IRT_NIL), xref, 0);  /* Guard for nil value. */
+      else if (xrefop == IR_HREF)
+	emitir(IRTG(oldv == niltvg(J2G(J)) ? IR_EQ : IR_NE, IRT_PGC),
+	       xref, lj_ir_kkptr(J, niltvg(J2G(J))));
+      if (ix->idxchain && lj_record_mm_lookup(J, ix, MM_newindex)) {
+	lj_assertJ(hasmm, "inconsistent metamethod handling");
+	goto handlemm;
+      }
+      lj_assertJ(!hasmm, "inconsistent metamethod handling");
+      if (oldv == niltvg(J2G(J))) {  /* Need to insert a new key. */
+	TRef key = ix->key;
+	if (tref_isinteger(key))  /* NEWREF needs a TValue as a key. */
+	  key = emitir(IRTN(IR_CONV), key, IRCONV_NUM_INT);
+	xref = emitir(IRT(IR_NEWREF, IRT_PGC), ix->tab, key);
+	keybarrier = 0;  /* NEWREF already takes care of the key barrier. */
+#ifdef LUAJIT_ENABLE_TABLE_BUMP
+	if ((J->flags & JIT_F_OPT_SINK))  /* Avoid a separate flag. */
+	  rec_idx_bump(J, ix);
+#endif
+      }
+    } else if (!lj_opt_fwd_wasnonnil(J, loadop, tref_ref(xref))) {
+      /* Cannot derive that the previous value was non-nil, must do checks. */
+      if (xrefop == IR_HREF)  /* Guard against store to niltv. */
+	emitir(IRTG(IR_NE, IRT_PGC), xref, lj_ir_kkptr(J, niltvg(J2G(J))));
+      if (ix->idxchain) {  /* Metamethod lookup required? */
+	/* A check for NULL metatable is cheaper (hoistable) than a load. */
+	if (!mt) {
+	  TRef mtref = emitir(IRT(IR_FLOAD, IRT_TAB), ix->tab, IRFL_TAB_META);
+	  emitir(IRTG(IR_EQ, IRT_TAB), mtref, lj_ir_knull(J, IRT_TAB));
+	} else {
+	  IRType t = itype2irt(oldv);
+	  emitir(IRTG(loadop, t), xref, 0);  /* Guard for non-nil value. */
+	}
+      }
+    } else {
+      keybarrier = 0;  /* Previous non-nil value kept the key alive. */
+    }
+    /* Convert int to number before storing. */
+    if (!LJ_DUALNUM && tref_isinteger(ix->val))
+      ix->val = emitir(IRTN(IR_CONV), ix->val, IRCONV_NUM_INT);
+    emitir(IRT(loadop+IRDELTA_L2S, tref_type(ix->val)), xref, ix->val);
+    if (keybarrier || tref_isgcv(ix->val))
+      emitir(IRT(IR_TBAR, IRT_NIL), ix->tab, 0);
+    /* Invalidate neg. metamethod cache for stores with certain string keys. */
+    if (!nommstr(J, ix->key)) {
+      TRef fref = emitir(IRT(IR_FREF, IRT_PGC), ix->tab, IRFL_TAB_NOMM);
+      emitir(IRT(IR_FSTORE, IRT_U8), fref, lj_ir_kint(J, 0));
+    }
+    J->needsnap = 1;
+    return 0;
+  }
+}
+
+/* Determine result type of table traversal. */
+static IRType rec_next_types(GCtab *t, uint32_t idx)
+{
+  for (; idx < t->asize; idx++) {
+    cTValue *a = arrayslot(t, idx);
+    if (LJ_LIKELY(!tvisnil(a)))
+      return (LJ_DUALNUM ? IRT_INT : IRT_NUM) + (itype2irt(a) << 8);
+  }
+  idx -= t->asize;
+  for (; idx <= t->hmask; idx++) {
+    Node *n = &noderef(t->node)[idx];
+    if (!tvisnil(&n->val))
+      return itype2irt(&n->key) + (itype2irt(&n->val) << 8);
+  }
+  return IRT_NIL + (IRT_NIL << 8);
+}
+
+/* Record a table traversal step aka next(). */
+int lj_record_next(jit_State *J, RecordIndex *ix)
+{
+  IRType t, tkey, tval;
+  TRef trvk;
+  t = rec_next_types(tabV(&ix->tabv), ix->keyv.u32.lo);
+  tkey = (t & 0xff); tval = (t >> 8);
+  trvk = lj_ir_call(J, IRCALL_lj_vm_next, ix->tab, ix->key);
+  if (ix->mobj || tkey == IRT_NIL) {
+    TRef idx = emitir(IRTI(IR_HIOP), trvk, trvk);
+    /* Always check for invalid key from next() for nil result. */
+    if (!ix->mobj) emitir(IRTGI(IR_NE), idx, lj_ir_kint(J, -1));
+    ix->mobj = idx;
+  }
+  ix->key = lj_record_vload(J, trvk, 1, tkey);
+  if (tkey == IRT_NIL || ix->idxchain) {  /* Omit value type check. */
+    ix->val = TREF_NIL;
+    return 1;
+  } else {  /* Need value. */
+    ix->val = lj_record_vload(J, trvk, 0, tval);
+    return 2;
+  }
+}
+
+static void rec_tsetm(jit_State *J, BCReg ra, BCReg rn, int32_t i)
+{
+  RecordIndex ix;
+  cTValue *basev = J->L->base;
+  GCtab *t = tabV(&basev[ra-1]);
+  settabV(J->L, &ix.tabv, t);
+  ix.tab = getslot(J, ra-1);
+  ix.idxchain = 0;
+#ifdef LUAJIT_ENABLE_TABLE_BUMP
+  if ((J->flags & JIT_F_OPT_SINK)) {
+    if (t->asize < i+rn-ra)
+      lj_tab_reasize(J->L, t, i+rn-ra);
+    setnilV(&ix.keyv);
+    rec_idx_bump(J, &ix);
+  }
+#endif
+  for (; ra < rn; i++, ra++) {
+    setintV(&ix.keyv, i);
+    ix.key = lj_ir_kint(J, i);
+    copyTV(J->L, &ix.valv, &basev[ra]);
+    ix.val = getslot(J, ra);
+    lj_record_idx(J, &ix);
+  }
+}
+
+/* -- Upvalue access ------------------------------------------------------ */
+
+/* Check whether upvalue is immutable and ok to constify. */
+static int rec_upvalue_constify(jit_State *J, GCupval *uvp)
+{
+  if (uvp->immutable) {
+    cTValue *o = uvval(uvp);
+    /* Don't constify objects that may retain large amounts of memory. */
+#if LJ_HASFFI
+    if (tviscdata(o)) {
+      GCcdata *cd = cdataV(o);
+      if (!cdataisv(cd) && !(cd->marked & LJ_GC_CDATA_FIN)) {
+	CType *ct = ctype_raw(ctype_ctsG(J2G(J)), cd->ctypeid);
+	if (!ctype_hassize(ct->info) || ct->size <= 16)
+	  return 1;
+      }
+      return 0;
+    }
+#else
+    UNUSED(J);
+#endif
+    if (!(tvistab(o) || tvisudata(o) || tvisthread(o)))
+      return 1;
+  }
+  return 0;
+}
+
+/* Record upvalue load/store. */
+static TRef rec_upvalue(jit_State *J, uint32_t uv, TRef val)
