build & link with luajit instead of lua5.1

1 files changed, 3125 insertions, 0 deletions

diff --git a/libs/luajit-cmake/luajit/src/lj_asm_x86.h b/libs/luajit-cmake/luajit/src/lj_asm_x86.h
new file mode 100644
index 0000000..2bf9d93
--- /dev/null
+++ b/libs/luajit-cmake/luajit/src/lj_asm_x86.h
@@ -0,0 +1,3125 @@
+/*
+** x86/x64 IR assembler (SSA IR -> machine code).
+** Copyright (C) 2005-2022 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+/* -- Guard handling ------------------------------------------------------ */
+
+/* Generate an exit stub group at the bottom of the reserved MCode memory. */
+static MCode *asm_exitstub_gen(ASMState *as, ExitNo group)
+{
+  ExitNo i, groupofs = (group*EXITSTUBS_PER_GROUP) & 0xff;
+  MCode *mxp = as->mcbot;
+  MCode *mxpstart = mxp;
+  if (mxp + (2+2)*EXITSTUBS_PER_GROUP+8+5 >= as->mctop)
+    asm_mclimit(as);
+  /* Push low byte of exitno for each exit stub. */
+  *mxp++ = XI_PUSHi8; *mxp++ = (MCode)groupofs;
+  for (i = 1; i < EXITSTUBS_PER_GROUP; i++) {
+    *mxp++ = XI_JMPs; *mxp++ = (MCode)((2+2)*(EXITSTUBS_PER_GROUP - i) - 2);
+    *mxp++ = XI_PUSHi8; *mxp++ = (MCode)(groupofs + i);
+  }
+  /* Push the high byte of the exitno for each exit stub group. */
+  *mxp++ = XI_PUSHi8; *mxp++ = (MCode)((group*EXITSTUBS_PER_GROUP)>>8);
+#if !LJ_GC64
+  /* Store DISPATCH at original stack slot 0. Account for the two push ops. */
+  *mxp++ = XI_MOVmi;
+  *mxp++ = MODRM(XM_OFS8, 0, RID_ESP);
+  *mxp++ = MODRM(XM_SCALE1, RID_ESP, RID_ESP);
+  *mxp++ = 2*sizeof(void *);
+  *(int32_t *)mxp = ptr2addr(J2GG(as->J)->dispatch); mxp += 4;
+#endif
+  /* Jump to exit handler which fills in the ExitState. */
+  *mxp++ = XI_JMP; mxp += 4;
+  *((int32_t *)(mxp-4)) = jmprel(as->J, mxp, (MCode *)(void *)lj_vm_exit_handler);
+  /* Commit the code for this group (even if assembly fails later on). */
+  lj_mcode_commitbot(as->J, mxp);
+  as->mcbot = mxp;
+  as->mclim = as->mcbot + MCLIM_REDZONE;
+  return mxpstart;
+}
+
+/* Setup all needed exit stubs. */
+static void asm_exitstub_setup(ASMState *as, ExitNo nexits)
+{
+  ExitNo i;
+  if (nexits >= EXITSTUBS_PER_GROUP*LJ_MAX_EXITSTUBGR)
+    lj_trace_err(as->J, LJ_TRERR_SNAPOV);
+  for (i = 0; i < (nexits+EXITSTUBS_PER_GROUP-1)/EXITSTUBS_PER_GROUP; i++)
+    if (as->J->exitstubgroup[i] == NULL)
+      as->J->exitstubgroup[i] = asm_exitstub_gen(as, i);
+}
+
+/* Emit conditional branch to exit for guard.
+** It's important to emit this *after* all registers have been allocated,
+** because rematerializations may invalidate the flags.
+*/
+static void asm_guardcc(ASMState *as, int cc)
+{
+  MCode *target = exitstub_addr(as->J, as->snapno);
+  MCode *p = as->mcp;
+  if (LJ_UNLIKELY(p == as->invmcp)) {
+    as->loopinv = 1;
+    *(int32_t *)(p+1) = jmprel(as->J, p+5, target);
+    target = p;
+    cc ^= 1;
+    if (as->realign) {
+      if (LJ_GC64 && LJ_UNLIKELY(as->mrm.base == RID_RIP))
+	as->mrm.ofs += 2;  /* Fixup RIP offset for pending fused load. */
+      emit_sjcc(as, cc, target);
+      return;
+    }
+  }
+  if (LJ_GC64 && LJ_UNLIKELY(as->mrm.base == RID_RIP))
+    as->mrm.ofs += 6;  /* Fixup RIP offset for pending fused load. */
+  emit_jcc(as, cc, target);
+}
+
+/* -- Memory operand fusion ----------------------------------------------- */
+
+/* Limit linear search to this distance. Avoids O(n^2) behavior. */
+#define CONFLICT_SEARCH_LIM	31
+
+/* Check if a reference is a signed 32 bit constant. */
+static int asm_isk32(ASMState *as, IRRef ref, int32_t *k)
+{
+  if (irref_isk(ref)) {
+    IRIns *ir = IR(ref);
+#if LJ_GC64
+    if (ir->o == IR_KNULL || !irt_is64(ir->t)) {
+      *k = ir->i;
+      return 1;
+    } else if (checki32((int64_t)ir_k64(ir)->u64)) {
+      *k = (int32_t)ir_k64(ir)->u64;
+      return 1;
+    }
+#else
+    if (ir->o != IR_KINT64) {
+      *k = ir->i;
+      return 1;
+    } else if (checki32((int64_t)ir_kint64(ir)->u64)) {
+      *k = (int32_t)ir_kint64(ir)->u64;
+      return 1;
+    }
+#endif
+  }
+  return 0;
+}
+
+/* Check if there's no conflicting instruction between curins and ref.
+** Also avoid fusing loads if there are multiple references.
+*/
+static int noconflict(ASMState *as, IRRef ref, IROp conflict, int noload)
+{
+  IRIns *ir = as->ir;
+  IRRef i = as->curins;
+  if (i > ref + CONFLICT_SEARCH_LIM)
+    return 0;  /* Give up, ref is too far away. */
+  while (--i > ref) {
+    if (ir[i].o == conflict)
+      return 0;  /* Conflict found. */
+    else if (!noload && (ir[i].op1 == ref || ir[i].op2 == ref))
+      return 0;
+  }
+  return 1;  /* Ok, no conflict. */
+}
+
+/* Fuse array base into memory operand. */
+static IRRef asm_fuseabase(ASMState *as, IRRef ref)
+{
+  IRIns *irb = IR(ref);
+  as->mrm.ofs = 0;
+  if (irb->o == IR_FLOAD) {
+    IRIns *ira = IR(irb->op1);
+    lj_assertA(irb->op2 == IRFL_TAB_ARRAY, "expected FLOAD TAB_ARRAY");
+    /* We can avoid the FLOAD of t->array for colocated arrays. */
+    if (ira->o == IR_TNEW && ira->op1 <= LJ_MAX_COLOSIZE &&
+	!neverfuse(as) && noconflict(as, irb->op1, IR_NEWREF, 1)) {
+      as->mrm.ofs = (int32_t)sizeof(GCtab);  /* Ofs to colocated array. */
+      return irb->op1;  /* Table obj. */
+    }
+  } else if (irb->o == IR_ADD && irref_isk(irb->op2)) {
+    /* Fuse base offset (vararg load). */
+    as->mrm.ofs = IR(irb->op2)->i;
+    return irb->op1;
+  }
+  return ref;  /* Otherwise use the given array base. */
+}
+
+/* Fuse array reference into memory operand. */
+static void asm_fusearef(ASMState *as, IRIns *ir, RegSet allow)
+{
+  IRIns *irx;
+  lj_assertA(ir->o == IR_AREF, "expected AREF");
+  as->mrm.base = (uint8_t)ra_alloc1(as, asm_fuseabase(as, ir->op1), allow);
+  irx = IR(ir->op2);
+  if (irref_isk(ir->op2)) {
+    as->mrm.ofs += 8*irx->i;
+    as->mrm.idx = RID_NONE;
+  } else {
+    rset_clear(allow, as->mrm.base);
+    as->mrm.scale = XM_SCALE8;
+    /* Fuse a constant ADD (e.g. t[i+1]) into the offset.
+    ** Doesn't help much without ABCelim, but reduces register pressure.
+    */
+    if (!LJ_64 &&  /* Has bad effects with negative index on x64. */
+	mayfuse(as, ir->op2) && ra_noreg(irx->r) &&
+	irx->o == IR_ADD && irref_isk(irx->op2)) {
+      as->mrm.ofs += 8*IR(irx->op2)->i;
+      as->mrm.idx = (uint8_t)ra_alloc1(as, irx->op1, allow);
+    } else {
+      as->mrm.idx = (uint8_t)ra_alloc1(as, ir->op2, allow);
+    }
+  }
+}
+
+/* Fuse array/hash/upvalue reference into memory operand.
+** Caveat: this may allocate GPRs for the base/idx registers. Be sure to
+** pass the final allow mask, excluding any GPRs used for other inputs.
+** In particular: 2-operand GPR instructions need to call ra_dest() first!
+*/
+static void asm_fuseahuref(ASMState *as, IRRef ref, RegSet allow)
+{
+  IRIns *ir = IR(ref);
+  if (ra_noreg(ir->r)) {
+    switch ((IROp)ir->o) {
+    case IR_AREF:
+      if (mayfuse(as, ref)) {
+	asm_fusearef(as, ir, allow);
+	return;
+      }
+      break;
+    case IR_HREFK:
+      if (mayfuse(as, ref)) {
+	as->mrm.base = (uint8_t)ra_alloc1(as, ir->op1, allow);
+	as->mrm.ofs = (int32_t)(IR(ir->op2)->op2 * sizeof(Node));
+	as->mrm.idx = RID_NONE;
+	return;
+      }
+      break;
+    case IR_UREFC:
+      if (irref_isk(ir->op1)) {
+	GCfunc *fn = ir_kfunc(IR(ir->op1));
+	GCupval *uv = &gcref(fn->l.uvptr[(ir->op2 >> 8)])->uv;
+#if LJ_GC64
+	int64_t ofs = dispofs(as, &uv->tv);
+	if (checki32(ofs) && checki32(ofs+4)) {
+	  as->mrm.ofs = (int32_t)ofs;
+	  as->mrm.base = RID_DISPATCH;
+	  as->mrm.idx = RID_NONE;
+	  return;
+	}
+#else
+	as->mrm.ofs = ptr2addr(&uv->tv);
+	as->mrm.base = as->mrm.idx = RID_NONE;
+	return;
+#endif
+      }
+      break;
+    case IR_TMPREF:
+#if LJ_GC64
+      as->mrm.ofs = (int32_t)dispofs(as, &J2G(as->J)->tmptv);
+      as->mrm.base = RID_DISPATCH;
+      as->mrm.idx = RID_NONE;
+#else
+      as->mrm.ofs = igcptr(&J2G(as->J)->tmptv);
+      as->mrm.base = as->mrm.idx = RID_NONE;
+#endif
+      return;
+    default:
+      break;
+    }
+  }
+  as->mrm.base = (uint8_t)ra_alloc1(as, ref, allow);
+  as->mrm.ofs = 0;
+  as->mrm.idx = RID_NONE;
+}
+
+/* Fuse FLOAD/FREF reference into memory operand. */
+static void asm_fusefref(ASMState *as, IRIns *ir, RegSet allow)
+{
+  lj_assertA(ir->o == IR_FLOAD || ir->o == IR_FREF,
+	     "bad IR op %d", ir->o);
+  as->mrm.idx = RID_NONE;
+  if (ir->op1 == REF_NIL) {  /* FLOAD from GG_State with offset. */
+#if LJ_GC64
+    as->mrm.ofs = (int32_t)(ir->op2 << 2) - GG_OFS(dispatch);
+    as->mrm.base = RID_DISPATCH;
+#else
+    as->mrm.ofs = (int32_t)(ir->op2 << 2) + ptr2addr(J2GG(as->J));
+    as->mrm.base = RID_NONE;
+#endif
+    return;
+  }
+  as->mrm.ofs = field_ofs[ir->op2];
+  if (irref_isk(ir->op1)) {
+    IRIns *op1 = IR(ir->op1);
+#if LJ_GC64
+    if (ir->op1 == REF_NIL) {
+      as->mrm.ofs -= GG_OFS(dispatch);
+      as->mrm.base = RID_DISPATCH;
+      return;
+    } else if (op1->o == IR_KPTR || op1->o == IR_KKPTR) {
+      intptr_t ofs = dispofs(as, ir_kptr(op1));
+      if (checki32(as->mrm.ofs + ofs)) {
+	as->mrm.ofs += (int32_t)ofs;
+	as->mrm.base = RID_DISPATCH;
+	return;
+      }
+    }
+#else
+    as->mrm.ofs += op1->i;
+    as->mrm.base = RID_NONE;
+    return;
+#endif
+  }
+  as->mrm.base = (uint8_t)ra_alloc1(as, ir->op1, allow);
+}
+
+/* Fuse string reference into memory operand. */
+static void asm_fusestrref(ASMState *as, IRIns *ir, RegSet allow)
+{
+  IRIns *irr;
+  lj_assertA(ir->o == IR_STRREF, "bad IR op %d", ir->o);
+  as->mrm.base = as->mrm.idx = RID_NONE;
+  as->mrm.scale = XM_SCALE1;
+  as->mrm.ofs = sizeof(GCstr);
+  if (!LJ_GC64 && irref_isk(ir->op1)) {
+    as->mrm.ofs += IR(ir->op1)->i;
+  } else {
+    Reg r = ra_alloc1(as, ir->op1, allow);
+    rset_clear(allow, r);
+    as->mrm.base = (uint8_t)r;
+  }
+  irr = IR(ir->op2);
+  if (irref_isk(ir->op2)) {
+    as->mrm.ofs += irr->i;
+  } else {
+    Reg r;
+    /* Fuse a constant add into the offset, e.g. string.sub(s, i+10). */
+    if (!LJ_64 &&  /* Has bad effects with negative index on x64. */
+	mayfuse(as, ir->op2) && irr->o == IR_ADD && irref_isk(irr->op2)) {
+      as->mrm.ofs += IR(irr->op2)->i;
+      r = ra_alloc1(as, irr->op1, allow);
+    } else {
+      r = ra_alloc1(as, ir->op2, allow);
+    }
+    if (as->mrm.base == RID_NONE)
+      as->mrm.base = (uint8_t)r;
+    else
+      as->mrm.idx = (uint8_t)r;
+  }
+}
+
+static void asm_fusexref(ASMState *as, IRRef ref, RegSet allow)
+{
+  IRIns *ir = IR(ref);
+  as->mrm.idx = RID_NONE;
+  if (ir->o == IR_KPTR || ir->o == IR_KKPTR) {
+#if LJ_GC64
+    intptr_t ofs = dispofs(as, ir_kptr(ir));
+    if (checki32(ofs)) {
+      as->mrm.ofs = (int32_t)ofs;
+      as->mrm.base = RID_DISPATCH;
+      return;
+    }
+  } if (0) {
+#else
+    as->mrm.ofs = ir->i;
+    as->mrm.base = RID_NONE;
+  } else if (ir->o == IR_STRREF) {
+    asm_fusestrref(as, ir, allow);
+#endif
+  } else {
+    as->mrm.ofs = 0;
+    if (canfuse(as, ir) && ir->o == IR_ADD && ra_noreg(ir->r)) {
+      /* Gather (base+idx*sz)+ofs as emitted by cdata ptr/array indexing. */
+      IRIns *irx;
+      IRRef idx;
+      Reg r;
+      if (asm_isk32(as, ir->op2, &as->mrm.ofs)) {  /* Recognize x+ofs. */
+	ref = ir->op1;
+	ir = IR(ref);
+	if (!(ir->o == IR_ADD && canfuse(as, ir) && ra_noreg(ir->r)))
+	  goto noadd;
+      }
+      as->mrm.scale = XM_SCALE1;
+      idx = ir->op1;
+      ref = ir->op2;
+      irx = IR(idx);
+      if (!(irx->o == IR_BSHL || irx->o == IR_ADD)) {  /* Try other operand. */
+	idx = ir->op2;
+	ref = ir->op1;
+	irx = IR(idx);
+      }
+      if (canfuse(as, irx) && ra_noreg(irx->r)) {
+	if (irx->o == IR_BSHL && irref_isk(irx->op2) && IR(irx->op2)->i <= 3) {
+	  /* Recognize idx<<b with b = 0-3, corresponding to sz = (1),2,4,8. */
+	  idx = irx->op1;
+	  as->mrm.scale = (uint8_t)(IR(irx->op2)->i << 6);
+	} else if (irx->o == IR_ADD && irx->op1 == irx->op2) {
+	  /* FOLD does idx*2 ==> idx<<1 ==> idx+idx. */
+	  idx = irx->op1;
+	  as->mrm.scale = XM_SCALE2;
+	}
+      }
+      r = ra_alloc1(as, idx, allow);
+      rset_clear(allow, r);
+      as->mrm.idx = (uint8_t)r;
+    }
+  noadd:
+    as->mrm.base = (uint8_t)ra_alloc1(as, ref, allow);
+  }
+}
+
+/* Fuse load of 64 bit IR constant into memory operand. */
+static Reg asm_fuseloadk64(ASMState *as, IRIns *ir)
+{
+  const uint64_t *k = &ir_k64(ir)->u64;
+  if (!LJ_GC64 || checki32((intptr_t)k)) {
+    as->mrm.ofs = ptr2addr(k);
+    as->mrm.base = RID_NONE;
+#if LJ_GC64
+  } else if (checki32(dispofs(as, k))) {
+    as->mrm.ofs = (int32_t)dispofs(as, k);
+    as->mrm.base = RID_DISPATCH;
+  } else if (checki32(mcpofs(as, k)) && checki32(mcpofs(as, k+1)) &&
+	     checki32(mctopofs(as, k)) && checki32(mctopofs(as, k+1))) {
+    as->mrm.ofs = (int32_t)mcpofs(as, k);
+    as->mrm.base = RID_RIP;
+  } else {  /* Intern 64 bit constant at bottom of mcode. */
+    if (ir->i) {
+      lj_assertA(*k == *(uint64_t*)(as->mctop - ir->i),
+		 "bad interned 64 bit constant");
+    } else {
+      while ((uintptr_t)as->mcbot & 7) *as->mcbot++ = XI_INT3;
+      *(uint64_t*)as->mcbot = *k;
+      ir->i = (int32_t)(as->mctop - as->mcbot);
+      as->mcbot += 8;
+      as->mclim = as->mcbot + MCLIM_REDZONE;
+      lj_mcode_commitbot(as->J, as->mcbot);
+    }
+    as->mrm.ofs = (int32_t)mcpofs(as, as->mctop - ir->i);
+    as->mrm.base = RID_RIP;
+#endif
+  }
+  as->mrm.idx = RID_NONE;
+  return RID_MRM;
+}
+
+/* Fuse load into memory operand.
+**
+** Important caveat: this may emit RIP-relative loads! So don't place any
+** code emitters between this function and the use of its result.
+** The only permitted exception is asm_guardcc().
