6035198545

Committed 31 Aug 2023 08:55AM UTC coverage: 88.225% (+0.4%) from 87.822%

Build # 6035198545

Build Type

push

github

Committed by

fckxorg

Commit Message

test: don't skip tool CLI flag for tarantool

That skipcond was introduced to overcome the obstacles
of LuaJIT's integration testing in Tarantool. Since
the required patch is now in the Tarantool master, this
skipcond is now unnecessary.

Related to tarantool/tarantool#5688

Run Details

5340 of 5975 branches covered (0.0%)

Branch coverage included in aggregate %.

20495 of 23308 relevant lines covered (87.93%)

1297339.67 hits per line

Source File
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99.56

/src/lj_parse.c

/*
** Lua parser (source code -> bytecode).
** Copyright (C) 2005-2017 Mike Pall. See Copyright Notice in luajit.h
**
** Major portions taken verbatim or adapted from the Lua interpreter.
** Copyright (C) 1994-2008 Lua.org, PUC-Rio. See Copyright Notice in lua.h
*/

#define lj_parse_c
#define LUA_CORE

#include "lj_obj.h"
#include "lj_gc.h"
#include "lj_err.h"
#include "lj_debug.h"
#include "lj_buf.h"
#include "lj_str.h"
#include "lj_tab.h"
#include "lj_func.h"
#include "lj_state.h"
#include "lj_bc.h"
#if LJ_HASFFI
#include "lj_ctype.h"
#endif
#include "lj_strfmt.h"
#include "lj_lex.h"
#include "lj_parse.h"
#include "lj_vm.h"
#include "lj_vmevent.h"
#if LJ_HASMEMPROF
#include "lj_memprof.h"
#endif
#if LJ_HASSYSPROF
#include "lj_sysprof.h"
#endif

/* -- Parser structures and definitions ----------------------------------- */

/* Expression kinds. */
typedef enum {
  /* Constant expressions must be first and in this order: */
  VKNIL,
  VKFALSE,
  VKTRUE,
  VKSTR,        /* sval = string value */
  VKNUM,        /* nval = number value */
  VKLAST = VKNUM,
  VKCDATA,        /* nval = cdata value, not treated as a constant expression */
  /* Non-constant expressions follow: */
  VLOCAL,        /* info = local register, aux = vstack index */
  VUPVAL,        /* info = upvalue index, aux = vstack index */
  VGLOBAL,        /* sval = string value */
  VINDEXED,        /* info = table register, aux = index reg/byte/string const */
  VJMP,                /* info = instruction PC */
  VRELOCABLE,        /* info = instruction PC */
  VNONRELOC,        /* info = result register */
  VCALL,        /* info = instruction PC, aux = base */
  VVOID
} ExpKind;

/* Expression descriptor. */
typedef struct ExpDesc {
  union {
    struct {
      uint32_t info;        /* Primary info. */
      uint32_t aux;        /* Secondary info. */
    } s;
    TValue nval;        /* Number value. */
    GCstr *sval;        /* String value. */
  } u;
  ExpKind k;
  BCPos t;                /* True condition jump list. */
  BCPos f;                /* False condition jump list. */
} ExpDesc;

/* Macros for expressions. */
#define expr_hasjump(e)                ((e)->t != (e)->f)

#define expr_isk(e)                ((e)->k <= VKLAST)
#define expr_isk_nojump(e)        (expr_isk(e) && !expr_hasjump(e))
#define expr_isnumk(e)                ((e)->k == VKNUM)
#define expr_isnumk_nojump(e)        (expr_isnumk(e) && !expr_hasjump(e))
#define expr_isstrk(e)                ((e)->k == VKSTR)

#define expr_numtv(e)                check_exp(expr_isnumk((e)), &(e)->u.nval)
#define expr_numberV(e)                numberVnum(expr_numtv((e)))

/* Initialize expression. */
static LJ_AINLINE void expr_init(ExpDesc *e, ExpKind k, uint32_t info)
{
  e->k = k;
  e->u.s.info = info;
  e->f = e->t = NO_JMP;
}

/* Check number constant for +-0. */
static int expr_numiszero(ExpDesc *e)
{
  TValue *o = expr_numtv(e);
  return tvisint(o) ? (intV(o) == 0) : tviszero(o);
}

/* Per-function linked list of scope blocks. */
typedef struct FuncScope {
  struct FuncScope *prev;        /* Link to outer scope. */
  MSize vstart;                        /* Start of block-local variables. */
  uint8_t nactvar;                /* Number of active vars outside the scope. */
  uint8_t flags;                /* Scope flags. */
} FuncScope;

#define FSCOPE_LOOP                0x01        /* Scope is a (breakable) loop. */
#define FSCOPE_BREAK                0x02        /* Break used in scope. */
#define FSCOPE_GOLA                0x04        /* Goto or label used in scope. */
#define FSCOPE_UPVAL                0x08        /* Upvalue in scope. */
#define FSCOPE_NOCLOSE                0x10        /* Do not close upvalues. */

#define NAME_BREAK                ((GCstr *)(uintptr_t)1)

/* Index into variable stack. */
typedef uint16_t VarIndex;
#define LJ_MAX_VSTACK                (65536 - LJ_MAX_UPVAL)

/* Variable/goto/label info. */
#define VSTACK_VAR_RW                0x01        /* R/W variable. */
#define VSTACK_GOTO                0x02        /* Pending goto. */
#define VSTACK_LABEL                0x04        /* Label. */

/* Per-function state. */
typedef struct FuncState {
  GCtab *kt;                        /* Hash table for constants. */
  LexState *ls;                        /* Lexer state. */
  lua_State *L;                        /* Lua state. */
  FuncScope *bl;                /* Current scope. */
  struct FuncState *prev;        /* Enclosing function. */
  BCPos pc;                        /* Next bytecode position. */
  BCPos lasttarget;                /* Bytecode position of last jump target. */
  BCPos jpc;                        /* Pending jump list to next bytecode. */
  BCReg freereg;                /* First free register. */
  BCReg nactvar;                /* Number of active local variables. */
  BCReg nkn, nkgc;                /* Number of lua_Number/GCobj constants */
  BCLine linedefined;                /* First line of the function definition. */
  BCInsLine *bcbase;                /* Base of bytecode stack. */
  BCPos bclim;                        /* Limit of bytecode stack. */
  MSize vbase;                        /* Base of variable stack for this function. */
  uint8_t flags;                /* Prototype flags. */
  uint8_t numparams;                /* Number of parameters. */
  uint8_t framesize;                /* Fixed frame size. */
  uint8_t nuv;                        /* Number of upvalues */
  VarIndex varmap[LJ_MAX_LOCVAR];  /* Map from register to variable idx. */
  VarIndex uvmap[LJ_MAX_UPVAL];        /* Map from upvalue to variable idx. */
  VarIndex uvtmp[LJ_MAX_UPVAL];        /* Temporary upvalue map. */
} FuncState;

/* Binary and unary operators. ORDER OPR */
typedef enum BinOpr {
  OPR_ADD, OPR_SUB, OPR_MUL, OPR_DIV, OPR_MOD, OPR_POW,  /* ORDER ARITH */
  OPR_CONCAT,
  OPR_NE, OPR_EQ,
  OPR_LT, OPR_GE, OPR_LE, OPR_GT,
  OPR_AND, OPR_OR,
  OPR_NOBINOPR
} BinOpr;

LJ_STATIC_ASSERT((int)BC_ISGE-(int)BC_ISLT == (int)OPR_GE-(int)OPR_LT);
LJ_STATIC_ASSERT((int)BC_ISLE-(int)BC_ISLT == (int)OPR_LE-(int)OPR_LT);
LJ_STATIC_ASSERT((int)BC_ISGT-(int)BC_ISLT == (int)OPR_GT-(int)OPR_LT);
LJ_STATIC_ASSERT((int)BC_SUBVV-(int)BC_ADDVV == (int)OPR_SUB-(int)OPR_ADD);
LJ_STATIC_ASSERT((int)BC_MULVV-(int)BC_ADDVV == (int)OPR_MUL-(int)OPR_ADD);
LJ_STATIC_ASSERT((int)BC_DIVVV-(int)BC_ADDVV == (int)OPR_DIV-(int)OPR_ADD);
LJ_STATIC_ASSERT((int)BC_MODVV-(int)BC_ADDVV == (int)OPR_MOD-(int)OPR_ADD);

#ifdef LUA_USE_ASSERT
#define lj_assertFS(c, ...)        (lj_assertG_(G(fs->L), (c), __VA_ARGS__))
#else
#define lj_assertFS(c, ...)        ((void)fs)
#endif

/* -- Error handling ------------------------------------------------------ */

LJ_NORET LJ_NOINLINE static void err_syntax(LexState *ls, ErrMsg em)
{
  lj_lex_error(ls, ls->tok, em);
}

LJ_NORET LJ_NOINLINE static void err_token(LexState *ls, LexToken tok)
{
  lj_lex_error(ls, ls->tok, LJ_ERR_XTOKEN, lj_lex_token2str(ls, tok));
}

LJ_NORET static void err_limit(FuncState *fs, uint32_t limit, const char *what)
{
  if (fs->linedefined == 0)
    lj_lex_error(fs->ls, 0, LJ_ERR_XLIMM, limit, what);
  else
    lj_lex_error(fs->ls, 0, LJ_ERR_XLIMF, fs->linedefined, limit, what);
}

#define checklimit(fs, v, l, m)                if ((v) >= (l)) err_limit(fs, l, m)
#define checklimitgt(fs, v, l, m)        if ((v) > (l)) err_limit(fs, l, m)
#define checkcond(ls, c, em)                { if (!(c)) err_syntax(ls, em); }

/* -- Management of constants --------------------------------------------- */

/* Return bytecode encoding for primitive constant. */
#define const_pri(e)                check_exp((e)->k <= VKTRUE, (e)->k)

#define tvhaskslot(o)        ((o)->u32.hi == 0)
#define tvkslot(o)        ((o)->u32.lo)

/* Add a number constant. */
static BCReg const_num(FuncState *fs, ExpDesc *e)
{
  lua_State *L = fs->L;
  TValue *o;
  lj_assertFS(expr_isnumk(e), "bad usage");
  o = lj_tab_set(L, fs->kt, &e->u.nval);
  if (tvhaskslot(o))
    return tvkslot(o);
  o->u64 = fs->nkn;
  return fs->nkn++;
}

/* Add a GC object constant. */
static BCReg const_gc(FuncState *fs, GCobj *gc, uint32_t itype)
{
  lua_State *L = fs->L;
  TValue key, *o;
  setgcV(L, &key, gc, itype);
  /* NOBARRIER: the key is new or kept alive. */
  o = lj_tab_set(L, fs->kt, &key);
  if (tvhaskslot(o))
    return tvkslot(o);
  o->u64 = fs->nkgc;
  return fs->nkgc++;
}

/* Add a string constant. */
static BCReg const_str(FuncState *fs, ExpDesc *e)
{
  lj_assertFS(expr_isstrk(e) || e->k == VGLOBAL, "bad usage");
  return const_gc(fs, obj2gco(e->u.sval), LJ_TSTR);
}

/* Anchor string constant to avoid GC. */
GCstr *lj_parse_keepstr(LexState *ls, const char *str, size_t len)
{
  /* NOBARRIER: the key is new or kept alive. */
  lua_State *L = ls->L;
  GCstr *s = lj_str_new(L, str, len);
  TValue *tv = lj_tab_setstr(L, ls->fs->kt, s);
  if (tvisnil(tv)) setboolV(tv, 1);
  lj_gc_check(L);
  return s;
}