+{
+  GCupval *uvp = &gcref(J->fn->l.uvptr[uv])->uv;
+  TRef fn = getcurrf(J);
+  IRRef uref;
+  int needbarrier = 0;
+  if (rec_upvalue_constify(J, uvp)) {  /* Try to constify immutable upvalue. */
+    TRef tr, kfunc;
+    lj_assertJ(val == 0, "bad usage");
+    if (!tref_isk(fn)) {  /* Late specialization of current function. */
+      if (J->pt->flags >= PROTO_CLC_POLY)
+	goto noconstify;
+      kfunc = lj_ir_kfunc(J, J->fn);
+      emitir(IRTG(IR_EQ, IRT_FUNC), fn, kfunc);
+#if LJ_FR2
+      J->base[-2] = kfunc;
+#else
+      J->base[-1] = kfunc | TREF_FRAME;
+#endif
+      fn = kfunc;
+    }
+    tr = lj_record_constify(J, uvval(uvp));
+    if (tr)
+      return tr;
+  }
+noconstify:
+  /* Note: this effectively limits LJ_MAX_UPVAL to 127. */
+  uv = (uv << 8) | (hashrot(uvp->dhash, uvp->dhash + HASH_BIAS) & 0xff);
+  if (!uvp->closed) {
+    uref = tref_ref(emitir(IRTG(IR_UREFO, IRT_PGC), fn, uv));
+    /* In current stack? */
+    if (uvval(uvp) >= tvref(J->L->stack) &&
+	uvval(uvp) < tvref(J->L->maxstack)) {
+      int32_t slot = (int32_t)(uvval(uvp) - (J->L->base - J->baseslot));
+      if (slot >= 0) {  /* Aliases an SSA slot? */
+	emitir(IRTG(IR_EQ, IRT_PGC),
+	       REF_BASE,
+	       emitir(IRT(IR_ADD, IRT_PGC), uref,
+		      lj_ir_kint(J, (slot - 1 - LJ_FR2) * -8)));
+	slot -= (int32_t)J->baseslot;  /* Note: slot number may be negative! */
+	if (val == 0) {
+	  return getslot(J, slot);
+	} else {
+	  J->base[slot] = val;
+	  if (slot >= (int32_t)J->maxslot) J->maxslot = (BCReg)(slot+1);
+	  return 0;
+	}
+      }
+    }
+    emitir(IRTG(IR_UGT, IRT_PGC),
+	   emitir(IRT(IR_SUB, IRT_PGC), uref, REF_BASE),
+	   lj_ir_kint(J, (J->baseslot + J->maxslot) * 8));
+  } else {
+    needbarrier = 1;
+    uref = tref_ref(emitir(IRTG(IR_UREFC, IRT_PGC), fn, uv));
+  }
+  if (val == 0) {  /* Upvalue load */
+    IRType t = itype2irt(uvval(uvp));
+    TRef res = emitir(IRTG(IR_ULOAD, t), uref, 0);
+    if (irtype_ispri(t)) res = TREF_PRI(t);  /* Canonicalize primitive refs. */
+    return res;
+  } else {  /* Upvalue store. */
+    /* Convert int to number before storing. */
+    if (!LJ_DUALNUM && tref_isinteger(val))
+      val = emitir(IRTN(IR_CONV), val, IRCONV_NUM_INT);
+    emitir(IRT(IR_USTORE, tref_type(val)), uref, val);
+    if (needbarrier && tref_isgcv(val))
+      emitir(IRT(IR_OBAR, IRT_NIL), uref, val);
+    J->needsnap = 1;
+    return 0;
+  }
+}
+
+/* -- Record calls to Lua functions --------------------------------------- */
+
+/* Check unroll limits for calls. */
+static void check_call_unroll(jit_State *J, TraceNo lnk)
+{
+  cTValue *frame = J->L->base - 1;
+  void *pc = mref(frame_func(frame)->l.pc, void);
+  int32_t depth = J->framedepth;
+  int32_t count = 0;
+  if ((J->pt->flags & PROTO_VARARG)) depth--;  /* Vararg frame still missing. */
+  for (; depth > 0; depth--) {  /* Count frames with same prototype. */
+    if (frame_iscont(frame)) depth--;
+    frame = frame_prev(frame);
+    if (mref(frame_func(frame)->l.pc, void) == pc)
+      count++;
+  }
+  if (J->pc == J->startpc) {
+    if (count + J->tailcalled > J->param[JIT_P_recunroll]) {
+      J->pc++;
+      if (J->framedepth + J->retdepth == 0)
+	lj_record_stop(J, LJ_TRLINK_TAILREC, J->cur.traceno);  /* Tail-rec. */
+      else
+	lj_record_stop(J, LJ_TRLINK_UPREC, J->cur.traceno);  /* Up-recursion. */
+    }
+  } else {
+    if (count > J->param[JIT_P_callunroll]) {
+      if (lnk) {  /* Possible tail- or up-recursion. */
+	lj_trace_flush(J, lnk);  /* Flush trace that only returns. */
+	/* Set a small, pseudo-random hotcount for a quick retry of JFUNC*. */
+	hotcount_set(J2GG(J), J->pc+1, lj_prng_u64(&J2G(J)->prng) & 15u);
+      }
+      lj_trace_err(J, LJ_TRERR_CUNROLL);
+    }
+  }
+}
+
+/* Record Lua function setup. */
+static void rec_func_setup(jit_State *J)
+{
+  GCproto *pt = J->pt;
+  BCReg s, numparams = pt->numparams;
+  if ((pt->flags & PROTO_NOJIT))
+    lj_trace_err(J, LJ_TRERR_CJITOFF);
+  if (J->baseslot + pt->framesize >= LJ_MAX_JSLOTS)
+    lj_trace_err(J, LJ_TRERR_STACKOV);
+  /* Fill up missing parameters with nil. */
+  for (s = J->maxslot; s < numparams; s++)
+    J->base[s] = TREF_NIL;
+  /* The remaining slots should never be read before they are written. */
+  J->maxslot = numparams;
+}
+
+/* Record Lua vararg function setup. */
+static void rec_func_vararg(jit_State *J)
+{
+  GCproto *pt = J->pt;
+  BCReg s, fixargs, vframe = J->maxslot+1+LJ_FR2;
+  lj_assertJ((pt->flags & PROTO_VARARG), "FUNCV in non-vararg function");
+  if (J->baseslot + vframe + pt->framesize >= LJ_MAX_JSLOTS)
+    lj_trace_err(J, LJ_TRERR_STACKOV);
+  J->base[vframe-1-LJ_FR2] = J->base[-1-LJ_FR2];  /* Copy function up. */
+#if LJ_FR2
+  J->base[vframe-1] = TREF_FRAME;
+#endif
+  /* Copy fixarg slots up and set their original slots to nil. */
+  fixargs = pt->numparams < J->maxslot ? pt->numparams : J->maxslot;
+  for (s = 0; s < fixargs; s++) {
+    J->base[vframe+s] = J->base[s];
+    J->base[s] = TREF_NIL;
+  }
+  J->maxslot = fixargs;
+  J->framedepth++;
+  J->base += vframe;
+  J->baseslot += vframe;
+}
+
+/* Record entry to a Lua function. */
