ljx

lj_asm_arm.h (71006B)

---

 /*
 ** ARM IR assembler (SSA IR -> machine code).
 ** Copyright (C) 2005-2016 Mike Pall. See Copyright Notice in luajit.h
 */
 
 /* -- Register allocator extensions --------------------------------------- */
 
 /* Allocate a register with a hint. */
 static Reg ra_hintalloc(ASMState *as, IRRef ref, Reg hint, RegSet allow)
 {
   Reg r = IR(ref)->r;
   if (ra_noreg(r)) {
     if (!ra_hashint(r) && !iscrossref(as, ref))
       ra_sethint(IR(ref)->r, hint);  /* Propagate register hint. */
     r = ra_allocref(as, ref, allow);
   }
   ra_noweak(as, r);
   return r;
 }
 
 /* Allocate a scratch register pair. */
 static Reg ra_scratchpair(ASMState *as, RegSet allow)
 {
   RegSet pick1 = as->freeset & allow;
   RegSet pick2 = pick1 & (pick1 >> 1) & RSET_GPREVEN;
   Reg r;
   if (pick2) {
     r = rset_picktop(pick2);
   } else {
     RegSet pick = pick1 & (allow >> 1) & RSET_GPREVEN;
     if (pick) {
       r = rset_picktop(pick);
       ra_restore(as, regcost_ref(as->cost[r+1]));
     } else {
       pick = pick1 & (allow << 1) & RSET_GPRODD;
       if (pick) {
 	r = ra_restore(as, regcost_ref(as->cost[rset_picktop(pick)-1]));
       } else {
 	r = ra_evict(as, allow & (allow >> 1) & RSET_GPREVEN);
 	ra_restore(as, regcost_ref(as->cost[r+1]));
       }
     }
   }
   lua_assert(rset_test(RSET_GPREVEN, r));
   ra_modified(as, r);
   ra_modified(as, r+1);
   RA_DBGX((as, "scratchpair    $r $r", r, r+1));
   return r;
 }
 
 #if !LJ_SOFTFP
 /* Allocate two source registers for three-operand instructions. */
 static Reg ra_alloc2(ASMState *as, IRIns *ir, RegSet allow)
 {
   IRIns *irl = IR(ir->op1), *irr = IR(ir->op2);
   Reg left = irl->r, right = irr->r;
   if (ra_hasreg(left)) {
     ra_noweak(as, left);
     if (ra_noreg(right))
       right = ra_allocref(as, ir->op2, rset_exclude(allow, left));
     else
       ra_noweak(as, right);
   } else if (ra_hasreg(right)) {
     ra_noweak(as, right);
     left = ra_allocref(as, ir->op1, rset_exclude(allow, right));
   } else if (ra_hashint(right)) {
     right = ra_allocref(as, ir->op2, allow);
     left = ra_alloc1(as, ir->op1, rset_exclude(allow, right));
   } else {
     left = ra_allocref(as, ir->op1, allow);
     right = ra_alloc1(as, ir->op2, rset_exclude(allow, left));
   }
   return left | (right << 8);
 }
 #endif
 
 /* -- Guard handling ------------------------------------------------------ */
 
 /* Generate an exit stub group at the bottom of the reserved MCode memory. */
 static MCode *asm_exitstub_gen(ASMState *as, ExitNo group)
 {
   MCode *mxp = as->mcbot;
   int i;
   if (mxp + 4*4+4*EXITSTUBS_PER_GROUP >= as->mctop)
     asm_mclimit(as);
   /* str lr, [sp]; bl ->vm_exit_handler; .long DISPATCH_address, group. */
   *mxp++ = ARMI_STR|ARMI_LS_P|ARMI_LS_U|ARMF_D(RID_LR)|ARMF_N(RID_SP);
   *mxp = ARMI_BL|((((MCode *)(void *)lj_vm_exit_handler-mxp)-2)&0x00ffffffu);
   mxp++;
   *mxp++ = (MCode)i32ptr(J2GG(as->J)->dispatch);  /* DISPATCH address */
   *mxp++ = group*EXITSTUBS_PER_GROUP;
   for (i = 0; i < EXITSTUBS_PER_GROUP; i++)
     *mxp++ = ARMI_B|((-6-i)&0x00ffffffu);
   lj_mcode_sync(as->mcbot, mxp);
   lj_mcode_commitbot(as->J, mxp);
   as->mcbot = mxp;
   as->mclim = as->mcbot + MCLIM_REDZONE;
   return mxp - EXITSTUBS_PER_GROUP;
 }
 
 /* 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. */
 static void asm_guardcc(ASMState *as, ARMCC cc)
 {
   MCode *target = exitstub_addr(as->J, as->snapno);
   MCode *p = as->mcp;
   if (LJ_UNLIKELY(p == as->invmcp)) {
     as->loopinv = 1;
     *p = ARMI_BL | ((target-p-2) & 0x00ffffffu);
     emit_branch(as, ARMF_CC(ARMI_B, cc^1), p+1);
     return;
   }
   emit_branch(as, ARMF_CC(ARMI_BL, cc), target);
 }
 
 /* -- Operand fusion ------------------------------------------------------ */
 
 /* Limit linear search to this distance. Avoids O(n^2) behavior. */
 #define CONFLICT_SEARCH_LIM	31
 
 /* Check if there's no conflicting instruction between curins and ref. */
 static int noconflict(ASMState *as, IRRef ref, IROp conflict)
 {
   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. */
   return 1;  /* Ok, no conflict. */
 }
 
 /* Fuse the array base of colocated arrays. */
 static int32_t asm_fuseabase(ASMState *as, IRRef ref)
 {
   IRIns *ir = IR(ref);
   if (ir->o == IR_TNEW && ir->op1 <= LJ_MAX_COLOSIZE &&
       !neverfuse(as) && noconflict(as, ref, IR_NEWREF))
     return (int32_t)sizeof(GCtab);
   return 0;
 }
 
 /* Fuse array/hash/upvalue reference into register+offset operand. */
 static Reg asm_fuseahuref(ASMState *as, IRRef ref, int32_t *ofsp, RegSet allow,
 			  int lim)
 {
   IRIns *ir = IR(ref);
   if (ra_noreg(ir->r)) {
     if (ir->o == IR_AREF) {
       if (mayfuse(as, ref)) {
 	if (irref_isk(ir->op2)) {
 	  IRRef tab = IR(ir->op1)->op1;
 	  int32_t ofs = asm_fuseabase(as, tab);
 	  IRRef refa = ofs ? tab : ir->op1;
 	  ofs += 8*IR(ir->op2)->i;
 	  if (ofs > -lim && ofs < lim) {
 	    *ofsp = ofs;
 	    return ra_alloc1(as, refa, allow);
 	  }
 	}
       }
     } else if (ir->o == IR_HREFK) {
       if (mayfuse(as, ref)) {
 	int32_t ofs = (int32_t)(IR(ir->op2)->op2 * sizeof(Node));
 	if (ofs < lim) {
 	  *ofsp = ofs;
 	  return ra_alloc1(as, ir->op1, allow);
 	}
       }
     } else if (ir->o == IR_UREFC) {
       if (irref_isk(ir->op1)) {
 	GCfunc *fn = ir_kfunc(IR(ir->op1));
 	int32_t ofs = i32ptr(&gcref(fn->l.uvptr[(ir->op2 >> 8)])->uv.tv);
 	*ofsp = (ofs & 255);  /* Mask out less bits to allow LDRD. */
 	return ra_allock(as, (ofs & ~255), allow);
       }
     }
   }
   *ofsp = 0;
   return ra_alloc1(as, ref, allow);
 }
 
 /* Fuse m operand into arithmetic/logic instructions. */
 static uint32_t asm_fuseopm(ASMState *as, ARMIns ai, IRRef ref, RegSet allow)
 {
   IRIns *ir = IR(ref);
   if (ra_hasreg(ir->r)) {
     ra_noweak(as, ir->r);
     return ARMF_M(ir->r);
   } else if (irref_isk(ref)) {
     uint32_t k = emit_isk12(ai, ir->i);
     if (k)
       return k;
   } else if (mayfuse(as, ref)) {
     if (ir->o >= IR_BSHL && ir->o <= IR_BROR) {
       Reg m = ra_alloc1(as, ir->op1, allow);
       ARMShift sh = ir->o == IR_BSHL ? ARMSH_LSL :
 		    ir->o == IR_BSHR ? ARMSH_LSR :
 		    ir->o == IR_BSAR ? ARMSH_ASR : ARMSH_ROR;
       if (irref_isk(ir->op2)) {
 	return m | ARMF_SH(sh, (IR(ir->op2)->i & 31));
       } else {
 	Reg s = ra_alloc1(as, ir->op2, rset_exclude(allow, m));
 	return m | ARMF_RSH(sh, s);
       }
     } else if (ir->o == IR_ADD && ir->op1 == ir->op2) {
       Reg m = ra_alloc1(as, ir->op1, allow);
       return m | ARMF_SH(ARMSH_LSL, 1);
     }
   }
   return ra_allocref(as, ref, allow);
 }
 
 /* Fuse shifts into loads/stores. Only bother with BSHL 2 => lsl #2. */
 static IRRef asm_fuselsl2(ASMState *as, IRRef ref)
 {
   IRIns *ir = IR(ref);
   if (ra_noreg(ir->r) && mayfuse(as, ref) && ir->o == IR_BSHL &&
       irref_isk(ir->op2) && IR(ir->op2)->i == 2)
     return ir->op1;
   return 0;  /* No fusion. */
 }
 
 /* Fuse XLOAD/XSTORE reference into load/store operand. */
 static void asm_fusexref(ASMState *as, ARMIns ai, Reg rd, IRRef ref,
 			 RegSet allow, int32_t ofs)
 {
   IRIns *ir = IR(ref);
   Reg base;
   if (ra_noreg(ir->r) && canfuse(as, ir)) {
     int32_t lim = (!LJ_SOFTFP && (ai & 0x08000000)) ? 1024 :
 		   (ai & 0x04000000) ? 4096 : 256;
     if (ir->o == IR_ADD) {
       int32_t ofs2;
       if (irref_isk(ir->op2) &&
 	  (ofs2 = ofs + IR(ir->op2)->i) > -lim && ofs2 < lim &&
 	  (!(!LJ_SOFTFP && (ai & 0x08000000)) || !(ofs2 & 3))) {
 	ofs = ofs2;
 	ref = ir->op1;
       } else if (ofs == 0 && !(!LJ_SOFTFP && (ai & 0x08000000))) {
 	IRRef lref = ir->op1, rref = ir->op2;
 	Reg rn, rm;
 	if ((ai & 0x04000000)) {
 	  IRRef sref = asm_fuselsl2(as, rref);
 	  if (sref) {
 	    rref = sref;
 	    ai |= ARMF_SH(ARMSH_LSL, 2);
 	  } else if ((sref = asm_fuselsl2(as, lref)) != 0) {
 	    lref = rref;
 	    rref = sref;
 	    ai |= ARMF_SH(ARMSH_LSL, 2);
 	  }
 	}
 	rn = ra_alloc1(as, lref, allow);
 	rm = ra_alloc1(as, rref, rset_exclude(allow, rn));
 	if ((ai & 0x04000000)) ai |= ARMI_LS_R;
 	emit_dnm(as, ai|ARMI_LS_P|ARMI_LS_U, rd, rn, rm);
 	return;
       }
     } else if (ir->o == IR_STRREF && !(!LJ_SOFTFP && (ai & 0x08000000))) {
       lua_assert(ofs == 0);
       ofs = (int32_t)sizeof(GCstr);
       if (irref_isk(ir->op2)) {
 	ofs += IR(ir->op2)->i;
 	ref = ir->op1;
       } else if (irref_isk(ir->op1)) {
 	ofs += IR(ir->op1)->i;
 	ref = ir->op2;
       } else {
 	/* NYI: Fuse ADD with constant. */
 	Reg rn = ra_alloc1(as, ir->op1, allow);
 	uint32_t m = asm_fuseopm(as, 0, ir->op2, rset_exclude(allow, rn));
 	if ((ai & 0x04000000))
 	  emit_lso(as, ai, rd, rd, ofs);
 	else
 	  emit_lsox(as, ai, rd, rd, ofs);
 	emit_dn(as, ARMI_ADD^m, rd, rn);
 	return;
       }
       if (ofs <= -lim || ofs >= lim) {
 	Reg rn = ra_alloc1(as, ref, allow);
 	Reg rm = ra_allock(as, ofs, rset_exclude(allow, rn));
 	if ((ai & 0x04000000)) ai |= ARMI_LS_R;
 	emit_dnm(as, ai|ARMI_LS_P|ARMI_LS_U, rd, rn, rm);
 	return;
       }
     }
   }
   base = ra_alloc1(as, ref, allow);
 #if !LJ_SOFTFP
   if ((ai & 0x08000000))
     emit_vlso(as, ai, rd, base, ofs);
   else
 #endif
   if ((ai & 0x04000000))
     emit_lso(as, ai, rd, base, ofs);
   else
     emit_lsox(as, ai, rd, base, ofs);
 }
 