+*/
+static Reg asm_fuseload(ASMState *as, IRRef ref, RegSet allow)
+{
+  IRIns *ir = IR(ref);
+  if (ra_hasreg(ir->r)) {
+    if (allow != RSET_EMPTY) {  /* Fast path. */
+      ra_noweak(as, ir->r);
+      return ir->r;
+    }
+  fusespill:
+    /* Force a spill if only memory operands are allowed (asm_x87load). */
+    as->mrm.base = RID_ESP;
+    as->mrm.ofs = ra_spill(as, ir);
+    as->mrm.idx = RID_NONE;
+    return RID_MRM;
+  }
+  if (ir->o == IR_KNUM) {
+    RegSet avail = as->freeset & ~as->modset & RSET_FPR;
+    lj_assertA(allow != RSET_EMPTY, "no register allowed");
+    if (!(avail & (avail-1)))  /* Fuse if less than two regs available. */
+      return asm_fuseloadk64(as, ir);
+  } else if (ref == REF_BASE || ir->o == IR_KINT64) {
+    RegSet avail = as->freeset & ~as->modset & RSET_GPR;
+    lj_assertA(allow != RSET_EMPTY, "no register allowed");
+    if (!(avail & (avail-1))) {  /* Fuse if less than two regs available. */
+      if (ref == REF_BASE) {
+#if LJ_GC64
+	as->mrm.ofs = (int32_t)dispofs(as, &J2G(as->J)->jit_base);
+	as->mrm.base = RID_DISPATCH;
+#else
+	as->mrm.ofs = ptr2addr(&J2G(as->J)->jit_base);
+	as->mrm.base = RID_NONE;
+#endif
+	as->mrm.idx = RID_NONE;
+	return RID_MRM;
+      } else {
+	return asm_fuseloadk64(as, ir);
+      }
+    }
+  } else if (mayfuse(as, ref)) {
+    RegSet xallow = (allow & RSET_GPR) ? allow : RSET_GPR;
+    if (ir->o == IR_SLOAD) {
+      if (!(ir->op2 & (IRSLOAD_PARENT|IRSLOAD_CONVERT)) &&
+	  noconflict(as, ref, IR_RETF, 0) &&
+	  !(LJ_GC64 && irt_isaddr(ir->t))) {
+	as->mrm.base = (uint8_t)ra_alloc1(as, REF_BASE, xallow);
+	as->mrm.ofs = 8*((int32_t)ir->op1-1-LJ_FR2) +
+		      (!LJ_FR2 && (ir->op2 & IRSLOAD_FRAME) ? 4 : 0);
+	as->mrm.idx = RID_NONE;
+	return RID_MRM;
+      }
+    } else if (ir->o == IR_FLOAD) {
+      /* Generic fusion is only ok for 32 bit operand (but see asm_comp). */
+      if ((irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t)) &&
+	  noconflict(as, ref, IR_FSTORE, 0)) {
+	asm_fusefref(as, ir, xallow);
+	return RID_MRM;
+      }
+    } else if (ir->o == IR_ALOAD || ir->o == IR_HLOAD || ir->o == IR_ULOAD) {
+      if (noconflict(as, ref, ir->o + IRDELTA_L2S, 0) &&
+	  !(LJ_GC64 && irt_isaddr(ir->t))) {
+	asm_fuseahuref(as, ir->op1, xallow);
+	return RID_MRM;
+      }
+    } else if (ir->o == IR_XLOAD) {
+      /* Generic fusion is not ok for 8/16 bit operands (but see asm_comp).
+      ** Fusing unaligned memory operands is ok on x86 (except for SIMD types).
+      */
+      if ((!irt_typerange(ir->t, IRT_I8, IRT_U16)) &&
+	  noconflict(as, ref, IR_XSTORE, 0)) {
+	asm_fusexref(as, ir->op1, xallow);
+	return RID_MRM;
+      }
+    } else if (ir->o == IR_VLOAD && IR(ir->op1)->o == IR_AREF &&
+	       !(LJ_GC64 && irt_isaddr(ir->t))) {
+      asm_fuseahuref(as, ir->op1, xallow);
+      as->mrm.ofs += 8 * ir->op2;
+      return RID_MRM;
+    }
+  }
+  if (ir->o == IR_FLOAD && ir->op1 == REF_NIL) {
+    asm_fusefref(as, ir, RSET_EMPTY);
+    return RID_MRM;
+  }
+  if (!(as->freeset & allow) && !emit_canremat(ref) &&
+      (allow == RSET_EMPTY || ra_hasspill(ir->s) || iscrossref(as, ref)))
+    goto fusespill;
+  return ra_allocref(as, ref, allow);
+}
+
+#if LJ_64
+/* Don't fuse a 32 bit load into a 64 bit operation. */
+static Reg asm_fuseloadm(ASMState *as, IRRef ref, RegSet allow, int is64)
+{
+  if (is64 && !irt_is64(IR(ref)->t))
+    return ra_alloc1(as, ref, allow);
+  return asm_fuseload(as, ref, allow);
+}
+#else
+#define asm_fuseloadm(as, ref, allow, is64)  asm_fuseload(as, (ref), (allow))
+#endif
+
+/* -- Calls --------------------------------------------------------------- */
+
+/* Count the required number of stack slots for a call. */
+static int asm_count_call_slots(ASMState *as, const CCallInfo *ci, IRRef *args)
+{
+  uint32_t i, nargs = CCI_XNARGS(ci);
+  int nslots = 0;
+#if LJ_64
+  if (LJ_ABI_WIN) {
+    nslots = (int)(nargs*2);  /* Only matters for more than four args. */
+  } else {
+    int ngpr = REGARG_NUMGPR, nfpr = REGARG_NUMFPR;
+    for (i = 0; i < nargs; i++)
+      if (args[i] && irt_isfp(IR(args[i])->t)) {
+	if (nfpr > 0) nfpr--; else nslots += 2;
+      } else {
+	if (ngpr > 0) ngpr--; else nslots += 2;
+      }
+  }
+#else
+  int ngpr = 0;
+  if ((ci->flags & CCI_CC_MASK) == CCI_CC_FASTCALL)
+    ngpr = 2;
+  else if ((ci->flags & CCI_CC_MASK) == CCI_CC_THISCALL)
+    ngpr = 1;
+  for (i = 0; i < nargs; i++)
+    if (args[i] && irt_isfp(IR(args[i])->t)) {
+      nslots += irt_isnum(IR(args[i])->t) ? 2 : 1;
+    } else {
+      if (ngpr > 0) ngpr--; else nslots++;
+    }
+#endif
+  return nslots;
+}
+
+/* Generate a call to a C function. */
+static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
+{
+  uint32_t n, nargs = CCI_XNARGS(ci);
+  int32_t ofs = STACKARG_OFS;
+#if LJ_64
+  uint32_t gprs = REGARG_GPRS;
+  Reg fpr = REGARG_FIRSTFPR;
+#if !LJ_ABI_WIN
+  MCode *patchnfpr = NULL;
+#endif
+#else
+  uint32_t gprs = 0;
+  if ((ci->flags & CCI_CC_MASK) != CCI_CC_CDECL) {
+    if ((ci->flags & CCI_CC_MASK) == CCI_CC_THISCALL)
+      gprs = (REGARG_GPRS & 31);
+    else if ((ci->flags & CCI_CC_MASK) == CCI_CC_FASTCALL)
+      gprs = REGARG_GPRS;
+  }
+#endif
+  if ((void *)ci->func)
+    emit_call(as, ci->func);
+#if LJ_64
+  if ((ci->flags & CCI_VARARG)) {  /* Special handling for vararg calls. */
+#if LJ_ABI_WIN
+    for (n = 0; n < 4 && n < nargs; n++) {
+      IRIns *ir = IR(args[n]);
+      if (irt_isfp(ir->t))  /* Duplicate FPRs in GPRs. */
+	emit_rr(as, XO_MOVDto, (irt_isnum(ir->t) ? REX_64 : 0) | (fpr+n),
+		((gprs >> (n*5)) & 31));  /* Either MOVD or MOVQ. */
+    }
+#else
+    patchnfpr = --as->mcp;  /* Indicate number of used FPRs in register al. */
+    *--as->mcp = XI_MOVrib | RID_EAX;
+#endif
+  }
+#endif
+  for (n = 0; n < nargs; n++) {  /* Setup args. */
+    IRRef ref = args[n];
+    IRIns *ir = IR(ref);
+    Reg r;
+#if LJ_64 && LJ_ABI_WIN
+    /* Windows/x64 argument registers are strictly positional. */
+    r = irt_isfp(ir->t) ? (fpr <= REGARG_LASTFPR ? fpr : 0) : (gprs & 31);
+    fpr++; gprs >>= 5;
+#elif LJ_64
+    /* POSIX/x64 argument registers are used in order of appearance. */
+    if (irt_isfp(ir->t)) {
+      r = fpr <= REGARG_LASTFPR ? fpr++ : 0;
+    } else {
+      r = gprs & 31; gprs >>= 5;
+    }
+#else
+    if (ref && irt_isfp(ir->t)) {
+      r = 0;
+    } else {
+      r = gprs & 31; gprs >>= 5;
+      if (!ref) continue;
+    }
+#endif
+    if (r) {  /* Argument is in a register. */
+      if (r < RID_MAX_GPR && ref < ASMREF_TMP1) {
+#if LJ_64
+	if (LJ_GC64 ? !(ir->o == IR_KINT || ir->o == IR_KNULL) : ir->o == IR_KINT64)
+	  emit_loadu64(as, r, ir_k64(ir)->u64);
+	else
+#endif
+	  emit_loadi(as, r, ir->i);
+      } else {
+	/* Must have been evicted. */
+	lj_assertA(rset_test(as->freeset, r), "reg %d not free", r);
+	if (ra_hasreg(ir->r)) {
+	  ra_noweak(as, ir->r);
+	  emit_movrr(as, ir, r, ir->r);
+	} else {
+	  ra_allocref(as, ref, RID2RSET(r));
+	}
+      }
+    } else if (irt_isfp(ir->t)) {  /* FP argument is on stack. */
+      lj_assertA(!(irt_isfloat(ir->t) && irref_isk(ref)),
+		 "unexpected float constant");
+      if (LJ_32 && (ofs & 4) && irref_isk(ref)) {
+	/* Split stores for unaligned FP consts. */
+	emit_movmroi(as, RID_ESP, ofs, (int32_t)ir_knum(ir)->u32.lo);
+	emit_movmroi(as, RID_ESP, ofs+4, (int32_t)ir_knum(ir)->u32.hi);
+      } else {
+	r = ra_alloc1(as, ref, RSET_FPR);
+	emit_rmro(as, irt_isnum(ir->t) ? XO_MOVSDto : XO_MOVSSto,
+		  r, RID_ESP, ofs);
+      }
+      ofs += (LJ_32 && irt_isfloat(ir->t)) ? 4 : 8;
+    } else {  /* Non-FP argument is on stack. */
+      if (LJ_32 && ref < ASMREF_TMP1) {
+	emit_movmroi(as, RID_ESP, ofs, ir->i);
+      } else {
+	r = ra_alloc1(as, ref, RSET_GPR);
+	emit_movtomro(as, REX_64 + r, RID_ESP, ofs);
+      }
+      ofs += sizeof(intptr_t);
+    }
+    checkmclim(as);
+  }
+#if LJ_64 && !LJ_ABI_WIN
+  if (patchnfpr) *patchnfpr = fpr - REGARG_FIRSTFPR;
+#endif
+}
+
+/* Setup result reg/sp for call. Evict scratch regs. */
+static void asm_setupresult(ASMState *as, IRIns *ir, const CCallInfo *ci)
+{
+  RegSet drop = RSET_SCRATCH;
+  int hiop = ((ir+1)->o == IR_HIOP && !irt_isnil((ir+1)->t));
+  if ((ci->flags & CCI_NOFPRCLOBBER))
+    drop &= ~RSET_FPR;
+  if (ra_hasreg(ir->r))
+    rset_clear(drop, ir->r);  /* Dest reg handled below. */
+  if (hiop && ra_hasreg((ir+1)->r))
+    rset_clear(drop, (ir+1)->r);  /* Dest reg handled below. */
+  ra_evictset(as, drop);  /* Evictions must be performed first. */
+  if (ra_used(ir)) {
+    if (irt_isfp(ir->t)) {
+      int32_t ofs = sps_scale(ir->s);  /* Use spill slot or temp slots. */
+#if LJ_64
+      if ((ci->flags & CCI_CASTU64)) {
+	Reg dest = ir->r;
+	if (ra_hasreg(dest)) {
+	  ra_free(as, dest);
+	  ra_modified(as, dest);
+	  emit_rr(as, XO_MOVD, dest|REX_64, RID_RET);  /* Really MOVQ. */
+	}
+	if (ofs) emit_movtomro(as, RID_RET|REX_64, RID_ESP, ofs);
+      } else {
+	ra_destreg(as, ir, RID_FPRET);
+      }
+#else
+      /* Number result is in x87 st0 for x86 calling convention. */
+      Reg dest = ir->r;
+      if (ra_hasreg(dest)) {
+	ra_free(as, dest);
+	ra_modified(as, dest);
+	emit_rmro(as, irt_isnum(ir->t) ? XO_MOVSD : XO_MOVSS,
+		  dest, RID_ESP, ofs);
+      }
+      if ((ci->flags & CCI_CASTU64)) {
+	emit_movtomro(as, RID_RETLO, RID_ESP, ofs);
+	emit_movtomro(as, RID_RETHI, RID_ESP, ofs+4);
+      } else {
+	emit_rmro(as, irt_isnum(ir->t) ? XO_FSTPq : XO_FSTPd,
+		  irt_isnum(ir->t) ? XOg_FSTPq : XOg_FSTPd, RID_ESP, ofs);
+      }
+#endif
+    } else if (hiop) {
+      ra_destpair(as, ir);
+    } else {
+      lj_assertA(!irt_ispri(ir->t), "PRI dest");
+      ra_destreg(as, ir, RID_RET);
+    }
+  } else if (LJ_32 && irt_isfp(ir->t) && !(ci->flags & CCI_CASTU64)) {
+    emit_x87op(as, XI_FPOP);  /* Pop unused result from x87 st0. */
+  }
+}
+
+/* Return a constant function pointer or NULL for indirect calls. */
+static void *asm_callx_func(ASMState *as, IRIns *irf, IRRef func)
+{
+#if LJ_32
+  UNUSED(as);
+  if (irref_isk(func))
+    return (void *)irf->i;
+#else
+  if (irref_isk(func)) {
+    MCode *p;
+    if (irf->o == IR_KINT64)
+      p = (MCode *)(void *)ir_k64(irf)->u64;
+    else
+      p = (MCode *)(void *)(uintptr_t)(uint32_t)irf->i;
+    if (p - as->mcp == (int32_t)(p - as->mcp))
+      return p;  /* Call target is still in +-2GB range. */
+    /* Avoid the indirect case of emit_call(). Try to hoist func addr. */
+  }
+#endif
+  return NULL;
+}
+
+static void asm_callx(ASMState *as, IRIns *ir)
+{
+  IRRef args[CCI_NARGS_MAX*2];
+  CCallInfo ci;
+  IRRef func;
+  IRIns *irf;
+  int32_t spadj = 0;
+  ci.flags = asm_callx_flags(as, ir);
+  asm_collectargs(as, ir, &ci, args);
+  asm_setupresult(as, ir, &ci);
+#if LJ_32
+  /* Have to readjust stack after non-cdecl calls due to callee cleanup. */
+  if ((ci.flags & CCI_CC_MASK) != CCI_CC_CDECL)
+    spadj = 4 * asm_count_call_slots(as, &ci, args);
+#endif
+  func = ir->op2; irf = IR(func);
+  if (irf->o == IR_CARG) { func = irf->op1; irf = IR(func); }
+  ci.func = (ASMFunction)asm_callx_func(as, irf, func);
+  if (!(void *)ci.func) {
+    /* Use a (hoistable) non-scratch register for indirect calls. */
+    RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
+    Reg r = ra_alloc1(as, func, allow);
+    if (LJ_32) emit_spsub(as, spadj);  /* Above code may cause restores! */
+    emit_rr(as, XO_GROUP5, XOg_CALL, r);
+  } else if (LJ_32) {
+    emit_spsub(as, spadj);
+  }
+  asm_gencall(as, &ci, args);
+}
+
+/* -- Returns ------------------------------------------------------------- */
+
+/* Return to lower frame. Guard that it goes to the right spot. */
+static void asm_retf(ASMState *as, IRIns *ir)
+{
+  Reg base = ra_alloc1(as, REF_BASE, RSET_GPR);
+#if LJ_FR2
+  Reg rpc = ra_scratch(as, rset_exclude(RSET_GPR, base));
+#endif
+  void *pc = ir_kptr(IR(ir->op2));
+  int32_t delta = 1+LJ_FR2+bc_a(*((const BCIns *)pc - 1));
+  as->topslot -= (BCReg)delta;
+  if ((int32_t)as->topslot < 0) as->topslot = 0;
+  irt_setmark(IR(REF_BASE)->t);  /* Children must not coalesce with BASE reg. */
+  emit_setgl(as, base, jit_base);
+  emit_addptr(as, base, -8*delta);
+  asm_guardcc(as, CC_NE);
+#if LJ_FR2
+  emit_rmro(as, XO_CMP, rpc|REX_GC64, base, -8);
+  emit_loadu64(as, rpc, u64ptr(pc));
+#else
+  emit_gmroi(as, XG_ARITHi(XOg_CMP), base, -4, ptr2addr(pc));
+#endif
+}
+
+/* -- Buffer operations --------------------------------------------------- */
+
+#if LJ_HASBUFFER
+static void asm_bufhdr_write(ASMState *as, Reg sb)
+{
+  Reg tmp = ra_scratch(as, rset_exclude(RSET_GPR, sb));
+  IRIns irgc;
+  irgc.ot = IRT(0, IRT_PGC);  /* GC type. */
+  emit_storeofs(as, &irgc, tmp, sb, offsetof(SBuf, L));
+  emit_opgl(as, XO_ARITH(XOg_OR), tmp|REX_GC64, cur_L);
+  emit_gri(as, XG_ARITHi(XOg_AND), tmp, SBUF_MASK_FLAG);
+  emit_loadofs(as, &irgc, tmp, sb, offsetof(SBuf, L));
+}
+#endif
+
+/* -- Type conversions ---------------------------------------------------- */
+
+static void asm_tointg(ASMState *as, IRIns *ir, Reg left)
+{
+  Reg tmp = ra_scratch(as, rset_exclude(RSET_FPR, left));
+  Reg dest = ra_dest(as, ir, RSET_GPR);
+  asm_guardcc(as, CC_P);
+  asm_guardcc(as, CC_NE);
+  emit_rr(as, XO_UCOMISD, left, tmp);
+  emit_rr(as, XO_CVTSI2SD, tmp, dest);
+  emit_rr(as, XO_XORPS, tmp, tmp);  /* Avoid partial register stall. */
+  emit_rr(as, XO_CVTTSD2SI, dest, left);
+  /* Can't fuse since left is needed twice. */
+}
+
+static void asm_tobit(ASMState *as, IRIns *ir)
+{
+  Reg dest = ra_dest(as, ir, RSET_GPR);
+  Reg tmp = ra_noreg(IR(ir->op1)->r) ?