+static void rec_func_lua(jit_State *J)
+{
+  rec_func_setup(J);
+  check_call_unroll(J, 0);
+}
+
+/* Record entry to an already compiled function. */
+static void rec_func_jit(jit_State *J, TraceNo lnk)
+{
+  GCtrace *T;
+  rec_func_setup(J);
+  T = traceref(J, lnk);
+  if (T->linktype == LJ_TRLINK_RETURN) {  /* Trace returns to interpreter? */
+    check_call_unroll(J, lnk);
+    /* Temporarily unpatch JFUNC* to continue recording across function. */
+    J->patchins = *J->pc;
+    J->patchpc = (BCIns *)J->pc;
+    *J->patchpc = T->startins;
+    return;
+  }
+  J->instunroll = 0;  /* Cannot continue across a compiled function. */
+  if (J->pc == J->startpc && J->framedepth + J->retdepth == 0)
+    lj_record_stop(J, LJ_TRLINK_TAILREC, J->cur.traceno);  /* Extra tail-rec. */
+  else
+    lj_record_stop(J, LJ_TRLINK_ROOT, lnk);  /* Link to the function. */
+}
+
+/* -- Vararg handling ----------------------------------------------------- */
+
+/* Detect y = select(x, ...) idiom. */
+static int select_detect(jit_State *J)
+{
+  BCIns ins = J->pc[1];
+  if (bc_op(ins) == BC_CALLM && bc_b(ins) == 2 && bc_c(ins) == 1) {
+    cTValue *func = &J->L->base[bc_a(ins)];
+    if (tvisfunc(func) && funcV(func)->c.ffid == FF_select) {
+      TRef kfunc = lj_ir_kfunc(J, funcV(func));
+      emitir(IRTG(IR_EQ, IRT_FUNC), getslot(J, bc_a(ins)), kfunc);
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/* Record vararg instruction. */
+static void rec_varg(jit_State *J, BCReg dst, ptrdiff_t nresults)
+{
+  int32_t numparams = J->pt->numparams;
+  ptrdiff_t nvararg = frame_delta(J->L->base-1) - numparams - 1 - LJ_FR2;
+  lj_assertJ(frame_isvarg(J->L->base-1), "VARG in non-vararg frame");
+  if (LJ_FR2 && dst > J->maxslot)
+    J->base[dst-1] = 0;  /* Prevent resurrection of unrelated slot. */
+  if (J->framedepth > 0) {  /* Simple case: varargs defined on-trace. */
+    ptrdiff_t i;
+    if (nvararg < 0) nvararg = 0;
+    if (nresults == -1) {
+      nresults = nvararg;
+      J->maxslot = dst + (BCReg)nvararg;
+    } else if (dst + nresults > J->maxslot) {
+      J->maxslot = dst + (BCReg)nresults;
+    }
+    for (i = 0; i < nresults; i++)
+      J->base[dst+i] = i < nvararg ? getslot(J, i - nvararg - 1 - LJ_FR2) : TREF_NIL;
+  } else {  /* Unknown number of varargs passed to trace. */
+    TRef fr = emitir(IRTI(IR_SLOAD), LJ_FR2, IRSLOAD_READONLY|IRSLOAD_FRAME);
+    int32_t frofs = 8*(1+LJ_FR2+numparams)+FRAME_VARG;
+    if (nresults >= 0) {  /* Known fixed number of results. */
+      ptrdiff_t i;
+      if (nvararg > 0) {
+	ptrdiff_t nload = nvararg >= nresults ? nresults : nvararg;
+	TRef vbase;
+	if (nvararg >= nresults)
+	  emitir(IRTGI(IR_GE), fr, lj_ir_kint(J, frofs+8*(int32_t)nresults));
+	else
+	  emitir(IRTGI(IR_EQ), fr,
+		 lj_ir_kint(J, (int32_t)frame_ftsz(J->L->base-1)));
+	vbase = emitir(IRT(IR_SUB, IRT_IGC), REF_BASE, fr);
+	vbase = emitir(IRT(IR_ADD, IRT_PGC), vbase, lj_ir_kint(J, frofs-8*(1+LJ_FR2)));
+	for (i = 0; i < nload; i++) {
+	  IRType t = itype2irt(&J->L->base[i-1-LJ_FR2-nvararg]);
+	  J->base[dst+i] = lj_record_vload(J, vbase, (MSize)i, t);
+	}
+      } else {
+	emitir(IRTGI(IR_LE), fr, lj_ir_kint(J, frofs));
+	nvararg = 0;
+      }
+      for (i = nvararg; i < nresults; i++)
+	J->base[dst+i] = TREF_NIL;
+      if (dst + (BCReg)nresults > J->maxslot)
+	J->maxslot = dst + (BCReg)nresults;
+    } else if (select_detect(J)) {  /* y = select(x, ...) */
+      TRef tridx = J->base[dst-1];
+      TRef tr = TREF_NIL;
+      ptrdiff_t idx = lj_ffrecord_select_mode(J, tridx, &J->L->base[dst-1]);
+      if (idx < 0) goto nyivarg;
+      if (idx != 0 && !tref_isinteger(tridx))
+	tridx = emitir(IRTGI(IR_CONV), tridx, IRCONV_INT_NUM|IRCONV_INDEX);
+      if (idx != 0 && tref_isk(tridx)) {
+	emitir(IRTGI(idx <= nvararg ? IR_GE : IR_LT),
+	       fr, lj_ir_kint(J, frofs+8*(int32_t)idx));
+	frofs -= 8;  /* Bias for 1-based index. */
+      } else if (idx <= nvararg) {  /* Compute size. */
+	TRef tmp = emitir(IRTI(IR_ADD), fr, lj_ir_kint(J, -frofs));
+	if (numparams)
+	  emitir(IRTGI(IR_GE), tmp, lj_ir_kint(J, 0));
+	tr = emitir(IRTI(IR_BSHR), tmp, lj_ir_kint(J, 3));
+	if (idx != 0) {
+	  tridx = emitir(IRTI(IR_ADD), tridx, lj_ir_kint(J, -1));
+	  rec_idx_abc(J, tr, tridx, (uint32_t)nvararg);
+	}
+      } else {
+	TRef tmp = lj_ir_kint(J, frofs);
+	if (idx != 0) {
+	  TRef tmp2 = emitir(IRTI(IR_BSHL), tridx, lj_ir_kint(J, 3));
+	  tmp = emitir(IRTI(IR_ADD), tmp2, tmp);
+	} else {
+	  tr = lj_ir_kint(J, 0);
+	}
+	emitir(IRTGI(IR_LT), fr, tmp);
+      }
+      if (idx != 0 && idx <= nvararg) {
+	IRType t;
+	TRef aref, vbase = emitir(IRT(IR_SUB, IRT_IGC), REF_BASE, fr);
+	vbase = emitir(IRT(IR_ADD, IRT_PGC), vbase,
+		       lj_ir_kint(J, frofs-(8<<LJ_FR2)));
+	t = itype2irt(&J->L->base[idx-2-LJ_FR2-nvararg]);
+	aref = emitir(IRT(IR_AREF, IRT_PGC), vbase, tridx);
+	tr = lj_record_vload(J, aref, 0, t);
+      }
+      J->base[dst-2-LJ_FR2] = tr;
+      J->maxslot = dst-1-LJ_FR2;
+      J->bcskip = 2;  /* Skip CALLM + select. */
+    } else {
+    nyivarg:
+      setintV(&J->errinfo, BC_VARG);
+      lj_trace_err_info(J, LJ_TRERR_NYIBC);
+    }
+  }