 #if !LJ_SOFTFP
 /* Fuse to multiply-add/sub instruction. */
 static int asm_fusemadd(ASMState *as, IRIns *ir, ARMIns ai, ARMIns air)
 {
   IRRef lref = ir->op1, rref = ir->op2;
   IRIns *irm;
   if (lref != rref &&
       ((mayfuse(as, lref) && (irm = IR(lref), irm->o == IR_MUL) &&
 	ra_noreg(irm->r)) ||
        (mayfuse(as, rref) && (irm = IR(rref), irm->o == IR_MUL) &&
 	(rref = lref, ai = air, ra_noreg(irm->r))))) {
     Reg dest = ra_dest(as, ir, RSET_FPR);
     Reg add = ra_hintalloc(as, rref, dest, RSET_FPR);
     Reg right, left = ra_alloc2(as, irm,
 			rset_exclude(rset_exclude(RSET_FPR, dest), add));
     right = (left >> 8); left &= 255;
     emit_dnm(as, ai, (dest & 15), (left & 15), (right & 15));
     if (dest != add) emit_dm(as, ARMI_VMOV_D, (dest & 15), (add & 15));
     return 1;
   }
   return 0;
 }
 #endif
 
 /* -- Calls --------------------------------------------------------------- */
 
 /* 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 = 0;
 #if LJ_SOFTFP
   Reg gpr = REGARG_FIRSTGPR;
 #else
   Reg gpr, fpr = REGARG_FIRSTFPR, fprodd = 0;
 #endif
   if ((void *)ci->func)
     emit_call(as, (void *)ci->func);
 #if !LJ_SOFTFP
   for (gpr = REGARG_FIRSTGPR; gpr <= REGARG_LASTGPR; gpr++)
     as->cost[gpr] = REGCOST(~0u, ASMREF_L);
   gpr = REGARG_FIRSTGPR;
 #endif
   for (n = 0; n < nargs; n++) {  /* Setup args. */
     IRRef ref = args[n];
     IRIns *ir = IR(ref);
 #if !LJ_SOFTFP
     if (ref && irt_isfp(ir->t)) {
       RegSet of = as->freeset;
       Reg src;
       if (!LJ_ABI_SOFTFP && !(ci->flags & CCI_VARARG)) {
 	if (irt_isnum(ir->t)) {
 	  if (fpr <= REGARG_LASTFPR) {
 	    ra_leftov(as, fpr, ref);
 	    fpr++;
 	    continue;
 	  }
 	} else if (fprodd) {  /* Ick. */
 	  src = ra_alloc1(as, ref, RSET_FPR);
 	  emit_dm(as, ARMI_VMOV_S, (fprodd & 15), (src & 15) | 0x00400000);
 	  fprodd = 0;
 	  continue;
 	} else if (fpr <= REGARG_LASTFPR) {
 	  ra_leftov(as, fpr, ref);
 	  fprodd = fpr++;
 	  continue;
 	}
 	/* Workaround to protect argument GPRs from being used for remat. */
 	as->freeset &= ~RSET_RANGE(REGARG_FIRSTGPR, REGARG_LASTGPR+1);
 	src = ra_alloc1(as, ref, RSET_FPR);  /* May alloc GPR to remat FPR. */
 	as->freeset |= (of & RSET_RANGE(REGARG_FIRSTGPR, REGARG_LASTGPR+1));
 	fprodd = 0;
 	goto stackfp;
       }
       /* Workaround to protect argument GPRs from being used for remat. */
       as->freeset &= ~RSET_RANGE(REGARG_FIRSTGPR, REGARG_LASTGPR+1);
       src = ra_alloc1(as, ref, RSET_FPR);  /* May alloc GPR to remat FPR. */
       as->freeset |= (of & RSET_RANGE(REGARG_FIRSTGPR, REGARG_LASTGPR+1));
       if (irt_isnum(ir->t)) gpr = (gpr+1) & ~1u;
       if (gpr <= REGARG_LASTGPR) {
 	lua_assert(rset_test(as->freeset, gpr));  /* Must have been evicted. */
 	if (irt_isnum(ir->t)) {
 	  lua_assert(rset_test(as->freeset, gpr+1));  /* Ditto. */
 	  emit_dnm(as, ARMI_VMOV_RR_D, gpr, gpr+1, (src & 15));
 	  gpr += 2;
 	} else {
 	  emit_dn(as, ARMI_VMOV_R_S, gpr, (src & 15));
 	  gpr++;
 	}
       } else {
       stackfp:
 	if (irt_isnum(ir->t)) ofs = (ofs + 4) & ~4;
 	emit_spstore(as, ir, src, ofs);
 	ofs += irt_isnum(ir->t) ? 8 : 4;
       }
     } else
 #endif
     {
       if (gpr <= REGARG_LASTGPR) {
 	lua_assert(rset_test(as->freeset, gpr));  /* Must have been evicted. */
 	if (ref) ra_leftov(as, gpr, ref);
 	gpr++;
       } else {
 	if (ref) {
 	  Reg r = ra_alloc1(as, ref, RSET_GPR);
 	  emit_spstore(as, ir, r, ofs);
 	}
 	ofs += 4;
       }
     }
   }
 }
 
 /* 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 (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)) {
     lua_assert(!irt_ispri(ir->t));
     if (!LJ_SOFTFP && irt_isfp(ir->t)) {
       if (LJ_ABI_SOFTFP || (ci->flags & (CCI_CASTU64|CCI_VARARG))) {
 	Reg dest = (ra_dest(as, ir, RSET_FPR) & 15);
 	if (irt_isnum(ir->t))
 	  emit_dnm(as, ARMI_VMOV_D_RR, RID_RETLO, RID_RETHI, dest);
 	else
 	  emit_dn(as, ARMI_VMOV_S_R, RID_RET, dest);
       } else {
 	ra_destreg(as, ir, RID_FPRET);
       }
     } else if (hiop) {
       ra_destpair(as, ir);
     } else {
       ra_destreg(as, ir, RID_RET);
     }
   }
   UNUSED(ci);
 }
 
 static void asm_callx(ASMState *as, IRIns *ir)
 {
   IRRef args[CCI_NARGS_MAX*2];
   CCallInfo ci;
   IRRef func;
   IRIns *irf;
   ci.flags = asm_callx_flags(as, ir);
   asm_collectargs(as, ir, &ci, args);
   asm_setupresult(as, ir, &ci);
   func = ir->op2; irf = IR(func);
   if (irf->o == IR_CARG) { func = irf->op1; irf = IR(func); }
   if (irref_isk(func)) {  /* Call to constant address. */
     ci.func = (ASMFunction)(void *)(irf->i);
   } else {  /* Need a non-argument register for indirect calls. */
     Reg freg = ra_alloc1(as, func, RSET_RANGE(RID_R4, RID_R12+1));
     emit_m(as, ARMI_BLXr, freg);
     ci.func = (ASMFunction)(void *)0;
   }
   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);
   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. */
   /* Need to force a spill on REF_BASE now to update the stack slot. */
   emit_lso(as, ARMI_STR, base, RID_SP, ra_spill(as, IR(REF_BASE)));
   emit_setgl(as, base, jit_base);
   emit_addptr(as, base, -8*delta);
   asm_guardcc(as, CC_NE);
   emit_nm(as, ARMI_CMP, RID_TMP,
 	  ra_allock(as, i32ptr(pc), rset_exclude(RSET_GPR, base)));
   emit_lso(as, ARMI_LDR, RID_TMP, base, -4);
 }
 
 /* -- Type conversions ---------------------------------------------------- */
 
 #if !LJ_SOFTFP
 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_NE);
   emit_d(as, ARMI_VMRS, 0);
   emit_dm(as, ARMI_VCMP_D, (tmp & 15), (left & 15));
   emit_dm(as, ARMI_VCVT_F64_S32, (tmp & 15), (tmp & 15));
   emit_dn(as, ARMI_VMOV_R_S, dest, (tmp & 15));
   emit_dm(as, ARMI_VCVT_S32_F64, (tmp & 15), (left & 15));
 }
 
 static void asm_tobit(ASMState *as, IRIns *ir)
 {
   RegSet allow = RSET_FPR;
   Reg left = ra_alloc1(as, ir->op1, allow);
   Reg right = ra_alloc1(as, ir->op2, rset_clear(allow, left));
   Reg tmp = ra_scratch(as, rset_clear(allow, right));
   Reg dest = ra_dest(as, ir, RSET_GPR);
   emit_dn(as, ARMI_VMOV_R_S, dest, (tmp & 15));
   emit_dnm(as, ARMI_VADD_D, (tmp & 15), (left & 15), (right & 15));
 }
 #endif
 
 static void asm_conv(ASMState *as, IRIns *ir)
 {
   IRType st = (IRType)(ir->op2 & IRCONV_SRCMASK);
 #if !LJ_SOFTFP
   int stfp = (st == IRT_NUM || st == IRT_FLOAT);
 #endif
   IRRef lref = ir->op1;
   /* 64 bit integer conversions are handled by SPLIT. */
   lua_assert(!irt_isint64(ir->t) && !(st == IRT_I64 || st == IRT_U64));
 #if LJ_SOFTFP
   /* FP conversions are handled by SPLIT. */
   lua_assert(!irt_isfp(ir->t) && !(st == IRT_NUM || st == IRT_FLOAT));
   /* Can't check for same types: SPLIT uses CONV int.int + BXOR for sfp NEG. */
 #else
   lua_assert(irt_type(ir->t) != st);
   if (irt_isfp(ir->t)) {
     Reg dest = ra_dest(as, ir, RSET_FPR);
     if (stfp) {  /* FP to FP conversion. */
       emit_dm(as, st == IRT_NUM ? ARMI_VCVT_F32_F64 : ARMI_VCVT_F64_F32,
 	      (dest & 15), (ra_alloc1(as, lref, RSET_FPR) & 15));
     } else {  /* Integer to FP conversion. */
       Reg left = ra_alloc1(as, lref, RSET_GPR);
       ARMIns ai = irt_isfloat(ir->t) ?
 	(st == IRT_INT ? ARMI_VCVT_F32_S32 : ARMI_VCVT_F32_U32) :
 	(st == IRT_INT ? ARMI_VCVT_F64_S32 : ARMI_VCVT_F64_U32);
       emit_dm(as, ai, (dest & 15), (dest & 15));
       emit_dn(as, ARMI_VMOV_S_R, left, (dest & 15));
     }
   } else if (stfp) {  /* FP to integer conversion. */
     if (irt_isguard(ir->t)) {
       /* Checked conversions are only supported from number to int. */
       lua_assert(irt_isint(ir->t) && st == IRT_NUM);
       asm_tointg(as, ir, ra_alloc1(as, lref, RSET_FPR));
     } else {
       Reg left = ra_alloc1(as, lref, RSET_FPR);
       Reg tmp = ra_scratch(as, rset_exclude(RSET_FPR, left));
       Reg dest = ra_dest(as, ir, RSET_GPR);
       ARMIns ai;
       emit_dn(as, ARMI_VMOV_R_S, dest, (tmp & 15));
       ai = irt_isint(ir->t) ?
 	(st == IRT_NUM ? ARMI_VCVT_S32_F64 : ARMI_VCVT_S32_F32) :
 	(st == IRT_NUM ? ARMI_VCVT_U32_F64 : ARMI_VCVT_U32_F32);
       emit_dm(as, ai, (tmp & 15), (left & 15));
     }
   } else
 #endif
   {
     Reg dest = ra_dest(as, ir, RSET_GPR);
     if (st >= IRT_I8 && st <= IRT_U16) {  /* Extend to 32 bit integer. */
       Reg left = ra_alloc1(as, lref, RSET_GPR);
       lua_assert(irt_isint(ir->t) || irt_isu32(ir->t));
       if ((as->flags & JIT_F_ARMV6)) {
 	ARMIns ai = st == IRT_I8 ? ARMI_SXTB :
 		    st == IRT_U8 ? ARMI_UXTB :
 		    st == IRT_I16 ? ARMI_SXTH : ARMI_UXTH;
 	emit_dm(as, ai, dest, left);
       } else if (st == IRT_U8) {
 	emit_dn(as, ARMI_AND|ARMI_K12|255, dest, left);
       } else {
 	uint32_t shift = st == IRT_I8 ? 24 : 16;
 	ARMShift sh = st == IRT_U16 ? ARMSH_LSR : ARMSH_ASR;
 	emit_dm(as, ARMI_MOV|ARMF_SH(sh, shift), dest, RID_TMP);
 	emit_dm(as, ARMI_MOV|ARMF_SH(ARMSH_LSL, shift), RID_TMP, left);
       }
     } else {  /* Handle 32/32 bit no-op (cast). */
       ra_leftov(as, dest, lref);  /* Do nothing, but may need to move regs. */
     }
   }
 }
 