#if LJ_HASFFI
/* Anchor cdata to avoid GC. */
void lj_parse_keepcdata(LexState *ls, TValue *tv, GCcdata *cd)
{
  /* NOBARRIER: the key is new or kept alive. */
  lua_State *L = ls->L;
  setcdataV(L, tv, cd);
  setboolV(lj_tab_set(L, ls->fs->kt, tv), 1);
}
#endif

/* -- Jump list handling -------------------------------------------------- */

/* Get next element in jump list. */
static BCPos jmp_next(FuncState *fs, BCPos pc)
{
  ptrdiff_t delta = bc_j(fs->bcbase[pc].ins);
  if ((BCPos)delta == NO_JMP)
    return NO_JMP;
  else
    return (BCPos)(((ptrdiff_t)pc+1)+delta);
}

/* Check if any of the instructions on the jump list produce no value. */
static int jmp_novalue(FuncState *fs, BCPos list)
{
  for (; list != NO_JMP; list = jmp_next(fs, list)) {
    BCIns p = fs->bcbase[list >= 1 ? list-1 : list].ins;
    if (!(bc_op(p) == BC_ISTC || bc_op(p) == BC_ISFC || bc_a(p) == NO_REG))
      return 1;
  }
  return 0;
}

/* Patch register of test instructions. */
static int jmp_patchtestreg(FuncState *fs, BCPos pc, BCReg reg)
{
  BCInsLine *ilp = &fs->bcbase[pc >= 1 ? pc-1 : pc];
  BCOp op = bc_op(ilp->ins);
  if (op == BC_ISTC || op == BC_ISFC) {
    if (reg != NO_REG && reg != bc_d(ilp->ins)) {
      setbc_a(&ilp->ins, reg);
    } else {  /* Nothing to store or already in the right register. */
      setbc_op(&ilp->ins, op+(BC_IST-BC_ISTC));
      setbc_a(&ilp->ins, 0);
    }
  } else if (bc_a(ilp->ins) == NO_REG) {
    if (reg == NO_REG) {
      ilp->ins = BCINS_AJ(BC_JMP, bc_a(fs->bcbase[pc].ins), 0);
    } else {
      setbc_a(&ilp->ins, reg);
      if (reg >= bc_a(ilp[1].ins))
        setbc_a(&ilp[1].ins, reg+1);
    }
  } else {
    return 0;  /* Cannot patch other instructions. */
  }
  return 1;
}

/* Drop values for all instructions on jump list. */
static void jmp_dropval(FuncState *fs, BCPos list)
{
  for (; list != NO_JMP; list = jmp_next(fs, list))
    jmp_patchtestreg(fs, list, NO_REG);
}

/* Patch jump instruction to target. */
static void jmp_patchins(FuncState *fs, BCPos pc, BCPos dest)
{
  BCIns *jmp = &fs->bcbase[pc].ins;
  BCPos offset = dest-(pc+1)+BCBIAS_J;
  lj_assertFS(dest != NO_JMP, "uninitialized jump target");
  if (offset > BCMAX_D)
    err_syntax(fs->ls, LJ_ERR_XJUMP);
  setbc_d(jmp, offset);
}

/* Append to jump list. */
static void jmp_append(FuncState *fs, BCPos *l1, BCPos l2)
{
  if (l2 == NO_JMP) {
    return;
  } else if (*l1 == NO_JMP) {
    *l1 = l2;
  } else {
    BCPos list = *l1;
    BCPos next;
    while ((next = jmp_next(fs, list)) != NO_JMP)  /* Find last element. */
      list = next;
    jmp_patchins(fs, list, l2);
  }
}

/* Patch jump list and preserve produced values. */
static void jmp_patchval(FuncState *fs, BCPos list, BCPos vtarget,
                         BCReg reg, BCPos dtarget)
{
  while (list != NO_JMP) {
    BCPos next = jmp_next(fs, list);
    if (jmp_patchtestreg(fs, list, reg))
      jmp_patchins(fs, list, vtarget);  /* Jump to target with value. */
    else
      jmp_patchins(fs, list, dtarget);  /* Jump to default target. */
    list = next;
  }
}

/* Jump to following instruction. Append to list of pending jumps. */
static void jmp_tohere(FuncState *fs, BCPos list)
{
  fs->lasttarget = fs->pc;
  jmp_append(fs, &fs->jpc, list);
}

/* Patch jump list to target. */
static void jmp_patch(FuncState *fs, BCPos list, BCPos target)
{
  if (target == fs->pc) {
    jmp_tohere(fs, list);
  } else {
    lj_assertFS(target < fs->pc, "bad jump target");
    jmp_patchval(fs, list, target, NO_REG, target);
  }
}

/* -- Bytecode register allocator ----------------------------------------- */

/* Bump frame size. */
static void bcreg_bump(FuncState *fs, BCReg n)
{
  BCReg sz = fs->freereg + n;
  if (sz > fs->framesize) {
    if (sz >= LJ_MAX_SLOTS)
      err_syntax(fs->ls, LJ_ERR_XSLOTS);
    fs->framesize = (uint8_t)sz;
  }
}

/* Reserve registers. */
static void bcreg_reserve(FuncState *fs, BCReg n)
{
  bcreg_bump(fs, n);
  fs->freereg += n;
}

/* Free register. */
static void bcreg_free(FuncState *fs, BCReg reg)
{
  if (reg >= fs->nactvar) {
    fs->freereg--;
    lj_assertFS(reg == fs->freereg, "bad regfree");
  }
}

/* Free register for expression. */
static void expr_free(FuncState *fs, ExpDesc *e)
{
  if (e->k == VNONRELOC)
    bcreg_free(fs, e->u.s.info);
}

/* -- Bytecode emitter ---------------------------------------------------- */

/* Emit bytecode instruction. */
static BCPos bcemit_INS(FuncState *fs, BCIns ins)
{
  BCPos pc = fs->pc;
  LexState *ls = fs->ls;
  jmp_patchval(fs, fs->jpc, pc, NO_REG, pc);
  fs->jpc = NO_JMP;
  if (LJ_UNLIKELY(pc >= fs->bclim)) {
    ptrdiff_t base = fs->bcbase - ls->bcstack;
    checklimit(fs, ls->sizebcstack, LJ_MAX_BCINS, "bytecode instructions");
    lj_mem_growvec(fs->L, ls->bcstack, ls->sizebcstack, LJ_MAX_BCINS,BCInsLine);
    fs->bclim = (BCPos)(ls->sizebcstack - base);
    fs->bcbase = ls->bcstack + base;
  }
  fs->bcbase[pc].ins = ins;
  fs->bcbase[pc].line = ls->lastline;
  fs->pc = pc+1;
  return pc;
}

#define bcemit_ABC(fs, o, a, b, c)        bcemit_INS(fs, BCINS_ABC(o, a, b, c))
#define bcemit_AD(fs, o, a, d)                bcemit_INS(fs, BCINS_AD(o, a, d))
#define bcemit_AJ(fs, o, a, j)                bcemit_INS(fs, BCINS_AJ(o, a, j))

#define bcptr(fs, e)                        (&(fs)->bcbase[(e)->u.s.info].ins)

/* -- Bytecode emitter for expressions ------------------------------------ */

/* Discharge non-constant expression to any register. */
static void expr_discharge(FuncState *fs, ExpDesc *e)
{
  BCIns ins;
  if (e->k == VUPVAL) {
    ins = BCINS_AD(BC_UGET, 0, e->u.s.info);
  } else if (e->k == VGLOBAL) {
    ins = BCINS_AD(BC_GGET, 0, const_str(fs, e));
  } else if (e->k == VINDEXED) {
    BCReg rc = e->u.s.aux;
    if ((int32_t)rc < 0) {
      ins = BCINS_ABC(BC_TGETS, 0, e->u.s.info, ~rc);
    } else if (rc > BCMAX_C) {
      ins = BCINS_ABC(BC_TGETB, 0, e->u.s.info, rc-(BCMAX_C+1));
    } else {
      bcreg_free(fs, rc);
      ins = BCINS_ABC(BC_TGETV, 0, e->u.s.info, rc);
    }
    bcreg_free(fs, e->u.s.info);
  } else if (e->k == VCALL) {
    e->u.s.info = e->u.s.aux;
    e->k = VNONRELOC;
    return;
  } else if (e->k == VLOCAL) {
    e->k = VNONRELOC;
    return;
  } else {
    return;
  }
  e->u.s.info = bcemit_INS(fs, ins);
  e->k = VRELOCABLE;
}

/* Emit bytecode to set a range of registers to nil. */
static void bcemit_nil(FuncState *fs, BCReg from, BCReg n)
{
  if (fs->pc > fs->lasttarget) {  /* No jumps to current position? */
    BCIns *ip = &fs->bcbase[fs->pc-1].ins;
    BCReg pto, pfrom = bc_a(*ip);
    switch (bc_op(*ip)) {  /* Try to merge with the previous instruction. */
    case BC_KPRI:
      if (bc_d(*ip) != ~LJ_TNIL) break;
      if (from == pfrom) {
        if (n == 1) return;
      } else if (from == pfrom+1) {
        from = pfrom;
        n++;
      } else {
        break;
      }
      *ip = BCINS_AD(BC_KNIL, from, from+n-1);  /* Replace KPRI. */
      return;
    case BC_KNIL:
      pto = bc_d(*ip);
      if (pfrom <= from && from <= pto+1) {  /* Can we connect both ranges? */
        if (from+n-1 > pto)
          setbc_d(ip, from+n-1);  /* Patch previous instruction range. */
        return;
      }
      break;
    default:
      break;
    }
  }
  /* Emit new instruction or replace old instruction. */
  bcemit_INS(fs, n == 1 ? BCINS_AD(BC_KPRI, from, VKNIL) :
                          BCINS_AD(BC_KNIL, from, from+n-1));
}

/* Discharge an expression to a specific register. Ignore branches. */
static void expr_toreg_nobranch(FuncState *fs, ExpDesc *e, BCReg reg)
{
  BCIns ins;
  expr_discharge(fs, e);
  if (e->k == VKSTR) {
    ins = BCINS_AD(BC_KSTR, reg, const_str(fs, e));
  } else if (e->k == VKNUM) {
#if LJ_DUALNUM
    cTValue *tv = expr_numtv(e);
    if (tvisint(tv) && checki16(intV(tv)))
      ins = BCINS_AD(BC_KSHORT, reg, (BCReg)(uint16_t)intV(tv));
    else
#else
    lua_Number n = expr_numberV(e);
    int32_t k = lj_num2int(n);
    if (checki16(k) && n == (lua_Number)k)
      ins = BCINS_AD(BC_KSHORT, reg, (BCReg)(uint16_t)k);
    else
#endif
      ins = BCINS_AD(BC_KNUM, reg, const_num(fs, e));
#if LJ_HASFFI
  } else if (e->k == VKCDATA) {
    fs->flags |= PROTO_FFI;
    ins = BCINS_AD(BC_KCDATA, reg,
                   const_gc(fs, obj2gco(cdataV(&e->u.nval)), LJ_TCDATA));
#endif
  } else if (e->k == VRELOCABLE) {
    setbc_a(bcptr(fs, e), reg);
    goto noins;
  } else if (e->k == VNONRELOC) {
    if (reg == e->u.s.info)
      goto noins;
    ins = BCINS_AD(BC_MOV, reg, e->u.s.info);
  } else if (e->k == VKNIL) {
    bcemit_nil(fs, reg, 1);
    goto noins;
  } else if (e->k <= VKTRUE) {
    ins = BCINS_AD(BC_KPRI, reg, const_pri(e));
  } else {
    lj_assertFS(e->k == VVOID || e->k == VJMP, "bad expr type %d", e->k);
    return;
  }
  bcemit_INS(fs, ins);
noins:
  e->u.s.info = reg;
  e->k = VNONRELOC;
}