+  if (J->baseslot + J->maxslot >= LJ_MAX_JSLOTS)
+    lj_trace_err(J, LJ_TRERR_STACKOV);
+}
+
+/* -- Record allocations -------------------------------------------------- */
+
+static TRef rec_tnew(jit_State *J, uint32_t ah)
+{
+  uint32_t asize = ah & 0x7ff;
+  uint32_t hbits = ah >> 11;
+  TRef tr;
+  if (asize == 0x7ff) asize = 0x801;
+  tr = emitir(IRTG(IR_TNEW, IRT_TAB), asize, hbits);
+#ifdef LUAJIT_ENABLE_TABLE_BUMP
+  J->rbchash[(tr & (RBCHASH_SLOTS-1))].ref = tref_ref(tr);
+  setmref(J->rbchash[(tr & (RBCHASH_SLOTS-1))].pc, J->pc);
+  setgcref(J->rbchash[(tr & (RBCHASH_SLOTS-1))].pt, obj2gco(J->pt));
+#endif
+  return tr;
+}
+
+/* -- Concatenation ------------------------------------------------------- */
+
+static TRef rec_cat(jit_State *J, BCReg baseslot, BCReg topslot)
+{
+  TRef *top = &J->base[topslot];
+  TValue savetv[5+LJ_FR2];
+  BCReg s;
+  RecordIndex ix;
+  lj_assertJ(baseslot < topslot, "bad CAT arg");
+  for (s = baseslot; s <= topslot; s++)
+    (void)getslot(J, s);  /* Ensure all arguments have a reference. */
+  if (tref_isnumber_str(top[0]) && tref_isnumber_str(top[-1])) {
+    TRef tr, hdr, *trp, *xbase, *base = &J->base[baseslot];
+    /* First convert numbers to strings. */
+    for (trp = top; trp >= base; trp--) {
+      if (tref_isnumber(*trp))
+	*trp = emitir(IRT(IR_TOSTR, IRT_STR), *trp,
+		      tref_isnum(*trp) ? IRTOSTR_NUM : IRTOSTR_INT);
+      else if (!tref_isstr(*trp))
+	break;
+    }
+    xbase = ++trp;
+    tr = hdr = emitir(IRT(IR_BUFHDR, IRT_PGC),
+		      lj_ir_kptr(J, &J2G(J)->tmpbuf), IRBUFHDR_RESET);
+    do {
+      tr = emitir(IRTG(IR_BUFPUT, IRT_PGC), tr, *trp++);
+    } while (trp <= top);
+    tr = emitir(IRTG(IR_BUFSTR, IRT_STR), tr, hdr);
+    J->maxslot = (BCReg)(xbase - J->base);
+    if (xbase == base) return tr;  /* Return simple concatenation result. */
+    /* Pass partial result. */
+    topslot = J->maxslot--;
+    *xbase = tr;
+    top = xbase;
+    setstrV(J->L, &ix.keyv, &J2G(J)->strempty);  /* Simulate string result. */
+  } else {
+    J->maxslot = topslot-1;
+    copyTV(J->L, &ix.keyv, &J->L->base[topslot]);
+  }
+  copyTV(J->L, &ix.tabv, &J->L->base[topslot-1]);
+  ix.tab = top[-1];
+  ix.key = top[0];
+  memcpy(savetv, &J->L->base[topslot-1], sizeof(savetv));  /* Save slots. */
+  rec_mm_arith(J, &ix, MM_concat);  /* Call __concat metamethod. */
+  memcpy(&J->L->base[topslot-1], savetv, sizeof(savetv));  /* Restore slots. */
+  return 0;  /* No result yet. */
+}
+
+/* -- Record bytecode ops ------------------------------------------------- */
+
+/* Prepare for comparison. */
+static void rec_comp_prep(jit_State *J)
+{
+  /* Prevent merging with snapshot #0 (GC exit) since we fixup the PC. */
+  if (J->cur.nsnap == 1 && J->cur.snap[0].ref == J->cur.nins)
+    emitir_raw(IRT(IR_NOP, IRT_NIL), 0, 0);
+  lj_snap_add(J);
+}
+
+/* Fixup comparison. */
+static void rec_comp_fixup(jit_State *J, const BCIns *pc, int cond)
+{
+  BCIns jmpins = pc[1];
+  const BCIns *npc = pc + 2 + (cond ? bc_j(jmpins) : 0);
+  SnapShot *snap = &J->cur.snap[J->cur.nsnap-1];
+  /* Set PC to opposite target to avoid re-recording the comp. in side trace. */
+#if LJ_FR2
+  SnapEntry *flink = &J->cur.snapmap[snap->mapofs + snap->nent];
+  uint64_t pcbase;
+  memcpy(&pcbase, flink, sizeof(uint64_t));
+  pcbase = (pcbase & 0xff) | (u64ptr(npc) << 8);
+  memcpy(flink, &pcbase, sizeof(uint64_t));
+#else
+  J->cur.snapmap[snap->mapofs + snap->nent] = SNAP_MKPC(npc);
+#endif
+  J->needsnap = 1;
+  if (bc_a(jmpins) < J->maxslot) J->maxslot = bc_a(jmpins);
+  lj_snap_shrink(J);  /* Shrink last snapshot if possible. */
+}
+
+/* Record the next bytecode instruction (_before_ it's executed). */
+void lj_record_ins(jit_State *J)
+{
+  cTValue *lbase;
+  RecordIndex ix;
+  const BCIns *pc;
+  BCIns ins;
+  BCOp op;
+  TRef ra, rb, rc;
+
+  /* Perform post-processing action before recording the next instruction. */
+  if (LJ_UNLIKELY(J->postproc != LJ_POST_NONE)) {
+    switch (J->postproc) {
+    case LJ_POST_FIXCOMP:  /* Fixup comparison. */
+      pc = (const BCIns *)(uintptr_t)J2G(J)->tmptv.u64;
+      rec_comp_fixup(J, pc, (!tvistruecond(&J2G(J)->tmptv2) ^ (bc_op(*pc)&1)));
+      /* fallthrough */
+    case LJ_POST_FIXGUARD:  /* Fixup and emit pending guard. */
+    case LJ_POST_FIXGUARDSNAP:  /* Fixup and emit pending guard and snapshot. */
+      if (!tvistruecond(&J2G(J)->tmptv2)) {
+	J->fold.ins.o ^= 1;  /* Flip guard to opposite. */
+	if (J->postproc == LJ_POST_FIXGUARDSNAP) {
+	  SnapShot *snap = &J->cur.snap[J->cur.nsnap-1];
+	  J->cur.snapmap[snap->mapofs+snap->nent-1]--;  /* False -> true. */
+	}
+      }
+      lj_opt_fold(J);  /* Emit pending guard. */
+      /* fallthrough */
+    case LJ_POST_FIXBOOL:
+      if (!tvistruecond(&J2G(J)->tmptv2)) {
+	BCReg s;
+	TValue *tv = J->L->base;
+	for (s = 0; s < J->maxslot; s++)  /* Fixup stack slot (if any). */
+	  if (J->base[s] == TREF_TRUE && tvisfalse(&tv[s])) {
+	    J->base[s] = TREF_FALSE;
+	    break;
+	  }
+      }
+      break;
+    case LJ_POST_FIXCONST:
+      {
+	BCReg s;
+	TValue *tv = J->L->base;
+	for (s = 0; s < J->maxslot; s++)  /* Constify stack slots (if any). */