 static void asm_strto(ASMState *as, IRIns *ir)
 {
   const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_strscan_num];
   IRRef args[2];
   Reg rlo = 0, rhi = 0, tmp;
   int destused = ra_used(ir);
   int32_t ofs = 0;
   ra_evictset(as, RSET_SCRATCH);
 #if LJ_SOFTFP
   if (destused) {
     if (ra_hasspill(ir->s) && ra_hasspill((ir+1)->s) &&
 	(ir->s & 1) == 0 && ir->s + 1 == (ir+1)->s) {
       int i;
       for (i = 0; i < 2; i++) {
 	Reg r = (ir+i)->r;
 	if (ra_hasreg(r)) {
 	  ra_free(as, r);
 	  ra_modified(as, r);
 	  emit_spload(as, ir+i, r, sps_scale((ir+i)->s));
 	}
       }
       ofs = sps_scale(ir->s);
       destused = 0;
     } else {
       rhi = ra_dest(as, ir+1, RSET_GPR);
       rlo = ra_dest(as, ir, rset_exclude(RSET_GPR, rhi));
     }
   }
   asm_guardcc(as, CC_EQ);
   if (destused) {
     emit_lso(as, ARMI_LDR, rhi, RID_SP, 4);
     emit_lso(as, ARMI_LDR, rlo, RID_SP, 0);
   }
 #else
   UNUSED(rhi);
   if (destused) {
     if (ra_hasspill(ir->s)) {
       ofs = sps_scale(ir->s);
       destused = 0;
       if (ra_hasreg(ir->r)) {
 	ra_free(as, ir->r);
 	ra_modified(as, ir->r);
 	emit_spload(as, ir, ir->r, ofs);
       }
     } else {
       rlo = ra_dest(as, ir, RSET_FPR);
     }
   }
   asm_guardcc(as, CC_EQ);
   if (destused)
     emit_vlso(as, ARMI_VLDR_D, rlo, RID_SP, 0);
 #endif
   emit_n(as, ARMI_CMP|ARMI_K12|0, RID_RET);  /* Test return status. */
   args[0] = ir->op1;      /* GCstr *str */
   args[1] = ASMREF_TMP1;  /* TValue *n  */
   asm_gencall(as, ci, args);
   tmp = ra_releasetmp(as, ASMREF_TMP1);
   if (ofs == 0)
     emit_dm(as, ARMI_MOV, tmp, RID_SP);
   else
     emit_opk(as, ARMI_ADD, tmp, RID_SP, ofs, RSET_GPR);
 }
 
 /* -- Memory references --------------------------------------------------- */
 
 /* Get pointer to TValue. */
 static void asm_tvptr(ASMState *as, Reg dest, IRRef ref)
 {
   IRIns *ir = IR(ref);
   if (irt_isnum(ir->t)) {
     if (irref_isk(ref)) {
       /* Use the number constant itself as a TValue. */
       ra_allockreg(as, i32ptr(ir_knum(ir)), dest);
     } else {
 #if LJ_SOFTFP
       lua_assert(0);
 #else
       /* Otherwise force a spill and use the spill slot. */
       emit_opk(as, ARMI_ADD, dest, RID_SP, ra_spill(as, ir), RSET_GPR);
 #endif
     }
   } else {
     /* Otherwise use [sp] and [sp+4] to hold the TValue. */
     RegSet allow = rset_exclude(RSET_GPR, dest);
     Reg type;
     emit_dm(as, ARMI_MOV, dest, RID_SP);
     if (!irt_ispri(ir->t)) {
       Reg src = ra_alloc1(as, ref, allow);
       emit_lso(as, ARMI_STR, src, RID_SP, 0);
     }
     if (LJ_SOFTFP && (ir+1)->o == IR_HIOP)
       type = ra_alloc1(as, ref+1, allow);
     else
       type = ra_allock(as, irt_toitype(ir->t), allow);
     emit_lso(as, ARMI_STR, type, RID_SP, 4);
   }
 }
 
 static void asm_aref(ASMState *as, IRIns *ir)
 {
   Reg dest = ra_dest(as, ir, RSET_GPR);
   Reg idx, base;
   if (irref_isk(ir->op2)) {
     IRRef tab = IR(ir->op1)->op1;
     int32_t ofs = asm_fuseabase(as, tab);
     IRRef refa = ofs ? tab : ir->op1;
     uint32_t k = emit_isk12(ARMI_ADD, ofs + 8*IR(ir->op2)->i);
     if (k) {
       base = ra_alloc1(as, refa, RSET_GPR);
       emit_dn(as, ARMI_ADD^k, dest, base);
       return;
     }
   }
   base = ra_alloc1(as, ir->op1, RSET_GPR);
   idx = ra_alloc1(as, ir->op2, rset_exclude(RSET_GPR, base));
   emit_dnm(as, ARMI_ADD|ARMF_SH(ARMSH_LSL, 3), dest, base, idx);
 }
 
 /* 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 = 0, keyhi = 0, keynumhi = RID_NONE, tmp = RID_TMP;
   IRRef refkey = ir->op2;
   IRIns *irkey = IR(refkey);
   IRType1 kt = irkey->t;
   int32_t k = 0, khi = emit_isk12(ARMI_CMP, irt_toitype(kt));
   uint32_t khash;
   MCLabel l_end, l_loop;
   rset_clear(allow, tab);
   if (!irref_isk(refkey) || irt_isstr(kt)) {
 #if LJ_SOFTFP
     key = ra_alloc1(as, refkey, allow);
     rset_clear(allow, key);
     if (irkey[1].o == IR_HIOP) {
       if (ra_hasreg((irkey+1)->r)) {
 	keynumhi = (irkey+1)->r;
 	keyhi = RID_TMP;
 	ra_noweak(as, keynumhi);
       } else {
 	keyhi = keynumhi = ra_allocref(as, refkey+1, allow);
       }
       rset_clear(allow, keynumhi);
       khi = 0;
     }
 #else
     if (irt_isnum(kt)) {
       key = ra_scratch(as, allow);
       rset_clear(allow, key);
       keyhi = keynumhi = ra_scratch(as, allow);
       rset_clear(allow, keyhi);
       khi = 0;
     } else {
       key = ra_alloc1(as, refkey, allow);
       rset_clear(allow, key);
     }
 #endif
   } else if (irt_isnum(kt)) {
     int32_t val = (int32_t)ir_knum(irkey)->u32.lo;
     k = emit_isk12(ARMI_CMP, val);
     if (!k) {
       key = ra_allock(as, val, allow);
       rset_clear(allow, key);
     }
     val = (int32_t)ir_knum(irkey)->u32.hi;
     khi = emit_isk12(ARMI_CMP, val);
     if (!khi) {
       keyhi = ra_allock(as, val, allow);
       rset_clear(allow, keyhi);
     }
   } else if (!irt_ispri(kt)) {
     k = emit_isk12(ARMI_CMP, irkey->i);
     if (!k) {
       key = ra_alloc1(as, refkey, allow);
       rset_clear(allow, key);
     }
   }
   if (!irt_ispri(kt))
     tmp = ra_scratchpair(as, allow);
 
   /* Key not found in chain: jump to exit (if merged) or load niltv. */
   l_end = emit_label(as);
   as->invmcp = NULL;
   if (merge == IR_NE)
     asm_guardcc(as, CC_AL);
   else if (destused)
     emit_loada(as, dest, niltvg(J2G(as->J)));
 
   /* Follow hash chain until the end. */
   l_loop = --as->mcp;
   emit_n(as, ARMI_CMP|ARMI_K12|0, dest);
   emit_lso(as, ARMI_LDR, dest, dest, (int32_t)offsetof(Node, next));
 
   /* Type and value comparison. */
   if (merge == IR_EQ)
     asm_guardcc(as, CC_EQ);
   else
     emit_branch(as, ARMF_CC(ARMI_B, CC_EQ), l_end);
   if (!irt_ispri(kt)) {
     emit_nm(as, ARMF_CC(ARMI_CMP, CC_EQ)^k, tmp, key);
     emit_nm(as, ARMI_CMP^khi, tmp+1, keyhi);
     emit_lsox(as, ARMI_LDRD, tmp, dest, (int32_t)offsetof(Node, key));
   } else {
     emit_n(as, ARMI_CMP^khi, tmp);
     emit_lso(as, ARMI_LDR, tmp, dest, (int32_t)offsetof(Node, key.it));
   }
   *l_loop = ARMF_CC(ARMI_B, CC_NE) | ((as->mcp-l_loop-2) & 0x00ffffffu);
 
   /* Load main position relative to tab->node into dest. */
   khash = irref_isk(refkey) ? ir_khash(irkey) : 1;
   if (khash == 0) {
     emit_lso(as, ARMI_LDR, dest, tab, (int32_t)offsetof(GCtab, node));
   } else {
     emit_dnm(as, ARMI_ADD|ARMF_SH(ARMSH_LSL, 3), dest, dest, tmp);
     emit_dnm(as, ARMI_ADD|ARMF_SH(ARMSH_LSL, 1), tmp, tmp, tmp);
     if (irt_isstr(kt)) {  /* Fetch of str->hash is cheaper than ra_allock. */
       emit_dnm(as, ARMI_AND, tmp, tmp+1, RID_TMP);
       emit_lso(as, ARMI_LDR, dest, tab, (int32_t)offsetof(GCtab, node));
       emit_lso(as, ARMI_LDR, tmp+1, key, (int32_t)offsetof(GCstr, hash));
       emit_lso(as, ARMI_LDR, RID_TMP, tab, (int32_t)offsetof(GCtab, hmask));
     } else if (irref_isk(refkey)) {
       emit_opk(as, ARMI_AND, tmp, RID_TMP, (int32_t)khash,
 	       rset_exclude(rset_exclude(RSET_GPR, tab), dest));
       emit_lso(as, ARMI_LDR, dest, tab, (int32_t)offsetof(GCtab, node));
       emit_lso(as, ARMI_LDR, RID_TMP, tab, (int32_t)offsetof(GCtab, hmask));
     } else {  /* Must match with hash*() in lj_tab.c. */
       if (ra_hasreg(keynumhi)) {  /* Canonicalize +-0.0 to 0.0. */
 	if (keyhi == RID_TMP)
 	  emit_dm(as, ARMF_CC(ARMI_MOV, CC_NE), keyhi, keynumhi);
 	emit_d(as, ARMF_CC(ARMI_MOV, CC_EQ)|ARMI_K12|0, keyhi);
       }
       emit_dnm(as, ARMI_AND, tmp, tmp, RID_TMP);
       emit_dnm(as, ARMI_SUB|ARMF_SH(ARMSH_ROR, 32-HASH_ROT3), tmp, tmp, tmp+1);
       emit_lso(as, ARMI_LDR, dest, tab, (int32_t)offsetof(GCtab, node));
       emit_dnm(as, ARMI_EOR|ARMF_SH(ARMSH_ROR, 32-((HASH_ROT2+HASH_ROT1)&31)),
 	       tmp, tmp+1, tmp);
       emit_lso(as, ARMI_LDR, RID_TMP, tab, (int32_t)offsetof(GCtab, hmask));
       emit_dnm(as, ARMI_SUB|ARMF_SH(ARMSH_ROR, 32-HASH_ROT1), tmp+1, tmp+1, tmp);
       if (ra_hasreg(keynumhi)) {
 	emit_dnm(as, ARMI_EOR, tmp+1, tmp, key);
 	emit_dnm(as, ARMI_ORR|ARMI_S, RID_TMP, tmp, key);  /* Test for +-0.0. */
 	emit_dnm(as, ARMI_ADD, tmp, keynumhi, keynumhi);
 #if !LJ_SOFTFP
 	emit_dnm(as, ARMI_VMOV_RR_D, key, keynumhi,
 		 (ra_alloc1(as, refkey, RSET_FPR) & 15));
 #endif
       } else {
 	emit_dnm(as, ARMI_EOR, tmp+1, tmp, key);
 	emit_opk(as, ARMI_ADD, tmp, key, (int32_t)HASH_BIAS,
 		 rset_exclude(rset_exclude(RSET_GPR, tab), key));
       }
     }
   }
 }
 