/* Forward declaration. */
static BCPos bcemit_jmp(FuncState *fs);

/* Discharge an expression to a specific register. */
static void expr_toreg(FuncState *fs, ExpDesc *e, BCReg reg)
{
  expr_toreg_nobranch(fs, e, reg);
  if (e->k == VJMP)
    jmp_append(fs, &e->t, e->u.s.info);  /* Add it to the true jump list. */
  if (expr_hasjump(e)) {  /* Discharge expression with branches. */
    BCPos jend, jfalse = NO_JMP, jtrue = NO_JMP;
    if (jmp_novalue(fs, e->t) || jmp_novalue(fs, e->f)) {
      BCPos jval = (e->k == VJMP) ? NO_JMP : bcemit_jmp(fs);
      jfalse = bcemit_AD(fs, BC_KPRI, reg, VKFALSE);
      bcemit_AJ(fs, BC_JMP, fs->freereg, 1);
      jtrue = bcemit_AD(fs, BC_KPRI, reg, VKTRUE);
      jmp_tohere(fs, jval);
    }
    jend = fs->pc;
    fs->lasttarget = jend;
    jmp_patchval(fs, e->f, jend, reg, jfalse);
    jmp_patchval(fs, e->t, jend, reg, jtrue);
  }
  e->f = e->t = NO_JMP;
  e->u.s.info = reg;
  e->k = VNONRELOC;
}

/* Discharge an expression to the next free register. */
static void expr_tonextreg(FuncState *fs, ExpDesc *e)
{
  expr_discharge(fs, e);
  expr_free(fs, e);
  bcreg_reserve(fs, 1);
  expr_toreg(fs, e, fs->freereg - 1);
}

/* Discharge an expression to any register. */
static BCReg expr_toanyreg(FuncState *fs, ExpDesc *e)
{
  expr_discharge(fs, e);
  if (e->k == VNONRELOC) {
    if (!expr_hasjump(e)) return e->u.s.info;  /* Already in a register. */
    if (e->u.s.info >= fs->nactvar) {
      expr_toreg(fs, e, e->u.s.info);  /* Discharge to temp. register. */
      return e->u.s.info;
    }
  }
  expr_tonextreg(fs, e);  /* Discharge to next register. */
  return e->u.s.info;
}

/* Partially discharge expression to a value. */
static void expr_toval(FuncState *fs, ExpDesc *e)
{
  if (expr_hasjump(e))
    expr_toanyreg(fs, e);
  else
    expr_discharge(fs, e);
}

/* Emit store for LHS expression. */
static void bcemit_store(FuncState *fs, ExpDesc *var, ExpDesc *e)
{
  BCIns ins;
  if (var->k == VLOCAL) {
    fs->ls->vstack[var->u.s.aux].info |= VSTACK_VAR_RW;
    expr_free(fs, e);
    expr_toreg(fs, e, var->u.s.info);
    return;
  } else if (var->k == VUPVAL) {
    fs->ls->vstack[var->u.s.aux].info |= VSTACK_VAR_RW;
    expr_toval(fs, e);
    if (e->k <= VKTRUE)
      ins = BCINS_AD(BC_USETP, var->u.s.info, const_pri(e));
    else if (e->k == VKSTR)
      ins = BCINS_AD(BC_USETS, var->u.s.info, const_str(fs, e));
    else if (e->k == VKNUM)
      ins = BCINS_AD(BC_USETN, var->u.s.info, const_num(fs, e));
    else
      ins = BCINS_AD(BC_USETV, var->u.s.info, expr_toanyreg(fs, e));
  } else if (var->k == VGLOBAL) {
    BCReg ra = expr_toanyreg(fs, e);
    ins = BCINS_AD(BC_GSET, ra, const_str(fs, var));
  } else {
    BCReg ra, rc;
    lj_assertFS(var->k == VINDEXED, "bad expr type %d", var->k);
    ra = expr_toanyreg(fs, e);
    rc = var->u.s.aux;
    if ((int32_t)rc < 0) {
      ins = BCINS_ABC(BC_TSETS, ra, var->u.s.info, ~rc);
    } else if (rc > BCMAX_C) {
      ins = BCINS_ABC(BC_TSETB, ra, var->u.s.info, rc-(BCMAX_C+1));
    } else {
#ifdef LUA_USE_ASSERT
      /* Free late alloced key reg to avoid assert on free of value reg. */
      /* This can only happen when called from expr_table(). */
      if (e->k == VNONRELOC && ra >= fs->nactvar && rc >= ra)
        bcreg_free(fs, rc);
#endif
      ins = BCINS_ABC(BC_TSETV, ra, var->u.s.info, rc);
    }
  }
  bcemit_INS(fs, ins);
  expr_free(fs, e);
}

/* Emit method lookup expression. */
static void bcemit_method(FuncState *fs, ExpDesc *e, ExpDesc *key)
{
  BCReg idx, func, obj = expr_toanyreg(fs, e);
  expr_free(fs, e);
  func = fs->freereg;
  bcemit_AD(fs, BC_MOV, func+1+LJ_FR2, obj);  /* Copy object to 1st argument. */
  lj_assertFS(expr_isstrk(key), "bad usage");
  idx = const_str(fs, key);
  if (idx <= BCMAX_C) {
    bcreg_reserve(fs, 2+LJ_FR2);
    bcemit_ABC(fs, BC_TGETS, func, obj, idx);
  } else {
    bcreg_reserve(fs, 3+LJ_FR2);
    bcemit_AD(fs, BC_KSTR, func+2+LJ_FR2, idx);
    bcemit_ABC(fs, BC_TGETV, func, obj, func+2+LJ_FR2);
    fs->freereg--;
  }
  e->u.s.info = func;
  e->k = VNONRELOC;
}

/* -- Bytecode emitter for branches --------------------------------------- */

/* Emit unconditional branch. */
static BCPos bcemit_jmp(FuncState *fs)
{
  BCPos jpc = fs->jpc;
  BCPos j = fs->pc - 1;
  BCIns *ip = &fs->bcbase[j].ins;
  fs->jpc = NO_JMP;
  if ((int32_t)j >= (int32_t)fs->lasttarget && bc_op(*ip) == BC_UCLO) {
    setbc_j(ip, NO_JMP);
    fs->lasttarget = j+1;
  } else {
    j = bcemit_AJ(fs, BC_JMP, fs->freereg, NO_JMP);
  }
  jmp_append(fs, &j, jpc);
  return j;
}

/* Invert branch condition of bytecode instruction. */
static void invertcond(FuncState *fs, ExpDesc *e)
{
  BCIns *ip = &fs->bcbase[e->u.s.info - 1].ins;
  setbc_op(ip, bc_op(*ip)^1);
}

/* Emit conditional branch. */
static BCPos bcemit_branch(FuncState *fs, ExpDesc *e, int cond)
{
  BCPos pc;
  if (e->k == VRELOCABLE) {
    BCIns *ip = bcptr(fs, e);
    if (bc_op(*ip) == BC_NOT) {
      *ip = BCINS_AD(cond ? BC_ISF : BC_IST, 0, bc_d(*ip));
      return bcemit_jmp(fs);
    }
  }
  if (e->k != VNONRELOC) {
    bcreg_reserve(fs, 1);
    expr_toreg_nobranch(fs, e, fs->freereg-1);
  }
  bcemit_AD(fs, cond ? BC_ISTC : BC_ISFC, NO_REG, e->u.s.info);
  pc = bcemit_jmp(fs);
  expr_free(fs, e);
  return pc;
}

/* Emit branch on true condition. */
static void bcemit_branch_t(FuncState *fs, ExpDesc *e)
{
  BCPos pc;
  expr_discharge(fs, e);
  if (e->k == VKSTR || e->k == VKNUM || e->k == VKTRUE)
    pc = NO_JMP;  /* Never jump. */
  else if (e->k == VJMP)
    invertcond(fs, e), pc = e->u.s.info;
  else if (e->k == VKFALSE || e->k == VKNIL)
    expr_toreg_nobranch(fs, e, NO_REG), pc = bcemit_jmp(fs);
  else
    pc = bcemit_branch(fs, e, 0);
  jmp_append(fs, &e->f, pc);
  jmp_tohere(fs, e->t);
  e->t = NO_JMP;
}

/* Emit branch on false condition. */
static void bcemit_branch_f(FuncState *fs, ExpDesc *e)
{
  BCPos pc;
  expr_discharge(fs, e);
  if (e->k == VKNIL || e->k == VKFALSE)
    pc = NO_JMP;  /* Never jump. */
  else if (e->k == VJMP)
    pc = e->u.s.info;
  else if (e->k == VKSTR || e->k == VKNUM || e->k == VKTRUE)
    expr_toreg_nobranch(fs, e, NO_REG), pc = bcemit_jmp(fs);
  else
    pc = bcemit_branch(fs, e, 1);
  jmp_append(fs, &e->t, pc);
  jmp_tohere(fs, e->f);
  e->f = NO_JMP;
}

/* -- Bytecode emitter for operators -------------------------------------- */

/* Try constant-folding of arithmetic operators. */
static int foldarith(BinOpr opr, ExpDesc *e1, ExpDesc *e2)
{
  TValue o;
  lua_Number n;
  if (!expr_isnumk_nojump(e1) || !expr_isnumk_nojump(e2)) return 0;
  n = lj_vm_foldarith(expr_numberV(e1), expr_numberV(e2), (int)opr-OPR_ADD);
  setnumV(&o, n);
  if (tvisnan(&o) || tvismzero(&o)) return 0;  /* Avoid NaN and -0 as consts. */
  if (LJ_DUALNUM) {
    int32_t k = lj_num2int(n);
    if ((lua_Number)k == n) {
      setintV(&e1->u.nval, k);
      return 1;
    }
  }
  setnumV(&e1->u.nval, n);
  return 1;
}

/* Emit arithmetic operator. */
static void bcemit_arith(FuncState *fs, BinOpr opr, ExpDesc *e1, ExpDesc *e2)
{
  BCReg rb, rc, t;
  uint32_t op;
  if (foldarith(opr, e1, e2))
    return;
  if (opr == OPR_POW) {
    op = BC_POW;
    rc = expr_toanyreg(fs, e2);
    rb = expr_toanyreg(fs, e1);
  } else {
    op = opr-OPR_ADD+BC_ADDVV;
    /* Must discharge 2nd operand first since VINDEXED might free regs. */
    expr_toval(fs, e2);
    if (expr_isnumk(e2) && (rc = const_num(fs, e2)) <= BCMAX_C)
      op -= BC_ADDVV-BC_ADDVN;
    else
      rc = expr_toanyreg(fs, e2);
    /* 1st operand discharged by bcemit_binop_left, but need KNUM/KSHORT. */
    lj_assertFS(expr_isnumk(e1) || e1->k == VNONRELOC,
                "bad expr type %d", e1->k);
    expr_toval(fs, e1);
    /* Avoid two consts to satisfy bytecode constraints. */
    if (expr_isnumk(e1) && !expr_isnumk(e2) &&
        (t = const_num(fs, e1)) <= BCMAX_B) {
      rb = rc; rc = t; op -= BC_ADDVV-BC_ADDNV;
    } else {
      rb = expr_toanyreg(fs, e1);
    }
  }
  /* Using expr_free might cause asserts if the order is wrong. */
  if (e1->k == VNONRELOC && e1->u.s.info >= fs->nactvar) fs->freereg--;
  if (e2->k == VNONRELOC && e2->u.s.info >= fs->nactvar) fs->freereg--;
  e1->u.s.info = bcemit_ABC(fs, op, 0, rb, rc);
  e1->k = VRELOCABLE;
}