+	  if (J->base[s] == TREF_NIL && !tvisnil(&tv[s]))
+	    J->base[s] = lj_record_constify(J, &tv[s]);
+      }
+      break;
+    case LJ_POST_FFRETRY:  /* Suppress recording of retried fast function. */
+      if (bc_op(*J->pc) >= BC__MAX)
+	return;
+      break;
+    default: lj_assertJ(0, "bad post-processing mode"); break;
+    }
+    J->postproc = LJ_POST_NONE;
+  }
+
+  /* Need snapshot before recording next bytecode (e.g. after a store). */
+  if (J->needsnap) {
+    J->needsnap = 0;
+    if (J->pt) lj_snap_purge(J);
+    lj_snap_add(J);
+    J->mergesnap = 1;
+  }
+
+  /* Skip some bytecodes. */
+  if (LJ_UNLIKELY(J->bcskip > 0)) {
+    J->bcskip--;
+    return;
+  }
+
+  /* Record only closed loops for root traces. */
+  pc = J->pc;
+  if (J->framedepth == 0 &&
+     (MSize)((char *)pc - (char *)J->bc_min) >= J->bc_extent)
+    lj_trace_err(J, LJ_TRERR_LLEAVE);
+
+#ifdef LUA_USE_ASSERT
+  rec_check_slots(J);
+  rec_check_ir(J);
+#endif
+
+#if LJ_HASPROFILE
+  rec_profile_ins(J, pc);
+#endif
+
+  /* Keep a copy of the runtime values of var/num/str operands. */
+#define rav	(&ix.valv)
+#define rbv	(&ix.tabv)
+#define rcv	(&ix.keyv)
+
+  lbase = J->L->base;
+  ins = *pc;
+  op = bc_op(ins);
+  ra = bc_a(ins);
+  ix.val = 0;
+  switch (bcmode_a(op)) {
+  case BCMvar:
+    copyTV(J->L, rav, &lbase[ra]); ix.val = ra = getslot(J, ra); break;
+  default: break;  /* Handled later. */
+  }
+  rb = bc_b(ins);
+  rc = bc_c(ins);
+  switch (bcmode_b(op)) {
+  case BCMnone: rb = 0; rc = bc_d(ins); break;  /* Upgrade rc to 'rd'. */
+  case BCMvar:
+    copyTV(J->L, rbv, &lbase[rb]); ix.tab = rb = getslot(J, rb); break;
+  default: break;  /* Handled later. */
+  }
+  switch (bcmode_c(op)) {
+  case BCMvar:
+    copyTV(J->L, rcv, &lbase[rc]); ix.key = rc = getslot(J, rc); break;
+  case BCMpri: setpriV(rcv, ~rc); ix.key = rc = TREF_PRI(IRT_NIL+rc); break;
+  case BCMnum: { cTValue *tv = proto_knumtv(J->pt, rc);
+    copyTV(J->L, rcv, tv); ix.key = rc = tvisint(tv) ? lj_ir_kint(J, intV(tv)) :
+    tv->u32.hi == LJ_KEYINDEX ? (lj_ir_kint(J, 0) | TREF_KEYINDEX) :
+    lj_ir_knumint(J, numV(tv)); } break;
+  case BCMstr: { GCstr *s = gco2str(proto_kgc(J->pt, ~(ptrdiff_t)rc));
+    setstrV(J->L, rcv, s); ix.key = rc = lj_ir_kstr(J, s); } break;
+  default: break;  /* Handled later. */
+  }
+
+  switch (op) {
+
+  /* -- Comparison ops ---------------------------------------------------- */
+
+  case BC_ISLT: case BC_ISGE: case BC_ISLE: case BC_ISGT:
+#if LJ_HASFFI
+    if (tref_iscdata(ra) || tref_iscdata(rc)) {
+      rec_mm_comp_cdata(J, &ix, op, ((int)op & 2) ? MM_le : MM_lt);
+      break;
+    }
+#endif
+    /* Emit nothing for two numeric or string consts. */
+    if (!(tref_isk2(ra,rc) && tref_isnumber_str(ra) && tref_isnumber_str(rc))) {
+      IRType ta = tref_isinteger(ra) ? IRT_INT : tref_type(ra);
+      IRType tc = tref_isinteger(rc) ? IRT_INT : tref_type(rc);
+      int irop;
+      if (ta != tc) {
+	/* Widen mixed number/int comparisons to number/number comparison. */
+	if (ta == IRT_INT && tc == IRT_NUM) {
+	  ra = emitir(IRTN(IR_CONV), ra, IRCONV_NUM_INT);
+	  ta = IRT_NUM;
+	} else if (ta == IRT_NUM && tc == IRT_INT) {
+	  rc = emitir(IRTN(IR_CONV), rc, IRCONV_NUM_INT);
+	} else if (LJ_52) {
+	  ta = IRT_NIL;  /* Force metamethod for different types. */
+	} else if (!((ta == IRT_FALSE || ta == IRT_TRUE) &&
+		     (tc == IRT_FALSE || tc == IRT_TRUE))) {
+	  break;  /* Interpreter will throw for two different types. */
+	}
+      }
+      rec_comp_prep(J);
+      irop = (int)op - (int)BC_ISLT + (int)IR_LT;
+      if (ta == IRT_NUM) {
+	if ((irop & 1)) irop ^= 4;  /* ISGE/ISGT are unordered. */
+	if (!lj_ir_numcmp(numberVnum(rav), numberVnum(rcv), (IROp)irop))
+	  irop ^= 5;
+      } else if (ta == IRT_INT) {
+	if (!lj_ir_numcmp(numberVnum(rav), numberVnum(rcv), (IROp)irop))
+	  irop ^= 1;
+      } else if (ta == IRT_STR) {
+	if (!lj_ir_strcmp(strV(rav), strV(rcv), (IROp)irop)) irop ^= 1;
+	ra = lj_ir_call(J, IRCALL_lj_str_cmp, ra, rc);
+	rc = lj_ir_kint(J, 0);
+	ta = IRT_INT;
+      } else {
+	rec_mm_comp(J, &ix, (int)op);
+	break;
+      }
+      emitir(IRTG(irop, ta), ra, rc);
+      rec_comp_fixup(J, J->pc, ((int)op ^ irop) & 1);
+    }
+    break;
+
+  case BC_ISEQV: case BC_ISNEV:
+  case BC_ISEQS: case BC_ISNES:
+  case BC_ISEQN: case BC_ISNEN:
+  case BC_ISEQP: case BC_ISNEP:
+#if LJ_HASFFI
+    if (tref_iscdata(ra) || tref_iscdata(rc)) {
+      rec_mm_comp_cdata(J, &ix, op, MM_eq);
+      break;
+    }
+#endif
+    /* Emit nothing for two non-table, non-udata consts. */
+    if (!(tref_isk2(ra, rc) && !(tref_istab(ra) || tref_isudata(ra)))) {
+      int diff;
+      rec_comp_prep(J);
+      diff = lj_record_objcmp(J, ra, rc, rav, rcv);
+      if (diff == 2 || !(tref_istab(ra) || tref_isudata(ra)))
+	rec_comp_fixup(J, J->pc, ((int)op & 1) == !diff);
+      else if (diff == 1)  /* Only check __eq if different, but same type. */
+	rec_mm_equal(J, &ix, (int)op);
+    }
+    break;
+
+  /* -- Unary test and copy ops ------------------------------------------- */
+
+  case BC_ISTC: case BC_ISFC:
+    if ((op & 1) == tref_istruecond(rc))