 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));
   int32_t kofs = ofs + (int32_t)offsetof(Node, key);
   Reg dest = (ra_used(ir) || ofs > 4095) ? ra_dest(as, ir, RSET_GPR) : RID_NONE;
   Reg node = ra_alloc1(as, ir->op1, RSET_GPR);
   Reg key = RID_NONE, type = RID_TMP, idx = node;
   RegSet allow = rset_exclude(RSET_GPR, node);
   lua_assert(ofs % sizeof(Node) == 0);
   if (ofs > 4095) {
     idx = dest;
     rset_clear(allow, dest);
     kofs = (int32_t)offsetof(Node, key);
   } else if (ra_hasreg(dest)) {
     emit_opk(as, ARMI_ADD, dest, node, ofs, allow);
   }
   asm_guardcc(as, CC_NE);
   if (!irt_ispri(irkey->t)) {
     RegSet even = (as->freeset & allow);
     even = even & (even >> 1) & RSET_GPREVEN;
     if (even) {
       key = ra_scratch(as, even);
       if (rset_test(as->freeset, key+1)) {
 	type = key+1;
 	ra_modified(as, type);
       }
     } else {
       key = ra_scratch(as, allow);
     }
     rset_clear(allow, key);
   }
   rset_clear(allow, type);
   if (irt_isnum(irkey->t)) {
     emit_opk(as, ARMF_CC(ARMI_CMP, CC_EQ), 0, type,
 	     (int32_t)ir_knum(irkey)->u32.hi, allow);
     emit_opk(as, ARMI_CMP, 0, key,
 	     (int32_t)ir_knum(irkey)->u32.lo, allow);
   } else {
     if (ra_hasreg(key))
       emit_opk(as, ARMF_CC(ARMI_CMP, CC_EQ), 0, key, irkey->i, allow);
     emit_n(as, ARMI_CMN|ARMI_K12|-irt_toitype(irkey->t), type);
   }
   emit_lso(as, ARMI_LDR, type, idx, kofs+4);
   if (ra_hasreg(key)) emit_lso(as, ARMI_LDR, key, idx, kofs);
   if (ofs > 4095)
     emit_opk(as, ARMI_ADD, dest, node, ofs, RSET_GPR);
 }
 
 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_lsptr(as, ARMI_LDR, dest, v);
   } else {
     Reg uv = ra_scratch(as, RSET_GPR);
     Reg func = ra_alloc1(as, ir->op1, RSET_GPR);
     if (ir->o == IR_UREFC) {
       asm_guardcc(as, CC_NE);
       emit_n(as, ARMI_CMP|ARMI_K12|1, RID_TMP);
       emit_opk(as, ARMI_ADD, dest, uv,
 	       (int32_t)offsetof(GCupval, tv), RSET_GPR);
       emit_lso(as, ARMI_LDRB, RID_TMP, uv, (int32_t)offsetof(GCupval, closed));
     } else {
       emit_lso(as, ARMI_LDR, dest, uv, (int32_t)offsetof(GCupval, v));
     }
     emit_lso(as, ARMI_LDR, uv, func,
 	     (int32_t)offsetof(GCfuncL, uvptr) + 4*(int32_t)(ir->op2 >> 8));
   }
 }
 
 static void asm_fref(ASMState *as, IRIns *ir)
 {
   UNUSED(as); UNUSED(ir);
   lua_assert(!ra_used(ir));
 }
 
 static void asm_strref(ASMState *as, IRIns *ir)
 {
   Reg dest = ra_dest(as, ir, RSET_GPR);
   IRRef ref = ir->op2, refk = ir->op1;
   Reg r;
   if (irref_isk(ref)) {
     IRRef tmp = refk; refk = ref; ref = tmp;
   } else if (!irref_isk(refk)) {
     uint32_t k, m = ARMI_K12|sizeof(GCstr);
     Reg right, left = ra_alloc1(as, ir->op1, RSET_GPR);
     IRIns *irr = IR(ir->op2);
     if (ra_hasreg(irr->r)) {
       ra_noweak(as, irr->r);
       right = irr->r;
     } else if (mayfuse(as, irr->op2) &&
 	       irr->o == IR_ADD && irref_isk(irr->op2) &&
 	       (k = emit_isk12(ARMI_ADD,
 			       (int32_t)sizeof(GCstr) + IR(irr->op2)->i))) {
       m = k;
       right = ra_alloc1(as, irr->op1, rset_exclude(RSET_GPR, left));
     } else {
       right = ra_allocref(as, ir->op2, rset_exclude(RSET_GPR, left));
     }
     emit_dn(as, ARMI_ADD^m, dest, dest);
     emit_dnm(as, ARMI_ADD, dest, left, right);
     return;
   }
   r = ra_alloc1(as, ref, RSET_GPR);
   emit_opk(as, ARMI_ADD, dest, r,
 	   sizeof(GCstr) + IR(refk)->i, rset_exclude(RSET_GPR, r));
 }
 
 /* -- Loads and stores ---------------------------------------------------- */
 
 static ARMIns asm_fxloadins(IRIns *ir)
 {
   switch (irt_type(ir->t)) {
   case IRT_I8: return ARMI_LDRSB;
   case IRT_U8: return ARMI_LDRB;
   case IRT_I16: return ARMI_LDRSH;
   case IRT_U16: return ARMI_LDRH;
   case IRT_NUM: lua_assert(!LJ_SOFTFP); return ARMI_VLDR_D;
   case IRT_FLOAT: if (!LJ_SOFTFP) return ARMI_VLDR_S;
   default: return ARMI_LDR;
   }
 }
 
 static ARMIns asm_fxstoreins(IRIns *ir)
 {
   switch (irt_type(ir->t)) {
   case IRT_I8: case IRT_U8: return ARMI_STRB;
   case IRT_I16: case IRT_U16: return ARMI_STRH;
   case IRT_NUM: lua_assert(!LJ_SOFTFP); return ARMI_VSTR_D;
   case IRT_FLOAT: if (!LJ_SOFTFP) return ARMI_VSTR_S;
   default: return ARMI_STR;
   }
 }
 
 static void asm_fload(ASMState *as, IRIns *ir)
 {
   if (ir->op1 == REF_NIL) {
     lua_assert(!ra_used(ir));  /* We can end up here if DCE is turned off. */
   } else {
     Reg dest = ra_dest(as, ir, RSET_GPR);
     Reg idx = ra_alloc1(as, ir->op1, RSET_GPR);
     ARMIns ai = asm_fxloadins(ir);
     int32_t ofs;
     if (ir->op2 == IRFL_TAB_ARRAY) {
       ofs = asm_fuseabase(as, ir->op1);
       if (ofs) {  /* Turn the t->array load into an add for colocated arrays. */
 	emit_dn(as, ARMI_ADD|ARMI_K12|ofs, dest, idx);
 	return;
       }
     }
     ofs = field_ofs[ir->op2];
     if ((ai & 0x04000000))
       emit_lso(as, ai, dest, idx, ofs);
     else
       emit_lsox(as, ai, dest, idx, ofs);
   }
 }
 
 static void asm_fstore(ASMState *as, IRIns *ir)
 {
   if (ir->r != RID_SINK) {
     Reg src = ra_alloc1(as, ir->op2, RSET_GPR);
     IRIns *irf = IR(ir->op1);
     Reg idx = ra_alloc1(as, irf->op1, rset_exclude(RSET_GPR, src));
     int32_t ofs = field_ofs[irf->op2];
     ARMIns ai = asm_fxstoreins(ir);
     if ((ai & 0x04000000))
       emit_lso(as, ai, src, idx, ofs);
     else
       emit_lsox(as, ai, src, idx, ofs);
   }
 }
 
 static void asm_xload(ASMState *as, IRIns *ir)
 {
   Reg dest = ra_dest(as, ir,
 		     (!LJ_SOFTFP && irt_isfp(ir->t)) ? RSET_FPR : RSET_GPR);
   lua_assert(!(ir->op2 & IRXLOAD_UNALIGNED));
   asm_fusexref(as, asm_fxloadins(ir), dest, ir->op1, RSET_GPR, 0);
 }
 
 static void asm_xstore_(ASMState *as, IRIns *ir, int32_t ofs)
 {
   if (ir->r != RID_SINK) {
     Reg src = ra_alloc1(as, ir->op2,
 			(!LJ_SOFTFP && irt_isfp(ir->t)) ? RSET_FPR : RSET_GPR);
     asm_fusexref(as, asm_fxstoreins(ir), src, ir->op1,
 		 rset_exclude(RSET_GPR, src), ofs);
   }
 }
 
 #define asm_xstore(as, ir)	asm_xstore_(as, ir, 0)
 
 static void asm_ahuvload(ASMState *as, IRIns *ir)
 {
   int hiop = (LJ_SOFTFP && (ir+1)->o == IR_HIOP);
   IRType t = hiop ? IRT_NUM : irt_type(ir->t);
   Reg dest = RID_NONE, type = RID_NONE, idx;
   RegSet allow = RSET_GPR;
   int32_t ofs = 0;
   if (hiop && ra_used(ir+1)) {
     type = ra_dest(as, ir+1, allow);
     rset_clear(allow, type);
   }
   if (ra_used(ir)) {
     lua_assert((LJ_SOFTFP ? 0 : irt_isnum(ir->t)) ||
 	       irt_isint(ir->t) || irt_isaddr(ir->t));
     dest = ra_dest(as, ir, (!LJ_SOFTFP && t == IRT_NUM) ? RSET_FPR : allow);
     rset_clear(allow, dest);
   }
   idx = asm_fuseahuref(as, ir->op1, &ofs, allow,
 		       (!LJ_SOFTFP && t == IRT_NUM) ? 1024 : 4096);
   if (!hiop || type == RID_NONE) {
     rset_clear(allow, idx);
     if (ofs < 256 && ra_hasreg(dest) && (dest & 1) == 0 &&
 	rset_test((as->freeset & allow), dest+1)) {
       type = dest+1;
       ra_modified(as, type);
     } else {
       type = RID_TMP;
     }
   }
   asm_guardcc(as, t == IRT_NUM ? CC_HS : CC_NE);
   emit_n(as, ARMI_CMN|ARMI_K12|-irt_toitype_(t), type);
   if (ra_hasreg(dest)) {
 #if !LJ_SOFTFP
     if (t == IRT_NUM)
       emit_vlso(as, ARMI_VLDR_D, dest, idx, ofs);
     else
 #endif
       emit_lso(as, ARMI_LDR, dest, idx, ofs);
   }
   emit_lso(as, ARMI_LDR, type, idx, ofs+4);
 }
 