+	      ra_alloc1(as, ir->op1, RSET_FPR) :
+	      ra_scratch(as, RSET_FPR);
+  Reg right;
+  emit_rr(as, XO_MOVDto, tmp, dest);
+  right = asm_fuseload(as, ir->op2, rset_exclude(RSET_FPR, tmp));
+  emit_mrm(as, XO_ADDSD, tmp, right);
+  ra_left(as, tmp, ir->op1);
+}
+
+static void asm_conv(ASMState *as, IRIns *ir)
+{
+  IRType st = (IRType)(ir->op2 & IRCONV_SRCMASK);
+  int st64 = (st == IRT_I64 || st == IRT_U64 || (LJ_64 && st == IRT_P64));
+  int stfp = (st == IRT_NUM || st == IRT_FLOAT);
+  IRRef lref = ir->op1;
+  lj_assertA(irt_type(ir->t) != st, "inconsistent types for CONV");
+  lj_assertA(!(LJ_32 && (irt_isint64(ir->t) || st64)),
+	     "IR %04d has unsplit 64 bit type",
+	     (int)(ir - as->ir) - REF_BIAS);
+  if (irt_isfp(ir->t)) {
+    Reg dest = ra_dest(as, ir, RSET_FPR);
+    if (stfp) {  /* FP to FP conversion. */
+      Reg left = asm_fuseload(as, lref, RSET_FPR);
+      emit_mrm(as, st == IRT_NUM ? XO_CVTSD2SS : XO_CVTSS2SD, dest, left);
+      if (left == dest) return;  /* Avoid the XO_XORPS. */
+    } else if (LJ_32 && st == IRT_U32) {  /* U32 to FP conversion on x86. */
+      /* number = (2^52+2^51 .. u32) - (2^52+2^51) */
+      cTValue *k = &as->J->k64[LJ_K64_TOBIT];
+      Reg bias = ra_scratch(as, rset_exclude(RSET_FPR, dest));
+      if (irt_isfloat(ir->t))
+	emit_rr(as, XO_CVTSD2SS, dest, dest);
+      emit_rr(as, XO_SUBSD, dest, bias);  /* Subtract 2^52+2^51 bias. */
+      emit_rr(as, XO_XORPS, dest, bias);  /* Merge bias and integer. */
+      emit_rma(as, XO_MOVSD, bias, k);
+      emit_mrm(as, XO_MOVD, dest, asm_fuseload(as, lref, RSET_GPR));
+      return;
+    } else {  /* Integer to FP conversion. */
+      Reg left = (LJ_64 && (st == IRT_U32 || st == IRT_U64)) ?
+		 ra_alloc1(as, lref, RSET_GPR) :
+		 asm_fuseloadm(as, lref, RSET_GPR, st64);
+      if (LJ_64 && st == IRT_U64) {
+	MCLabel l_end = emit_label(as);
+	cTValue *k = &as->J->k64[LJ_K64_2P64];
+	emit_rma(as, XO_ADDSD, dest, k);  /* Add 2^64 to compensate. */
+	emit_sjcc(as, CC_NS, l_end);
+	emit_rr(as, XO_TEST, left|REX_64, left);  /* Check if u64 >= 2^63. */
+      }
+      emit_mrm(as, irt_isnum(ir->t) ? XO_CVTSI2SD : XO_CVTSI2SS,
+	       dest|((LJ_64 && (st64 || st == IRT_U32)) ? REX_64 : 0), left);
+    }
+    emit_rr(as, XO_XORPS, dest, dest);  /* Avoid partial register stall. */
+  } else if (stfp) {  /* FP to integer conversion. */
+    if (irt_isguard(ir->t)) {
+      /* Checked conversions are only supported from number to int. */
+      lj_assertA(irt_isint(ir->t) && st == IRT_NUM,
+		 "bad type for checked CONV");
+      asm_tointg(as, ir, ra_alloc1(as, lref, RSET_FPR));
+    } else {
+      Reg dest = ra_dest(as, ir, RSET_GPR);
+      x86Op op = st == IRT_NUM ? XO_CVTTSD2SI : XO_CVTTSS2SI;
+      if (LJ_64 ? irt_isu64(ir->t) : irt_isu32(ir->t)) {
+	/* LJ_64: For inputs >= 2^63 add -2^64, convert again. */
+	/* LJ_32: For inputs >= 2^31 add -2^31, convert again and add 2^31. */
+	Reg tmp = ra_noreg(IR(lref)->r) ? ra_alloc1(as, lref, RSET_FPR) :
+					  ra_scratch(as, RSET_FPR);
+	MCLabel l_end = emit_label(as);
+	if (LJ_32)
+	  emit_gri(as, XG_ARITHi(XOg_ADD), dest, (int32_t)0x80000000);
+	emit_rr(as, op, dest|REX_64, tmp);
+	if (st == IRT_NUM)
+	  emit_rma(as, XO_ADDSD, tmp, &as->J->k64[LJ_K64_M2P64_31]);
+	else
+	  emit_rma(as, XO_ADDSS, tmp, &as->J->k32[LJ_K32_M2P64_31]);
+	emit_sjcc(as, CC_NS, l_end);
+	emit_rr(as, XO_TEST, dest|REX_64, dest);  /* Check if dest negative. */
+	emit_rr(as, op, dest|REX_64, tmp);
+	ra_left(as, tmp, lref);
+      } else {
+	if (LJ_64 && irt_isu32(ir->t))
+	  emit_rr(as, XO_MOV, dest, dest);  /* Zero hiword. */
+	emit_mrm(as, op,
+		 dest|((LJ_64 &&
+			(irt_is64(ir->t) || irt_isu32(ir->t))) ? REX_64 : 0),
+		 asm_fuseload(as, lref, RSET_FPR));
+      }
+    }
+  } else if (st >= IRT_I8 && st <= IRT_U16) {  /* Extend to 32 bit integer. */
+    Reg left, dest = ra_dest(as, ir, RSET_GPR);
+    RegSet allow = RSET_GPR;
+    x86Op op;
+    lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t), "bad type for CONV EXT");
+    if (st == IRT_I8) {
+      op = XO_MOVSXb; allow = RSET_GPR8; dest |= FORCE_REX;
+    } else if (st == IRT_U8) {
+      op = XO_MOVZXb; allow = RSET_GPR8; dest |= FORCE_REX;
+    } else if (st == IRT_I16) {
+      op = XO_MOVSXw;
+    } else {
+      op = XO_MOVZXw;
+    }
+    left = asm_fuseload(as, lref, allow);
+    /* Add extra MOV if source is already in wrong register. */
+    if (!LJ_64 && left != RID_MRM && !rset_test(allow, left)) {
+      Reg tmp = ra_scratch(as, allow);
+      emit_rr(as, op, dest, tmp);
+      emit_rr(as, XO_MOV, tmp, left);
+    } else {
+      emit_mrm(as, op, dest, left);
+    }
+  } else {  /* 32/64 bit integer conversions. */
+    if (LJ_32) {  /* Only need to handle 32/32 bit no-op (cast) on x86. */
+      Reg dest = ra_dest(as, ir, RSET_GPR);
+      ra_left(as, dest, lref);  /* Do nothing, but may need to move regs. */
+    } else if (irt_is64(ir->t)) {
+      Reg dest = ra_dest(as, ir, RSET_GPR);
+      if (st64 || !(ir->op2 & IRCONV_SEXT)) {
+	/* 64/64 bit no-op (cast) or 32 to 64 bit zero extension. */
+	ra_left(as, dest, lref);  /* Do nothing, but may need to move regs. */
+      } else {  /* 32 to 64 bit sign extension. */
+	Reg left = asm_fuseload(as, lref, RSET_GPR);
+	emit_mrm(as, XO_MOVSXd, dest|REX_64, left);
+      }
+    } else {
+      Reg dest = ra_dest(as, ir, RSET_GPR);
+      if (st64 && !(ir->op2 & IRCONV_NONE)) {
+	Reg left = asm_fuseload(as, lref, RSET_GPR);
+	/* This is either a 32 bit reg/reg mov which zeroes the hiword
+	** or a load of the loword from a 64 bit address.
+	*/
+	emit_mrm(as, XO_MOV, dest, left);
+      } else {  /* 32/32 bit no-op (cast). */
+	ra_left(as, dest, lref);  /* Do nothing, but may need to move regs. */
+      }
+    }
+  }
+}
+
+#if LJ_32 && LJ_HASFFI
+/* No SSE conversions to/from 64 bit on x86, so resort to ugly x87 code. */
+
+/* 64 bit integer to FP conversion in 32 bit mode. */
+static void asm_conv_fp_int64(ASMState *as, IRIns *ir)
+{
+  Reg hi = ra_alloc1(as, ir->op1, RSET_GPR);
+  Reg lo = ra_alloc1(as, (ir-1)->op1, rset_exclude(RSET_GPR, hi));
+  int32_t ofs = sps_scale(ir->s);  /* Use spill slot or temp slots. */
+  Reg dest = ir->r;
+  if (ra_hasreg(dest)) {
+    ra_free(as, dest);
+    ra_modified(as, dest);
+    emit_rmro(as, irt_isnum(ir->t) ? XO_MOVSD : XO_MOVSS, dest, RID_ESP, ofs);
+  }
+  emit_rmro(as, irt_isnum(ir->t) ? XO_FSTPq : XO_FSTPd,
+	    irt_isnum(ir->t) ? XOg_FSTPq : XOg_FSTPd, RID_ESP, ofs);
+  if (((ir-1)->op2 & IRCONV_SRCMASK) == IRT_U64) {
+    /* For inputs in [2^63,2^64-1] add 2^64 to compensate. */
+    MCLabel l_end = emit_label(as);
+    emit_rma(as, XO_FADDq, XOg_FADDq, &as->J->k64[LJ_K64_2P64]);
+    emit_sjcc(as, CC_NS, l_end);
+    emit_rr(as, XO_TEST, hi, hi);  /* Check if u64 >= 2^63. */
+  } else {
+    lj_assertA(((ir-1)->op2 & IRCONV_SRCMASK) == IRT_I64, "bad type for CONV");
+  }
+  emit_rmro(as, XO_FILDq, XOg_FILDq, RID_ESP, 0);
+  /* NYI: Avoid narrow-to-wide store-to-load forwarding stall. */
+  emit_rmro(as, XO_MOVto, hi, RID_ESP, 4);
+  emit_rmro(as, XO_MOVto, lo, RID_ESP, 0);
+}
+
+/* FP to 64 bit integer conversion in 32 bit mode. */
+static void asm_conv_int64_fp(ASMState *as, IRIns *ir)
+{
+  IRType st = (IRType)((ir-1)->op2 & IRCONV_SRCMASK);
+  IRType dt = (((ir-1)->op2 & IRCONV_DSTMASK) >> IRCONV_DSH);
+  Reg lo, hi;
+  lj_assertA(st == IRT_NUM || st == IRT_FLOAT, "bad type for CONV");
+  lj_assertA(dt == IRT_I64 || dt == IRT_U64, "bad type for CONV");
+  hi = ra_dest(as, ir, RSET_GPR);
+  lo = ra_dest(as, ir-1, rset_exclude(RSET_GPR, hi));
+  if (ra_used(ir-1)) emit_rmro(as, XO_MOV, lo, RID_ESP, 0);
+  /* NYI: Avoid wide-to-narrow store-to-load forwarding stall. */
+  if (!(as->flags & JIT_F_SSE3)) {  /* Set FPU rounding mode to default. */
+    emit_rmro(as, XO_FLDCW, XOg_FLDCW, RID_ESP, 4);
+    emit_rmro(as, XO_MOVto, lo, RID_ESP, 4);
+    emit_gri(as, XG_ARITHi(XOg_AND), lo, 0xf3ff);
+  }
+  if (dt == IRT_U64) {
+    /* For inputs in [2^63,2^64-1] add -2^64 and convert again. */
+    MCLabel l_pop, l_end = emit_label(as);
+    emit_x87op(as, XI_FPOP);
+    l_pop = emit_label(as);
+    emit_sjmp(as, l_end);
+    emit_rmro(as, XO_MOV, hi, RID_ESP, 4);
+    if ((as->flags & JIT_F_SSE3))
+      emit_rmro(as, XO_FISTTPq, XOg_FISTTPq, RID_ESP, 0);
+    else
+      emit_rmro(as, XO_FISTPq, XOg_FISTPq, RID_ESP, 0);
+    emit_rma(as, XO_FADDq, XOg_FADDq, &as->J->k64[LJ_K64_M2P64]);
+    emit_sjcc(as, CC_NS, l_pop);
+    emit_rr(as, XO_TEST, hi, hi);  /* Check if out-of-range (2^63). */
+  }
+  emit_rmro(as, XO_MOV, hi, RID_ESP, 4);
+  if ((as->flags & JIT_F_SSE3)) {  /* Truncation is easy with SSE3. */
+    emit_rmro(as, XO_FISTTPq, XOg_FISTTPq, RID_ESP, 0);
+  } else {  /* Otherwise set FPU rounding mode to truncate before the store. */
+    emit_rmro(as, XO_FISTPq, XOg_FISTPq, RID_ESP, 0);
+    emit_rmro(as, XO_FLDCW, XOg_FLDCW, RID_ESP, 0);
+    emit_rmro(as, XO_MOVtow, lo, RID_ESP, 0);
+    emit_rmro(as, XO_ARITHw(XOg_OR), lo, RID_ESP, 0);
+    emit_loadi(as, lo, 0xc00);
+    emit_rmro(as, XO_FNSTCW, XOg_FNSTCW, RID_ESP, 0);
+  }
+  if (dt == IRT_U64)
+    emit_x87op(as, XI_FDUP);
+  emit_mrm(as, st == IRT_NUM ? XO_FLDq : XO_FLDd,
+	   st == IRT_NUM ? XOg_FLDq: XOg_FLDd,
+	   asm_fuseload(as, ir->op1, RSET_EMPTY));
+}
+
+static void asm_conv64(ASMState *as, IRIns *ir)
+{
+  if (irt_isfp(ir->t))
+    asm_conv_fp_int64(as, ir);
+  else
+    asm_conv_int64_fp(as, ir);
+}
+#endif
+
+static void asm_strto(ASMState *as, IRIns *ir)
+{
+  /* Force a spill slot for the destination register (if any). */
+  const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_strscan_num];
+  IRRef args[2];
+  RegSet drop = RSET_SCRATCH;
+  if ((drop & RSET_FPR) != RSET_FPR && ra_hasreg(ir->r))
+    rset_set(drop, ir->r);  /* WIN64 doesn't spill all FPRs. */
+  ra_evictset(as, drop);
+  asm_guardcc(as, CC_E);
+  emit_rr(as, XO_TEST, RID_RET, RID_RET);  /* Test return status. */
+  args[0] = ir->op1;      /* GCstr *str */
+  args[1] = ASMREF_TMP1;  /* TValue *n  */
+  asm_gencall(as, ci, args);
+  /* Store the result to the spill slot or temp slots. */
+  emit_rmro(as, XO_LEA, ra_releasetmp(as, ASMREF_TMP1)|REX_64,
+	    RID_ESP, sps_scale(ir->s));
+}
+
+/* -- Memory references --------------------------------------------------- */
+
+/* Get pointer to TValue. */
+static void asm_tvptr(ASMState *as, Reg dest, IRRef ref, MSize mode)
+{
+  if ((mode & IRTMPREF_IN1)) {
+    IRIns *ir = IR(ref);
+    if (irt_isnum(ir->t)) {
+      if (irref_isk(ref) && !(mode & IRTMPREF_OUT1)) {
+	/* Use the number constant itself as a TValue. */
+	emit_loada(as, dest, ir_knum(ir));
+	return;
+      }
+      emit_rmro(as, XO_MOVSDto, ra_alloc1(as, ref, RSET_FPR), dest, 0);
+    } else {
+#if LJ_GC64
+      if (irref_isk(ref)) {
+	TValue k;
+	lj_ir_kvalue(as->J->L, &k, ir);
+	emit_movmroi(as, dest, 4, k.u32.hi);
+	emit_movmroi(as, dest, 0, k.u32.lo);
+      } else {
+	/* TODO: 64 bit store + 32 bit load-modify-store is suboptimal. */
+	Reg src = ra_alloc1(as, ref, rset_exclude(RSET_GPR, dest));
+	if (irt_is64(ir->t)) {
+	  emit_u32(as, irt_toitype(ir->t) << 15);
+	  emit_rmro(as, XO_ARITHi, XOg_OR, dest, 4);
+	} else {
+	  emit_movmroi(as, dest, 4, (irt_toitype(ir->t) << 15));
+	}
+	emit_movtomro(as, REX_64IR(ir, src), dest, 0);
+      }
+#else
+      if (!irref_isk(ref)) {
+	Reg src = ra_alloc1(as, ref, rset_exclude(RSET_GPR, dest));
+	emit_movtomro(as, REX_64IR(ir, src), dest, 0);
+      } else if (!irt_ispri(ir->t)) {
+	emit_movmroi(as, dest, 0, ir->i);
+      }
+      if (!(LJ_64 && irt_islightud(ir->t)))
+	emit_movmroi(as, dest, 4, irt_toitype(ir->t));
+#endif
+    }
+  }
+  emit_loada(as, dest, &J2G(as->J)->tmptv); /* g->tmptv holds the TValue(s). */
+}
+
+static void asm_aref(ASMState *as, IRIns *ir)
+{
+  Reg dest = ra_dest(as, ir, RSET_GPR);
+  asm_fusearef(as, ir, RSET_GPR);
+  if (!(as->mrm.idx == RID_NONE && as->mrm.ofs == 0))
+    emit_mrm(as, XO_LEA, dest|REX_GC64, RID_MRM);
+  else if (as->mrm.base != dest)
+    emit_rr(as, XO_MOV, dest|REX_GC64, as->mrm.base);
+}
+
+/* Inlined hash lookup. Specialized for key type and for const keys.