+      rc = 0;  /* Don't store if condition is not true. */
+    /* fallthrough */
+  case BC_IST: case BC_ISF:  /* Type specialization suffices. */
+    if (bc_a(pc[1]) < J->maxslot)
+      J->maxslot = bc_a(pc[1]);  /* Shrink used slots. */
+    break;
+
+  case BC_ISTYPE: case BC_ISNUM:
+    /* These coercions need to correspond with lj_meta_istype(). */
+    if (LJ_DUALNUM && rc == ~LJ_TNUMX+1)
+      ra = lj_opt_narrow_toint(J, ra);
+    else if (rc == ~LJ_TNUMX+2)
+      ra = lj_ir_tonum(J, ra);
+    else if (rc == ~LJ_TSTR+1)
+      ra = lj_ir_tostr(J, ra);
+    /* else: type specialization suffices. */
+    J->base[bc_a(ins)] = ra;
+    break;
+
+  /* -- Unary ops --------------------------------------------------------- */
+
+  case BC_NOT:
+    /* Type specialization already forces const result. */
+    rc = tref_istruecond(rc) ? TREF_FALSE : TREF_TRUE;
+    break;
+
+  case BC_LEN:
+    if (tref_isstr(rc))
+      rc = emitir(IRTI(IR_FLOAD), rc, IRFL_STR_LEN);
+    else if (!LJ_52 && tref_istab(rc))
+      rc = emitir(IRTI(IR_ALEN), rc, TREF_NIL);
+    else
+      rc = rec_mm_len(J, rc, rcv);
+    break;
+
+  /* -- Arithmetic ops ---------------------------------------------------- */
+
+  case BC_UNM:
+    if (tref_isnumber_str(rc)) {
+      rc = lj_opt_narrow_unm(J, rc, rcv);
+    } else {
+      ix.tab = rc;
+      copyTV(J->L, &ix.tabv, rcv);
+      rc = rec_mm_arith(J, &ix, MM_unm);
+    }
+    break;
+
+  case BC_ADDNV: case BC_SUBNV: case BC_MULNV: case BC_DIVNV: case BC_MODNV:
+    /* Swap rb/rc and rbv/rcv. rav is temp. */
+    ix.tab = rc; ix.key = rc = rb; rb = ix.tab;
+    copyTV(J->L, rav, rbv);
+    copyTV(J->L, rbv, rcv);
+    copyTV(J->L, rcv, rav);
+    if (op == BC_MODNV)
+      goto recmod;
+    /* fallthrough */
+  case BC_ADDVN: case BC_SUBVN: case BC_MULVN: case BC_DIVVN:
+  case BC_ADDVV: case BC_SUBVV: case BC_MULVV: case BC_DIVVV: {
+    MMS mm = bcmode_mm(op);
+    if (tref_isnumber_str(rb) && tref_isnumber_str(rc))
+      rc = lj_opt_narrow_arith(J, rb, rc, rbv, rcv,
+			       (int)mm - (int)MM_add + (int)IR_ADD);
+    else
+      rc = rec_mm_arith(J, &ix, mm);
+    break;
+    }
+
+  case BC_MODVN: case BC_MODVV:
+  recmod:
+    if (tref_isnumber_str(rb) && tref_isnumber_str(rc))
+      rc = lj_opt_narrow_mod(J, rb, rc, rbv, rcv);
+    else
+      rc = rec_mm_arith(J, &ix, MM_mod);
+    break;
+
+  case BC_POW:
+    if (tref_isnumber_str(rb) && tref_isnumber_str(rc))
+      rc = lj_opt_narrow_arith(J, rb, rc, rbv, rcv, IR_POW);
+    else
+      rc = rec_mm_arith(J, &ix, MM_pow);
+    break;
+
+  /* -- Miscellaneous ops ------------------------------------------------- */
+
+  case BC_CAT:
+    rc = rec_cat(J, rb, rc);
+    break;
+
+  /* -- Constant and move ops --------------------------------------------- */
+
+  case BC_MOV:
+    /* Clear gap of method call to avoid resurrecting previous refs. */
+    if (ra > J->maxslot) {
+#if LJ_FR2
+      memset(J->base + J->maxslot, 0, (ra - J->maxslot) * sizeof(TRef));
+#else
+      J->base[ra-1] = 0;
+#endif
+    }
+    break;
+  case BC_KSTR: case BC_KNUM: case BC_KPRI:
+    break;
+  case BC_KSHORT:
+    rc = lj_ir_kint(J, (int32_t)(int16_t)rc);
+    break;
+  case BC_KNIL:
+    if (LJ_FR2 && ra > J->maxslot)
+      J->base[ra-1] = 0;
+    while (ra <= rc)
+      J->base[ra++] = TREF_NIL;
+    if (rc >= J->maxslot) J->maxslot = rc+1;
+    break;
+#if LJ_HASFFI
+  case BC_KCDATA:
+    rc = lj_ir_kgc(J, proto_kgc(J->pt, ~(ptrdiff_t)rc), IRT_CDATA);
+    break;
+#endif
+
+  /* -- Upvalue and function ops ------------------------------------------ */
+
+  case BC_UGET:
+    rc = rec_upvalue(J, rc, 0);
+    break;
+  case BC_USETV: case BC_USETS: case BC_USETN: case BC_USETP:
+    rec_upvalue(J, ra, rc);
+    break;
+
+  /* -- Table ops --------------------------------------------------------- */
+
+  case BC_GGET: case BC_GSET:
+    settabV(J->L, &ix.tabv, tabref(J->fn->l.env));
+    ix.tab = emitir(IRT(IR_FLOAD, IRT_TAB), getcurrf(J), IRFL_FUNC_ENV);
+    ix.idxchain = LJ_MAX_IDXCHAIN;
+    rc = lj_record_idx(J, &ix);
+    break;
+
+  case BC_TGETB: case BC_TSETB:
+    setintV(&ix.keyv, (int32_t)rc);
+    ix.key = lj_ir_kint(J, (int32_t)rc);
+    /* fallthrough */
+  case BC_TGETV: case BC_TGETS: case BC_TSETV: case BC_TSETS:
+    ix.idxchain = LJ_MAX_IDXCHAIN;
+    rc = lj_record_idx(J, &ix);
+    break;
+  case BC_TGETR: case BC_TSETR:
+    ix.idxchain = 0;
+    rc = lj_record_idx(J, &ix);
+    break;
+
+  case BC_TSETM:
+    rec_tsetm(J, ra, (BCReg)(J->L->top - J->L->base), (int32_t)rcv->u32.lo);
+    break;
+
+  case BC_TNEW:
+    rc = rec_tnew(J, rc);
+    break;
+  case BC_TDUP:
+    rc = emitir(IRTG(IR_TDUP, IRT_TAB),
+		lj_ir_ktab(J, gco2tab(proto_kgc(J->pt, ~(ptrdiff_t)rc))), 0);
+#ifdef LUAJIT_ENABLE_TABLE_BUMP
+    J->rbchash[(rc & (RBCHASH_SLOTS-1))].ref = tref_ref(rc);
+    setmref(J->rbchash[(rc & (RBCHASH_SLOTS-1))].pc, pc);
+    setgcref(J->rbchash[(rc & (RBCHASH_SLOTS-1))].pt, obj2gco(J->pt));
+#endif
+    break;
+
+  /* -- Calls and vararg handling ----------------------------------------- */
+
+  case BC_ITERC:
+    J->base[ra] = getslot(J, ra-3);