 static void asm_ahustore(ASMState *as, IRIns *ir)
 {
   if (ir->r != RID_SINK) {
     RegSet allow = RSET_GPR;
     Reg idx, src = RID_NONE, type = RID_NONE;
     int32_t ofs = 0;
 #if !LJ_SOFTFP
     if (irt_isnum(ir->t)) {
       src = ra_alloc1(as, ir->op2, RSET_FPR);
       idx = asm_fuseahuref(as, ir->op1, &ofs, allow, 1024);
       emit_vlso(as, ARMI_VSTR_D, src, idx, ofs);
     } else
 #endif
     {
       int hiop = (LJ_SOFTFP && (ir+1)->o == IR_HIOP);
       if (!irt_ispri(ir->t)) {
 	src = ra_alloc1(as, ir->op2, allow);
 	rset_clear(allow, src);
       }
       if (hiop)
 	type = ra_alloc1(as, (ir+1)->op2, allow);
       else
 	type = ra_allock(as, (int32_t)irt_toitype(ir->t), allow);
       idx = asm_fuseahuref(as, ir->op1, &ofs, rset_exclude(allow, type), 4096);
       if (ra_hasreg(src)) emit_lso(as, ARMI_STR, src, idx, ofs);
       emit_lso(as, ARMI_STR, type, idx, ofs+4);
     }
   }
 }
 
 static void asm_sload(ASMState *as, IRIns *ir)
 {
   int32_t ofs = 8*((int32_t)ir->op1-1) + ((ir->op2 & IRSLOAD_FRAME) ? 4 : 0);
   int hiop = (LJ_SOFTFP && (ir+1)->o == IR_HIOP);
   IRType t = hiop ? IRT_NUM : irt_type(ir->t);
   Reg dest = RID_NONE, type = RID_NONE, base;
   RegSet allow = RSET_GPR;
   lua_assert(!(ir->op2 & IRSLOAD_PARENT));  /* Handled by asm_head_side(). */
   lua_assert(irt_isguard(ir->t) || !(ir->op2 & IRSLOAD_TYPECHECK));
 #if LJ_SOFTFP
   lua_assert(!(ir->op2 & IRSLOAD_CONVERT));  /* Handled by LJ_SOFTFP SPLIT. */
   if (hiop && ra_used(ir+1)) {
     type = ra_dest(as, ir+1, allow);
     rset_clear(allow, type);
   }
 #else
   if ((ir->op2 & IRSLOAD_CONVERT) && irt_isguard(ir->t) && t == IRT_INT) {
     dest = ra_scratch(as, RSET_FPR);
     asm_tointg(as, ir, dest);
     t = IRT_NUM;  /* Continue with a regular number type check. */
   } else
 #endif
   if (ra_used(ir)) {
     Reg tmp = RID_NONE;
     if ((ir->op2 & IRSLOAD_CONVERT))
       tmp = ra_scratch(as, t == IRT_INT ? RSET_FPR : RSET_GPR);
     lua_assert((LJ_SOFTFP ? 0 : irt_isnum(ir->t)) ||
 	       irt_isint(ir->t) || irt_isaddr(ir->t));
     dest = ra_dest(as, ir, (!LJ_SOFTFP && t == IRT_NUM) ? RSET_FPR : allow);
     rset_clear(allow, dest);
     base = ra_alloc1(as, REF_BASE, allow);
     if ((ir->op2 & IRSLOAD_CONVERT)) {
       if (t == IRT_INT) {
 	emit_dn(as, ARMI_VMOV_R_S, dest, (tmp & 15));
 	emit_dm(as, ARMI_VCVT_S32_F64, (tmp & 15), (tmp & 15));
 	t = IRT_NUM;  /* Check for original type. */
       } else {
 	emit_dm(as, ARMI_VCVT_F64_S32, (dest & 15), (dest & 15));
 	emit_dn(as, ARMI_VMOV_S_R, tmp, (dest & 15));
 	t = IRT_INT;  /* Check for original type. */
       }
       dest = tmp;
     }
     goto dotypecheck;
   }
   base = ra_alloc1(as, REF_BASE, allow);
 dotypecheck:
   rset_clear(allow, base);
   if ((ir->op2 & IRSLOAD_TYPECHECK)) {
     if (ra_noreg(type)) {
       if (ofs < 256 && ra_hasreg(dest) && (dest & 1) == 0 &&
 	  rset_test((as->freeset & allow), dest+1)) {
 	type = dest+1;
 	ra_modified(as, type);
       } else {
 	type = RID_TMP;
       }
     }
     asm_guardcc(as, t == IRT_NUM ? CC_HS : CC_NE);
     emit_n(as, ARMI_CMN|ARMI_K12|-irt_toitype_(t), type);
   }
   if (ra_hasreg(dest)) {
 #if !LJ_SOFTFP
     if (t == IRT_NUM) {
       if (ofs < 1024) {
 	emit_vlso(as, ARMI_VLDR_D, dest, base, ofs);
       } else {
 	if (ra_hasreg(type)) emit_lso(as, ARMI_LDR, type, base, ofs+4);
 	emit_vlso(as, ARMI_VLDR_D, dest, RID_TMP, 0);
 	emit_opk(as, ARMI_ADD, RID_TMP, base, ofs, allow);
 	return;
       }
     } else
 #endif
       emit_lso(as, ARMI_LDR, dest, base, ofs);
   }
   if (ra_hasreg(type)) emit_lso(as, ARMI_LDR, type, base, ofs+4);
 }
 
 /* -- 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];
   RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
   RegSet drop = RSET_SCRATCH;
   lua_assert(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL));
 
   as->gcsteps++;
   if (ra_hasreg(ir->r))
     rset_clear(drop, ir->r);  /* Dest reg handled below. */
   ra_evictset(as, drop);
   if (ra_used(ir))
     ra_destreg(as, ir, RID_RET);  /* GCcdata * */
 
   /* Initialize immutable cdata object. */
   if (ir->o == IR_CNEWI) {
     int32_t ofs = sizeof(GCcdata);
     lua_assert(sz == 4 || sz == 8);
     if (sz == 8) {
       ofs += 4; ir++;
       lua_assert(ir->o == IR_HIOP);
     }
     for (;;) {
       Reg r = ra_alloc1(as, ir->op2, allow);
       emit_lso(as, ARMI_STR, r, RID_RET, ofs);
       rset_clear(allow, r);
       if (ofs == sizeof(GCcdata)) break;
       ofs -= 4; ir--;
     }
   } 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;
   }
 
   /* Initialize gct and ctypeid. lj_mem_newgco() already sets marked. */
   {
     uint32_t k = emit_isk12(ARMI_MOV, id);
     Reg r = k ? RID_R1 : ra_allock(as, id, allow);
     emit_lso(as, ARMI_STRB, RID_TMP, RID_RET, offsetof(GCcdata, gct));
     emit_lsox(as, ARMI_STRH, r, RID_RET, offsetof(GCcdata, ctypeid));
     emit_d(as, ARMI_MOV|ARMI_K12|~LJ_TCDATA, RID_TMP);
     if (k) emit_d(as, ARMI_MOV^k, RID_R1);
   }
   args[0] = ASMREF_L;     /* lua_State *L */
   args[1] = ASMREF_TMP1;  /* MSize size   */
   asm_gencall(as, ci, args);
   ra_allockreg(as, (int32_t)(sz+sizeof(GCcdata)),
 	       ra_releasetmp(as, ASMREF_TMP1));
 }
 #else
 #define asm_cnew(as, ir)	((void)0)
 #endif
 
 /* -- Write barriers ------------------------------------------------------ */
 
 static void asm_tbar(ASMState *as, IRIns *ir)
 {
   Reg tab = ra_alloc1(as, ir->op1, RSET_GPR);
   Reg link = ra_scratch(as, rset_exclude(RSET_GPR, tab));
   Reg gr = ra_allock(as, i32ptr(J2G(as->J)),
 		     rset_exclude(rset_exclude(RSET_GPR, tab), link));
   Reg mark = RID_TMP;
   MCLabel l_end = emit_label(as);
   emit_lso(as, ARMI_STR, link, tab, (int32_t)offsetof(GCtab, gclist));
   emit_lso(as, ARMI_STRB, mark, tab, (int32_t)offsetof(GCtab, marked));
   emit_lso(as, ARMI_STR, tab, gr,
 	   (int32_t)offsetof(global_State, gc.grayagain));
   emit_dn(as, ARMI_BIC|ARMI_K12|LJ_GC_BLACK, mark, mark);
   emit_lso(as, ARMI_LDR, link, gr,
 	   (int32_t)offsetof(global_State, gc.grayagain));
   emit_branch(as, ARMF_CC(ARMI_B, CC_EQ), l_end);
   emit_n(as, ARMI_TST|ARMI_K12|LJ_GC_BLACK, mark);
   emit_lso(as, ARMI_LDRB, mark, tab, (int32_t)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, val, tmp;
   /* No need for other object barriers (yet). */
   lua_assert(IR(ir->op1)->o == IR_UREFC);
   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);
   if ((l_end[-1] >> 28) == CC_AL)
     l_end[-1] = ARMF_CC(l_end[-1], CC_NE);
   else
     emit_branch(as, ARMF_CC(ARMI_B, CC_EQ), l_end);
   ra_allockreg(as, i32ptr(J2G(as->J)), ra_releasetmp(as, ASMREF_TMP1));
   obj = IR(ir->op1)->r;
   tmp = ra_scratch(as, rset_exclude(RSET_GPR, obj));
   emit_n(as, ARMF_CC(ARMI_TST, CC_NE)|ARMI_K12|LJ_GC_BLACK, tmp);
   emit_n(as, ARMI_TST|ARMI_K12|LJ_GC_WHITES, RID_TMP);
   val = ra_alloc1(as, ir->op2, rset_exclude(RSET_GPR, obj));
   emit_lso(as, ARMI_LDRB, tmp, obj,
 	   (int32_t)offsetof(GCupval, marked)-(int32_t)offsetof(GCupval, tv));
   emit_lso(as, ARMI_LDRB, RID_TMP, val, (int32_t)offsetof(GChead, marked));
 }
 
 /* -- Arithmetic and logic operations ------------------------------------- */
 
 #if !LJ_SOFTFP
 static void asm_fparith(ASMState *as, IRIns *ir, ARMIns ai)
 {
   Reg dest = ra_dest(as, ir, RSET_FPR);
   Reg right, left = ra_alloc2(as, ir, RSET_FPR);
   right = (left >> 8); left &= 255;
   emit_dnm(as, ai, (dest & 15), (left & 15), (right & 15));
 }
 
 static void asm_fpunary(ASMState *as, IRIns *ir, ARMIns ai)
 {
   Reg dest = ra_dest(as, ir, RSET_FPR);
   Reg left = ra_hintalloc(as, ir->op1, dest, RSET_FPR);
   emit_dm(as, ai, (dest & 15), (left & 15));
 }
 
 static void asm_callround(ASMState *as, IRIns *ir, int id)
 {
   /* The modified regs must match with the *.dasc implementation. */
   RegSet drop = RID2RSET(RID_R0)|RID2RSET(RID_R1)|RID2RSET(RID_R2)|
 		RID2RSET(RID_R3)|RID2RSET(RID_R12);
   RegSet of;
   Reg dest, src;
   ra_evictset(as, drop);
   dest = ra_dest(as, ir, RSET_FPR);
   emit_dnm(as, ARMI_VMOV_D_RR, RID_RETLO, RID_RETHI, (dest & 15));
   emit_call(as, id == IRFPM_FLOOR ? (void *)lj_vm_floor_sf :
 		id == IRFPM_CEIL ? (void *)lj_vm_ceil_sf :
 				   (void *)lj_vm_trunc_sf);
   /* Workaround to protect argument GPRs from being used for remat. */
   of = as->freeset;
   as->freeset &= ~RSET_RANGE(RID_R0, RID_R1+1);
   as->cost[RID_R0] = as->cost[RID_R1] = REGCOST(~0u, ASMREF_L);
   src = ra_alloc1(as, ir->op1, RSET_FPR);  /* May alloc GPR to remat FPR. */
   as->freeset |= (of & RSET_RANGE(RID_R0, RID_R1+1));
   emit_dnm(as, ARMI_VMOV_RR_D, RID_R0, RID_R1, (src & 15));
 }
 
 static void asm_fpmath(ASMState *as, IRIns *ir)
 {
   if (ir->op2 == IRFPM_EXP2 && asm_fpjoin_pow(as, ir))
     return;
   if (ir->op2 <= IRFPM_TRUNC)
     asm_callround(as, ir, ir->op2);
   else if (ir->op2 == IRFPM_SQRT)
     asm_fpunary(as, ir, ARMI_VSQRT_D);
   else
     asm_callid(as, ir, IRCALL_lj_vm_floor + ir->op2);
 }
 #endif
 