+** The equivalent C code is:
+**   Node *n = hashkey(t, key);
+**   do {
+**     if (lj_obj_equal(&n->key, key)) return &n->val;
+**   } while ((n = nextnode(n)));
+**   return niltv(L);
+*/
+static void asm_href(ASMState *as, IRIns *ir, IROp merge)
+{
+  RegSet allow = RSET_GPR;
+  int destused = ra_used(ir);
+  Reg dest = ra_dest(as, ir, allow);
+  Reg tab = ra_alloc1(as, ir->op1, rset_clear(allow, dest));
+  Reg key = RID_NONE, tmp = RID_NONE;
+  IRIns *irkey = IR(ir->op2);
+  int isk = irref_isk(ir->op2);
+  IRType1 kt = irkey->t;
+  uint32_t khash;
+  MCLabel l_end, l_loop, l_next;
+
+  if (!isk) {
+    rset_clear(allow, tab);
+    key = ra_alloc1(as, ir->op2, irt_isnum(kt) ? RSET_FPR : allow);
+    if (LJ_GC64 || !irt_isstr(kt))
+      tmp = ra_scratch(as, rset_exclude(allow, key));
+  }
+
+  /* Key not found in chain: jump to exit (if merged) or load niltv. */
+  l_end = emit_label(as);
+  if (merge == IR_NE)
+    asm_guardcc(as, CC_E);  /* XI_JMP is not found by lj_asm_patchexit. */
+  else if (destused)
+    emit_loada(as, dest, niltvg(J2G(as->J)));
+
+  /* Follow hash chain until the end. */
+  l_loop = emit_sjcc_label(as, CC_NZ);
+  emit_rr(as, XO_TEST, dest|REX_GC64, dest);
+  emit_rmro(as, XO_MOV, dest|REX_GC64, dest, offsetof(Node, next));
+  l_next = emit_label(as);
+
+  /* Type and value comparison. */
+  if (merge == IR_EQ)
+    asm_guardcc(as, CC_E);
+  else
+    emit_sjcc(as, CC_E, l_end);
+  if (irt_isnum(kt)) {
+    if (isk) {
+      /* Assumes -0.0 is already canonicalized to +0.0. */
+      emit_gmroi(as, XG_ARITHi(XOg_CMP), dest, offsetof(Node, key.u32.lo),
+		 (int32_t)ir_knum(irkey)->u32.lo);
+      emit_sjcc(as, CC_NE, l_next);
+      emit_gmroi(as, XG_ARITHi(XOg_CMP), dest, offsetof(Node, key.u32.hi),
+		 (int32_t)ir_knum(irkey)->u32.hi);
+    } else {
+      emit_sjcc(as, CC_P, l_next);
+      emit_rmro(as, XO_UCOMISD, key, dest, offsetof(Node, key.n));
+      emit_sjcc(as, CC_AE, l_next);
+      /* The type check avoids NaN penalties and complaints from Valgrind. */
+#if LJ_64 && !LJ_GC64
+      emit_u32(as, LJ_TISNUM);
+      emit_rmro(as, XO_ARITHi, XOg_CMP, dest, offsetof(Node, key.it));
+#else
+      emit_i8(as, LJ_TISNUM);
+      emit_rmro(as, XO_ARITHi8, XOg_CMP, dest, offsetof(Node, key.it));
+#endif
+    }
+#if LJ_64 && !LJ_GC64
+  } else if (irt_islightud(kt)) {
+    emit_rmro(as, XO_CMP, key|REX_64, dest, offsetof(Node, key.u64));
+#endif
+#if LJ_GC64
+  } else if (irt_isaddr(kt)) {
+    if (isk) {
+      TValue k;
+      k.u64 = ((uint64_t)irt_toitype(irkey->t) << 47) | irkey[1].tv.u64;
+      emit_gmroi(as, XG_ARITHi(XOg_CMP), dest, offsetof(Node, key.u32.lo),
+		 k.u32.lo);
+      emit_sjcc(as, CC_NE, l_next);
+      emit_gmroi(as, XG_ARITHi(XOg_CMP), dest, offsetof(Node, key.u32.hi),
+		 k.u32.hi);
+    } else {
+      emit_rmro(as, XO_CMP, tmp|REX_64, dest, offsetof(Node, key.u64));
+    }
+  } else {
+    lj_assertA(irt_ispri(kt) && !irt_isnil(kt), "bad HREF key type");
+    emit_u32(as, (irt_toitype(kt)<<15)|0x7fff);
+    emit_rmro(as, XO_ARITHi, XOg_CMP, dest, offsetof(Node, key.it));
+#else
+  } else {
+    if (!irt_ispri(kt)) {
+      lj_assertA(irt_isaddr(kt), "bad HREF key type");
+      if (isk)
+	emit_gmroi(as, XG_ARITHi(XOg_CMP), dest, offsetof(Node, key.gcr),
+		   ptr2addr(ir_kgc(irkey)));
+      else
+	emit_rmro(as, XO_CMP, key, dest, offsetof(Node, key.gcr));
+      emit_sjcc(as, CC_NE, l_next);
+    }
+    lj_assertA(!irt_isnil(kt), "bad HREF key type");
+    emit_i8(as, irt_toitype(kt));
+    emit_rmro(as, XO_ARITHi8, XOg_CMP, dest, offsetof(Node, key.it));
+#endif
+  }
+  emit_sfixup(as, l_loop);
+  checkmclim(as);
+#if LJ_GC64
+  if (!isk && irt_isaddr(kt)) {
+    emit_rr(as, XO_OR, tmp|REX_64, key);
+    emit_loadu64(as, tmp, (uint64_t)irt_toitype(kt) << 47);
+  }
+#endif
+
+  /* Load main position relative to tab->node into dest. */
+  khash = isk ? ir_khash(as, irkey) : 1;
+  if (khash == 0) {
+    emit_rmro(as, XO_MOV, dest|REX_GC64, tab, offsetof(GCtab, node));
+  } else {
+    emit_rmro(as, XO_ARITH(XOg_ADD), dest|REX_GC64, tab, offsetof(GCtab,node));
+    emit_shifti(as, XOg_SHL, dest, 3);
+    emit_rmrxo(as, XO_LEA, dest, dest, dest, XM_SCALE2, 0);
+    if (isk) {
+      emit_gri(as, XG_ARITHi(XOg_AND), dest, (int32_t)khash);
+      emit_rmro(as, XO_MOV, dest, tab, offsetof(GCtab, hmask));
+    } else if (irt_isstr(kt)) {
+      emit_rmro(as, XO_ARITH(XOg_AND), dest, key, offsetof(GCstr, sid));
+      emit_rmro(as, XO_MOV, dest, tab, offsetof(GCtab, hmask));
+    } else {  /* Must match with hashrot() in lj_tab.c. */
+      emit_rmro(as, XO_ARITH(XOg_AND), dest, tab, offsetof(GCtab, hmask));
+      emit_rr(as, XO_ARITH(XOg_SUB), dest, tmp);
+      emit_shifti(as, XOg_ROL, tmp, HASH_ROT3);
+      emit_rr(as, XO_ARITH(XOg_XOR), dest, tmp);
+      emit_shifti(as, XOg_ROL, dest, HASH_ROT2);
+      emit_rr(as, XO_ARITH(XOg_SUB), tmp, dest);
+      emit_shifti(as, XOg_ROL, dest, HASH_ROT1);
+      emit_rr(as, XO_ARITH(XOg_XOR), tmp, dest);
+      if (irt_isnum(kt)) {
+	emit_rr(as, XO_ARITH(XOg_ADD), dest, dest);
+#if LJ_64
+	emit_shifti(as, XOg_SHR|REX_64, dest, 32);
+	emit_rr(as, XO_MOV, tmp, dest);
+	emit_rr(as, XO_MOVDto, key|REX_64, dest);
+#else
+	emit_rmro(as, XO_MOV, dest, RID_ESP, ra_spill(as, irkey)+4);
+	emit_rr(as, XO_MOVDto, key, tmp);
+#endif
+      } else {
+	emit_rr(as, XO_MOV, tmp, key);
+#if LJ_GC64
+	checkmclim(as);
+	emit_gri(as, XG_ARITHi(XOg_XOR), dest, irt_toitype(kt) << 15);
+	if ((as->flags & JIT_F_BMI2)) {
+	  emit_i8(as, 32);
+	  emit_mrm(as, XV_RORX|VEX_64, dest, key);
+	} else {
+	  emit_shifti(as, XOg_SHR|REX_64, dest, 32);
+	  emit_rr(as, XO_MOV, dest|REX_64, key|REX_64);
+	}
+#else
+	emit_rmro(as, XO_LEA, dest, key, HASH_BIAS);
+#endif
+      }
+    }
+  }
+}
+
+static void asm_hrefk(ASMState *as, IRIns *ir)
+{
+  IRIns *kslot = IR(ir->op2);
+  IRIns *irkey = IR(kslot->op1);
+  int32_t ofs = (int32_t)(kslot->op2 * sizeof(Node));
+  Reg dest = ra_used(ir) ? ra_dest(as, ir, RSET_GPR) : RID_NONE;
+  Reg node = ra_alloc1(as, ir->op1, RSET_GPR);
+#if !LJ_64
+  MCLabel l_exit;
+#endif
+  lj_assertA(ofs % sizeof(Node) == 0, "unaligned HREFK slot");
+  if (ra_hasreg(dest)) {
+    if (ofs != 0) {
+      if (dest == node)
+	emit_gri(as, XG_ARITHi(XOg_ADD), dest|REX_GC64, ofs);
+      else
+	emit_rmro(as, XO_LEA, dest|REX_GC64, node, ofs);
+    } else if (dest != node) {
+      emit_rr(as, XO_MOV, dest|REX_GC64, node);
+    }
+  }
+  asm_guardcc(as, CC_NE);
+#if LJ_64
+  if (!irt_ispri(irkey->t)) {
+    Reg key = ra_scratch(as, rset_exclude(RSET_GPR, node));
+    emit_rmro(as, XO_CMP, key|REX_64, node,
+	       ofs + (int32_t)offsetof(Node, key.u64));
+    lj_assertA(irt_isnum(irkey->t) || irt_isgcv(irkey->t),
+	       "bad HREFK key type");
+    /* Assumes -0.0 is already canonicalized to +0.0. */
+    emit_loadu64(as, key, irt_isnum(irkey->t) ? ir_knum(irkey)->u64 :
+#if LJ_GC64
+			  ((uint64_t)irt_toitype(irkey->t) << 47) |
+			  (uint64_t)ir_kgc(irkey));
+#else
+			  ((uint64_t)irt_toitype(irkey->t) << 32) |
+			  (uint64_t)(uint32_t)ptr2addr(ir_kgc(irkey)));
+#endif
+  } else {
+    lj_assertA(!irt_isnil(irkey->t), "bad HREFK key type");
+#if LJ_GC64
+    emit_i32(as, (irt_toitype(irkey->t)<<15)|0x7fff);
+    emit_rmro(as, XO_ARITHi, XOg_CMP, node,
+	      ofs + (int32_t)offsetof(Node, key.it));
+#else
+    emit_i8(as, irt_toitype(irkey->t));
+    emit_rmro(as, XO_ARITHi8, XOg_CMP, node,
+	      ofs + (int32_t)offsetof(Node, key.it));
+#endif
+  }
+#else
+  l_exit = emit_label(as);
+  if (irt_isnum(irkey->t)) {
+    /* Assumes -0.0 is already canonicalized to +0.0. */
+    emit_gmroi(as, XG_ARITHi(XOg_CMP), node,
+	       ofs + (int32_t)offsetof(Node, key.u32.lo),
+	       (int32_t)ir_knum(irkey)->u32.lo);
+    emit_sjcc(as, CC_NE, l_exit);
+    emit_gmroi(as, XG_ARITHi(XOg_CMP), node,
+	       ofs + (int32_t)offsetof(Node, key.u32.hi),
+	       (int32_t)ir_knum(irkey)->u32.hi);
+  } else {
+    if (!irt_ispri(irkey->t)) {
+      lj_assertA(irt_isgcv(irkey->t), "bad HREFK key type");
+      emit_gmroi(as, XG_ARITHi(XOg_CMP), node,
+		 ofs + (int32_t)offsetof(Node, key.gcr),
+		 ptr2addr(ir_kgc(irkey)));
+      emit_sjcc(as, CC_NE, l_exit);
+    }
+    lj_assertA(!irt_isnil(irkey->t), "bad HREFK key type");
+    emit_i8(as, irt_toitype(irkey->t));
+    emit_rmro(as, XO_ARITHi8, XOg_CMP, node,
+	      ofs + (int32_t)offsetof(Node, key.it));
+  }
+#endif
+}
+
+static void asm_uref(ASMState *as, IRIns *ir)
+{
+  Reg dest = ra_dest(as, ir, RSET_GPR);
+  if (irref_isk(ir->op1)) {
+    GCfunc *fn = ir_kfunc(IR(ir->op1));
+    MRef *v = &gcref(fn->l.uvptr[(ir->op2 >> 8)])->uv.v;
+    emit_rma(as, XO_MOV, dest|REX_GC64, v);
+  } else {
+    Reg uv = ra_scratch(as, RSET_GPR);
+    Reg func = ra_alloc1(as, ir->op1, RSET_GPR);
+    if (ir->o == IR_UREFC) {
+      emit_rmro(as, XO_LEA, dest|REX_GC64, uv, offsetof(GCupval, tv));
+      asm_guardcc(as, CC_NE);
+      emit_i8(as, 1);
+      emit_rmro(as, XO_ARITHib, XOg_CMP, uv, offsetof(GCupval, closed));
+    } else {
+      emit_rmro(as, XO_MOV, dest|REX_GC64, uv, offsetof(GCupval, v));
+    }
+    emit_rmro(as, XO_MOV, uv|REX_GC64, func,
+	      (int32_t)offsetof(GCfuncL, uvptr) +
+	      (int32_t)sizeof(MRef) * (int32_t)(ir->op2 >> 8));
+  }
+}
+
+static void asm_fref(ASMState *as, IRIns *ir)
+{
+  Reg dest = ra_dest(as, ir, RSET_GPR);
+  asm_fusefref(as, ir, RSET_GPR);
+  emit_mrm(as, XO_LEA, dest, RID_MRM);
+}
+
+static void asm_strref(ASMState *as, IRIns *ir)
+{
+  Reg dest = ra_dest(as, ir, RSET_GPR);
+  asm_fusestrref(as, ir, RSET_GPR);
+  if (as->mrm.base == RID_NONE)
+    emit_loadi(as, dest, as->mrm.ofs);
+  else if (as->mrm.base == dest && as->mrm.idx == RID_NONE)
+    emit_gri(as, XG_ARITHi(XOg_ADD), dest|REX_GC64, as->mrm.ofs);
+  else
+    emit_mrm(as, XO_LEA, dest|REX_GC64, RID_MRM);
+}
+
+/* -- Loads and stores ---------------------------------------------------- */
+
+static void asm_fxload(ASMState *as, IRIns *ir)
+{
+  Reg dest = ra_dest(as, ir, irt_isfp(ir->t) ? RSET_FPR : RSET_GPR);
+  x86Op xo;
+  if (ir->o == IR_FLOAD)
+    asm_fusefref(as, ir, RSET_GPR);
+  else
+    asm_fusexref(as, ir->op1, RSET_GPR);
+  /* ir->op2 is ignored -- unaligned loads are ok on x86. */
+  switch (irt_type(ir->t)) {
+  case IRT_I8: xo = XO_MOVSXb; break;
+  case IRT_U8: xo = XO_MOVZXb; break;
+  case IRT_I16: xo = XO_MOVSXw; break;
+  case IRT_U16: xo = XO_MOVZXw; break;
+  case IRT_NUM: xo = XO_MOVSD; break;
+  case IRT_FLOAT: xo = XO_MOVSS; break;
+  default:
+    if (LJ_64 && irt_is64(ir->t))
+      dest |= REX_64;
+    else
+      lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t),
+		 "unsplit 64 bit load");
+    xo = XO_MOV;
+    break;
+  }
+  emit_mrm(as, xo, dest, RID_MRM);
+}
+
+#define asm_fload(as, ir)	asm_fxload(as, ir)
+#define asm_xload(as, ir)	asm_fxload(as, ir)
+
+static void asm_fxstore(ASMState *as, IRIns *ir)
+{
+  RegSet allow = RSET_GPR;
+  Reg src = RID_NONE, osrc = RID_NONE;
+  int32_t k = 0;
+  if (ir->r == RID_SINK)
+    return;
+  /* The IRT_I16/IRT_U16 stores should never be simplified for constant
+  ** values since mov word [mem], imm16 has a length-changing prefix.