/* Emit comparison operator. */
static void bcemit_comp(FuncState *fs, BinOpr opr, ExpDesc *e1, ExpDesc *e2)
{
  ExpDesc *eret = e1;
  BCIns ins;
  expr_toval(fs, e1);
  if (opr == OPR_EQ || opr == OPR_NE) {
    BCOp op = opr == OPR_EQ ? BC_ISEQV : BC_ISNEV;
    BCReg ra;
    if (expr_isk(e1)) { e1 = e2; e2 = eret; }  /* Need constant in 2nd arg. */
    ra = expr_toanyreg(fs, e1);  /* First arg must be in a reg. */
    expr_toval(fs, e2);
    switch (e2->k) {
    case VKNIL: case VKFALSE: case VKTRUE:
      ins = BCINS_AD(op+(BC_ISEQP-BC_ISEQV), ra, const_pri(e2));
      break;
    case VKSTR:
      ins = BCINS_AD(op+(BC_ISEQS-BC_ISEQV), ra, const_str(fs, e2));
      break;
    case VKNUM:
      ins = BCINS_AD(op+(BC_ISEQN-BC_ISEQV), ra, const_num(fs, e2));
      break;
    default:
      ins = BCINS_AD(op, ra, expr_toanyreg(fs, e2));
      break;
    }
  } else {
    uint32_t op = opr-OPR_LT+BC_ISLT;
    BCReg ra, rd;
    if ((op-BC_ISLT) & 1) {  /* GT -> LT, GE -> LE */
      e1 = e2; e2 = eret;  /* Swap operands. */
      op = ((op-BC_ISLT)^3)+BC_ISLT;
      expr_toval(fs, e1);
      ra = expr_toanyreg(fs, e1);
      rd = expr_toanyreg(fs, e2);
    } else {
      rd = expr_toanyreg(fs, e2);
      ra = expr_toanyreg(fs, e1);
    }
    ins = BCINS_AD(op, ra, rd);
  }
  /* Using expr_free might cause asserts if the order is wrong. */
  if (e1->k == VNONRELOC && e1->u.s.info >= fs->nactvar) fs->freereg--;
  if (e2->k == VNONRELOC && e2->u.s.info >= fs->nactvar) fs->freereg--;
  bcemit_INS(fs, ins);
  eret->u.s.info = bcemit_jmp(fs);
  eret->k = VJMP;
}

/* Fixup left side of binary operator. */
static void bcemit_binop_left(FuncState *fs, BinOpr op, ExpDesc *e)
{
  if (op == OPR_AND) {
    bcemit_branch_t(fs, e);
  } else if (op == OPR_OR) {
    bcemit_branch_f(fs, e);
  } else if (op == OPR_CONCAT) {
    expr_tonextreg(fs, e);
  } else if (op == OPR_EQ || op == OPR_NE) {
    if (!expr_isk_nojump(e)) expr_toanyreg(fs, e);
  } else {
    if (!expr_isnumk_nojump(e)) expr_toanyreg(fs, e);
  }
}

/* Emit binary operator. */
static void bcemit_binop(FuncState *fs, BinOpr op, ExpDesc *e1, ExpDesc *e2)
{
  if (op <= OPR_POW) {
    bcemit_arith(fs, op, e1, e2);
  } else if (op == OPR_AND) {
    lj_assertFS(e1->t == NO_JMP, "jump list not closed");
    expr_discharge(fs, e2);
    jmp_append(fs, &e2->f, e1->f);
    *e1 = *e2;
  } else if (op == OPR_OR) {
    lj_assertFS(e1->f == NO_JMP, "jump list not closed");
    expr_discharge(fs, e2);
    jmp_append(fs, &e2->t, e1->t);
    *e1 = *e2;
  } else if (op == OPR_CONCAT) {
    expr_toval(fs, e2);
    if (e2->k == VRELOCABLE && bc_op(*bcptr(fs, e2)) == BC_CAT) {
      lj_assertFS(e1->u.s.info == bc_b(*bcptr(fs, e2))-1,
                  "bad CAT stack layout");
      expr_free(fs, e1);
      setbc_b(bcptr(fs, e2), e1->u.s.info);
      e1->u.s.info = e2->u.s.info;
    } else {
      expr_tonextreg(fs, e2);
      expr_free(fs, e2);
      expr_free(fs, e1);
      e1->u.s.info = bcemit_ABC(fs, BC_CAT, 0, e1->u.s.info, e2->u.s.info);
    }
    e1->k = VRELOCABLE;
  } else {
    lj_assertFS(op == OPR_NE || op == OPR_EQ ||
               op == OPR_LT || op == OPR_GE || op == OPR_LE || op == OPR_GT,
               "bad binop %d", op);
    bcemit_comp(fs, op, e1, e2);
  }
}

/* Emit unary operator. */
static void bcemit_unop(FuncState *fs, BCOp op, ExpDesc *e)
{
  if (op == BC_NOT) {
    /* Swap true and false lists. */
    { BCPos temp = e->f; e->f = e->t; e->t = temp; }
    jmp_dropval(fs, e->f);
    jmp_dropval(fs, e->t);
    expr_discharge(fs, e);
    if (e->k == VKNIL || e->k == VKFALSE) {
      e->k = VKTRUE;
      return;
    } else if (expr_isk(e) || (LJ_HASFFI && e->k == VKCDATA)) {
      e->k = VKFALSE;
      return;
    } else if (e->k == VJMP) {
      invertcond(fs, e);
      return;
    } else if (e->k == VRELOCABLE) {
      bcreg_reserve(fs, 1);
      setbc_a(bcptr(fs, e), fs->freereg-1);
      e->u.s.info = fs->freereg-1;
      e->k = VNONRELOC;
    } else {
      lj_assertFS(e->k == VNONRELOC, "bad expr type %d", e->k);
    }
  } else {
    lj_assertFS(op == BC_UNM || op == BC_LEN, "bad unop %d", op);
    if (op == BC_UNM && !expr_hasjump(e)) {  /* Constant-fold negations. */
#if LJ_HASFFI
      if (e->k == VKCDATA) {  /* Fold in-place since cdata is not interned. */
        GCcdata *cd = cdataV(&e->u.nval);
        int64_t *p = (int64_t *)cdataptr(cd);
        if (cd->ctypeid == CTID_COMPLEX_DOUBLE)
          p[1] ^= (int64_t)U64x(80000000,00000000);
        else
          *p = -*p;
        return;
      } else
#endif
      if (expr_isnumk(e) && !expr_numiszero(e)) {  /* Avoid folding to -0. */
        TValue *o = expr_numtv(e);
        if (tvisint(o)) {
          int32_t k = intV(o);
          if (k == -k)
            setnumV(o, -(lua_Number)k);
          else
            setintV(o, -k);
          return;
        } else {
          o->u64 ^= U64x(80000000,00000000);
          return;
        }
      }
    }
    expr_toanyreg(fs, e);
  }
  expr_free(fs, e);
  e->u.s.info = bcemit_AD(fs, op, 0, e->u.s.info);
  e->k = VRELOCABLE;
}

/* -- Lexer support ------------------------------------------------------- */

/* Check and consume optional token. */
static int lex_opt(LexState *ls, LexToken tok)
{
  if (ls->tok == tok) {
    lj_lex_next(ls);
    return 1;
  }
  return 0;
}

/* Check and consume token. */
static void lex_check(LexState *ls, LexToken tok)
{
  if (ls->tok != tok)
    err_token(ls, tok);
  lj_lex_next(ls);
}

/* Check for matching token. */
static void lex_match(LexState *ls, LexToken what, LexToken who, BCLine line)
{
  if (!lex_opt(ls, what)) {
    if (line == ls->linenumber) {
      err_token(ls, what);
    } else {
      const char *swhat = lj_lex_token2str(ls, what);
      const char *swho = lj_lex_token2str(ls, who);
      lj_lex_error(ls, ls->tok, LJ_ERR_XMATCH, swhat, swho, line);
    }
  }
}

/* Check for string token. */
static GCstr *lex_str(LexState *ls)
{
  GCstr *s;
  if (ls->tok != TK_name && (LJ_52 || ls->tok != TK_goto))
    err_token(ls, TK_name);
  s = strV(&ls->tokval);
  lj_lex_next(ls);
  return s;
}

/* -- Variable handling --------------------------------------------------- */

#define var_get(ls, fs, i)        ((ls)->vstack[(fs)->varmap[(i)]])

/* Define a new local variable. */
static void var_new(LexState *ls, BCReg n, GCstr *name)
{
  FuncState *fs = ls->fs;
  MSize vtop = ls->vtop;
  checklimit(fs, fs->nactvar+n, LJ_MAX_LOCVAR, "local variables");
  if (LJ_UNLIKELY(vtop >= ls->sizevstack)) {
    if (ls->sizevstack >= LJ_MAX_VSTACK)
      lj_lex_error(ls, 0, LJ_ERR_XLIMC, LJ_MAX_VSTACK);
    lj_mem_growvec(ls->L, ls->vstack, ls->sizevstack, LJ_MAX_VSTACK, VarInfo);
  }
  lj_assertFS((uintptr_t)name < VARNAME__MAX ||
              lj_tab_getstr(fs->kt, name) != NULL,
              "unanchored variable name");
  /* NOBARRIER: name is anchored in fs->kt and ls->vstack is not a GCobj. */
  setgcref(ls->vstack[vtop].name, obj2gco(name));
  fs->varmap[fs->nactvar+n] = (uint16_t)vtop;
  ls->vtop = vtop+1;
}

#define var_new_lit(ls, n, v) \
  var_new(ls, (n), lj_parse_keepstr(ls, "" v, sizeof(v)-1))

#define var_new_fixed(ls, n, vn) \
  var_new(ls, (n), (GCstr *)(uintptr_t)(vn))

/* Add local variables. */
static void var_add(LexState *ls, BCReg nvars)
{
  FuncState *fs = ls->fs;
  BCReg nactvar = fs->nactvar;
  while (nvars--) {
    VarInfo *v = &var_get(ls, fs, nactvar);
    v->startpc = fs->pc;
    v->slot = nactvar++;
    v->info = 0;
  }
  fs->nactvar = nactvar;
}

/* Remove local variables. */
static void var_remove(LexState *ls, BCReg tolevel)
{
  FuncState *fs = ls->fs;
  while (fs->nactvar > tolevel)
    var_get(ls, fs, --fs->nactvar).endpc = fs->pc;
}