 static int asm_swapops(ASMState *as, IRRef lref, IRRef rref)
 {
   IRIns *ir;
   if (irref_isk(rref))
     return 0;  /* Don't swap constants to the left. */
   if (irref_isk(lref))
     return 1;  /* But swap constants to the right. */
   ir = IR(rref);
   if ((ir->o >= IR_BSHL && ir->o <= IR_BROR) ||
       (ir->o == IR_ADD && ir->op1 == ir->op2))
     return 0;  /* Don't swap fusable operands to the left. */
   ir = IR(lref);
   if ((ir->o >= IR_BSHL && ir->o <= IR_BROR) ||
       (ir->o == IR_ADD && ir->op1 == ir->op2))
     return 1;  /* But swap fusable operands to the right. */
   return 0;  /* Otherwise don't swap. */
 }
 
 static void asm_intop(ASMState *as, IRIns *ir, ARMIns ai)
 {
   IRRef lref = ir->op1, rref = ir->op2;
   Reg left, dest = ra_dest(as, ir, RSET_GPR);
   uint32_t m;
   if (asm_swapops(as, lref, rref)) {
     IRRef tmp = lref; lref = rref; rref = tmp;
     if ((ai & ~ARMI_S) == ARMI_SUB || (ai & ~ARMI_S) == ARMI_SBC)
       ai ^= (ARMI_SUB^ARMI_RSB);
   }
   left = ra_hintalloc(as, lref, dest, RSET_GPR);
   m = asm_fuseopm(as, ai, rref, rset_exclude(RSET_GPR, left));
   if (irt_isguard(ir->t)) {  /* For IR_ADDOV etc. */
     asm_guardcc(as, CC_VS);
     ai |= ARMI_S;
   }
   emit_dn(as, ai^m, dest, left);
 }
 
 static void asm_intop_s(ASMState *as, IRIns *ir, ARMIns ai)
 {
   if (as->flagmcp == as->mcp) {  /* Drop cmp r, #0. */
     as->flagmcp = NULL;
     as->mcp++;
     ai |= ARMI_S;
   }
   asm_intop(as, ir, ai);
 }
 
 static void asm_intneg(ASMState *as, IRIns *ir, ARMIns ai)
 {
   Reg dest = ra_dest(as, ir, RSET_GPR);
   Reg left = ra_hintalloc(as, ir->op1, dest, RSET_GPR);
   emit_dn(as, ai|ARMI_K12|0, dest, left);
 }
 
 /* NYI: use add/shift for MUL(OV) with constants. FOLD only does 2^k. */
 static void asm_intmul(ASMState *as, IRIns *ir)
 {
   Reg dest = ra_dest(as, ir, RSET_GPR);
   Reg left = ra_alloc1(as, ir->op1, rset_exclude(RSET_GPR, dest));
   Reg right = ra_alloc1(as, ir->op2, rset_exclude(RSET_GPR, left));
   Reg tmp = RID_NONE;
   /* ARMv5 restriction: dest != left and dest_hi != left. */
   if (dest == left && left != right) { left = right; right = dest; }
   if (irt_isguard(ir->t)) {  /* IR_MULOV */
     if (!(as->flags & JIT_F_ARMV6) && dest == left)
       tmp = left = ra_scratch(as, rset_exclude(RSET_GPR, left));
     asm_guardcc(as, CC_NE);
     emit_nm(as, ARMI_TEQ|ARMF_SH(ARMSH_ASR, 31), RID_TMP, dest);
     emit_dnm(as, ARMI_SMULL|ARMF_S(right), dest, RID_TMP, left);
   } else {
     if (!(as->flags & JIT_F_ARMV6) && dest == left) tmp = left = RID_TMP;
     emit_nm(as, ARMI_MUL|ARMF_S(right), dest, left);
   }
   /* Only need this for the dest == left == right case. */
   if (ra_hasreg(tmp)) emit_dm(as, ARMI_MOV, tmp, right);
 }
 
 static void asm_add(ASMState *as, IRIns *ir)
 {
 #if !LJ_SOFTFP
   if (irt_isnum(ir->t)) {
     if (!asm_fusemadd(as, ir, ARMI_VMLA_D, ARMI_VMLA_D))
       asm_fparith(as, ir, ARMI_VADD_D);
     return;
   }
 #endif
   asm_intop_s(as, ir, ARMI_ADD);
 }
 
 static void asm_sub(ASMState *as, IRIns *ir)
 {
 #if !LJ_SOFTFP
   if (irt_isnum(ir->t)) {
     if (!asm_fusemadd(as, ir, ARMI_VNMLS_D, ARMI_VMLS_D))
       asm_fparith(as, ir, ARMI_VSUB_D);
     return;
   }
 #endif
   asm_intop_s(as, ir, ARMI_SUB);
 }
 
 static void asm_mul(ASMState *as, IRIns *ir)
 {
 #if !LJ_SOFTFP
   if (irt_isnum(ir->t)) {
     asm_fparith(as, ir, ARMI_VMUL_D);
     return;
   }
 #endif
   asm_intmul(as, ir);
 }
 
 #define asm_addov(as, ir)	asm_add(as, ir)
 #define asm_subov(as, ir)	asm_sub(as, ir)
 #define asm_mulov(as, ir)	asm_mul(as, ir)
 
 #if !LJ_SOFTFP
 #define asm_div(as, ir)		asm_fparith(as, ir, ARMI_VDIV_D)
 #define asm_pow(as, ir)		asm_callid(as, ir, IRCALL_lj_vm_powi)
 #define asm_abs(as, ir)		asm_fpunary(as, ir, ARMI_VABS_D)
 #define asm_atan2(as, ir)	asm_callid(as, ir, IRCALL_atan2)
 #define asm_ldexp(as, ir)	asm_callid(as, ir, IRCALL_ldexp)
 #endif
 
 #define asm_mod(as, ir)		asm_callid(as, ir, IRCALL_lj_vm_modi)
 
 static void asm_neg(ASMState *as, IRIns *ir)
 {
 #if !LJ_SOFTFP
   if (irt_isnum(ir->t)) {
     asm_fpunary(as, ir, ARMI_VNEG_D);
     return;
   }
 #endif
   asm_intneg(as, ir, ARMI_RSB);
 }
 
 static void asm_bitop(ASMState *as, IRIns *ir, ARMIns ai)
 {
   if (as->flagmcp == as->mcp) {  /* Try to drop cmp r, #0. */
     uint32_t cc = (as->mcp[1] >> 28);
     as->flagmcp = NULL;
     if (cc <= CC_NE) {
       as->mcp++;
       ai |= ARMI_S;
     } else if (cc == CC_GE) {
       *++as->mcp ^= ((CC_GE^CC_PL) << 28);
       ai |= ARMI_S;
     } else if (cc == CC_LT) {
       *++as->mcp ^= ((CC_LT^CC_MI) << 28);
       ai |= ARMI_S;
     }  /* else: other conds don't work with bit ops. */
   }
   if (ir->op2 == 0) {
     Reg dest = ra_dest(as, ir, RSET_GPR);
     uint32_t m = asm_fuseopm(as, ai, ir->op1, RSET_GPR);
     emit_d(as, ai^m, dest);
   } else {
     /* NYI: Turn BAND !k12 into uxtb, uxth or bfc or shl+shr. */
     asm_intop(as, ir, ai);
   }
 }
 
 #define asm_bnot(as, ir)	asm_bitop(as, ir, ARMI_MVN)
 
 static void asm_bswap(ASMState *as, IRIns *ir)
 {
   Reg dest = ra_dest(as, ir, RSET_GPR);
   Reg left = ra_alloc1(as, ir->op1, RSET_GPR);
   if ((as->flags & JIT_F_ARMV6)) {
     emit_dm(as, ARMI_REV, dest, left);
   } else {
     Reg tmp2 = dest;
     if (tmp2 == left)
       tmp2 = ra_scratch(as, rset_exclude(rset_exclude(RSET_GPR, dest), left));
     emit_dnm(as, ARMI_EOR|ARMF_SH(ARMSH_LSR, 8), dest, tmp2, RID_TMP);
     emit_dm(as, ARMI_MOV|ARMF_SH(ARMSH_ROR, 8), tmp2, left);
     emit_dn(as, ARMI_BIC|ARMI_K12|256*8|255, RID_TMP, RID_TMP);
     emit_dnm(as, ARMI_EOR|ARMF_SH(ARMSH_ROR, 16), RID_TMP, left, left);
   }
 }
 
 #define asm_band(as, ir)	asm_bitop(as, ir, ARMI_AND)
 #define asm_bor(as, ir)		asm_bitop(as, ir, ARMI_ORR)
 #define asm_bxor(as, ir)	asm_bitop(as, ir, ARMI_EOR)
 
 static void asm_bitshift(ASMState *as, IRIns *ir, ARMShift sh)
 {
   if (irref_isk(ir->op2)) {  /* Constant shifts. */
     /* NYI: Turn SHL+SHR or BAND+SHR into uxtb, uxth or ubfx. */
     /* NYI: Turn SHL+ASR into sxtb, sxth or sbfx. */
     Reg dest = ra_dest(as, ir, RSET_GPR);
     Reg left = ra_alloc1(as, ir->op1, RSET_GPR);
     int32_t shift = (IR(ir->op2)->i & 31);
     emit_dm(as, ARMI_MOV|ARMF_SH(sh, shift), dest, left);
   } else {
     Reg dest = ra_dest(as, ir, RSET_GPR);
     Reg left = ra_alloc1(as, ir->op1, RSET_GPR);
     Reg right = ra_alloc1(as, ir->op2, rset_exclude(RSET_GPR, left));
     emit_dm(as, ARMI_MOV|ARMF_RSH(sh, right), dest, left);
   }
 }
 
 #define asm_bshl(as, ir)	asm_bitshift(as, ir, ARMSH_LSL)
 #define asm_bshr(as, ir)	asm_bitshift(as, ir, ARMSH_LSR)
 #define asm_bsar(as, ir)	asm_bitshift(as, ir, ARMSH_ASR)
 #define asm_bror(as, ir)	asm_bitshift(as, ir, ARMSH_ROR)
 #define asm_brol(as, ir)	lua_assert(0)
 
 static void asm_intmin_max(ASMState *as, IRIns *ir, int cc)
 {
   uint32_t kcmp = 0, kmov = 0;
   Reg dest = ra_dest(as, ir, RSET_GPR);
   Reg left = ra_hintalloc(as, ir->op1, dest, RSET_GPR);
   Reg right = 0;
   if (irref_isk(ir->op2)) {
     kcmp = emit_isk12(ARMI_CMP, IR(ir->op2)->i);
     if (kcmp) kmov = emit_isk12(ARMI_MOV, IR(ir->op2)->i);
   }
   if (!kmov) {
     kcmp = 0;
     right = ra_alloc1(as, ir->op2, rset_exclude(RSET_GPR, left));
   }
   if (kmov || dest != right) {
     emit_dm(as, ARMF_CC(ARMI_MOV, cc)^kmov, dest, right);
     cc ^= 1;  /* Must use opposite conditions for paired moves. */
   } else {
     cc ^= (CC_LT^CC_GT);  /* Otherwise may swap CC_LT <-> CC_GT. */
   }
   if (dest != left) emit_dm(as, ARMF_CC(ARMI_MOV, cc), dest, left);
   emit_nm(as, ARMI_CMP^kcmp, left, right);
 }
 