+  */
+  if (irt_isi16(ir->t) || irt_isu16(ir->t) || irt_isfp(ir->t) ||
+      !asm_isk32(as, ir->op2, &k)) {
+    RegSet allow8 = irt_isfp(ir->t) ? RSET_FPR :
+		    (irt_isi8(ir->t) || irt_isu8(ir->t)) ? RSET_GPR8 : RSET_GPR;
+    src = osrc = ra_alloc1(as, ir->op2, allow8);
+    if (!LJ_64 && !rset_test(allow8, src)) {  /* Already in wrong register. */
+      rset_clear(allow, osrc);
+      src = ra_scratch(as, allow8);
+    }
+    rset_clear(allow, src);
+  }
+  if (ir->o == IR_FSTORE) {
+    asm_fusefref(as, IR(ir->op1), allow);
+  } else {
+    asm_fusexref(as, ir->op1, allow);
+    if (LJ_32 && ir->o == IR_HIOP) as->mrm.ofs += 4;
+  }
+  if (ra_hasreg(src)) {
+    x86Op xo;
+    switch (irt_type(ir->t)) {
+    case IRT_I8: case IRT_U8: xo = XO_MOVtob; src |= FORCE_REX; break;
+    case IRT_I16: case IRT_U16: xo = XO_MOVtow; break;
+    case IRT_NUM: xo = XO_MOVSDto; break;
+    case IRT_FLOAT: xo = XO_MOVSSto; break;
+#if LJ_64 && !LJ_GC64
+    case IRT_LIGHTUD:
+      /* NYI: mask 64 bit lightuserdata. */
+      lj_assertA(0, "store of lightuserdata");
+#endif
+    default:
+      if (LJ_64 && irt_is64(ir->t))
+	src |= REX_64;
+      else
+	lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t),
+		   "unsplit 64 bit store");
+      xo = XO_MOVto;
+      break;
+    }
+    emit_mrm(as, xo, src, RID_MRM);
+    if (!LJ_64 && src != osrc) {
+      ra_noweak(as, osrc);
+      emit_rr(as, XO_MOV, src, osrc);
+    }
+  } else {
+    if (irt_isi8(ir->t) || irt_isu8(ir->t)) {
+      emit_i8(as, k);
+      emit_mrm(as, XO_MOVmib, 0, RID_MRM);
+    } else {
+      lj_assertA(irt_is64(ir->t) || irt_isint(ir->t) || irt_isu32(ir->t) ||
+		 irt_isaddr(ir->t), "bad store type");
+      emit_i32(as, k);
+      emit_mrm(as, XO_MOVmi, REX_64IR(ir, 0), RID_MRM);
+    }
+  }
+}
+
+#define asm_fstore(as, ir)	asm_fxstore(as, ir)
+#define asm_xstore(as, ir)	asm_fxstore(as, ir)
+
+#if LJ_64 && !LJ_GC64
+static Reg asm_load_lightud64(ASMState *as, IRIns *ir, int typecheck)
+{
+  if (ra_used(ir) || typecheck) {
+    Reg dest = ra_dest(as, ir, RSET_GPR);
+    if (typecheck) {
+      Reg tmp = ra_scratch(as, rset_exclude(RSET_GPR, dest));
+      asm_guardcc(as, CC_NE);
+      emit_i8(as, -2);
+      emit_rr(as, XO_ARITHi8, XOg_CMP, tmp);
+      emit_shifti(as, XOg_SAR|REX_64, tmp, 47);
+      emit_rr(as, XO_MOV, tmp|REX_64, dest);
+    }
+    return dest;
+  } else {
+    return RID_NONE;
+  }
+}
+#endif
+
+static void asm_ahuvload(ASMState *as, IRIns *ir)
+{
+#if LJ_GC64
+  Reg tmp = RID_NONE;
+#endif
+  lj_assertA(irt_isnum(ir->t) || irt_ispri(ir->t) || irt_isaddr(ir->t) ||
+	     (LJ_DUALNUM && irt_isint(ir->t)),
+	     "bad load type %d", irt_type(ir->t));
+#if LJ_64 && !LJ_GC64
+  if (irt_islightud(ir->t)) {
+    Reg dest = asm_load_lightud64(as, ir, 1);
+    if (ra_hasreg(dest)) {
+      asm_fuseahuref(as, ir->op1, RSET_GPR);
+      if (ir->o == IR_VLOAD) as->mrm.ofs += 8 * ir->op2;
+      emit_mrm(as, XO_MOV, dest|REX_64, RID_MRM);
+    }
+    return;
+  } else
+#endif
+  if (ra_used(ir)) {
+    RegSet allow = irt_isnum(ir->t) ? RSET_FPR : RSET_GPR;
+    Reg dest = ra_dest(as, ir, allow);
+    asm_fuseahuref(as, ir->op1, RSET_GPR);
+    if (ir->o == IR_VLOAD) as->mrm.ofs += 8 * ir->op2;
+#if LJ_GC64
+    if (irt_isaddr(ir->t)) {
+      emit_shifti(as, XOg_SHR|REX_64, dest, 17);
+      asm_guardcc(as, CC_NE);
+      emit_i8(as, irt_toitype(ir->t));
+      emit_rr(as, XO_ARITHi8, XOg_CMP, dest);
+      emit_i8(as, XI_O16);
+      if ((as->flags & JIT_F_BMI2)) {
+	emit_i8(as, 47);
+	emit_mrm(as, XV_RORX|VEX_64, dest, RID_MRM);
+      } else {
+	emit_shifti(as, XOg_ROR|REX_64, dest, 47);
+	emit_mrm(as, XO_MOV, dest|REX_64, RID_MRM);
+      }
+      return;
+    } else
+#endif
+    emit_mrm(as, dest < RID_MAX_GPR ? XO_MOV : XO_MOVSD, dest, RID_MRM);
+  } else {
+    RegSet gpr = RSET_GPR;
+#if LJ_GC64
+    if (irt_isaddr(ir->t)) {
+      tmp = ra_scratch(as, RSET_GPR);
+      gpr = rset_exclude(gpr, tmp);
+    }
+#endif
+    asm_fuseahuref(as, ir->op1, gpr);
+    if (ir->o == IR_VLOAD) as->mrm.ofs += 8 * ir->op2;
+  }
+  /* Always do the type check, even if the load result is unused. */
+  as->mrm.ofs += 4;
+  asm_guardcc(as, irt_isnum(ir->t) ? CC_AE : CC_NE);
+  if (LJ_64 && irt_type(ir->t) >= IRT_NUM) {
+    lj_assertA(irt_isinteger(ir->t) || irt_isnum(ir->t),
+	       "bad load type %d", irt_type(ir->t));
+#if LJ_GC64
+    emit_u32(as, LJ_TISNUM << 15);
+#else
+    emit_u32(as, LJ_TISNUM);
+#endif
+    emit_mrm(as, XO_ARITHi, XOg_CMP, RID_MRM);
+#if LJ_GC64
+  } else if (irt_isaddr(ir->t)) {
+    as->mrm.ofs -= 4;
+    emit_i8(as, irt_toitype(ir->t));
+    emit_mrm(as, XO_ARITHi8, XOg_CMP, tmp);
+    emit_shifti(as, XOg_SAR|REX_64, tmp, 47);
+    emit_mrm(as, XO_MOV, tmp|REX_64, RID_MRM);
+  } else if (irt_isnil(ir->t)) {
+    as->mrm.ofs -= 4;
+    emit_i8(as, -1);
+    emit_mrm(as, XO_ARITHi8, XOg_CMP|REX_64, RID_MRM);
+  } else {
+    emit_u32(as, (irt_toitype(ir->t) << 15) | 0x7fff);
+    emit_mrm(as, XO_ARITHi, XOg_CMP, RID_MRM);
+#else
+  } else {
+    emit_i8(as, irt_toitype(ir->t));
+    emit_mrm(as, XO_ARITHi8, XOg_CMP, RID_MRM);
+#endif
+  }
+}
+
+static void asm_ahustore(ASMState *as, IRIns *ir)
+{
+  if (ir->r == RID_SINK)
+    return;
+  if (irt_isnum(ir->t)) {
+    Reg src = ra_alloc1(as, ir->op2, RSET_FPR);
+    asm_fuseahuref(as, ir->op1, RSET_GPR);
+    emit_mrm(as, XO_MOVSDto, src, RID_MRM);
+#if LJ_64 && !LJ_GC64
+  } else if (irt_islightud(ir->t)) {
+    Reg src = ra_alloc1(as, ir->op2, RSET_GPR);
+    asm_fuseahuref(as, ir->op1, rset_exclude(RSET_GPR, src));
+    emit_mrm(as, XO_MOVto, src|REX_64, RID_MRM);
+#endif
+#if LJ_GC64
+  } else if (irref_isk(ir->op2)) {
+    TValue k;
+    lj_ir_kvalue(as->J->L, &k, IR(ir->op2));
+    asm_fuseahuref(as, ir->op1, RSET_GPR);
+    if (tvisnil(&k)) {
+      emit_i32(as, -1);
+      emit_mrm(as, XO_MOVmi, REX_64, RID_MRM);
+    } else {
+      emit_u32(as, k.u32.lo);
+      emit_mrm(as, XO_MOVmi, 0, RID_MRM);
+      as->mrm.ofs += 4;
+      emit_u32(as, k.u32.hi);
+      emit_mrm(as, XO_MOVmi, 0, RID_MRM);
+    }
+#endif
+  } else {
+    IRIns *irr = IR(ir->op2);
+    RegSet allow = RSET_GPR;
+    Reg src = RID_NONE;
+    if (!irref_isk(ir->op2)) {
+      src = ra_alloc1(as, ir->op2, allow);
+      rset_clear(allow, src);
+    }
+    asm_fuseahuref(as, ir->op1, allow);
+    if (ra_hasreg(src)) {
+#if LJ_GC64
+      if (!(LJ_DUALNUM && irt_isinteger(ir->t))) {
+	/* TODO: 64 bit store + 32 bit load-modify-store is suboptimal. */
+	as->mrm.ofs += 4;
+	emit_u32(as, irt_toitype(ir->t) << 15);
+	emit_mrm(as, XO_ARITHi, XOg_OR, RID_MRM);
+	as->mrm.ofs -= 4;
+	emit_mrm(as, XO_MOVto, src|REX_64, RID_MRM);
+	return;
+      }
+#endif
+      emit_mrm(as, XO_MOVto, src, RID_MRM);
+    } else if (!irt_ispri(irr->t)) {
+      lj_assertA(irt_isaddr(ir->t) || (LJ_DUALNUM && irt_isinteger(ir->t)),
+		 "bad store type");
+      emit_i32(as, irr->i);
+      emit_mrm(as, XO_MOVmi, 0, RID_MRM);
+    }
+    as->mrm.ofs += 4;
+#if LJ_GC64
+    lj_assertA(LJ_DUALNUM && irt_isinteger(ir->t), "bad store type");
+    emit_i32(as, LJ_TNUMX << 15);
+#else
+    emit_i32(as, (int32_t)irt_toitype(ir->t));
+#endif
+    emit_mrm(as, XO_MOVmi, 0, RID_MRM);
+  }
+}
+
+static void asm_sload(ASMState *as, IRIns *ir)
+{
+  int32_t ofs = 8*((int32_t)ir->op1-1-LJ_FR2) +
+		(!LJ_FR2 && (ir->op2 & IRSLOAD_FRAME) ? 4 : 0);
+  IRType1 t = ir->t;
+  Reg base;
+  lj_assertA(!(ir->op2 & IRSLOAD_PARENT),
+	     "bad parent SLOAD"); /* Handled by asm_head_side(). */
+  lj_assertA(irt_isguard(t) || !(ir->op2 & IRSLOAD_TYPECHECK),
+	     "inconsistent SLOAD variant");
+  lj_assertA(LJ_DUALNUM ||
+	     !irt_isint(t) ||
+	     (ir->op2 & (IRSLOAD_CONVERT|IRSLOAD_FRAME|IRSLOAD_KEYINDEX)),
+	     "bad SLOAD type");
+  if ((ir->op2 & IRSLOAD_CONVERT) && irt_isguard(t) && irt_isint(t)) {
+    Reg left = ra_scratch(as, RSET_FPR);
+    asm_tointg(as, ir, left);  /* Frees dest reg. Do this before base alloc. */
+    base = ra_alloc1(as, REF_BASE, RSET_GPR);
+    emit_rmro(as, XO_MOVSD, left, base, ofs);
+    t.irt = IRT_NUM;  /* Continue with a regular number type check. */
+#if LJ_64 && !LJ_GC64
+  } else if (irt_islightud(t)) {
+    Reg dest = asm_load_lightud64(as, ir, (ir->op2 & IRSLOAD_TYPECHECK));
+    if (ra_hasreg(dest)) {
+      base = ra_alloc1(as, REF_BASE, RSET_GPR);
+      emit_rmro(as, XO_MOV, dest|REX_64, base, ofs);
+    }
+    return;
+#endif
+  } else if (ra_used(ir)) {
+    RegSet allow = irt_isnum(t) ? RSET_FPR : RSET_GPR;
+    Reg dest = ra_dest(as, ir, allow);
+    base = ra_alloc1(as, REF_BASE, RSET_GPR);
+    lj_assertA(irt_isnum(t) || irt_isint(t) || irt_isaddr(t),
+	       "bad SLOAD type %d", irt_type(t));
+    if ((ir->op2 & IRSLOAD_CONVERT)) {
+      t.irt = irt_isint(t) ? IRT_NUM : IRT_INT;  /* Check for original type. */
+      emit_rmro(as, irt_isint(t) ? XO_CVTSI2SD : XO_CVTTSD2SI, dest, base, ofs);
+    } else {
+#if LJ_GC64
+      if (irt_isaddr(t)) {
+	/* LJ_GC64 type check + tag removal without BMI2 and with BMI2:
+	**
+	**  mov r64, [addr]    rorx r64, [addr], 47
+	**  ror r64, 47
+	**  cmp r16, itype     cmp r16, itype
+	**  jne ->exit         jne ->exit
+	**  shr r64, 16        shr r64, 16
+	*/
+	emit_shifti(as, XOg_SHR|REX_64, dest, 17);
+	if ((ir->op2 & IRSLOAD_TYPECHECK)) {
+	  asm_guardcc(as, CC_NE);
+	  emit_i8(as, irt_toitype(t));
+	  emit_rr(as, XO_ARITHi8, XOg_CMP, dest);
+	  emit_i8(as, XI_O16);
+	}
+	if ((as->flags & JIT_F_BMI2)) {
+	  emit_i8(as, 47);
+	  emit_rmro(as, XV_RORX|VEX_64, dest, base, ofs);
+	} else {
+	  if ((ir->op2 & IRSLOAD_TYPECHECK))
+	    emit_shifti(as, XOg_ROR|REX_64, dest, 47);
+	  else
+	    emit_shifti(as, XOg_SHL|REX_64, dest, 17);
+	  emit_rmro(as, XO_MOV, dest|REX_64, base, ofs);
+	}
+	return;
+      } else
+#endif
+      emit_rmro(as, irt_isnum(t) ? XO_MOVSD : XO_MOV, dest, base, ofs);
+    }
+  } else {
+    if (!(ir->op2 & IRSLOAD_TYPECHECK))
+      return;  /* No type check: avoid base alloc. */
+    base = ra_alloc1(as, REF_BASE, RSET_GPR);
+  }
+  if ((ir->op2 & IRSLOAD_TYPECHECK)) {
+    /* Need type check, even if the load result is unused. */
+    asm_guardcc(as, irt_isnum(t) ? CC_AE : CC_NE);
+    if ((LJ_64 && irt_type(t) >= IRT_NUM) || (ir->op2 & IRSLOAD_KEYINDEX)) {
+      lj_assertA(irt_isinteger(t) || irt_isnum(t),
+		 "bad SLOAD type %d", irt_type(t));
+      emit_u32(as, (ir->op2 & IRSLOAD_KEYINDEX) ? LJ_KEYINDEX :
+		   LJ_GC64 ? (LJ_TISNUM << 15) : LJ_TISNUM);
+      emit_rmro(as, XO_ARITHi, XOg_CMP, base, ofs+4);
+#if LJ_GC64
+    } else if (irt_isnil(t)) {
+      /* LJ_GC64 type check for nil:
+      **
+      **   cmp qword [addr], -1
+      **   jne ->exit
+      */
+      emit_i8(as, -1);
+      emit_rmro(as, XO_ARITHi8, XOg_CMP|REX_64, base, ofs);
+    } else if (irt_ispri(t)) {
+      emit_u32(as, (irt_toitype(t) << 15) | 0x7fff);
+      emit_rmro(as, XO_ARITHi, XOg_CMP, base, ofs+4);
+    } else {
+      /* LJ_GC64 type check only:
+      **
+      **   mov r64, [addr]
+      **   sar r64, 47
+      **   cmp r32, itype
+      **   jne ->exit
+      */
+      Reg tmp = ra_scratch(as, rset_exclude(RSET_GPR, base));
+      emit_i8(as, irt_toitype(t));
+      emit_rr(as, XO_ARITHi8, XOg_CMP, tmp);
+      emit_shifti(as, XOg_SAR|REX_64, tmp, 47);
+      emit_rmro(as, XO_MOV, tmp|REX_64, base, ofs);
+#else
+    } else {
+      emit_i8(as, irt_toitype(t));
+      emit_rmro(as, XO_ARITHi8, XOg_CMP, base, ofs+4);
+#endif
+    }
+  }
+}
+
+/* -- Allocations --------------------------------------------------------- */
+
+#if LJ_HASFFI
+static void asm_cnew(ASMState *as, IRIns *ir)
+{
+  CTState *cts = ctype_ctsG(J2G(as->J));
+  CTypeID id = (CTypeID)IR(ir->op1)->i;
+  CTSize sz;
+  CTInfo info = lj_ctype_info(cts, id, &sz);
+  const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_mem_newgco];
+  IRRef args[4];
+  lj_assertA(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL),
+	     "bad CNEW/CNEWI operands");
+
+  as->gcsteps++;
+  asm_setupresult(as, ir, ci);  /* GCcdata * */
+
+  /* Initialize immutable cdata object. */
+  if (ir->o == IR_CNEWI) {
+    RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
+#if LJ_64
+    Reg r64 = sz == 8 ? REX_64 : 0;
+    if (irref_isk(ir->op2)) {
+      IRIns *irk = IR(ir->op2);
+      uint64_t k = (irk->o == IR_KINT64 ||
+		    (LJ_GC64 && (irk->o == IR_KPTR || irk->o == IR_KKPTR))) ?
+		   ir_k64(irk)->u64 : (uint64_t)(uint32_t)irk->i;
+      if (sz == 4 || checki32((int64_t)k)) {
+	emit_i32(as, (int32_t)k);
+	emit_rmro(as, XO_MOVmi, r64, RID_RET, sizeof(GCcdata));
+      } else {
+	emit_movtomro(as, RID_ECX + r64, RID_RET, sizeof(GCcdata));
+	emit_loadu64(as, RID_ECX, k);
+      }
+    } else {
+      Reg r = ra_alloc1(as, ir->op2, allow);
+      emit_movtomro(as, r + r64, RID_RET, sizeof(GCcdata));
+    }
+#else
+    int32_t ofs = sizeof(GCcdata);
+    if (sz == 8) {
+      ofs += 4; ir++;
+      lj_assertA(ir->o == IR_HIOP, "missing CNEWI HIOP");
+    }
+    do {
+      if (irref_isk(ir->op2)) {
+	emit_movmroi(as, RID_RET, ofs, IR(ir->op2)->i);
+      } else {
+	Reg r = ra_alloc1(as, ir->op2, allow);
+	emit_movtomro(as, r, RID_RET, ofs);
+	rset_clear(allow, r);
+      }
+      if (ofs == sizeof(GCcdata)) break;
+      ofs -= 4; ir--;
+    } while (1);
+#endif
+    lj_assertA(sz == 4 || sz == 8, "bad CNEWI size %d", sz);
+  } else if (ir->op2 != REF_NIL) {  /* Create VLA/VLS/aligned cdata. */
+    ci = &lj_ir_callinfo[IRCALL_lj_cdata_newv];
+    args[0] = ASMREF_L;     /* lua_State *L */
+    args[1] = ir->op1;      /* CTypeID id   */
+    args[2] = ir->op2;      /* CTSize sz    */
+    args[3] = ASMREF_TMP1;  /* CTSize align */
+    asm_gencall(as, ci, args);
+    emit_loadi(as, ra_releasetmp(as, ASMREF_TMP1), (int32_t)ctype_align(info));
+    return;
+  }
+
+  /* Combine initialization of marked, gct and ctypeid. */
+  emit_movtomro(as, RID_ECX, RID_RET, offsetof(GCcdata, marked));
+  emit_gri(as, XG_ARITHi(XOg_OR), RID_ECX,
+	   (int32_t)((~LJ_TCDATA<<8)+(id<<16)));
+  emit_gri(as, XG_ARITHi(XOg_AND), RID_ECX, LJ_GC_WHITES);
+  emit_opgl(as, XO_MOVZXb, RID_ECX, gc.currentwhite);
+
+  args[0] = ASMREF_L;     /* lua_State *L */
+  args[1] = ASMREF_TMP1;  /* MSize size   */
+  asm_gencall(as, ci, args);
+  emit_loadi(as, ra_releasetmp(as, ASMREF_TMP1), (int32_t)(sz+sizeof(GCcdata)));
+}
+#endif
+
+/* -- Write barriers ------------------------------------------------------ */
+
+static void asm_tbar(ASMState *as, IRIns *ir)
+{
+  Reg tab = ra_alloc1(as, ir->op1, RSET_GPR);
+  Reg tmp = ra_scratch(as, rset_exclude(RSET_GPR, tab));
+  MCLabel l_end = emit_label(as);
+  emit_movtomro(as, tmp|REX_GC64, tab, offsetof(GCtab, gclist));
+  emit_setgl(as, tab, gc.grayagain);
+  emit_getgl(as, tmp, gc.grayagain);
+  emit_i8(as, ~LJ_GC_BLACK);
+  emit_rmro(as, XO_ARITHib, XOg_AND, tab, offsetof(GCtab, marked));
+  emit_sjcc(as, CC_Z, l_end);
+  emit_i8(as, LJ_GC_BLACK);
+  emit_rmro(as, XO_GROUP3b, XOg_TEST, tab, offsetof(GCtab, marked));
+}
+
+static void asm_obar(ASMState *as, IRIns *ir)
+{
+  const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_gc_barrieruv];
+  IRRef args[2];
+  MCLabel l_end;
+  Reg obj;
+  /* No need for other object barriers (yet). */
+  lj_assertA(IR(ir->op1)->o == IR_UREFC, "bad OBAR type");
+  ra_evictset(as, RSET_SCRATCH);
+  l_end = emit_label(as);
+  args[0] = ASMREF_TMP1;  /* global_State *g */
+  args[1] = ir->op1;      /* TValue *tv      */
+  asm_gencall(as, ci, args);
+  emit_loada(as, ra_releasetmp(as, ASMREF_TMP1), J2G(as->J));
+  obj = IR(ir->op1)->r;
+  emit_sjcc(as, CC_Z, l_end);
+  emit_i8(as, LJ_GC_WHITES);
+  if (irref_isk(ir->op2)) {
+    GCobj *vp = ir_kgc(IR(ir->op2));
+    emit_rma(as, XO_GROUP3b, XOg_TEST, &vp->gch.marked);
+  } else {
+    Reg val = ra_alloc1(as, ir->op2, rset_exclude(RSET_SCRATCH&RSET_GPR, obj));
+    emit_rmro(as, XO_GROUP3b, XOg_TEST, val, (int32_t)offsetof(GChead, marked));
+  }
+  emit_sjcc(as, CC_Z, l_end);
+  emit_i8(as, LJ_GC_BLACK);
+  emit_rmro(as, XO_GROUP3b, XOg_TEST, obj,
+	    (int32_t)offsetof(GCupval, marked)-(int32_t)offsetof(GCupval, tv));
+}
+
+/* -- FP/int arithmetic and logic operations ------------------------------ */
+
+/* Load reference onto x87 stack. Force a spill to memory if needed. */
+static void asm_x87load(ASMState *as, IRRef ref)
+{
+  IRIns *ir = IR(ref);
+  if (ir->o == IR_KNUM) {
+    cTValue *tv = ir_knum(ir);
+    if (tvispzero(tv))  /* Use fldz only for +0. */
+      emit_x87op(as, XI_FLDZ);
+    else if (tvispone(tv))
+      emit_x87op(as, XI_FLD1);
+    else
+      emit_rma(as, XO_FLDq, XOg_FLDq, tv);
+  } else if (ir->o == IR_CONV && ir->op2 == IRCONV_NUM_INT && !ra_used(ir) &&
+	     !irref_isk(ir->op1) && mayfuse(as, ir->op1)) {
+    IRIns *iri = IR(ir->op1);
+    emit_rmro(as, XO_FILDd, XOg_FILDd, RID_ESP, ra_spill(as, iri));
+  } else {
+    emit_mrm(as, XO_FLDq, XOg_FLDq, asm_fuseload(as, ref, RSET_EMPTY));
+  }
+}
+
+static void asm_fpmath(ASMState *as, IRIns *ir)
+{
+  IRFPMathOp fpm = (IRFPMathOp)ir->op2;
+  if (fpm == IRFPM_SQRT) {
+    Reg dest = ra_dest(as, ir, RSET_FPR);
+    Reg left = asm_fuseload(as, ir->op1, RSET_FPR);
+    emit_mrm(as, XO_SQRTSD, dest, left);
+  } else if (fpm <= IRFPM_TRUNC) {
+    if (as->flags & JIT_F_SSE4_1) {  /* SSE4.1 has a rounding instruction. */
+      Reg dest = ra_dest(as, ir, RSET_FPR);
+      Reg left = asm_fuseload(as, ir->op1, RSET_FPR);
+      /* ROUNDSD has a 4-byte opcode which doesn't fit in x86Op.