/* Lookup local variable name. */
static BCReg var_lookup_local(FuncState *fs, GCstr *n)
{
  int i;
  for (i = fs->nactvar-1; i >= 0; i--) {
    if (n == strref(var_get(fs->ls, fs, i).name))
      return (BCReg)i;
  }
  return (BCReg)-1;  /* Not found. */
}

/* Lookup or add upvalue index. */
static MSize var_lookup_uv(FuncState *fs, MSize vidx, ExpDesc *e)
{
  MSize i, n = fs->nuv;
  for (i = 0; i < n; i++)
    if (fs->uvmap[i] == vidx)
      return i;  /* Already exists. */
  /* Otherwise create a new one. */
  checklimit(fs, fs->nuv, LJ_MAX_UPVAL, "upvalues");
  lj_assertFS(e->k == VLOCAL || e->k == VUPVAL, "bad expr type %d", e->k);
  fs->uvmap[n] = (uint16_t)vidx;
  fs->uvtmp[n] = (uint16_t)(e->k == VLOCAL ? vidx : LJ_MAX_VSTACK+e->u.s.info);
  fs->nuv = n+1;
  return n;
}

/* Forward declaration. */
static void fscope_uvmark(FuncState *fs, BCReg level);

/* Recursively lookup variables in enclosing functions. */
static MSize var_lookup_(FuncState *fs, GCstr *name, ExpDesc *e, int first)
{
  if (fs) {
    BCReg reg = var_lookup_local(fs, name);
    if ((int32_t)reg >= 0) {  /* Local in this function? */
      expr_init(e, VLOCAL, reg);
      if (!first)
        fscope_uvmark(fs, reg);  /* Scope now has an upvalue. */
      return (MSize)(e->u.s.aux = (uint32_t)fs->varmap[reg]);
    } else {
      MSize vidx = var_lookup_(fs->prev, name, e, 0);  /* Var in outer func? */
      if ((int32_t)vidx >= 0) {  /* Yes, make it an upvalue here. */
        e->u.s.info = (uint8_t)var_lookup_uv(fs, vidx, e);
        e->k = VUPVAL;
        return vidx;
      }
    }
  } else {  /* Not found in any function, must be a global. */
    expr_init(e, VGLOBAL, 0);
    e->u.sval = name;
  }
  return (MSize)-1;  /* Global. */
}

/* Lookup variable name. */
#define var_lookup(ls, e) \
  var_lookup_((ls)->fs, lex_str(ls), (e), 1)

/* -- Goto an label handling ---------------------------------------------- */

/* Add a new goto or label. */
static MSize gola_new(LexState *ls, GCstr *name, uint8_t info, BCPos pc)
{
  FuncState *fs = ls->fs;
  MSize vtop = ls->vtop;
  if (LJ_UNLIKELY(vtop >= ls->sizevstack)) {
    if (ls->sizevstack >= LJ_MAX_VSTACK)
      lj_lex_error(ls, 0, LJ_ERR_XLIMC, LJ_MAX_VSTACK);
    lj_mem_growvec(ls->L, ls->vstack, ls->sizevstack, LJ_MAX_VSTACK, VarInfo);
  }
  lj_assertFS(name == NAME_BREAK || lj_tab_getstr(fs->kt, name) != NULL,
              "unanchored label name");
  /* NOBARRIER: name is anchored in fs->kt and ls->vstack is not a GCobj. */
  setgcref(ls->vstack[vtop].name, obj2gco(name));
  ls->vstack[vtop].startpc = pc;
  ls->vstack[vtop].slot = (uint8_t)fs->nactvar;
  ls->vstack[vtop].info = info;
  ls->vtop = vtop+1;
  return vtop;
}

#define gola_isgoto(v)                ((v)->info & VSTACK_GOTO)
#define gola_islabel(v)                ((v)->info & VSTACK_LABEL)
#define gola_isgotolabel(v)        ((v)->info & (VSTACK_GOTO|VSTACK_LABEL))

/* Patch goto to jump to label. */
static void gola_patch(LexState *ls, VarInfo *vg, VarInfo *vl)
{
  FuncState *fs = ls->fs;
  BCPos pc = vg->startpc;
  setgcrefnull(vg->name);  /* Invalidate pending goto. */
  setbc_a(&fs->bcbase[pc].ins, vl->slot);
  jmp_patch(fs, pc, vl->startpc);
}

/* Patch goto to close upvalues. */
static void gola_close(LexState *ls, VarInfo *vg)
{
  FuncState *fs = ls->fs;
  BCPos pc = vg->startpc;
  BCIns *ip = &fs->bcbase[pc].ins;
  lj_assertFS(gola_isgoto(vg), "expected goto");
  lj_assertFS(bc_op(*ip) == BC_JMP || bc_op(*ip) == BC_UCLO,
              "bad bytecode op %d", bc_op(*ip));
  setbc_a(ip, vg->slot);
  if (bc_op(*ip) == BC_JMP) {
    BCPos next = jmp_next(fs, pc);
    if (next != NO_JMP) jmp_patch(fs, next, pc);  /* Jump to UCLO. */
    setbc_op(ip, BC_UCLO);  /* Turn into UCLO. */
    setbc_j(ip, NO_JMP);
  }
}

/* Resolve pending forward gotos for label. */
static void gola_resolve(LexState *ls, FuncScope *bl, MSize idx)
{
  VarInfo *vg = ls->vstack + bl->vstart;
  VarInfo *vl = ls->vstack + idx;
  for (; vg < vl; vg++)
    if (gcrefeq(vg->name, vl->name) && gola_isgoto(vg)) {
      if (vg->slot < vl->slot) {
        GCstr *name = strref(var_get(ls, ls->fs, vg->slot).name);
        lj_assertLS((uintptr_t)name >= VARNAME__MAX, "expected goto name");
        ls->linenumber = ls->fs->bcbase[vg->startpc].line;
        lj_assertLS(strref(vg->name) != NAME_BREAK, "unexpected break");
        lj_lex_error(ls, 0, LJ_ERR_XGSCOPE,
                     strdata(strref(vg->name)), strdata(name));
      }
      gola_patch(ls, vg, vl);
    }
}

/* Fixup remaining gotos and labels for scope. */
static void gola_fixup(LexState *ls, FuncScope *bl)
{
  VarInfo *v = ls->vstack + bl->vstart;
  VarInfo *ve = ls->vstack + ls->vtop;
  for (; v < ve; v++) {
    GCstr *name = strref(v->name);
    if (name != NULL) {  /* Only consider remaining valid gotos/labels. */
      if (gola_islabel(v)) {
        VarInfo *vg;
        setgcrefnull(v->name);  /* Invalidate label that goes out of scope. */
        for (vg = v+1; vg < ve; vg++)  /* Resolve pending backward gotos. */
          if (strref(vg->name) == name && gola_isgoto(vg)) {
            if ((bl->flags&FSCOPE_UPVAL) && vg->slot > v->slot)
              gola_close(ls, vg);
            gola_patch(ls, vg, v);
          }
      } else if (gola_isgoto(v)) {
        if (bl->prev) {  /* Propagate goto or break to outer scope. */
          bl->prev->flags |= name == NAME_BREAK ? FSCOPE_BREAK : FSCOPE_GOLA;
          v->slot = bl->nactvar;
          if ((bl->flags & FSCOPE_UPVAL))
            gola_close(ls, v);
        } else {  /* No outer scope: undefined goto label or no loop. */
          ls->linenumber = ls->fs->bcbase[v->startpc].line;
          if (name == NAME_BREAK)
            lj_lex_error(ls, 0, LJ_ERR_XBREAK);
          else
            lj_lex_error(ls, 0, LJ_ERR_XLUNDEF, strdata(name));
        }
      }
    }
  }
}

/* Find existing label. */
static VarInfo *gola_findlabel(LexState *ls, GCstr *name)
{
  VarInfo *v = ls->vstack + ls->fs->bl->vstart;
  VarInfo *ve = ls->vstack + ls->vtop;
  for (; v < ve; v++)
    if (strref(v->name) == name && gola_islabel(v))
      return v;
  return NULL;
}

/* -- Scope handling ------------------------------------------------------ */

/* Begin a scope. */
static void fscope_begin(FuncState *fs, FuncScope *bl, int flags)
{
  bl->nactvar = (uint8_t)fs->nactvar;
  bl->flags = flags;
  bl->vstart = fs->ls->vtop;
  bl->prev = fs->bl;
  fs->bl = bl;
  lj_assertFS(fs->freereg == fs->nactvar, "bad regalloc");
}

/* End a scope. */
static void fscope_end(FuncState *fs)
{
  FuncScope *bl = fs->bl;
  LexState *ls = fs->ls;
  fs->bl = bl->prev;
  var_remove(ls, bl->nactvar);
  fs->freereg = fs->nactvar;
  lj_assertFS(bl->nactvar == fs->nactvar, "bad regalloc");
  if ((bl->flags & (FSCOPE_UPVAL|FSCOPE_NOCLOSE)) == FSCOPE_UPVAL)
    bcemit_AJ(fs, BC_UCLO, bl->nactvar, 0);
  if ((bl->flags & FSCOPE_BREAK)) {
    if ((bl->flags & FSCOPE_LOOP)) {
      MSize idx = gola_new(ls, NAME_BREAK, VSTACK_LABEL, fs->pc);
      ls->vtop = idx;  /* Drop break label immediately. */
      gola_resolve(ls, bl, idx);
    } else {  /* Need the fixup step to propagate the breaks. */
      gola_fixup(ls, bl);
      return;
    }
  }
  if ((bl->flags & FSCOPE_GOLA)) {
    gola_fixup(ls, bl);
  }
}

/* Mark scope as having an upvalue. */
static void fscope_uvmark(FuncState *fs, BCReg level)
{
  FuncScope *bl;
  for (bl = fs->bl; bl && bl->nactvar > level; bl = bl->prev)
    ;
  if (bl)
    bl->flags |= FSCOPE_UPVAL;
}

/* -- Function state management ------------------------------------------- */

/* Fixup bytecode for prototype. */
static void fs_fixup_bc(FuncState *fs, GCproto *pt, BCIns *bc, MSize n)
{
  BCInsLine *base = fs->bcbase;
  MSize i;
  pt->sizebc = n;
  bc[0] = BCINS_AD((fs->flags & PROTO_VARARG) ? BC_FUNCV : BC_FUNCF,
                   fs->framesize, 0);
  for (i = 1; i < n; i++)
    bc[i] = base[i].ins;
}

/* Fixup upvalues for child prototype, step #2. */
static void fs_fixup_uv2(FuncState *fs, GCproto *pt)
{
  VarInfo *vstack = fs->ls->vstack;
  uint16_t *uv = proto_uv(pt);
  MSize i, n = pt->sizeuv;
  for (i = 0; i < n; i++) {
    VarIndex vidx = uv[i];
    if (vidx >= LJ_MAX_VSTACK)
      uv[i] = vidx - LJ_MAX_VSTACK;
    else if ((vstack[vidx].info & VSTACK_VAR_RW))
      uv[i] = vstack[vidx].slot | PROTO_UV_LOCAL;
    else
      uv[i] = vstack[vidx].slot | PROTO_UV_LOCAL | PROTO_UV_IMMUTABLE;
  }
}