+    J->base[ra+1+LJ_FR2] = getslot(J, ra-2);
+    J->base[ra+2+LJ_FR2] = getslot(J, ra-1);
+    { /* Do the actual copy now because lj_record_call needs the values. */
+      TValue *b = &J->L->base[ra];
+      copyTV(J->L, b, b-3);
+      copyTV(J->L, b+1+LJ_FR2, b-2);
+      copyTV(J->L, b+2+LJ_FR2, b-1);
+    }
+    lj_record_call(J, ra, (ptrdiff_t)rc-1);
+    break;
+
+  /* L->top is set to L->base+ra+rc+NARGS-1+1. See lj_dispatch_ins(). */
+  case BC_CALLM:
+    rc = (BCReg)(J->L->top - J->L->base) - ra - LJ_FR2;
+    /* fallthrough */
+  case BC_CALL:
+    lj_record_call(J, ra, (ptrdiff_t)rc-1);
+    break;
+
+  case BC_CALLMT:
+    rc = (BCReg)(J->L->top - J->L->base) - ra - LJ_FR2;
+    /* fallthrough */
+  case BC_CALLT:
+    lj_record_tailcall(J, ra, (ptrdiff_t)rc-1);
+    break;
+
+  case BC_VARG:
+    rec_varg(J, ra, (ptrdiff_t)rb-1);
+    break;
+
+  /* -- Returns ----------------------------------------------------------- */
+
+  case BC_RETM:
+    /* L->top is set to L->base+ra+rc+NRESULTS-1, see lj_dispatch_ins(). */
+    rc = (BCReg)(J->L->top - J->L->base) - ra + 1;
+    /* fallthrough */
+  case BC_RET: case BC_RET0: case BC_RET1:
+#if LJ_HASPROFILE
+    rec_profile_ret(J);
+#endif
+    lj_record_ret(J, ra, (ptrdiff_t)rc-1);
+    break;
+
+  /* -- Loops and branches ------------------------------------------------ */
+
+  case BC_FORI:
+    if (rec_for(J, pc, 0) != LOOPEV_LEAVE)
+      J->loopref = J->cur.nins;
+    break;
+  case BC_JFORI:
+    lj_assertJ(bc_op(pc[(ptrdiff_t)rc-BCBIAS_J]) == BC_JFORL,
+	       "JFORI does not point to JFORL");
+    if (rec_for(J, pc, 0) != LOOPEV_LEAVE)  /* Link to existing loop. */
+      lj_record_stop(J, LJ_TRLINK_ROOT, bc_d(pc[(ptrdiff_t)rc-BCBIAS_J]));
+    /* Continue tracing if the loop is not entered. */
+    break;
+
+  case BC_FORL:
+    rec_loop_interp(J, pc, rec_for(J, pc+((ptrdiff_t)rc-BCBIAS_J), 1));
+    break;
+  case BC_ITERL:
+    rec_loop_interp(J, pc, rec_iterl(J, *pc));
+    break;
+  case BC_ITERN:
+    rec_loop_interp(J, pc, rec_itern(J, ra, rb));
+    break;
+  case BC_LOOP:
+    rec_loop_interp(J, pc, rec_loop(J, ra, 1));
+    break;
+
+  case BC_JFORL:
+    rec_loop_jit(J, rc, rec_for(J, pc+bc_j(traceref(J, rc)->startins), 1));
+    break;
+  case BC_JITERL:
+    rec_loop_jit(J, rc, rec_iterl(J, traceref(J, rc)->startins));
+    break;
+  case BC_JLOOP:
+    rec_loop_jit(J, rc, rec_loop(J, ra,
+				 !bc_isret(bc_op(traceref(J, rc)->startins)) &&
+				 bc_op(traceref(J, rc)->startins) != BC_ITERN));
+    break;
+
+  case BC_IFORL:
+  case BC_IITERL:
+  case BC_ILOOP:
+  case BC_IFUNCF:
+  case BC_IFUNCV:
+    lj_trace_err(J, LJ_TRERR_BLACKL);
+    break;
+
+  case BC_JMP:
+    if (ra < J->maxslot)
+      J->maxslot = ra;  /* Shrink used slots. */
+    break;
+
+  case BC_ISNEXT:
+    rec_isnext(J, ra);
+    break;
+
+  /* -- Function headers -------------------------------------------------- */
+
+  case BC_FUNCF:
+    rec_func_lua(J);
+    break;
+  case BC_JFUNCF:
+    rec_func_jit(J, rc);
+    break;
+
+  case BC_FUNCV:
+    rec_func_vararg(J);
+    rec_func_lua(J);
+    break;
+  case BC_JFUNCV:
+    /* Cannot happen. No hotcall counting for varag funcs. */
+    lj_assertJ(0, "unsupported vararg hotcall");
+    break;
+
+  case BC_FUNCC:
+  case BC_FUNCCW:
+    lj_ffrecord_func(J);
+    break;
+
+  default:
+    if (op >= BC__MAX) {
+      lj_ffrecord_func(J);
+      break;
+    }
+    /* fallthrough */
+  case BC_UCLO:
+  case BC_FNEW:
+    setintV(&J->errinfo, (int32_t)op);
+    lj_trace_err_info(J, LJ_TRERR_NYIBC);
+    break;
+  }
+
+  /* rc == 0 if we have no result yet, e.g. pending __index metamethod call. */
+  if (bcmode_a(op) == BCMdst && rc) {
+    J->base[ra] = rc;
+    if (ra >= J->maxslot) {
+#if LJ_FR2
+      if (ra > J->maxslot) J->base[ra-1] = 0;
+#endif
+      J->maxslot = ra+1;
+    }
+  }
+
+#undef rav
+#undef rbv
+#undef rcv
+
+  /* Limit the number of recorded IR instructions and constants. */
+  if (J->cur.nins > REF_FIRST+(IRRef)J->param[JIT_P_maxrecord] ||
+      J->cur.nk < REF_BIAS-(IRRef)J->param[JIT_P_maxirconst])
+    lj_trace_err(J, LJ_TRERR_TRACEOV);
+}
+
+/* -- Recording setup ----------------------------------------------------- */
+
+/* Setup recording for a root trace started by a hot loop. */
+static const BCIns *rec_setup_root(jit_State *J)
+{
+  /* Determine the next PC and the bytecode range for the loop. */
+  const BCIns *pcj, *pc = J->pc;
+  BCIns ins = *pc;
+  BCReg ra = bc_a(ins);
+  switch (bc_op(ins)) {
+  case BC_FORL:
+    J->bc_extent = (MSize)(-bc_j(ins))*sizeof(BCIns);
+    pc += 1+bc_j(ins);
+    J->bc_min = pc;
+    break;
+  case BC_ITERL:
+    if (bc_op(pc[-1]) == BC_JLOOP)
+      lj_trace_err(J, LJ_TRERR_LINNER);
+    lj_assertJ(bc_op(pc[-1]) == BC_ITERC, "no ITERC before ITERL");
+    J->maxslot = ra + bc_b(pc[-1]) - 1;
+    J->bc_extent = (MSize)(-bc_j(ins))*sizeof(BCIns);
+    pc += 1+bc_j(ins);
+    lj_assertJ(bc_op(pc[-1]) == BC_JMP, "ITERL does not point to JMP+1");
+    J->bc_min = pc;
+    break;
+  case BC_ITERN:
+    lj_assertJ(bc_op(pc[1]) == BC_ITERL, "no ITERL after ITERN");