+      ** Let's pretend it's a 3-byte opcode, and compensate afterwards.
+      ** This is atrocious, but the alternatives are much worse.
+      */
+      /* Round down/up/trunc == 1001/1010/1011. */
+      emit_i8(as, 0x09 + fpm);
+      emit_mrm(as, XO_ROUNDSD, dest, left);
+      if (LJ_64 && as->mcp[1] != (MCode)(XO_ROUNDSD >> 16)) {
+	as->mcp[0] = as->mcp[1]; as->mcp[1] = 0x0f;  /* Swap 0F and REX. */
+      }
+      *--as->mcp = 0x66;  /* 1st byte of ROUNDSD opcode. */
+    } else {  /* Call helper functions for SSE2 variant. */
+      /* The modified regs must match with the *.dasc implementation. */
+      RegSet drop = RSET_RANGE(RID_XMM0, RID_XMM3+1)|RID2RSET(RID_EAX);
+      if (ra_hasreg(ir->r))
+	rset_clear(drop, ir->r);  /* Dest reg handled below. */
+      ra_evictset(as, drop);
+      ra_destreg(as, ir, RID_XMM0);
+      emit_call(as, fpm == IRFPM_FLOOR ? lj_vm_floor_sse :
+		    fpm == IRFPM_CEIL ? lj_vm_ceil_sse : lj_vm_trunc_sse);
+      ra_left(as, RID_XMM0, ir->op1);
+    }
+  } else {
+    asm_callid(as, ir, IRCALL_lj_vm_floor + fpm);
+  }
+}
+
+static void asm_ldexp(ASMState *as, IRIns *ir)
+{
+  int32_t ofs = sps_scale(ir->s);  /* Use spill slot or temp slots. */
+  Reg dest = ir->r;
+  if (ra_hasreg(dest)) {
+    ra_free(as, dest);
+    ra_modified(as, dest);
+    emit_rmro(as, XO_MOVSD, dest, RID_ESP, ofs);
+  }
+  emit_rmro(as, XO_FSTPq, XOg_FSTPq, RID_ESP, ofs);
+  emit_x87op(as, XI_FPOP1);
+  emit_x87op(as, XI_FSCALE);
+  asm_x87load(as, ir->op1);
+  asm_x87load(as, ir->op2);
+}
+
+static int asm_swapops(ASMState *as, IRIns *ir)
+{
+  IRIns *irl = IR(ir->op1);
+  IRIns *irr = IR(ir->op2);
+  lj_assertA(ra_noreg(irr->r), "bad usage");
+  if (!irm_iscomm(lj_ir_mode[ir->o]))
+    return 0;  /* Can't swap non-commutative operations. */
+  if (irref_isk(ir->op2))
+    return 0;  /* Don't swap constants to the left. */
+  if (ra_hasreg(irl->r))
+    return 1;  /* Swap if left already has a register. */
+  if (ra_samehint(ir->r, irr->r))
+    return 1;  /* Swap if dest and right have matching hints. */
+  if (as->curins > as->loopref) {  /* In variant part? */
+    if (ir->op2 < as->loopref && !irt_isphi(irr->t))
+      return 0;  /* Keep invariants on the right. */
+    if (ir->op1 < as->loopref && !irt_isphi(irl->t))
+      return 1;  /* Swap invariants to the right. */
+  }
+  if (opisfusableload(irl->o))
+    return 1;  /* Swap fusable loads to the right. */
+  return 0;  /* Otherwise don't swap. */
+}
+
+static void asm_fparith(ASMState *as, IRIns *ir, x86Op xo)
+{
+  IRRef lref = ir->op1;
+  IRRef rref = ir->op2;
+  RegSet allow = RSET_FPR;
+  Reg dest;
+  Reg right = IR(rref)->r;
+  if (ra_hasreg(right)) {
+    rset_clear(allow, right);
+    ra_noweak(as, right);
+  }
+  dest = ra_dest(as, ir, allow);
+  if (lref == rref) {
+    right = dest;
+  } else if (ra_noreg(right)) {
+    if (asm_swapops(as, ir)) {
+      IRRef tmp = lref; lref = rref; rref = tmp;
+    }
+    right = asm_fuseload(as, rref, rset_clear(allow, dest));
+  }
+  emit_mrm(as, xo, dest, right);
+  ra_left(as, dest, lref);
+}
+
+static void asm_intarith(ASMState *as, IRIns *ir, x86Arith xa)
+{
+  IRRef lref = ir->op1;
+  IRRef rref = ir->op2;
+  RegSet allow = RSET_GPR;
+  Reg dest, right;
+  int32_t k = 0;
+  if (as->flagmcp == as->mcp) {  /* Drop test r,r instruction. */
+    MCode *p = as->mcp + ((LJ_64 && *as->mcp < XI_TESTb) ? 3 : 2);
+    MCode *q = p[0] == 0x0f ? p+1 : p;
+    if ((*q & 15) < 14) {
+      if ((*q & 15) >= 12) *q -= 4;  /* L <->S, NL <-> NS */
+      as->flagmcp = NULL;
+      as->mcp = p;
+    }  /* else: cannot transform LE/NLE to cc without use of OF. */
+  }
+  right = IR(rref)->r;
+  if (ra_hasreg(right)) {
+    rset_clear(allow, right);
+    ra_noweak(as, right);
+  }
+  dest = ra_dest(as, ir, allow);
+  if (lref == rref) {
+    right = dest;
+  } else if (ra_noreg(right) && !asm_isk32(as, rref, &k)) {
+    if (asm_swapops(as, ir)) {
+      IRRef tmp = lref; lref = rref; rref = tmp;
+    }
+    right = asm_fuseloadm(as, rref, rset_clear(allow, dest), irt_is64(ir->t));
+  }
+  if (irt_isguard(ir->t))  /* For IR_ADDOV etc. */
+    asm_guardcc(as, CC_O);
+  if (xa != XOg_X_IMUL) {
+    if (ra_hasreg(right))
+      emit_mrm(as, XO_ARITH(xa), REX_64IR(ir, dest), right);
+    else
+      emit_gri(as, XG_ARITHi(xa), REX_64IR(ir, dest), k);
+  } else if (ra_hasreg(right)) {  /* IMUL r, mrm. */
+    emit_mrm(as, XO_IMUL, REX_64IR(ir, dest), right);
+  } else {  /* IMUL r, r, k. */
+    /* NYI: use lea/shl/add/sub (FOLD only does 2^k) depending on CPU. */
+    Reg left = asm_fuseloadm(as, lref, RSET_GPR, irt_is64(ir->t));
+    x86Op xo;
+    if (checki8(k)) { emit_i8(as, k); xo = XO_IMULi8;
+    } else { emit_i32(as, k); xo = XO_IMULi; }
+    emit_mrm(as, xo, REX_64IR(ir, dest), left);
+    return;
+  }
+  ra_left(as, dest, lref);
+}
+
+/* LEA is really a 4-operand ADD with an independent destination register,
+** up to two source registers and an immediate. One register can be scaled
+** by 1, 2, 4 or 8. This can be used to avoid moves or to fuse several
+** instructions.
+**
+** Currently only a few common cases are supported:
+** - 3-operand ADD:    y = a+b; y = a+k   with a and b already allocated
+** - Left ADD fusion:  y = (a+b)+k; y = (a+k)+b
+** - Right ADD fusion: y = a+(b+k)
+** The ommited variants have already been reduced by FOLD.
+**
+** There are more fusion opportunities, like gathering shifts or joining
+** common references. But these are probably not worth the trouble, since
+** array indexing is not decomposed and already makes use of all fields
+** of the ModRM operand.
+*/
+static int asm_lea(ASMState *as, IRIns *ir)
+{
+  IRIns *irl = IR(ir->op1);
+  IRIns *irr = IR(ir->op2);
+  RegSet allow = RSET_GPR;
+  Reg dest;
+  as->mrm.base = as->mrm.idx = RID_NONE;
+  as->mrm.scale = XM_SCALE1;
+  as->mrm.ofs = 0;
+  if (ra_hasreg(irl->r)) {
+    rset_clear(allow, irl->r);
+    ra_noweak(as, irl->r);
+    as->mrm.base = irl->r;
+    if (irref_isk(ir->op2) || ra_hasreg(irr->r)) {
+      /* The PHI renaming logic does a better job in some cases. */
+      if (ra_hasreg(ir->r) &&
+	  ((irt_isphi(irl->t) && as->phireg[ir->r] == ir->op1) ||
+	   (irt_isphi(irr->t) && as->phireg[ir->r] == ir->op2)))
+	return 0;
+      if (irref_isk(ir->op2)) {
+	as->mrm.ofs = irr->i;
+      } else {
+	rset_clear(allow, irr->r);
+	ra_noweak(as, irr->r);
+	as->mrm.idx = irr->r;
+      }
+    } else if (irr->o == IR_ADD && mayfuse(as, ir->op2) &&
+	       irref_isk(irr->op2)) {
+      Reg idx = ra_alloc1(as, irr->op1, allow);
+      rset_clear(allow, idx);
+      as->mrm.idx = (uint8_t)idx;
+      as->mrm.ofs = IR(irr->op2)->i;
+    } else {
+      return 0;
+    }
+  } else if (ir->op1 != ir->op2 && irl->o == IR_ADD && mayfuse(as, ir->op1) &&
+	     (irref_isk(ir->op2) || irref_isk(irl->op2))) {
+    Reg idx, base = ra_alloc1(as, irl->op1, allow);
+    rset_clear(allow, base);
+    as->mrm.base = (uint8_t)base;
+    if (irref_isk(ir->op2)) {
+      as->mrm.ofs = irr->i;
+      idx = ra_alloc1(as, irl->op2, allow);
+    } else {
+      as->mrm.ofs = IR(irl->op2)->i;
+      idx = ra_alloc1(as, ir->op2, allow);
+    }
+    rset_clear(allow, idx);
+    as->mrm.idx = (uint8_t)idx;
+  } else {
+    return 0;
+  }
+  dest = ra_dest(as, ir, allow);
+  emit_mrm(as, XO_LEA, dest, RID_MRM);
+  return 1;  /* Success. */
+}
+
+static void asm_add(ASMState *as, IRIns *ir)
+{
+  if (irt_isnum(ir->t))
+    asm_fparith(as, ir, XO_ADDSD);
+  else if (as->flagmcp == as->mcp || irt_is64(ir->t) || !asm_lea(as, ir))
+    asm_intarith(as, ir, XOg_ADD);
+}
+
+static void asm_sub(ASMState *as, IRIns *ir)
+{
+  if (irt_isnum(ir->t))
+    asm_fparith(as, ir, XO_SUBSD);
+  else  /* Note: no need for LEA trick here. i-k is encoded as i+(-k). */
+    asm_intarith(as, ir, XOg_SUB);
+}
+
+static void asm_mul(ASMState *as, IRIns *ir)
+{
+  if (irt_isnum(ir->t))
+    asm_fparith(as, ir, XO_MULSD);
+  else
+    asm_intarith(as, ir, XOg_X_IMUL);
+}
+
+#define asm_fpdiv(as, ir)	asm_fparith(as, ir, XO_DIVSD)
+
+static void asm_neg_not(ASMState *as, IRIns *ir, x86Group3 xg)
+{
+  Reg dest = ra_dest(as, ir, RSET_GPR);
+  emit_rr(as, XO_GROUP3, REX_64IR(ir, xg), dest);
+  ra_left(as, dest, ir->op1);
+}
+
+static void asm_neg(ASMState *as, IRIns *ir)
+{
+  if (irt_isnum(ir->t))
+    asm_fparith(as, ir, XO_XORPS);
+  else
+    asm_neg_not(as, ir, XOg_NEG);
+}
+
+#define asm_abs(as, ir)		asm_fparith(as, ir, XO_ANDPS)
+
+static void asm_intmin_max(ASMState *as, IRIns *ir, int cc)
+{
+  Reg right, dest = ra_dest(as, ir, RSET_GPR);
+  IRRef lref = ir->op1, rref = ir->op2;
+  if (irref_isk(rref)) { lref = rref; rref = ir->op1; }
+  right = ra_alloc1(as, rref, rset_exclude(RSET_GPR, dest));
+  emit_rr(as, XO_CMOV + (cc<<24), REX_64IR(ir, dest), right);
+  emit_rr(as, XO_CMP, REX_64IR(ir, dest), right);
+  ra_left(as, dest, lref);
+}
+
+static void asm_min(ASMState *as, IRIns *ir)
+{
+  if (irt_isnum(ir->t))
+    asm_fparith(as, ir, XO_MINSD);
+  else
+    asm_intmin_max(as, ir, CC_G);
+}
+
+static void asm_max(ASMState *as, IRIns *ir)
+{
+  if (irt_isnum(ir->t))
+    asm_fparith(as, ir, XO_MAXSD);
+  else
+    asm_intmin_max(as, ir, CC_L);
+}
+
+/* Note: don't use LEA for overflow-checking arithmetic! */
+#define asm_addov(as, ir)	asm_intarith(as, ir, XOg_ADD)
+#define asm_subov(as, ir)	asm_intarith(as, ir, XOg_SUB)
+#define asm_mulov(as, ir)	asm_intarith(as, ir, XOg_X_IMUL)
+
+#define asm_bnot(as, ir)	asm_neg_not(as, ir, XOg_NOT)
+
+static void asm_bswap(ASMState *as, IRIns *ir)
+{
+  Reg dest = ra_dest(as, ir, RSET_GPR);
+  as->mcp = emit_op(XO_BSWAP + ((dest&7) << 24),
+		    REX_64IR(ir, 0), dest, 0, as->mcp, 1);
+  ra_left(as, dest, ir->op1);
+}
+
+#define asm_band(as, ir)	asm_intarith(as, ir, XOg_AND)
+#define asm_bor(as, ir)		asm_intarith(as, ir, XOg_OR)
+#define asm_bxor(as, ir)	asm_intarith(as, ir, XOg_XOR)
+
+static void asm_bitshift(ASMState *as, IRIns *ir, x86Shift xs, x86Op xv)
+{
+  IRRef rref = ir->op2;
+  IRIns *irr = IR(rref);
+  Reg dest;
+  if (irref_isk(rref)) {  /* Constant shifts. */
+    int shift;
+    dest = ra_dest(as, ir, RSET_GPR);
+    shift = irr->i & (irt_is64(ir->t) ? 63 : 31);
+    if (!xv && shift && (as->flags & JIT_F_BMI2)) {
+      Reg left = asm_fuseloadm(as, ir->op1, RSET_GPR, irt_is64(ir->t));
+      if (left != dest) {  /* BMI2 rotate right by constant. */
+	emit_i8(as, xs == XOg_ROL ? -shift : shift);
+	emit_mrm(as, VEX_64IR(ir, XV_RORX), dest, left);
+	return;
+      }
+    }
+    switch (shift) {
+    case 0: break;
+    case 1: emit_rr(as, XO_SHIFT1, REX_64IR(ir, xs), dest); break;
+    default: emit_shifti(as, REX_64IR(ir, xs), dest, shift); break;
+    }
+  } else if ((as->flags & JIT_F_BMI2) && xv) {	/* BMI2 variable shifts. */
+    Reg left, right;
+    dest = ra_dest(as, ir, RSET_GPR);
+    right = ra_alloc1(as, rref, RSET_GPR);
+    left = asm_fuseloadm(as, ir->op1, rset_exclude(RSET_GPR, right),
+			 irt_is64(ir->t));
+    emit_mrm(as, VEX_64IR(ir, xv) ^ (right << 19), dest, left);
+    return;
+  } else {  /* Variable shifts implicitly use register cl (i.e. ecx). */
+    Reg right;
+    dest = ra_dest(as, ir, rset_exclude(RSET_GPR, RID_ECX));
+    if (dest == RID_ECX) {
+      dest = ra_scratch(as, rset_exclude(RSET_GPR, RID_ECX));
+      emit_rr(as, XO_MOV, REX_64IR(ir, RID_ECX), dest);
+    }
+    right = irr->r;
+    if (ra_noreg(right))
+      right = ra_allocref(as, rref, RID2RSET(RID_ECX));
+    else if (right != RID_ECX)
+      ra_scratch(as, RID2RSET(RID_ECX));
+    emit_rr(as, XO_SHIFTcl, REX_64IR(ir, xs), dest);
+    ra_noweak(as, right);
+    if (right != RID_ECX)
+      emit_rr(as, XO_MOV, RID_ECX, right);
+  }
+  ra_left(as, dest, ir->op1);
+  /*
+  ** Note: avoid using the flags resulting from a shift or rotate!
+  ** All of them cause a partial flag stall, except for r,1 shifts
+  ** (but not rotates). And a shift count of 0 leaves the flags unmodified.