 #if LJ_SOFTFP
 static void asm_sfpmin_max(ASMState *as, IRIns *ir, int cc)
 {
   const CCallInfo *ci = &lj_ir_callinfo[IRCALL_softfp_cmp];
   RegSet drop = RSET_SCRATCH;
   Reg r;
   IRRef args[4];
   args[0] = ir->op1; args[1] = (ir+1)->op1;
   args[2] = ir->op2; args[3] = (ir+1)->op2;
   /* __aeabi_cdcmple preserves r0-r3. */
   if (ra_hasreg(ir->r)) rset_clear(drop, ir->r);
   if (ra_hasreg((ir+1)->r)) rset_clear(drop, (ir+1)->r);
   if (!rset_test(as->freeset, RID_R2) &&
       regcost_ref(as->cost[RID_R2]) == args[2]) rset_clear(drop, RID_R2);
   if (!rset_test(as->freeset, RID_R3) &&
       regcost_ref(as->cost[RID_R3]) == args[3]) rset_clear(drop, RID_R3);
   ra_evictset(as, drop);
   ra_destpair(as, ir);
   emit_dm(as, ARMF_CC(ARMI_MOV, cc), RID_RETHI, RID_R3);
   emit_dm(as, ARMF_CC(ARMI_MOV, cc), RID_RETLO, RID_R2);
   emit_call(as, (void *)ci->func);
   for (r = RID_R0; r <= RID_R3; r++)
     ra_leftov(as, r, args[r-RID_R0]);
 }
 #else
 static void asm_fpmin_max(ASMState *as, IRIns *ir, int cc)
 {
   Reg dest = (ra_dest(as, ir, RSET_FPR) & 15);
   Reg right, left = ra_alloc2(as, ir, RSET_FPR);
   right = ((left >> 8) & 15); left &= 15;
   if (dest != left) emit_dm(as, ARMF_CC(ARMI_VMOV_D, cc^1), dest, left);
   if (dest != right) emit_dm(as, ARMF_CC(ARMI_VMOV_D, cc), dest, right);
   emit_d(as, ARMI_VMRS, 0);
   emit_dm(as, ARMI_VCMP_D, left, right);
 }
 #endif
 
 static void asm_min_max(ASMState *as, IRIns *ir, int cc, int fcc)
 {
 #if LJ_SOFTFP
   UNUSED(fcc);
 #else
   if (irt_isnum(ir->t))
     asm_fpmin_max(as, ir, fcc);
   else
 #endif
     asm_intmin_max(as, ir, cc);
 }
 
 #define asm_min(as, ir)		asm_min_max(as, ir, CC_GT, CC_HI)
 #define asm_max(as, ir)		asm_min_max(as, ir, CC_LT, CC_LO)
 
 /* -- Comparisons --------------------------------------------------------- */
 
 /* Map of comparisons to flags. ORDER IR. */
 static const uint8_t asm_compmap[IR_ABC+1] = {
   /* op  FP swp  int cc   FP cc */
   /* LT       */ CC_GE + (CC_HS << 4),
   /* GE    x  */ CC_LT + (CC_HI << 4),
   /* LE       */ CC_GT + (CC_HI << 4),
   /* GT    x  */ CC_LE + (CC_HS << 4),
   /* ULT   x  */ CC_HS + (CC_LS << 4),
   /* UGE      */ CC_LO + (CC_LO << 4),
   /* ULE   x  */ CC_HI + (CC_LO << 4),
   /* UGT      */ CC_LS + (CC_LS << 4),
   /* EQ       */ CC_NE + (CC_NE << 4),
   /* NE       */ CC_EQ + (CC_EQ << 4),
   /* ABC      */ CC_LS + (CC_LS << 4)  /* Same as UGT. */
 };
 
 #if LJ_SOFTFP
 /* FP comparisons. */
 static void asm_sfpcomp(ASMState *as, IRIns *ir)
 {
   const CCallInfo *ci = &lj_ir_callinfo[IRCALL_softfp_cmp];
   RegSet drop = RSET_SCRATCH;
   Reg r;
   IRRef args[4];
   int swp = (((ir->o ^ (ir->o >> 2)) & ~(ir->o >> 3) & 1) << 1);
   args[swp^0] = ir->op1; args[swp^1] = (ir+1)->op1;
   args[swp^2] = ir->op2; args[swp^3] = (ir+1)->op2;
   /* __aeabi_cdcmple preserves r0-r3. This helps to reduce spills. */
   for (r = RID_R0; r <= RID_R3; r++)
     if (!rset_test(as->freeset, r) &&
 	regcost_ref(as->cost[r]) == args[r-RID_R0]) rset_clear(drop, r);
   ra_evictset(as, drop);
   asm_guardcc(as, (asm_compmap[ir->o] >> 4));
   emit_call(as, (void *)ci->func);
   for (r = RID_R0; r <= RID_R3; r++)
     ra_leftov(as, r, args[r-RID_R0]);
 }
 #else
 /* FP comparisons. */
 static void asm_fpcomp(ASMState *as, IRIns *ir)
 {
   Reg left, right;
   ARMIns ai;
   int swp = ((ir->o ^ (ir->o >> 2)) & ~(ir->o >> 3) & 1);
   if (!swp && irref_isk(ir->op2) && ir_knum(IR(ir->op2))->u64 == 0) {
     left = (ra_alloc1(as, ir->op1, RSET_FPR) & 15);
     right = 0;
     ai = ARMI_VCMPZ_D;
   } else {
     left = ra_alloc2(as, ir, RSET_FPR);
     if (swp) {
       right = (left & 15); left = ((left >> 8) & 15);
     } else {
       right = ((left >> 8) & 15); left &= 15;
     }
     ai = ARMI_VCMP_D;
   }
   asm_guardcc(as, (asm_compmap[ir->o] >> 4));
   emit_d(as, ARMI_VMRS, 0);
   emit_dm(as, ai, left, right);
 }
 #endif
 
 /* Integer comparisons. */
 static void asm_intcomp(ASMState *as, IRIns *ir)
 {
   ARMCC cc = (asm_compmap[ir->o] & 15);
   IRRef lref = ir->op1, rref = ir->op2;
   Reg left;
   uint32_t m;
   int cmpprev0 = 0;
   lua_assert(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t));
   if (asm_swapops(as, lref, rref)) {
     Reg tmp = lref; lref = rref; rref = tmp;
     if (cc >= CC_GE) cc ^= 7;  /* LT <-> GT, LE <-> GE */
     else if (cc > CC_NE) cc ^= 11;  /* LO <-> HI, LS <-> HS */
   }
   if (irref_isk(rref) && IR(rref)->i == 0) {
     IRIns *irl = IR(lref);
     cmpprev0 = (irl+1 == ir);
     /* Combine comp(BAND(left, right), 0) into tst left, right. */
     if (cmpprev0 && irl->o == IR_BAND && !ra_used(irl)) {
       IRRef blref = irl->op1, brref = irl->op2;
       uint32_t m2 = 0;
       Reg bleft;
       if (asm_swapops(as, blref, brref)) {
 	Reg tmp = blref; blref = brref; brref = tmp;
       }
       if (irref_isk(brref)) {
 	m2 = emit_isk12(ARMI_AND, IR(brref)->i);
 	if ((m2 & (ARMI_AND^ARMI_BIC)))
 	  goto notst;  /* Not beneficial if we miss a constant operand. */
       }
       if (cc == CC_GE) cc = CC_PL;
       else if (cc == CC_LT) cc = CC_MI;
       else if (cc > CC_NE) goto notst;  /* Other conds don't work with tst. */
       bleft = ra_alloc1(as, blref, RSET_GPR);
       if (!m2) m2 = asm_fuseopm(as, 0, brref, rset_exclude(RSET_GPR, bleft));
       asm_guardcc(as, cc);
       emit_n(as, ARMI_TST^m2, bleft);
       return;
     }
   }
 notst:
   left = ra_alloc1(as, lref, RSET_GPR);
   m = asm_fuseopm(as, ARMI_CMP, rref, rset_exclude(RSET_GPR, left));
   asm_guardcc(as, cc);
   emit_n(as, ARMI_CMP^m, left);
   /* Signed comparison with zero and referencing previous ins? */
   if (cmpprev0 && (cc <= CC_NE || cc >= CC_GE))
     as->flagmcp = as->mcp;  /* Allow elimination of the compare. */
 }
 
 static void asm_comp(ASMState *as, IRIns *ir)
 {
 #if !LJ_SOFTFP
   if (irt_isnum(ir->t))
     asm_fpcomp(as, ir);
   else
 #endif
     asm_intcomp(as, ir);
 }
 
 #define asm_equal(as, ir)	asm_comp(as, ir)
 
 #if LJ_HASFFI
 /* 64 bit integer comparisons. */
 static void asm_int64comp(ASMState *as, IRIns *ir)
 {
   int signedcomp = (ir->o <= IR_GT);
   ARMCC cclo, cchi;
   Reg leftlo, lefthi;
   uint32_t mlo, mhi;
   RegSet allow = RSET_GPR, oldfree;
 
   /* Always use unsigned comparison for loword. */
   cclo = asm_compmap[ir->o + (signedcomp ? 4 : 0)] & 15;
   leftlo = ra_alloc1(as, ir->op1, allow);
   oldfree = as->freeset;
   mlo = asm_fuseopm(as, ARMI_CMP, ir->op2, rset_clear(allow, leftlo));
   allow &= ~(oldfree & ~as->freeset);  /* Update for allocs of asm_fuseopm. */
 
   /* Use signed or unsigned comparison for hiword. */
   cchi = asm_compmap[ir->o] & 15;
   lefthi = ra_alloc1(as, (ir+1)->op1, allow);
   mhi = asm_fuseopm(as, ARMI_CMP, (ir+1)->op2, rset_clear(allow, lefthi));
 
   /* All register allocations must be performed _before_ this point. */
   if (signedcomp) {
     MCLabel l_around = emit_label(as);
     asm_guardcc(as, cclo);
     emit_n(as, ARMI_CMP^mlo, leftlo);
     emit_branch(as, ARMF_CC(ARMI_B, CC_NE), l_around);
     if (cchi == CC_GE || cchi == CC_LE) cchi ^= 6;  /* GE -> GT, LE -> LT */
     asm_guardcc(as, cchi);
   } else {
     asm_guardcc(as, cclo);
     emit_n(as, ARMF_CC(ARMI_CMP, CC_EQ)^mlo, leftlo);
   }
   emit_n(as, ARMI_CMP^mhi, lefthi);
 }
 #endif
 
 /* -- Support for 64 bit ops in 32 bit mode ------------------------------- */
 
 /* Hiword op of a split 64 bit op. Previous op must be the loword op. */
 static void asm_hiop(ASMState *as, IRIns *ir)
 {
 #if LJ_HASFFI || LJ_SOFTFP
   /* 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 ((ir-1)->o <= IR_NE) {  /* 64 bit integer or FP comparisons. ORDER IR. */
     as->curins--;  /* Always skip the loword comparison. */
 #if LJ_SOFTFP
     if (!irt_isint(ir->t)) {
       asm_sfpcomp(as, ir-1);
       return;
     }
 #endif
 #if LJ_HASFFI
     asm_int64comp(as, ir-1);
 #endif
     return;
 #if LJ_SOFTFP
   } else if ((ir-1)->o == IR_MIN || (ir-1)->o == IR_MAX) {
     as->curins--;  /* Always skip the loword min/max. */
     if (uselo || usehi)
       asm_sfpmin_max(as, ir-1, (ir-1)->o == IR_MIN ? CC_HI : CC_LO);
     return;
 #elif LJ_HASFFI
   } else if ((ir-1)->o == IR_CONV) {
     as->curins--;  /* Always skip the CONV. */
     if (usehi || uselo)
       asm_conv64(as, ir);
     return;
 #endif
   } else if ((ir-1)->o == IR_XSTORE) {
     if ((ir-1)->r != RID_SINK)
       asm_xstore_(as, ir, 4);
     return;
   }
   if (!usehi) return;  /* Skip unused hiword op for all remaining ops. */
   switch ((ir-1)->o) {
 #if LJ_HASFFI
   case IR_ADD:
     as->curins--;
     asm_intop(as, ir, ARMI_ADC);
     asm_intop(as, ir-1, ARMI_ADD|ARMI_S);
     break;
   case IR_SUB:
     as->curins--;
     asm_intop(as, ir, ARMI_SBC);
     asm_intop(as, ir-1, ARMI_SUB|ARMI_S);
     break;
   case IR_NEG:
     as->curins--;
     asm_intneg(as, ir, ARMI_RSC);
     asm_intneg(as, ir-1, ARMI_RSB|ARMI_S);
     break;
 #endif
 #if LJ_SOFTFP
   case IR_SLOAD: case IR_ALOAD: case IR_HLOAD: case IR_ULOAD: case IR_VLOAD:
   case IR_STRTO:
     if (!uselo)
       ra_allocref(as, ir->op1, RSET_GPR);  /* Mark lo op as used. */
     break;
 #endif
   case IR_CALLN:
   case IR_CALLS:
   case IR_CALLXS:
     if (!uselo)
       ra_allocref(as, ir->op1, RID2RSET(RID_RETLO));  /* Mark lo op as used. */
     break;
 #if LJ_SOFTFP
   case IR_ASTORE: case IR_HSTORE: case IR_USTORE: case IR_TOSTR:
 #endif
   case IR_CNEWI:
     /* Nothing to do here. Handled by lo op itself. */
     break;
   default: lua_assert(0); break;
   }
 #else
   UNUSED(as); UNUSED(ir); lua_assert(0);
 #endif
 }
 