/* Fixup constants for prototype. */
static void fs_fixup_k(FuncState *fs, GCproto *pt, void *kptr)
{
  GCtab *kt;
  TValue *array;
  Node *node;
  MSize i, hmask;
  checklimitgt(fs, fs->nkn, BCMAX_D+1, "constants");
  checklimitgt(fs, fs->nkgc, BCMAX_D+1, "constants");
  setmref(pt->k, kptr);
  pt->sizekn = fs->nkn;
  pt->sizekgc = fs->nkgc;
  kt = fs->kt;
  array = tvref(kt->array);
  for (i = 0; i < kt->asize; i++)
    if (tvhaskslot(&array[i])) {
      TValue *tv = &((TValue *)kptr)[tvkslot(&array[i])];
      if (LJ_DUALNUM)
        setintV(tv, (int32_t)i);
      else
        setnumV(tv, (lua_Number)i);
    }
  node = noderef(kt->node);
  hmask = kt->hmask;
  for (i = 0; i <= hmask; i++) {
    Node *n = &node[i];
    if (tvhaskslot(&n->val)) {
      ptrdiff_t kidx = (ptrdiff_t)tvkslot(&n->val);
      lj_assertFS(!tvisint(&n->key), "unexpected integer key");
      if (tvisnum(&n->key)) {
        TValue *tv = &((TValue *)kptr)[kidx];
        if (LJ_DUALNUM) {
          lua_Number nn = numV(&n->key);
          int32_t k = lj_num2int(nn);
          lj_assertFS(!tvismzero(&n->key), "unexpected -0 key");
          if ((lua_Number)k == nn)
            setintV(tv, k);
          else
            *tv = n->key;
        } else {
          *tv = n->key;
        }
      } else {
        GCobj *o = gcV(&n->key);
        setgcref(((GCRef *)kptr)[~kidx], o);
        lj_gc_objbarrier(fs->L, pt, o);
        if (tvisproto(&n->key))
          fs_fixup_uv2(fs, gco2pt(o));
      }
    }
  }
}

/* Fixup upvalues for prototype, step #1. */
static void fs_fixup_uv1(FuncState *fs, GCproto *pt, uint16_t *uv)
{
  setmref(pt->uv, uv);
  pt->sizeuv = fs->nuv;
  memcpy(uv, fs->uvtmp, fs->nuv*sizeof(VarIndex));
}

#ifndef LUAJIT_DISABLE_DEBUGINFO
/* Prepare lineinfo for prototype. */
static size_t fs_prep_line(FuncState *fs, BCLine numline)
{
  return (fs->pc-1) << (numline < 256 ? 0 : numline < 65536 ? 1 : 2);
}

/* Fixup lineinfo for prototype. */
static void fs_fixup_line(FuncState *fs, GCproto *pt,
                          void *lineinfo, BCLine numline)
{
  BCInsLine *base = fs->bcbase + 1;
  BCLine first = fs->linedefined;
  MSize i = 0, n = fs->pc-1;
  pt->firstline = fs->linedefined;
  pt->numline = numline;
  setmref(pt->lineinfo, lineinfo);
  if (LJ_LIKELY(numline < 256)) {
    uint8_t *li = (uint8_t *)lineinfo;
    do {
      BCLine delta = base[i].line - first;
      lj_assertFS(delta >= 0 && delta < 256, "bad line delta");
      li[i] = (uint8_t)delta;
    } while (++i < n);
  } else if (LJ_LIKELY(numline < 65536)) {
    uint16_t *li = (uint16_t *)lineinfo;
    do {
      BCLine delta = base[i].line - first;
      lj_assertFS(delta >= 0 && delta < 65536, "bad line delta");
      li[i] = (uint16_t)delta;
    } while (++i < n);
  } else {
    uint32_t *li = (uint32_t *)lineinfo;
    do {
      BCLine delta = base[i].line - first;
      lj_assertFS(delta >= 0, "bad line delta");
      li[i] = (uint32_t)delta;
    } while (++i < n);
  }
}

/* Prepare variable info for prototype. */
static size_t fs_prep_var(LexState *ls, FuncState *fs, size_t *ofsvar)
{
  VarInfo *vs =ls->vstack, *ve;
  MSize i, n;
  BCPos lastpc;
  lj_buf_reset(&ls->sb);  /* Copy to temp. string buffer. */
  /* Store upvalue names. */
  for (i = 0, n = fs->nuv; i < n; i++) {
    GCstr *s = strref(vs[fs->uvmap[i]].name);
    MSize len = s->len+1;
    char *p = lj_buf_more(&ls->sb, len);
    p = lj_buf_wmem(p, strdata(s), len);
    setsbufP(&ls->sb, p);
  }
  *ofsvar = sbuflen(&ls->sb);
  lastpc = 0;
  /* Store local variable names and compressed ranges. */
  for (ve = vs + ls->vtop, vs += fs->vbase; vs < ve; vs++) {
    if (!gola_isgotolabel(vs)) {
      GCstr *s = strref(vs->name);
      BCPos startpc;
      char *p;
      if ((uintptr_t)s < VARNAME__MAX) {
        p = lj_buf_more(&ls->sb, 1 + 2*5);
        *p++ = (char)(uintptr_t)s;
      } else {
        MSize len = s->len+1;
        p = lj_buf_more(&ls->sb, len + 2*5);
        p = lj_buf_wmem(p, strdata(s), len);
      }
      startpc = vs->startpc;
      p = lj_strfmt_wuleb128(p, startpc-lastpc);
      p = lj_strfmt_wuleb128(p, vs->endpc-startpc);
      setsbufP(&ls->sb, p);
      lastpc = startpc;
    }
  }
  lj_buf_putb(&ls->sb, '\0');  /* Terminator for varinfo. */
  return sbuflen(&ls->sb);
}

/* Fixup variable info for prototype. */
static void fs_fixup_var(LexState *ls, GCproto *pt, uint8_t *p, size_t ofsvar)
{
  setmref(pt->uvinfo, p);
  setmref(pt->varinfo, (char *)p + ofsvar);
  memcpy(p, sbufB(&ls->sb), sbuflen(&ls->sb));  /* Copy from temp. buffer. */
}
#else

/* Initialize with empty debug info, if disabled. */
#define fs_prep_line(fs, numline)                (UNUSED(numline), 0)
#define fs_fixup_line(fs, pt, li, numline) \
  pt->firstline = pt->numline = 0, setmref((pt)->lineinfo, NULL)
#define fs_prep_var(ls, fs, ofsvar)                (UNUSED(ofsvar), 0)
#define fs_fixup_var(ls, pt, p, ofsvar) \
  setmref((pt)->uvinfo, NULL), setmref((pt)->varinfo, NULL)

#endif

/* Check if bytecode op returns. */
static int bcopisret(BCOp op)
{
  switch (op) {
  case BC_CALLMT: case BC_CALLT:
  case BC_RETM: case BC_RET: case BC_RET0: case BC_RET1:
    return 1;
  default:
    return 0;
  }
}

/* Fixup return instruction for prototype. */
static void fs_fixup_ret(FuncState *fs)
{
  BCPos lastpc = fs->pc;
  if (lastpc <= fs->lasttarget || !bcopisret(bc_op(fs->bcbase[lastpc-1].ins))) {
    if ((fs->bl->flags & FSCOPE_UPVAL))
      bcemit_AJ(fs, BC_UCLO, 0, 0);
    bcemit_AD(fs, BC_RET0, 0, 1);  /* Need final return. */
  }
  fs->bl->flags |= FSCOPE_NOCLOSE;  /* Handled above. */
  fscope_end(fs);
  lj_assertFS(fs->bl == NULL, "bad scope nesting");
  /* May need to fixup returns encoded before first function was created. */
  if (fs->flags & PROTO_FIXUP_RETURN) {
    BCPos pc;
    for (pc = 1; pc < lastpc; pc++) {
      BCIns ins = fs->bcbase[pc].ins;
      BCPos offset;
      switch (bc_op(ins)) {
      case BC_CALLMT: case BC_CALLT:
      case BC_RETM: case BC_RET: case BC_RET0: case BC_RET1:
        offset = bcemit_INS(fs, ins);  /* Copy original instruction. */
        fs->bcbase[offset].line = fs->bcbase[pc].line;
        offset = offset-(pc+1)+BCBIAS_J;
        if (offset > BCMAX_D)
          err_syntax(fs->ls, LJ_ERR_XFIXUP);
        /* Replace with UCLO plus branch. */
        fs->bcbase[pc].ins = BCINS_AD(BC_UCLO, 0, offset);
        break;
      case BC_FNEW:
        return;  /* We're done. */
      default:
        break;
      }
    }
  }
}

/* Finish a FuncState and return the new prototype. */
static GCproto *fs_finish(LexState *ls, BCLine line)
{
  lua_State *L = ls->L;
  FuncState *fs = ls->fs;
  BCLine numline = line - fs->linedefined;
  size_t sizept, ofsk, ofsuv, ofsli, ofsdbg, ofsvar;
  GCproto *pt;

  /* Apply final fixups. */
  fs_fixup_ret(fs);

  /* Calculate total size of prototype including all colocated arrays. */
  sizept = sizeof(GCproto) + fs->pc*sizeof(BCIns) + fs->nkgc*sizeof(GCRef);
  sizept = (sizept + sizeof(TValue)-1) & ~(sizeof(TValue)-1);
  ofsk = sizept; sizept += fs->nkn*sizeof(TValue);
  ofsuv = sizept; sizept += ((fs->nuv+1)&~1)*2;
  ofsli = sizept; sizept += fs_prep_line(fs, numline);
  ofsdbg = sizept; sizept += fs_prep_var(ls, fs, &ofsvar);

  /* Allocate prototype and initialize its fields. */
  pt = (GCproto *)lj_mem_newgco(L, (MSize)sizept);
  pt->gct = ~LJ_TPROTO;
  pt->sizept = (MSize)sizept;
  pt->trace = 0;
  pt->flags = (uint8_t)(fs->flags & ~(PROTO_HAS_RETURN|PROTO_FIXUP_RETURN));
  pt->numparams = fs->numparams;
  pt->framesize = fs->framesize;
  setgcref(pt->chunkname, obj2gco(ls->chunkname));

  /* Close potentially uninitialized gap between bc and kgc. */
  *(uint32_t *)((char *)pt + ofsk - sizeof(GCRef)*(fs->nkgc+1)) = 0;
  fs_fixup_bc(fs, pt, (BCIns *)((char *)pt + sizeof(GCproto)), fs->pc);
  fs_fixup_k(fs, pt, (void *)((char *)pt + ofsk));
  fs_fixup_uv1(fs, pt, (uint16_t *)((char *)pt + ofsuv));
  fs_fixup_line(fs, pt, (void *)((char *)pt + ofsli), numline);
  fs_fixup_var(ls, pt, (uint8_t *)((char *)pt + ofsdbg), ofsvar);

  lj_vmevent_send(L, BC,
    setprotoV(L, L->top++, pt);
  );

  /* Add a new prototype to the profiler. */
#if LJ_HASMEMPROF
  lj_memprof_add_proto(pt);
#endif
#if LJ_HASSYSPROF
  lj_sysprof_add_proto(pt);
#endif

  L->top--;  /* Pop table of constants. */
  ls->vtop = fs->vbase;  /* Reset variable stack. */
  ls->fs = fs->prev;
  lj_assertL(ls->fs != NULL || ls->tok == TK_eof, "bad parser state");
  return pt;
}