+    J->maxslot = ra;
+    J->bc_extent = (MSize)(-bc_j(pc[1]))*sizeof(BCIns);
+    J->bc_min = pc+2 + bc_j(pc[1]);
+    J->state = LJ_TRACE_RECORD_1ST;  /* Record the first ITERN, too. */
+    break;
+  case BC_LOOP:
+    /* Only check BC range for real loops, but not for "repeat until true". */
+    pcj = pc + bc_j(ins);
+    ins = *pcj;
+    if (bc_op(ins) == BC_JMP && bc_j(ins) < 0) {
+      J->bc_min = pcj+1 + bc_j(ins);
+      J->bc_extent = (MSize)(-bc_j(ins))*sizeof(BCIns);
+    }
+    J->maxslot = ra;
+    pc++;
+    break;
+  case BC_RET:
+  case BC_RET0:
+  case BC_RET1:
+    /* No bytecode range check for down-recursive root traces. */
+    J->maxslot = ra + bc_d(ins) - 1;
+    break;
+  case BC_FUNCF:
+    /* No bytecode range check for root traces started by a hot call. */
+    J->maxslot = J->pt->numparams;
+    pc++;
+    break;
+  case BC_CALLM:
+  case BC_CALL:
+  case BC_ITERC:
+    /* No bytecode range check for stitched traces. */
+    pc++;
+    break;
+  default:
+    lj_assertJ(0, "bad root trace start bytecode %d", bc_op(ins));
+    break;
+  }
+  return pc;
+}
+
+/* Setup for recording a new trace. */
+void lj_record_setup(jit_State *J)
+{
+  uint32_t i;
+
+  /* Initialize state related to current trace. */
+  memset(J->slot, 0, sizeof(J->slot));
+  memset(J->chain, 0, sizeof(J->chain));
+#ifdef LUAJIT_ENABLE_TABLE_BUMP
+  memset(J->rbchash, 0, sizeof(J->rbchash));
+#endif
+  memset(J->bpropcache, 0, sizeof(J->bpropcache));
+  J->scev.idx = REF_NIL;
+  setmref(J->scev.pc, NULL);
+
+  J->baseslot = 1+LJ_FR2;  /* Invoking function is at base[-1-LJ_FR2]. */
+  J->base = J->slot + J->baseslot;
+  J->maxslot = 0;
+  J->framedepth = 0;
+  J->retdepth = 0;
+
+  J->instunroll = J->param[JIT_P_instunroll];
+  J->loopunroll = J->param[JIT_P_loopunroll];
+  J->tailcalled = 0;
+  J->loopref = 0;
+
+  J->bc_min = NULL;  /* Means no limit. */
+  J->bc_extent = ~(MSize)0;
+
+  /* Emit instructions for fixed references. Also triggers initial IR alloc. */
+  emitir_raw(IRT(IR_BASE, IRT_PGC), J->parent, J->exitno);
+  for (i = 0; i <= 2; i++) {
+    IRIns *ir = IR(REF_NIL-i);
+    ir->i = 0;
+    ir->t.irt = (uint8_t)(IRT_NIL+i);
+    ir->o = IR_KPRI;
+    ir->prev = 0;
+  }
+  J->cur.nk = REF_TRUE;
+
+  J->startpc = J->pc;
+  setmref(J->cur.startpc, J->pc);
+  if (J->parent) {  /* Side trace. */
+    GCtrace *T = traceref(J, J->parent);
+    TraceNo root = T->root ? T->root : J->parent;
+    J->cur.root = (uint16_t)root;
+    J->cur.startins = BCINS_AD(BC_JMP, 0, 0);
+    /* Check whether we could at least potentially form an extra loop. */
+    if (J->exitno == 0 && T->snap[0].nent == 0) {
+      /* We can narrow a FORL for some side traces, too. */
+      if (J->pc > proto_bc(J->pt) && bc_op(J->pc[-1]) == BC_JFORI &&
+	  bc_d(J->pc[bc_j(J->pc[-1])-1]) == root) {
+	lj_snap_add(J);
+	rec_for_loop(J, J->pc-1, &J->scev, 1);
+	goto sidecheck;
+      }
+    } else {
+      J->startpc = NULL;  /* Prevent forming an extra loop. */
+    }
+    lj_snap_replay(J, T);
+  sidecheck:
+    if ((traceref(J, J->cur.root)->nchild >= J->param[JIT_P_maxside] ||
+	 T->snap[J->exitno].count >= J->param[JIT_P_hotexit] +
+				     J->param[JIT_P_tryside])) {
+      if (bc_op(*J->pc) == BC_JLOOP) {
+	BCIns startins = traceref(J, bc_d(*J->pc))->startins;
+	if (bc_op(startins) == BC_ITERN)
+	  rec_itern(J, bc_a(startins), bc_b(startins));
+      }
+      lj_record_stop(J, LJ_TRLINK_INTERP, 0);
+    }
+  } else {  /* Root trace. */
+    J->cur.root = 0;
+    J->cur.startins = *J->pc;
+    J->pc = rec_setup_root(J);
+    /* Note: the loop instruction itself is recorded at the end and not
+    ** at the start! So snapshot #0 needs to point to the *next* instruction.
+    ** The one exception is BC_ITERN, which sets LJ_TRACE_RECORD_1ST.
+    */
+    lj_snap_add(J);
+    if (bc_op(J->cur.startins) == BC_FORL)
+      rec_for_loop(J, J->pc-1, &J->scev, 1);
+    else if (bc_op(J->cur.startins) == BC_ITERC)
+      J->startpc = NULL;
+    if (1 + J->pt->framesize >= LJ_MAX_JSLOTS)
+      lj_trace_err(J, LJ_TRERR_STACKOV);
+  }
+#if LJ_HASPROFILE
+  J->prev_pt = NULL;
+  J->prev_line = -1;
+#endif
+#ifdef LUAJIT_ENABLE_CHECKHOOK
+  /* Regularly check for instruction/line hooks from compiled code and
+  ** exit to the interpreter if the hooks are set.
+  **
+  ** This is a compile-time option and disabled by default, since the
+  ** hook checks may be quite expensive in tight loops.
+  **
+  ** Note this is only useful if hooks are *not* set most of the time.
+  ** Use this only if you want to *asynchronously* interrupt the execution.
+  **
+  ** You can set the instruction hook via lua_sethook() with a count of 1
+  ** from a signal handler or another native thread. Please have a look
+  ** at the first few functions in luajit.c for an example (Ctrl-C handler).
+  */
+  {
+    TRef tr = emitir(IRT(IR_XLOAD, IRT_U8),
+		     lj_ir_kptr(J, &J2G(J)->hookmask), IRXLOAD_VOLATILE);
+    tr = emitir(IRTI(IR_BAND), tr, lj_ir_kint(J, (LUA_MASKLINE|LUA_MASKCOUNT)));
+    emitir(IRTGI(IR_EQ), tr, lj_ir_kint(J, 0));
+  }
+#endif
+}
+
+#undef IR
+#undef emitir_raw
+#undef emitir
+
+#endif