 /* -- Profiling ----------------------------------------------------------- */
 
 static void asm_prof(ASMState *as, IRIns *ir)
 {
   UNUSED(ir);
   asm_guardcc(as, CC_NE);
   emit_n(as, ARMI_TST|ARMI_K12|HOOK_PROFILE, RID_TMP);
   emit_lsptr(as, ARMI_LDRB, RID_TMP, (void *)&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)
 {
   Reg pbase;
   uint32_t k;
   if (irp) {
     if (!ra_hasspill(irp->s)) {
       pbase = irp->r;
       lua_assert(ra_hasreg(pbase));
     } else if (allow) {
       pbase = rset_pickbot(allow);
     } else {
       pbase = RID_RET;
       emit_lso(as, ARMI_LDR, RID_RET, RID_SP, 0);  /* Restore temp. register. */
     }
   } else {
     pbase = RID_BASE;
   }
   emit_branch(as, ARMF_CC(ARMI_BL, CC_LS), exitstub_addr(as->J, exitno));
   k = emit_isk12(0, (int32_t)(8*topslot));
   lua_assert(k);
   emit_n(as, ARMI_CMP^k, RID_TMP);
   emit_dnm(as, ARMI_SUB, RID_TMP, RID_TMP, pbase);
   emit_lso(as, ARMI_LDR, RID_TMP, RID_TMP,
 	   (int32_t)offsetof(lua_State, maxstack));
   if (irp) {  /* Must not spill arbitrary registers in head of side trace. */
     int32_t i = i32ptr(&J2G(as->J)->cur_L);
     if (ra_hasspill(irp->s))
       emit_lso(as, ARMI_LDR, pbase, RID_SP, sps_scale(irp->s));
     emit_lso(as, ARMI_LDR, RID_TMP, RID_TMP, (i & 4095));
     if (ra_hasspill(irp->s) && !allow)
       emit_lso(as, ARMI_STR, RID_RET, RID_SP, 0);  /* Save temp. register. */
     emit_loadi(as, RID_TMP, (i & ~4095));
   } else {
     emit_getgl(as, RID_TMP, cur_L);
   }
 }
 
 /* Restore Lua stack from on-trace state. */
 static void asm_stack_restore(ASMState *as, SnapShot *snap)
 {
   SnapEntry *map = &as->T->snapmap[snap->mapofs];
   SnapEntry *flinks = &as->T->snapmap[snap_nextofs(as->T, snap)-1];
   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);
     IRRef ref = snap_ref(sn);
     IRIns *ir = IR(ref);
     if ((sn & SNAP_NORESTORE))
       continue;
     if (irt_isnum(ir->t)) {
 #if LJ_SOFTFP
       RegSet odd = rset_exclude(RSET_GPRODD, RID_BASE);
       Reg tmp;
       lua_assert(irref_isk(ref));  /* LJ_SOFTFP: must be a number constant. */
       tmp = ra_allock(as, (int32_t)ir_knum(ir)->u32.lo,
 		      rset_exclude(RSET_GPREVEN, RID_BASE));
       emit_lso(as, ARMI_STR, tmp, RID_BASE, ofs);
       if (rset_test(as->freeset, tmp+1)) odd = RID2RSET(tmp+1);
       tmp = ra_allock(as, (int32_t)ir_knum(ir)->u32.hi, odd);
       emit_lso(as, ARMI_STR, tmp, RID_BASE, ofs+4);
 #else
       Reg src = ra_alloc1(as, ref, RSET_FPR);
       emit_vlso(as, ARMI_VSTR_D, src, RID_BASE, ofs);
 #endif
     } else {
       RegSet odd = rset_exclude(RSET_GPRODD, RID_BASE);
       Reg type;
       lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t));
       if (!irt_ispri(ir->t)) {
 	Reg src = ra_alloc1(as, ref, rset_exclude(RSET_GPREVEN, RID_BASE));
 	emit_lso(as, ARMI_STR, src, RID_BASE, ofs);
 	if (rset_test(as->freeset, src+1)) odd = RID2RSET(src+1);
       }
       if ((sn & (SNAP_CONT|SNAP_FRAME))) {
 	if (s == 0) continue;  /* Do not overwrite link to previous frame. */
 	type = ra_allock(as, (int32_t)(*flinks--), odd);
 #if LJ_SOFTFP
       } else if ((sn & SNAP_SOFTFPNUM)) {
 	type = ra_alloc1(as, ref+1, rset_exclude(RSET_GPRODD, RID_BASE));
 #endif
       } else {
 	type = ra_allock(as, (int32_t)irt_toitype(ir->t), odd);
       }
       emit_lso(as, ARMI_STR, type, RID_BASE, ofs+4);
     }
     checkmclim(as);
   }
   lua_assert(map + nent == flinks);
 }
 
 /* -- 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 tmp1, tmp2;
   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_n(as, ARMI_CMP|ARMI_K12|0, RID_RET);
   args[0] = ASMREF_TMP1;  /* global_State *g */
   args[1] = ASMREF_TMP2;  /* MSize steps     */
   asm_gencall(as, ci, args);
   tmp1 = ra_releasetmp(as, ASMREF_TMP1);
   tmp2 = ra_releasetmp(as, ASMREF_TMP2);
   emit_loadi(as, tmp2, as->gcsteps);
   /* Jump around GC step if GC total < GC threshold. */
   emit_branch(as, ARMF_CC(ARMI_B, CC_LS), l_end);
   emit_nm(as, ARMI_CMP, RID_TMP, tmp2);
   emit_lso(as, ARMI_LDR, tmp2, tmp1,
 	   (int32_t)offsetof(global_State, gc.threshold));
   emit_lso(as, ARMI_LDR, RID_TMP, tmp1,
 	   (int32_t)offsetof(global_State, gc.total));
   ra_allockreg(as, i32ptr(J2G(as->J)), tmp1);
   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->loopinv) {  /* Inverted loop branch? */
     /* asm_guardcc already inverted the bcc and patched the final bl. */
     p[-2] |= ((uint32_t)(target-p) & 0x00ffffffu);
   } else {
     p[-1] = ARMI_B | ((uint32_t)((target-p)-1) & 0x00ffffffu);
   }
 }
 
 /* -- Head of trace ------------------------------------------------------- */
 
 /* Reload L register from g->cur_L. */
 static void asm_head_lreg(ASMState *as)
 {
   IRIns *ir = IR(ASMREF_L);
   if (ra_used(ir)) {
     Reg r = ra_dest(as, ir, RSET_GPR);
     emit_getgl(as, r, cur_L);
     ra_evictk(as);
   }
 }
 
 /* Coalesce BASE register for a root trace. */
 static void asm_head_root_base(ASMState *as)
 {
   IRIns *ir;
   asm_head_lreg(as);
   ir = IR(REF_BASE);
   if (ra_hasreg(ir->r) && (rset_test(as->modset, ir->r) || irt_ismarked(ir->t)))
     ra_spill(as, ir);
   ra_destreg(as, ir, RID_BASE);
 }
 
 /* Coalesce BASE register for a side trace. */
 static RegSet asm_head_side_base(ASMState *as, IRIns *irp, RegSet allow)
 {
   IRIns *ir;
   asm_head_lreg(as);
   ir = IR(REF_BASE);
   if (ra_hasreg(ir->r) && (rset_test(as->modset, ir->r) || irt_ismarked(ir->t)))
     ra_spill(as, ir);
   if (ra_hasspill(irp->s)) {
     rset_clear(allow, ra_dest(as, ir, allow));
   } else {
     Reg r = irp->r;
     lua_assert(ra_hasreg(r));
     rset_clear(allow, r);
     if (r != ir->r && !rset_test(as->freeset, r))
       ra_restore(as, regcost_ref(as->cost[r]));
     ra_destreg(as, ir, r);
   }
   return allow;
 }
 
 /* -- Tail of trace ------------------------------------------------------- */
 
 /* Fixup the tail code. */
 static void asm_tail_fixup(ASMState *as, TraceNo lnk)
 {
   MCode *p = as->mctop;
   MCode *target;
   int32_t spadj = as->T->spadjust;
   if (spadj == 0) {
     as->mctop = --p;
   } else {
     /* Patch stack adjustment. */
     uint32_t k = emit_isk12(ARMI_ADD, spadj);
     lua_assert(k);
     p[-2] = (ARMI_ADD^k) | ARMF_D(RID_SP) | ARMF_N(RID_SP);
   }
   /* Patch exit branch. */
   target = lnk ? traceref(as->J, lnk)->mcode : (MCode *)lj_vm_exit_interp;
   p[-1] = ARMI_B|(((target-p)-1)&0x00ffffffu);
 }
 
 /* Prepare tail of code. */
 static void asm_tail_prep(ASMState *as)
 {
   MCode *p = as->mctop - 1;  /* Leave room for exit branch. */
   if (as->loopref) {
     as->invmcp = as->mcp = p;
   } else {
     as->mcp = p-1;  /* Leave room for stack pointer adjustment. */
     as->invmcp = NULL;
   }
   *p = 0;  /* Prevent load/store merging. */
 }
 
 /* -- 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];
   uint32_t i, nargs = CCI_XNARGS(ci);
   int nslots = 0, ngpr = REGARG_NUMGPR, nfpr = REGARG_NUMFPR, fprodd = 0;
   asm_collectargs(as, ir, ci, args);
   for (i = 0; i < nargs; i++) {
     if (!LJ_SOFTFP && args[i] && irt_isfp(IR(args[i])->t)) {
       if (!LJ_ABI_SOFTFP && !(ci->flags & CCI_VARARG)) {
 	if (irt_isnum(IR(args[i])->t)) {
 	  if (nfpr > 0) nfpr--;
 	  else fprodd = 0, nslots = (nslots + 3) & ~1;
 	} else {
 	  if (fprodd) fprodd--;
 	  else if (nfpr > 0) fprodd = 1, nfpr--;
 	  else nslots++;
 	}
       } else if (irt_isnum(IR(args[i])->t)) {
 	ngpr &= ~1;
 	if (ngpr > 0) ngpr -= 2; else nslots += 2;
       } else {
 	if (ngpr > 0) ngpr--; else nslots++;
       }
     } else {
       if (ngpr > 0) ngpr--; else nslots++;
     }
   }
   if (nslots > as->evenspill)  /* Leave room for args in stack slots. */
     as->evenspill = nslots;
   return REGSP_HINT(RID_RET);
 }
 
 static void asm_setup_target(ASMState *as)
 {
   /* May need extra exit for asm_stack_check on side traces. */
   asm_exitstub_setup(as, as->T->nsnap + (as->parent ? 1 : 0));
 }
 
 /* -- Trace patching ------------------------------------------------------ */
 
 /* 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 *pe = (MCode *)((char *)p + T->szmcode);
   MCode *cstart = NULL, *cend = p;
   MCode *mcarea = lj_mcode_patch(J, p, 0);
   MCode *px = exitstub_addr(J, exitno) - 2;
   for (; p < pe; p++) {
     /* Look for bl_cc exitstub, replace with b_cc target. */
     uint32_t ins = *p;
     if ((ins & 0x0f000000u) == 0x0b000000u && ins < 0xf0000000u &&
 	((ins ^ (px-p)) & 0x00ffffffu) == 0) {
       *p = (ins & 0xfe000000u) | (((target-p)-2) & 0x00ffffffu);
       cend = p+1;
       if (!cstart) cstart = p;
     }
   }
   lua_assert(cstart != NULL);
   lj_mcode_sync(cstart, cend);
   lj_mcode_patch(J, mcarea, 1);
 }