/* Initialize a new FuncState. */
static void fs_init(LexState *ls, FuncState *fs)
{
  lua_State *L = ls->L;
  fs->prev = ls->fs; ls->fs = fs;  /* Append to list. */
  fs->ls = ls;
  fs->vbase = ls->vtop;
  fs->L = L;
  fs->pc = 0;
  fs->lasttarget = 0;
  fs->jpc = NO_JMP;
  fs->freereg = 0;
  fs->nkgc = 0;
  fs->nkn = 0;
  fs->nactvar = 0;
  fs->nuv = 0;
  fs->bl = NULL;
  fs->flags = 0;
  fs->framesize = 1;  /* Minimum frame size. */
  fs->kt = lj_tab_new(L, 0, 0);
  /* Anchor table of constants in stack to avoid being collected. */
  settabV(L, L->top, fs->kt);
  incr_top(L);
}

/* -- Expressions --------------------------------------------------------- */

/* Forward declaration. */
static void expr(LexState *ls, ExpDesc *v);

/* Return string expression. */
static void expr_str(LexState *ls, ExpDesc *e)
{
  expr_init(e, VKSTR, 0);
  e->u.sval = lex_str(ls);
}

/* Return index expression. */
static void expr_index(FuncState *fs, ExpDesc *t, ExpDesc *e)
{
  /* Already called: expr_toval(fs, e). */
  t->k = VINDEXED;
  if (expr_isnumk(e)) {
#if LJ_DUALNUM
    if (tvisint(expr_numtv(e))) {
      int32_t k = intV(expr_numtv(e));
      if (checku8(k)) {
        t->u.s.aux = BCMAX_C+1+(uint32_t)k;  /* 256..511: const byte key */
        return;
      }
    }
#else
    lua_Number n = expr_numberV(e);
    int32_t k = lj_num2int(n);
    if (checku8(k) && n == (lua_Number)k) {
      t->u.s.aux = BCMAX_C+1+(uint32_t)k;  /* 256..511: const byte key */
      return;
    }
#endif
  } else if (expr_isstrk(e)) {
    BCReg idx = const_str(fs, e);
    if (idx <= BCMAX_C) {
      t->u.s.aux = ~idx;  /* -256..-1: const string key */
      return;
    }
  }
  t->u.s.aux = expr_toanyreg(fs, e);  /* 0..255: register */
}

/* Parse index expression with named field. */
static void expr_field(LexState *ls, ExpDesc *v)
{
  FuncState *fs = ls->fs;
  ExpDesc key;
  expr_toanyreg(fs, v);
  lj_lex_next(ls);  /* Skip dot or colon. */
  expr_str(ls, &key);
  expr_index(fs, v, &key);
}

/* Parse index expression with brackets. */
static void expr_bracket(LexState *ls, ExpDesc *v)
{
  lj_lex_next(ls);  /* Skip '['. */
  expr(ls, v);
  expr_toval(ls->fs, v);
  lex_check(ls, ']');
}

/* Get value of constant expression. */
static void expr_kvalue(FuncState *fs, TValue *v, ExpDesc *e)
{
  UNUSED(fs);
  if (e->k <= VKTRUE) {
    setpriV(v, ~(uint32_t)e->k);
  } else if (e->k == VKSTR) {
    setgcVraw(v, obj2gco(e->u.sval), LJ_TSTR);
  } else {
    lj_assertFS(tvisnumber(expr_numtv(e)), "bad number constant");
    *v = *expr_numtv(e);
  }
}

/* Parse table constructor expression. */
static void expr_table(LexState *ls, ExpDesc *e)
{
  FuncState *fs = ls->fs;
  BCLine line = ls->linenumber;
  GCtab *t = NULL;
  int vcall = 0, needarr = 0, fixt = 0;
  uint32_t narr = 1;  /* First array index. */
  uint32_t nhash = 0;  /* Number of hash entries. */
  BCReg freg = fs->freereg;
  BCPos pc = bcemit_AD(fs, BC_TNEW, freg, 0);
  expr_init(e, VNONRELOC, freg);
  bcreg_reserve(fs, 1);
  freg++;
  lex_check(ls, '{');
  while (ls->tok != '}') {
    ExpDesc key, val;
    vcall = 0;
    if (ls->tok == '[') {
      expr_bracket(ls, &key);  /* Already calls expr_toval. */
      if (!expr_isk(&key)) expr_index(fs, e, &key);
      if (expr_isnumk(&key) && expr_numiszero(&key)) needarr = 1; else nhash++;
      lex_check(ls, '=');
    } else if ((ls->tok == TK_name || (!LJ_52 && ls->tok == TK_goto)) &&
               lj_lex_lookahead(ls) == '=') {
      expr_str(ls, &key);
      lex_check(ls, '=');
      nhash++;
    } else {
      expr_init(&key, VKNUM, 0);
      setintV(&key.u.nval, (int)narr);
      narr++;
      needarr = vcall = 1;
    }
    expr(ls, &val);
    if (expr_isk(&key) && key.k != VKNIL &&
        (key.k == VKSTR || expr_isk_nojump(&val))) {
      TValue k, *v;
      if (!t) {  /* Create template table on demand. */
        BCReg kidx;
        t = lj_tab_new(fs->L, needarr ? narr : 0, hsize2hbits(nhash));
        kidx = const_gc(fs, obj2gco(t), LJ_TTAB);
        fs->bcbase[pc].ins = BCINS_AD(BC_TDUP, freg-1, kidx);
      }
      vcall = 0;
      expr_kvalue(fs, &k, &key);
      v = lj_tab_set(fs->L, t, &k);
      lj_gc_anybarriert(fs->L, t);
      if (expr_isk_nojump(&val)) {  /* Add const key/value to template table. */
        expr_kvalue(fs, v, &val);
      } else {  /* Otherwise create dummy string key (avoids lj_tab_newkey). */
        settabV(fs->L, v, t);  /* Preserve key with table itself as value. */
        fixt = 1;   /* Fix this later, after all resizes. */
        goto nonconst;
      }
    } else {
    nonconst:
      if (val.k != VCALL) { expr_toanyreg(fs, &val); vcall = 0; }
      if (expr_isk(&key)) expr_index(fs, e, &key);
      bcemit_store(fs, e, &val);
    }
    fs->freereg = freg;
    if (!lex_opt(ls, ',') && !lex_opt(ls, ';')) break;
  }
  lex_match(ls, '}', '{', line);
  if (vcall) {
    BCInsLine *ilp = &fs->bcbase[fs->pc-1];
    ExpDesc en;
    lj_assertFS(bc_a(ilp->ins) == freg &&
                bc_op(ilp->ins) == (narr > 256 ? BC_TSETV : BC_TSETB),
                "bad CALL code generation");
    expr_init(&en, VKNUM, 0);
    en.u.nval.u32.lo = narr-1;
    en.u.nval.u32.hi = 0x43300000;  /* Biased integer to avoid denormals. */
    if (narr > 256) { fs->pc--; ilp--; }
    ilp->ins = BCINS_AD(BC_TSETM, freg, const_num(fs, &en));
    setbc_b(&ilp[-1].ins, 0);
  }
  if (pc == fs->pc-1) {  /* Make expr relocable if possible. */
    e->u.s.info = pc;
    fs->freereg--;
    e->k = VRELOCABLE;
  } else {
    e->k = VNONRELOC;  /* May have been changed by expr_index. */
  }
  if (!t) {  /* Construct TNEW RD: hhhhhaaaaaaaaaaa. */
    BCIns *ip = &fs->bcbase[pc].ins;
    if (!needarr) narr = 0;
    else if (narr < 3) narr = 3;
    else if (narr > 0x7ff) narr = 0x7ff;
    setbc_d(ip, narr|(hsize2hbits(nhash)<<11));
  } else {
    if (needarr && t->asize < narr)
      lj_tab_reasize(fs->L, t, narr-1);
    if (fixt) {  /* Fix value for dummy keys in template table. */
      Node *node = noderef(t->node);
      uint32_t i, hmask = t->hmask;
      for (i = 0; i <= hmask; i++) {
        Node *n = &node[i];
        if (tvistab(&n->val)) {
          lj_assertFS(tabV(&n->val) == t, "bad dummy key in template table");
          setnilV(&n->val);  /* Turn value into nil. */
        }
      }
    }
    lj_gc_check(fs->L);
  }
}

/* Parse function parameters. */
static BCReg parse_params(LexState *ls, int needself)
{
  FuncState *fs = ls->fs;
  BCReg nparams = 0;
  lex_check(ls, '(');
  if (needself)
    var_new_lit(ls, nparams++, "self");
  if (ls->tok != ')') {
    do {
      if (ls->tok == TK_name || (!LJ_52 && ls->tok == TK_goto)) {
        var_new(ls, nparams++, lex_str(ls));
      } else if (ls->tok == TK_dots) {
        lj_lex_next(ls);
        fs->flags |= PROTO_VARARG;
        break;
      } else {
        err_syntax(ls, LJ_ERR_XPARAM);
      }
    } while (lex_opt(ls, ','));
  }
  var_add(ls, nparams);
  lj_assertFS(fs->nactvar == nparams, "bad regalloc");
  bcreg_reserve(fs, nparams);
  lex_check(ls, ')');
  return nparams;
}

/* Forward declaration. */
static void parse_chunk(LexState *ls);

/* Parse body of a function. */
static void parse_body(LexState *ls, ExpDesc *e, int needself, BCLine line)
{
  FuncState fs, *pfs = ls->fs;
  FuncScope bl;
  GCproto *pt;
  ptrdiff_t oldbase = pfs->bcbase - ls->bcstack;
  fs_init(ls, &fs);
  fscope_begin(&fs, &bl, 0);
  fs.linedefined = line;
  fs.numparams = (uint8_t)parse_params(ls, needself);
  fs.bcbase = pfs->bcbase + pfs->pc;
  fs.bclim = pfs->bclim - pfs->pc;
  bcemit_AD(&fs, BC_FUNCF, 0, 0);  /* Placeholder. */
  parse_chunk(ls);
  if (ls->tok != TK_end) lex_match(ls, TK_end, TK_function, line);
  pt = fs_finish(ls, (ls->lastline = ls->linenumber));
  pfs->bcbase = ls->bcstack + oldbase;  /* May have been reallocated. */
  pfs->bclim = (BCPos)(ls->sizebcstack - oldbase);
  /* Store new prototype in the constant array of the parent. */
  expr_init(e, VRELOCABLE,
            bcemit_AD(pfs, BC_FNEW, 0, const_gc(pfs, obj2gco(pt), LJ_TPROTO)));
#if LJ_HASFFI
  pfs->flags |= (fs.flags & PROTO_FFI);
#endif
  if (!(pfs->flags & PROTO_CHILD)) {
    if (pfs->flags & PROTO_HAS_RETURN)
      pfs->flags |= PROTO_FIXUP_RETURN;
    pfs->flags |= PROTO_CHILD;
  }
  lj_lex_next(ls);
}

/* Parse expression list. Last expression is left open. */
static BCReg expr_list(LexState *ls, ExpDesc *v)
{
  BCReg n = 1;
  expr(ls, v);
  while (lex_opt(ls, ',')) {
    expr_tonextreg(ls->fs, v);
    expr(ls, v);
    n++;
  }
  return n;
}