+  */
+}
+
+#define asm_bshl(as, ir)	asm_bitshift(as, ir, XOg_SHL, XV_SHLX)
+#define asm_bshr(as, ir)	asm_bitshift(as, ir, XOg_SHR, XV_SHRX)
+#define asm_bsar(as, ir)	asm_bitshift(as, ir, XOg_SAR, XV_SARX)
+#define asm_brol(as, ir)	asm_bitshift(as, ir, XOg_ROL, 0)
+#define asm_bror(as, ir)	asm_bitshift(as, ir, XOg_ROR, 0)
+
+/* -- Comparisons --------------------------------------------------------- */
+
+/* Virtual flags for unordered FP comparisons. */
+#define VCC_U	0x1000		/* Unordered. */
+#define VCC_P	0x2000		/* Needs extra CC_P branch. */
+#define VCC_S	0x4000		/* Swap avoids CC_P branch. */
+#define VCC_PS	(VCC_P|VCC_S)
+
+/* Map of comparisons to flags. ORDER IR. */
+#define COMPFLAGS(ci, cin, cu, cf)	((ci)+((cu)<<4)+((cin)<<8)+(cf))
+static const uint16_t asm_compmap[IR_ABC+1] = {
+  /*                 signed non-eq unsigned flags */
+  /* LT  */ COMPFLAGS(CC_GE, CC_G,  CC_AE, VCC_PS),
+  /* GE  */ COMPFLAGS(CC_L,  CC_L,  CC_B,  0),
+  /* LE  */ COMPFLAGS(CC_G,  CC_G,  CC_A,  VCC_PS),
+  /* GT  */ COMPFLAGS(CC_LE, CC_L,  CC_BE, 0),
+  /* ULT */ COMPFLAGS(CC_AE, CC_A,  CC_AE, VCC_U),
+  /* UGE */ COMPFLAGS(CC_B,  CC_B,  CC_B,  VCC_U|VCC_PS),
+  /* ULE */ COMPFLAGS(CC_A,  CC_A,  CC_A,  VCC_U),
+  /* UGT */ COMPFLAGS(CC_BE, CC_B,  CC_BE, VCC_U|VCC_PS),
+  /* EQ  */ COMPFLAGS(CC_NE, CC_NE, CC_NE, VCC_P),
+  /* NE  */ COMPFLAGS(CC_E,  CC_E,  CC_E,  VCC_U|VCC_P),
+  /* ABC */ COMPFLAGS(CC_BE, CC_B,  CC_BE, VCC_U|VCC_PS)  /* Same as UGT. */
+};
+
+/* FP and integer comparisons. */
+static void asm_comp(ASMState *as, IRIns *ir)
+{
+  uint32_t cc = asm_compmap[ir->o];
+  if (irt_isnum(ir->t)) {
+    IRRef lref = ir->op1;
+    IRRef rref = ir->op2;
+    Reg left, right;
+    MCLabel l_around;
+    /*
+    ** An extra CC_P branch is required to preserve ordered/unordered
+    ** semantics for FP comparisons. This can be avoided by swapping
+    ** the operands and inverting the condition (except for EQ and UNE).
+    ** So always try to swap if possible.
+    **
+    ** Another option would be to swap operands to achieve better memory
+    ** operand fusion. But it's unlikely that this outweighs the cost
+    ** of the extra branches.
+    */
+    if (cc & VCC_S) {  /* Swap? */
+      IRRef tmp = lref; lref = rref; rref = tmp;
+      cc ^= (VCC_PS|(5<<4));  /* A <-> B, AE <-> BE, PS <-> none */
+    }
+    left = ra_alloc1(as, lref, RSET_FPR);
+    l_around = emit_label(as);
+    asm_guardcc(as, cc >> 4);
+    if (cc & VCC_P) {  /* Extra CC_P branch required? */
+      if (!(cc & VCC_U)) {
+	asm_guardcc(as, CC_P);  /* Branch to exit for ordered comparisons. */
+      } else if (l_around != as->invmcp) {
+	emit_sjcc(as, CC_P, l_around);  /* Branch around for unordered. */
+      } else {
+	/* Patched to mcloop by asm_loop_fixup. */
+	as->loopinv = 2;
+	if (as->realign)
+	  emit_sjcc(as, CC_P, as->mcp);
+	else
+	  emit_jcc(as, CC_P, as->mcp);
+      }
+    }
+    right = asm_fuseload(as, rref, rset_exclude(RSET_FPR, left));
+    emit_mrm(as, XO_UCOMISD, left, right);
+  } else {
+    IRRef lref = ir->op1, rref = ir->op2;
+    IROp leftop = (IROp)(IR(lref)->o);
+    Reg r64 = REX_64IR(ir, 0);
+    int32_t imm = 0;
+    lj_assertA(irt_is64(ir->t) || irt_isint(ir->t) ||
+	       irt_isu32(ir->t) || irt_isaddr(ir->t) || irt_isu8(ir->t),
+	       "bad comparison data type %d", irt_type(ir->t));
+    /* Swap constants (only for ABC) and fusable loads to the right. */
+    if (irref_isk(lref) || (!irref_isk(rref) && opisfusableload(leftop))) {
+      if ((cc & 0xc) == 0xc) cc ^= 0x53;  /* L <-> G, LE <-> GE */
+      else if ((cc & 0xa) == 0x2) cc ^= 0x55;  /* A <-> B, AE <-> BE */
+      lref = ir->op2; rref = ir->op1;
+    }
+    if (asm_isk32(as, rref, &imm)) {
+      IRIns *irl = IR(lref);
+      /* Check wether we can use test ins. Not for unsigned, since CF=0. */
+      int usetest = (imm == 0 && (cc & 0xa) != 0x2);
+      if (usetest && irl->o == IR_BAND && irl+1 == ir && !ra_used(irl)) {
+	/* Combine comp(BAND(ref, r/imm), 0) into test mrm, r/imm. */
+	Reg right, left = RID_NONE;
+	RegSet allow = RSET_GPR;
+	if (!asm_isk32(as, irl->op2, &imm)) {
+	  left = ra_alloc1(as, irl->op2, allow);
+	  rset_clear(allow, left);
+	} else {  /* Try to Fuse IRT_I8/IRT_U8 loads, too. See below. */
+	  IRIns *irll = IR(irl->op1);
+	  if (opisfusableload((IROp)irll->o) &&
+	      (irt_isi8(irll->t) || irt_isu8(irll->t))) {
+	    IRType1 origt = irll->t;  /* Temporarily flip types. */
+	    irll->t.irt = (irll->t.irt & ~IRT_TYPE) | IRT_INT;
+	    as->curins--;  /* Skip to BAND to avoid failing in noconflict(). */
+	    right = asm_fuseload(as, irl->op1, RSET_GPR);
+	    as->curins++;
+	    irll->t = origt;
+	    if (right != RID_MRM) goto test_nofuse;
+	    /* Fusion succeeded, emit test byte mrm, imm8. */
+	    asm_guardcc(as, cc);
+	    emit_i8(as, (imm & 0xff));
+	    emit_mrm(as, XO_GROUP3b, XOg_TEST, RID_MRM);
+	    return;
+	  }
+	}
+	as->curins--;  /* Skip to BAND to avoid failing in noconflict(). */
+	right = asm_fuseloadm(as, irl->op1, allow, r64);
+	as->curins++;  /* Undo the above. */
+      test_nofuse:
+	asm_guardcc(as, cc);
+	if (ra_noreg(left)) {
+	  emit_i32(as, imm);
+	  emit_mrm(as, XO_GROUP3, r64 + XOg_TEST, right);
+	} else {
+	  emit_mrm(as, XO_TEST, r64 + left, right);
+	}
+      } else {
+	Reg left;
+	if (opisfusableload((IROp)irl->o) &&
+	    ((irt_isu8(irl->t) && checku8(imm)) ||
+	     ((irt_isi8(irl->t) || irt_isi16(irl->t)) && checki8(imm)) ||
+	     (irt_isu16(irl->t) && checku16(imm) && checki8((int16_t)imm)))) {
+	  /* Only the IRT_INT case is fused by asm_fuseload.
+	  ** The IRT_I8/IRT_U8 loads and some IRT_I16/IRT_U16 loads
+	  ** are handled here.
+	  ** Note that cmp word [mem], imm16 should not be generated,
+	  ** since it has a length-changing prefix. Compares of a word
+	  ** against a sign-extended imm8 are ok, however.
+	  */
+	  IRType1 origt = irl->t;  /* Temporarily flip types. */
+	  irl->t.irt = (irl->t.irt & ~IRT_TYPE) | IRT_INT;
+	  left = asm_fuseload(as, lref, RSET_GPR);
+	  irl->t = origt;
+	  if (left == RID_MRM) {  /* Fusion succeeded? */
+	    if (irt_isu8(irl->t) || irt_isu16(irl->t))
+	      cc >>= 4;  /* Need unsigned compare. */
+	    asm_guardcc(as, cc);
+	    emit_i8(as, imm);
+	    emit_mrm(as, (irt_isi8(origt) || irt_isu8(origt)) ?
+			 XO_ARITHib : XO_ARITHiw8, r64 + XOg_CMP, RID_MRM);
+	    return;
+	  }  /* Otherwise handle register case as usual. */
+	} else {
+	  left = asm_fuseloadm(as, lref,
+			       irt_isu8(ir->t) ? RSET_GPR8 : RSET_GPR, r64);
+	}
+	asm_guardcc(as, cc);
+	if (usetest && left != RID_MRM) {
+	  /* Use test r,r instead of cmp r,0. */
+	  x86Op xo = XO_TEST;
+	  if (irt_isu8(ir->t)) {
+	    lj_assertA(ir->o == IR_EQ || ir->o == IR_NE, "bad usage");
+	    xo = XO_TESTb;
+	    if (!rset_test(RSET_RANGE(RID_EAX, RID_EBX+1), left)) {
+	      if (LJ_64) {
+		left |= FORCE_REX;
+	      } else {
+		emit_i32(as, 0xff);
+		emit_mrm(as, XO_GROUP3, XOg_TEST, left);
+		return;
+	      }
+	    }
+	  }
+	  emit_rr(as, xo, r64 + left, left);
+	  if (irl+1 == ir)  /* Referencing previous ins? */
+	    as->flagmcp = as->mcp;  /* Set flag to drop test r,r if possible. */
+	} else {
+	  emit_gmrmi(as, XG_ARITHi(XOg_CMP), r64 + left, imm);
+	}
+      }
+    } else {
+      Reg left = ra_alloc1(as, lref, RSET_GPR);
+      Reg right = asm_fuseloadm(as, rref, rset_exclude(RSET_GPR, left), r64);
+      asm_guardcc(as, cc);
+      emit_mrm(as, XO_CMP, r64 + left, right);
+    }
+  }
+}
+
+#define asm_equal(as, ir)	asm_comp(as, ir)
+
+#if LJ_32 && LJ_HASFFI
+/* 64 bit integer comparisons in 32 bit mode. */
+static void asm_comp_int64(ASMState *as, IRIns *ir)
+{
+  uint32_t cc = asm_compmap[(ir-1)->o];
+  RegSet allow = RSET_GPR;
+  Reg lefthi = RID_NONE, leftlo = RID_NONE;
+  Reg righthi = RID_NONE, rightlo = RID_NONE;
+  MCLabel l_around;
+  x86ModRM mrm;
+
+  as->curins--;  /* Skip loword ins. Avoids failing in noconflict(), too. */
+
+  /* Allocate/fuse hiword operands. */
+  if (irref_isk(ir->op2)) {
+    lefthi = asm_fuseload(as, ir->op1, allow);
+  } else {
+    lefthi = ra_alloc1(as, ir->op1, allow);
+    rset_clear(allow, lefthi);
+    righthi = asm_fuseload(as, ir->op2, allow);
+    if (righthi == RID_MRM) {
+      if (as->mrm.base != RID_NONE) rset_clear(allow, as->mrm.base);
+      if (as->mrm.idx != RID_NONE) rset_clear(allow, as->mrm.idx);
+    } else {
+      rset_clear(allow, righthi);
+    }
+  }
+  mrm = as->mrm;  /* Save state for hiword instruction. */
+
+  /* Allocate/fuse loword operands. */
+  if (irref_isk((ir-1)->op2)) {
+    leftlo = asm_fuseload(as, (ir-1)->op1, allow);
+  } else {
+    leftlo = ra_alloc1(as, (ir-1)->op1, allow);
+    rset_clear(allow, leftlo);
+    rightlo = asm_fuseload(as, (ir-1)->op2, allow);
+  }
+
+  /* All register allocations must be performed _before_ this point. */
+  l_around = emit_label(as);
+  as->invmcp = as->flagmcp = NULL;  /* Cannot use these optimizations. */
+
+  /* Loword comparison and branch. */
+  asm_guardcc(as, cc >> 4);  /* Always use unsigned compare for loword. */
+  if (ra_noreg(rightlo)) {
+    int32_t imm = IR((ir-1)->op2)->i;
+    if (imm == 0 && ((cc >> 4) & 0xa) != 0x2 && leftlo != RID_MRM)
+      emit_rr(as, XO_TEST, leftlo, leftlo);
+    else
+      emit_gmrmi(as, XG_ARITHi(XOg_CMP), leftlo, imm);
+  } else {
+    emit_mrm(as, XO_CMP, leftlo, rightlo);
+  }
+
+  /* Hiword comparison and branches. */
+  if ((cc & 15) != CC_NE)
+    emit_sjcc(as, CC_NE, l_around);  /* Hiword unequal: skip loword compare. */
+  if ((cc & 15) != CC_E)
+    asm_guardcc(as, cc >> 8);  /* Hiword compare without equality check. */
+  as->mrm = mrm;  /* Restore state. */
+  if (ra_noreg(righthi)) {
+    int32_t imm = IR(ir->op2)->i;
+    if (imm == 0 && (cc & 0xa) != 0x2 && lefthi != RID_MRM)
+      emit_rr(as, XO_TEST, lefthi, lefthi);
+    else
+      emit_gmrmi(as, XG_ARITHi(XOg_CMP), lefthi, imm);
+  } else {
+    emit_mrm(as, XO_CMP, lefthi, righthi);
+  }
+}
+#endif
+
+/* -- Split register ops -------------------------------------------------- */
+
+/* Hiword op of a split 32/32 or 64/64 bit op. Previous op is the loword op. */
+static void asm_hiop(ASMState *as, IRIns *ir)
+{
+  /* HIOP is marked as a store because it needs its own DCE logic. */
+  int uselo = ra_used(ir-1), usehi = ra_used(ir);  /* Loword/hiword used? */
+  if (LJ_UNLIKELY(!(as->flags & JIT_F_OPT_DCE))) uselo = usehi = 1;
+#if LJ_32 && LJ_HASFFI
+  if ((ir-1)->o == IR_CONV) {  /* Conversions to/from 64 bit. */
+    as->curins--;  /* Always skip the CONV. */
+    if (usehi || uselo)
+      asm_conv64(as, ir);
+    return;
+  } else if ((ir-1)->o <= IR_NE) {  /* 64 bit integer comparisons. ORDER IR. */
+    asm_comp_int64(as, ir);
+    return;
+  } else if ((ir-1)->o == IR_XSTORE) {
+    if ((ir-1)->r != RID_SINK)
+      asm_fxstore(as, ir);
+    return;
+  }
+#endif
+  if (!usehi) return;  /* Skip unused hiword op for all remaining ops. */
+  switch ((ir-1)->o) {
+#if LJ_32 && LJ_HASFFI
+  case IR_ADD:
+    as->flagmcp = NULL;
+    as->curins--;
+    asm_intarith(as, ir, XOg_ADC);
+    asm_intarith(as, ir-1, XOg_ADD);
+    break;
+  case IR_SUB:
+    as->flagmcp = NULL;
+    as->curins--;
+    asm_intarith(as, ir, XOg_SBB);
+    asm_intarith(as, ir-1, XOg_SUB);
+    break;
+  case IR_NEG: {
+    Reg dest = ra_dest(as, ir, RSET_GPR);
+    emit_rr(as, XO_GROUP3, XOg_NEG, dest);
+    emit_i8(as, 0);
+    emit_rr(as, XO_ARITHi8, XOg_ADC, dest);
+    ra_left(as, dest, ir->op1);
+    as->curins--;
+    asm_neg_not(as, ir-1, XOg_NEG);
+    break;
+    }
+  case IR_CNEWI:
+    /* Nothing to do here. Handled by CNEWI itself. */
+    break;
+#endif
+  case IR_CALLN: case IR_CALLL: case IR_CALLS: case IR_CALLXS:
+    if (!uselo)
+      ra_allocref(as, ir->op1, RID2RSET(RID_RETLO));  /* Mark lo op as used. */
+    break;
+  default: lj_assertA(0, "bad HIOP for op %d", (ir-1)->o); break;
+  }
+}
+
+/* -- Profiling ----------------------------------------------------------- */
+
+static void asm_prof(ASMState *as, IRIns *ir)
+{
+  UNUSED(ir);
+  asm_guardcc(as, CC_NE);
+  emit_i8(as, HOOK_PROFILE);
+  emit_rma(as, XO_GROUP3b, XOg_TEST, &J2G(as->J)->hookmask);
+}
+
+/* -- Stack handling ------------------------------------------------------ */
+
+/* Check Lua stack size for overflow. Use exit handler as fallback. */
+static void asm_stack_check(ASMState *as, BCReg topslot,
+			    IRIns *irp, RegSet allow, ExitNo exitno)
+{
+  /* Try to get an unused temp. register, otherwise spill/restore eax. */
+  Reg pbase = irp ? irp->r : RID_BASE;
+  Reg r = allow ? rset_pickbot(allow) : RID_EAX;
+  emit_jcc(as, CC_B, exitstub_addr(as->J, exitno));
+  if (allow == RSET_EMPTY)  /* Restore temp. register. */
+    emit_rmro(as, XO_MOV, r|REX_64, RID_ESP, 0);
+  else
+    ra_modified(as, r);
+  emit_gri(as, XG_ARITHi(XOg_CMP), r|REX_GC64, (int32_t)(8*topslot));
+  if (ra_hasreg(pbase) && pbase != r)
+    emit_rr(as, XO_ARITH(XOg_SUB), r|REX_GC64, pbase);
+  else
+#if LJ_GC64
+    emit_rmro(as, XO_ARITH(XOg_SUB), r|REX_64, RID_DISPATCH,
+	      (int32_t)dispofs(as, &J2G(as->J)->jit_base));
+#else
+    emit_rmro(as, XO_ARITH(XOg_SUB), r, RID_NONE,
+	      ptr2addr(&J2G(as->J)->jit_base));
+#endif
+  emit_rmro(as, XO_MOV, r|REX_GC64, r, offsetof(lua_State, maxstack));
+  emit_getgl(as, r, cur_L);
+  if (allow == RSET_EMPTY)  /* Spill temp. register. */
+    emit_rmro(as, XO_MOVto, r|REX_64, RID_ESP, 0);
+}
+
+/* Restore Lua stack from on-trace state. */
+static void asm_stack_restore(ASMState *as, SnapShot *snap)
+{
+  SnapEntry *map = &as->T->snapmap[snap->mapofs];
+#if !LJ_FR2 || defined(LUA_USE_ASSERT)
+  SnapEntry *flinks = &as->T->snapmap[snap_nextofs(as->T, snap)-1-LJ_FR2];
+#endif
+  MSize n, nent = snap->nent;
+  /* Store the value of all modified slots to the Lua stack. */
+  for (n = 0; n < nent; n++) {
+    SnapEntry sn = map[n];
+    BCReg s = snap_slot(sn);
+    int32_t ofs = 8*((int32_t)s-1-LJ_FR2);
+    IRRef ref = snap_ref(sn);
+    IRIns *ir = IR(ref);
+    if ((sn & SNAP_NORESTORE))
+      continue;
+    if ((sn & SNAP_KEYINDEX)) {
+      emit_movmroi(as, RID_BASE, ofs+4, LJ_KEYINDEX);
+      if (irref_isk(ref)) {
+	emit_movmroi(as, RID_BASE, ofs, ir->i);
+      } else {
+	Reg src = ra_alloc1(as, ref, rset_exclude(RSET_GPR, RID_BASE));
+	emit_movtomro(as, src, RID_BASE, ofs);
+      }
+    } else if (irt_isnum(ir->t)) {
+      Reg src = ra_alloc1(as, ref, RSET_FPR);
+      emit_rmro(as, XO_MOVSDto, src, RID_BASE, ofs);
+    } else {
+      lj_assertA(irt_ispri(ir->t) || irt_isaddr(ir->t) ||
+		 (LJ_DUALNUM && irt_isinteger(ir->t)),
+		 "restore of IR type %d", irt_type(ir->t));
+      if (!irref_isk(ref)) {
+	Reg src = ra_alloc1(as, ref, rset_exclude(RSET_GPR, RID_BASE));
+#if LJ_GC64
+	if (irt_is64(ir->t)) {
+	  /* TODO: 64 bit store + 32 bit load-modify-store is suboptimal. */
+	  emit_u32(as, irt_toitype(ir->t) << 15);
+	  emit_rmro(as, XO_ARITHi, XOg_OR, RID_BASE, ofs+4);
+	} else if (LJ_DUALNUM && irt_isinteger(ir->t)) {
+	  emit_movmroi(as, RID_BASE, ofs+4, LJ_TISNUM << 15);
+	} else {
+	  emit_movmroi(as, RID_BASE, ofs+4, (irt_toitype(ir->t)<<15)|0x7fff);
+	}
+#endif
+	emit_movtomro(as, REX_64IR(ir, src), RID_BASE, ofs);
+#if LJ_GC64
+      } else {
+	TValue k;
+	lj_ir_kvalue(as->J->L, &k, ir);
+	if (tvisnil(&k)) {
+	  emit_i32(as, -1);
+	  emit_rmro(as, XO_MOVmi, REX_64, RID_BASE, ofs);
+	} else {
+	  emit_movmroi(as, RID_BASE, ofs+4, k.u32.hi);
+	  emit_movmroi(as, RID_BASE, ofs, k.u32.lo);
+	}
+#else
+      } else if (!irt_ispri(ir->t)) {
+	emit_movmroi(as, RID_BASE, ofs, ir->i);
+#endif
+      }
+      if ((sn & (SNAP_CONT|SNAP_FRAME))) {
+#if !LJ_FR2
+	if (s != 0)  /* Do not overwrite link to previous frame. */
+	  emit_movmroi(as, RID_BASE, ofs+4, (int32_t)(*flinks--));
+#endif
+#if !LJ_GC64
+      } else {
+	if (!(LJ_64 && irt_islightud(ir->t)))
+	  emit_movmroi(as, RID_BASE, ofs+4, irt_toitype(ir->t));
+#endif
+      }
+    }
+    checkmclim(as);
+  }
+  lj_assertA(map + nent == flinks, "inconsistent frames in snapshot");
+}
+
+/* -- GC handling --------------------------------------------------------- */
+
+/* Check GC threshold and do one or more GC steps. */
+static void asm_gc_check(ASMState *as)
+{
+  const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_gc_step_jit];
+  IRRef args[2];
+  MCLabel l_end;
+  Reg tmp;
+  ra_evictset(as, RSET_SCRATCH);
+  l_end = emit_label(as);
+  /* Exit trace if in GCSatomic or GCSfinalize. Avoids syncing GC objects. */
+  asm_guardcc(as, CC_NE);  /* Assumes asm_snap_prep() already done. */
+  emit_rr(as, XO_TEST, RID_RET, RID_RET);
+  args[0] = ASMREF_TMP1;  /* global_State *g */
+  args[1] = ASMREF_TMP2;  /* MSize steps     */
+  asm_gencall(as, ci, args);
+  tmp = ra_releasetmp(as, ASMREF_TMP1);
+#if LJ_GC64
+  emit_rmro(as, XO_LEA, tmp|REX_64, RID_DISPATCH, GG_DISP2G);
+#else
+  emit_loada(as, tmp, J2G(as->J));
+#endif
+  emit_loadi(as, ra_releasetmp(as, ASMREF_TMP2), as->gcsteps);
+  /* Jump around GC step if GC total < GC threshold. */
+  emit_sjcc(as, CC_B, l_end);
+  emit_opgl(as, XO_ARITH(XOg_CMP), tmp|REX_GC64, gc.threshold);
+  emit_getgl(as, tmp, gc.total);
+  as->gcsteps = 0;
+  checkmclim(as);
+}
+
+/* -- Loop handling ------------------------------------------------------- */
+
+/* Fixup the loop branch. */
+static void asm_loop_fixup(ASMState *as)
+{
+  MCode *p = as->mctop;
+  MCode *target = as->mcp;
+  if (as->realign) {  /* Realigned loops use short jumps. */
+    as->realign = NULL;  /* Stop another retry. */
+    lj_assertA(((intptr_t)target & 15) == 0, "loop realign failed");
+    if (as->loopinv) {  /* Inverted loop branch? */
+      p -= 5;
+      p[0] = XI_JMP;
+      lj_assertA(target - p >= -128, "loop realign failed");
+      p[-1] = (MCode)(target - p);  /* Patch sjcc. */
+      if (as->loopinv == 2)
+	p[-3] = (MCode)(target - p + 2);  /* Patch opt. short jp. */
+    } else {
+      lj_assertA(target - p >= -128, "loop realign failed");
+      p[-1] = (MCode)(int8_t)(target - p);  /* Patch short jmp. */
+      p[-2] = XI_JMPs;
+    }
+  } else {
+    MCode *newloop;
+    p[-5] = XI_JMP;
+    if (as->loopinv) {  /* Inverted loop branch? */
+      /* asm_guardcc already inverted the jcc and patched the jmp. */
+      p -= 5;
+      newloop = target+4;
+      *(int32_t *)(p-4) = (int32_t)(target - p);  /* Patch jcc. */
+      if (as->loopinv == 2) {
+	*(int32_t *)(p-10) = (int32_t)(target - p + 6);  /* Patch opt. jp. */
+	newloop = target+8;
+      }
+    } else {  /* Otherwise just patch jmp. */
+      *(int32_t *)(p-4) = (int32_t)(target - p);
+      newloop = target+3;
+    }
+    /* Realign small loops and shorten the loop branch. */
+    if (newloop >= p - 128) {
+      as->realign = newloop;  /* Force a retry and remember alignment. */
+      as->curins = as->stopins;  /* Abort asm_trace now. */
+      as->T->nins = as->orignins;  /* Remove any added renames. */
+    }
+  }
+}
+
+/* Fixup the tail of the loop. */
+static void asm_loop_tail_fixup(ASMState *as)
+{
+  UNUSED(as);  /* Nothing to do. */
+}
+
+/* -- Head of trace ------------------------------------------------------- */
+
+/* Coalesce BASE register for a root trace. */
+static void asm_head_root_base(ASMState *as)
+{
+  IRIns *ir = IR(REF_BASE);
+  Reg r = ir->r;
+  if (ra_hasreg(r)) {
+    ra_free(as, r);
+    if (rset_test(as->modset, r) || irt_ismarked(ir->t))
+      ir->r = RID_INIT;  /* No inheritance for modified BASE register. */
+    if (r != RID_BASE)
+      emit_rr(as, XO_MOV, r|REX_GC64, RID_BASE);
+  }
+}
+
+/* Coalesce or reload BASE register for a side trace. */
+static RegSet asm_head_side_base(ASMState *as, IRIns *irp, RegSet allow)
+{
+  IRIns *ir = IR(REF_BASE);
+  Reg r = ir->r;
+  if (ra_hasreg(r)) {
+    ra_free(as, r);
+    if (rset_test(as->modset, r) || irt_ismarked(ir->t))
+      ir->r = RID_INIT;  /* No inheritance for modified BASE register. */
+    if (irp->r == r) {
+      rset_clear(allow, r);  /* Mark same BASE register as coalesced. */
+    } else if (ra_hasreg(irp->r) && rset_test(as->freeset, irp->r)) {
+      /* Move from coalesced parent reg. */
+      rset_clear(allow, irp->r);
+      emit_rr(as, XO_MOV, r|REX_GC64, irp->r);
+    } else {
+      emit_getgl(as, r, jit_base);  /* Otherwise reload BASE. */
+    }
+  }
+  return allow;
+}
+
+/* -- Tail of trace ------------------------------------------------------- */
+
+/* Fixup the tail code. */
+static void asm_tail_fixup(ASMState *as, TraceNo lnk)
+{
+  /* Note: don't use as->mcp swap + emit_*: emit_op overwrites more bytes. */
+  MCode *p = as->mctop;
+  MCode *target, *q;
+  int32_t spadj = as->T->spadjust;
+  if (spadj == 0) {
+    p -= LJ_64 ? 7 : 6;
+  } else {
+    MCode *p1;
+    /* Patch stack adjustment. */
+    if (checki8(spadj)) {
+      p -= 3;
+      p1 = p-6;
+      *p1 = (MCode)spadj;
+    } else {
+      p1 = p-9;
+      *(int32_t *)p1 = spadj;
+    }
+#if LJ_64
+    p1[-3] = 0x48;
+#endif
+    p1[-2] = (MCode)(checki8(spadj) ? XI_ARITHi8 : XI_ARITHi);
+    p1[-1] = MODRM(XM_REG, XOg_ADD, RID_ESP);
+  }
+  /* Patch exit branch. */
+  target = lnk ? traceref(as->J, lnk)->mcode : (MCode *)lj_vm_exit_interp;
+  *(int32_t *)(p-4) = jmprel(as->J, p, target);
+  p[-5] = XI_JMP;
+  /* Drop unused mcode tail. Fill with NOPs to make the prefetcher happy. */
+  for (q = as->mctop-1; q >= p; q--)
+    *q = XI_NOP;
+  as->mctop = p;
+}
+
+/* Prepare tail of code. */
+static void asm_tail_prep(ASMState *as)
+{
+  MCode *p = as->mctop;
+  /* Realign and leave room for backwards loop branch or exit branch. */
+  if (as->realign) {
+    int i = ((int)(intptr_t)as->realign) & 15;
+    /* Fill unused mcode tail with NOPs to make the prefetcher happy. */
+    while (i-- > 0)
+      *--p = XI_NOP;
+    as->mctop = p;
+    p -= (as->loopinv ? 5 : 2);  /* Space for short/near jmp. */
+  } else {
+    p -= 5;  /* Space for exit branch (near jmp). */
+  }
+  if (as->loopref) {
+    as->invmcp = as->mcp = p;
+  } else {
+    /* Leave room for ESP adjustment: add esp, imm or lea esp, [esp+imm] */
+    as->mcp = p - (LJ_64 ? 7 : 6);
+    as->invmcp = NULL;
+  }
+}
+
+/* -- Trace setup --------------------------------------------------------- */
+
+/* Ensure there are enough stack slots for call arguments. */
+static Reg asm_setup_call_slots(ASMState *as, IRIns *ir, const CCallInfo *ci)
+{
+  IRRef args[CCI_NARGS_MAX*2];
+  int nslots;
+  asm_collectargs(as, ir, ci, args);
+  nslots = asm_count_call_slots(as, ci, args);
+  if (nslots > as->evenspill)  /* Leave room for args in stack slots. */
+    as->evenspill = nslots;
+#if LJ_64
+  return irt_isfp(ir->t) ? REGSP_HINT(RID_FPRET) : REGSP_HINT(RID_RET);
+#else
+  return irt_isfp(ir->t) ? REGSP_INIT : REGSP_HINT(RID_RET);
+#endif
+}
+
+/* Target-specific setup. */
+static void asm_setup_target(ASMState *as)
+{
+  asm_exitstub_setup(as, as->T->nsnap);
+  as->mrm.base = 0;
+}
+
+/* -- Trace patching ------------------------------------------------------ */
+
+static const uint8_t map_op1[256] = {
+0x92,0x92,0x92,0x92,0x52,0x45,0x51,0x51,0x92,0x92,0x92,0x92,0x52,0x45,0x51,0x20,
+0x92,0x92,0x92,0x92,0x52,0x45,0x51,0x51,0x92,0x92,0x92,0x92,0x52,0x45,0x51,0x51,
+0x92,0x92,0x92,0x92,0x52,0x45,0x10,0x51,0x92,0x92,0x92,0x92,0x52,0x45,0x10,0x51,
+0x92,0x92,0x92,0x92,0x52,0x45,0x10,0x51,0x92,0x92,0x92,0x92,0x52,0x45,0x10,0x51,
+#if LJ_64
+0x10,0x10,0x10,0x10,0x10,0x10,0x10,0x10,0x14,0x14,0x14,0x14,0x14,0x14,0x14,0x14,
+#else
+0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,
+#endif
+0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,
+0x51,0x51,0x92,0x92,0x10,0x10,0x12,0x11,0x45,0x86,0x52,0x93,0x51,0x51,0x51,0x51,
+0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,
+0x93,0x86,0x93,0x93,0x92,0x92,0x92,0x92,0x92,0x92,0x92,0x92,0x92,0x92,0x92,0x92,
+0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0x47,0x51,0x51,0x51,0x51,0x51,
+#if LJ_64
+0x59,0x59,0x59,0x59,0x51,0x51,0x51,0x51,0x52,0x45,0x51,0x51,0x51,0x51,0x51,0x51,
+#else
+0x55,0x55,0x55,0x55,0x51,0x51,0x51,0x51,0x52,0x45,0x51,0x51,0x51,0x51,0x51,0x51,
+#endif
+0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x05,0x05,0x05,0x05,0x05,0x05,0x05,0x05,
+0x93,0x93,0x53,0x51,0x70,0x71,0x93,0x86,0x54,0x51,0x53,0x51,0x51,0x52,0x51,0x51,
+0x92,0x92,0x92,0x92,0x52,0x52,0x51,0x51,0x92,0x92,0x92,0x92,0x92,0x92,0x92,0x92,
+0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x45,0x45,0x47,0x52,0x51,0x51,0x51,0x51,
+0x10,0x51,0x10,0x10,0x51,0x51,0x63,0x66,0x51,0x51,0x51,0x51,0x51,0x51,0x92,0x92
+};
+
+static const uint8_t map_op2[256] = {
+0x93,0x93,0x93,0x93,0x52,0x52,0x52,0x52,0x52,0x52,0x51,0x52,0x51,0x93,0x52,0x94,
+0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x53,0x53,0x53,0x53,0x53,0x53,0x53,0x53,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x34,0x51,0x35,0x51,0x51,0x51,0x51,0x51,
+0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x53,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x94,0x54,0x54,0x54,0x93,0x93,0x93,0x52,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,0x46,
+0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x52,0x52,0x52,0x93,0x94,0x93,0x51,0x51,0x52,0x52,0x52,0x93,0x94,0x93,0x93,0x93,
+0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x94,0x93,0x93,0x93,0x93,0x93,
+0x93,0x93,0x94,0x93,0x94,0x94,0x94,0x93,0x52,0x52,0x52,0x52,0x52,0x52,0x52,0x52,
+0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,
+0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x93,0x52
+};
+
+static uint32_t asm_x86_inslen(const uint8_t* p)
+{
+  uint32_t result = 0;
+  uint32_t prefixes = 0;
+  uint32_t x = map_op1[*p];
+  for (;;) {
+    switch (x >> 4) {
+    case 0: return result + x + (prefixes & 4);
+    case 1: prefixes |= x; x = map_op1[*++p]; result++; break;
+    case 2: x = map_op2[*++p]; break;
+    case 3: p++; goto mrm;
+    case 4: result -= (prefixes & 2);  /* fallthrough */
+    case 5: return result + (x & 15);
+    case 6:  /* Group 3. */
+      if (p[1] & 0x38) x = 2;
+      else if ((prefixes & 2) && (x == 0x66)) x = 4;
+      goto mrm;
+    case 7: /* VEX c4/c5. */
+      if (LJ_32 && p[1] < 0xc0) {
+	x = 2;
+	goto mrm;
+      }
+      if (x == 0x70) {
+	x = *++p & 0x1f;
+	result++;
+	if (x >= 2) {
+	  p += 2;
+	  result += 2;
+	  goto mrm;
+	}
+      }
+      p++;
+      result++;
+      x = map_op2[*++p];
+      break;
+    case 8: result -= (prefixes & 2);  /* fallthrough */
+    case 9: mrm:  /* ModR/M and possibly SIB. */
+      result += (x & 15);
+      x = *++p;
+      switch (x >> 6) {
+      case 0: if ((x & 7) == 5) return result + 4; break;
+      case 1: result++; break;
+      case 2: result += 4; break;
+      case 3: return result;
+      }
+      if ((x & 7) == 4) {
+	result++;
+	if (x < 0x40 && (p[1] & 7) == 5) result += 4;
+      }
+      return result;
+    }
+  }
+}
+
+/* Patch exit jumps of existing machine code to a new target. */
+void lj_asm_patchexit(jit_State *J, GCtrace *T, ExitNo exitno, MCode *target)
+{
+  MCode *p = T->mcode;
+  MCode *mcarea = lj_mcode_patch(J, p, 0);
+  MSize len = T->szmcode;
+  MCode *px = exitstub_addr(J, exitno) - 6;
+  MCode *pe = p+len-6;
+  MCode *pgc = NULL;
+#if LJ_GC64
+  uint32_t statei = (uint32_t)(GG_OFS(g.vmstate) - GG_OFS(dispatch));
+#else
+  uint32_t statei = u32ptr(&J2G(J)->vmstate);
+#endif
+  if (len > 5 && p[len-5] == XI_JMP && p+len-6 + *(int32_t *)(p+len-4) == px)
+    *(int32_t *)(p+len-4) = jmprel(J, p+len, target);
+  /* Do not patch parent exit for a stack check. Skip beyond vmstate update. */
+  for (; p < pe; p += asm_x86_inslen(p)) {
+    intptr_t ofs = LJ_GC64 ? (p[0] & 0xf0) == 0x40 : LJ_64;
+    if (*(uint32_t *)(p+2+ofs) == statei && p[ofs+LJ_GC64-LJ_64] == XI_MOVmi)
+      break;
+  }
+  lj_assertJ(p < pe, "instruction length decoder failed");
+  for (; p < pe; p += asm_x86_inslen(p)) {
+    if ((*(uint16_t *)p & 0xf0ff) == 0x800f && p + *(int32_t *)(p+2) == px &&
+	p != pgc) {
+      *(int32_t *)(p+2) = jmprel(J, p+6, target);
+    } else if (*p == XI_CALL &&
+	      (void *)(p+5+*(int32_t *)(p+1)) == (void *)lj_gc_step_jit) {
+      pgc = p+7;  /* Do not patch GC check exit. */
+    }
+  }
+  lj_mcode_sync(T->mcode, T->mcode + T->szmcode);
+  lj_mcode_patch(J, mcarea, 1);
+}
+