/* Parse function argument list. */
static void parse_args(LexState *ls, ExpDesc *e)
{
  FuncState *fs = ls->fs;
  ExpDesc args;
  BCIns ins;
  BCReg base;
  BCLine line = ls->linenumber;
  if (ls->tok == '(') {
#if !LJ_52
    if (line != ls->lastline)
      err_syntax(ls, LJ_ERR_XAMBIG);
#endif
    lj_lex_next(ls);
    if (ls->tok == ')') {  /* f(). */
      args.k = VVOID;
    } else {
      expr_list(ls, &args);
      if (args.k == VCALL)  /* f(a, b, g()) or f(a, b, ...). */
        setbc_b(bcptr(fs, &args), 0);  /* Pass on multiple results. */
    }
    lex_match(ls, ')', '(', line);
  } else if (ls->tok == '{') {
    expr_table(ls, &args);
  } else if (ls->tok == TK_string) {
    expr_init(&args, VKSTR, 0);
    args.u.sval = strV(&ls->tokval);
    lj_lex_next(ls);
  } else {
    err_syntax(ls, LJ_ERR_XFUNARG);
    return;  /* Silence compiler. */
  }
  lj_assertFS(e->k == VNONRELOC, "bad expr type %d", e->k);
  base = e->u.s.info;  /* Base register for call. */
  if (args.k == VCALL) {
    ins = BCINS_ABC(BC_CALLM, base, 2, args.u.s.aux - base - 1 - LJ_FR2);
  } else {
    if (args.k != VVOID)
      expr_tonextreg(fs, &args);
    ins = BCINS_ABC(BC_CALL, base, 2, fs->freereg - base - LJ_FR2);
  }
  expr_init(e, VCALL, bcemit_INS(fs, ins));
  e->u.s.aux = base;
  fs->bcbase[fs->pc - 1].line = line;
  fs->freereg = base+1;  /* Leave one result by default. */
}

/* Parse primary expression. */
static void expr_primary(LexState *ls, ExpDesc *v)
{
  FuncState *fs = ls->fs;
  /* Parse prefix expression. */
  if (ls->tok == '(') {
    BCLine line = ls->linenumber;
    lj_lex_next(ls);
    expr(ls, v);
    lex_match(ls, ')', '(', line);
    expr_discharge(ls->fs, v);
  } else if (ls->tok == TK_name || (!LJ_52 && ls->tok == TK_goto)) {
    var_lookup(ls, v);
  } else {
    err_syntax(ls, LJ_ERR_XSYMBOL);
  }
  for (;;) {  /* Parse multiple expression suffixes. */
    if (ls->tok == '.') {
      expr_field(ls, v);
    } else if (ls->tok == '[') {
      ExpDesc key;
      expr_toanyreg(fs, v);
      expr_bracket(ls, &key);
      expr_index(fs, v, &key);
    } else if (ls->tok == ':') {
      ExpDesc key;
      lj_lex_next(ls);
      expr_str(ls, &key);
      bcemit_method(fs, v, &key);
      parse_args(ls, v);
    } else if (ls->tok == '(' || ls->tok == TK_string || ls->tok == '{') {
      expr_tonextreg(fs, v);
      if (LJ_FR2) bcreg_reserve(fs, 1);
      parse_args(ls, v);
    } else {
      break;
    }
  }
}

/* Parse simple expression. */
static void expr_simple(LexState *ls, ExpDesc *v)
{
  switch (ls->tok) {
  case TK_number:
    expr_init(v, (LJ_HASFFI && tviscdata(&ls->tokval)) ? VKCDATA : VKNUM, 0);
    copyTV(ls->L, &v->u.nval, &ls->tokval);
    break;
  case TK_string:
    expr_init(v, VKSTR, 0);
    v->u.sval = strV(&ls->tokval);
    break;
  case TK_nil:
    expr_init(v, VKNIL, 0);
    break;
  case TK_true:
    expr_init(v, VKTRUE, 0);
    break;
  case TK_false:
    expr_init(v, VKFALSE, 0);
    break;
  case TK_dots: {  /* Vararg. */
    FuncState *fs = ls->fs;
    BCReg base;
    checkcond(ls, fs->flags & PROTO_VARARG, LJ_ERR_XDOTS);
    bcreg_reserve(fs, 1);
    base = fs->freereg-1;
    expr_init(v, VCALL, bcemit_ABC(fs, BC_VARG, base, 2, fs->numparams));
    v->u.s.aux = base;
    break;
  }
  case '{':  /* Table constructor. */
    expr_table(ls, v);
    return;
  case TK_function:
    lj_lex_next(ls);
    parse_body(ls, v, 0, ls->linenumber);
    return;
  default:
    expr_primary(ls, v);
    return;
  }
  lj_lex_next(ls);
}

/* Manage syntactic levels to avoid blowing up the stack. */
static void synlevel_begin(LexState *ls)
{
  if (++ls->level >= LJ_MAX_XLEVEL)
    lj_lex_error(ls, 0, LJ_ERR_XLEVELS);
}

#define synlevel_end(ls)        ((ls)->level--)

/* Convert token to binary operator. */
static BinOpr token2binop(LexToken tok)
{
  switch (tok) {
  case '+':        return OPR_ADD;
  case '-':        return OPR_SUB;
  case '*':        return OPR_MUL;
  case '/':        return OPR_DIV;
  case '%':        return OPR_MOD;
  case '^':        return OPR_POW;
  case TK_concat: return OPR_CONCAT;
  case TK_ne:        return OPR_NE;
  case TK_eq:        return OPR_EQ;
  case '<':        return OPR_LT;
  case TK_le:        return OPR_LE;
  case '>':        return OPR_GT;
  case TK_ge:        return OPR_GE;
  case TK_and:        return OPR_AND;
  case TK_or:        return OPR_OR;
  default:        return OPR_NOBINOPR;
  }
}

/* Priorities for each binary operator. ORDER OPR. */
static const struct {
  uint8_t left;                /* Left priority. */
  uint8_t right;        /* Right priority. */
} priority[] = {
  {6,6}, {6,6}, {7,7}, {7,7}, {7,7},        /* ADD SUB MUL DIV MOD */
  {10,9}, {5,4},                        /* POW CONCAT (right associative) */
  {3,3}, {3,3},                                /* EQ NE */
  {3,3}, {3,3}, {3,3}, {3,3},                /* LT GE GT LE */
  {2,2}, {1,1}                                /* AND OR */
};

#define UNARY_PRIORITY                8  /* Priority for unary operators. */

/* Forward declaration. */
static BinOpr expr_binop(LexState *ls, ExpDesc *v, uint32_t limit);

/* Parse unary expression. */
static void expr_unop(LexState *ls, ExpDesc *v)
{
  BCOp op;
  if (ls->tok == TK_not) {
    op = BC_NOT;
  } else if (ls->tok == '-') {
    op = BC_UNM;
  } else if (ls->tok == '#') {
    op = BC_LEN;
  } else {
    expr_simple(ls, v);
    return;
  }
  lj_lex_next(ls);
  expr_binop(ls, v, UNARY_PRIORITY);
  bcemit_unop(ls->fs, op, v);
}

/* Parse binary expressions with priority higher than the limit. */
static BinOpr expr_binop(LexState *ls, ExpDesc *v, uint32_t limit)
{
  BinOpr op;
  synlevel_begin(ls);
  expr_unop(ls, v);
  op = token2binop(ls->tok);
  while (op != OPR_NOBINOPR && priority[op].left > limit) {
    ExpDesc v2;
    BinOpr nextop;
    lj_lex_next(ls);
    bcemit_binop_left(ls->fs, op, v);
    /* Parse binary expression with higher priority. */
    nextop = expr_binop(ls, &v2, priority[op].right);
    bcemit_binop(ls->fs, op, v, &v2);
    op = nextop;
  }
  synlevel_end(ls);
  return op;  /* Return unconsumed binary operator (if any). */
}

/* Parse expression. */
static void expr(LexState *ls, ExpDesc *v)
{
  expr_binop(ls, v, 0);  /* Priority 0: parse whole expression. */
}

/* Assign expression to the next register. */
static void expr_next(LexState *ls)
{
  ExpDesc e;
  expr(ls, &e);
  expr_tonextreg(ls->fs, &e);
}

/* Parse conditional expression. */
static BCPos expr_cond(LexState *ls)
{
  ExpDesc v;
  expr(ls, &v);
  if (v.k == VKNIL) v.k = VKFALSE;
  bcemit_branch_t(ls->fs, &v);
  return v.f;
}

/* -- Assignments --------------------------------------------------------- */

/* List of LHS variables. */
typedef struct LHSVarList {
  ExpDesc v;                        /* LHS variable. */
  struct LHSVarList *prev;        /* Link to previous LHS variable. */
} LHSVarList;

/* Eliminate write-after-read hazards for local variable assignment. */
static void assign_hazard(LexState *ls, LHSVarList *lh, const ExpDesc *v)
{
  FuncState *fs = ls->fs;
  BCReg reg = v->u.s.info;  /* Check against this variable. */
  BCReg tmp = fs->freereg;  /* Rename to this temp. register (if needed). */
  int hazard = 0;
  for (; lh; lh = lh->prev) {
    if (lh->v.k == VINDEXED) {
      if (lh->v.u.s.info == reg) {  /* t[i], t = 1, 2 */
        hazard = 1;
        lh->v.u.s.info = tmp;
      }
      if (lh->v.u.s.aux == reg) {  /* t[i], i = 1, 2 */
        hazard = 1;
        lh->v.u.s.aux = tmp;
      }
    }
  }
  if (hazard) {
    bcemit_AD(fs, BC_MOV, tmp, reg);  /* Rename conflicting variable. */
    bcreg_reserve(fs, 1);
  }
}

/* Adjust LHS/RHS of an assignment. */
static void assign_adjust(LexState *ls, BCReg nvars, BCReg nexps, ExpDesc *e)
{
  FuncState *fs = ls->fs;
  int32_t extra = (int32_t)nvars - (int32_t)nexps;
  if (e->k == VCALL) {
    extra++;  /* Compensate for the VCALL itself. */
    if (extra < 0) extra = 0;
    setbc_b(bcptr(fs, e), extra+1);  /* Fixup call results. */
    if (extra > 1) bcreg_reserve(fs, (BCReg)extra-1);
  } else {
    if (e->k != VVOID)
      expr_tonextreg(fs, e);  /* Close last expression. */
    if (extra > 0) {  /* Leftover LHS are set to nil. */
      BCReg reg = fs->freereg;
      bcreg_reserve(fs, (BCReg)extra);
      bcemit_nil(fs, reg, (BCReg)extra);
    }
  }
  if (nexps > nvars)
    ls->fs->freereg -= nexps - nvars;  /* Drop leftover regs. */
}

/* Recursively parse assignment statement. */
static void parse_assignment(LexState *ls, LHSVarList *lh, BCReg nvars)
{
  ExpDesc e;
  checkcond(ls, VLOCAL <= lh->v.k && lh->v.k <= VINDEXED, LJ_ERR_XSYNTAX);
  if (lex_opt(ls, ',')) {  /* Collect LHS list and recurse upwards. */
    LHSVarList vl;
    vl.prev = lh;
    expr_primary(ls, &vl.v);
    if (vl.v.k == VLOCAL)
      assign_hazard(ls, lh, &vl.v);
    checklimit(ls->fs, ls->level + nvars, LJ_MAX_XLEVEL, "variable names");
    parse_assignment(ls, &vl, nvars+1);
  } else {  /* Parse RHS. */
    BCReg nexps;
    lex_check(ls, '=');
    nexps = expr_list(ls, &e);
    if (nexps == nvars) {
      if (e.k == VCALL) {
        if (bc_op(*bcptr(ls->fs, &e)) == BC_VARG) {  /* Vararg assignment. */
          ls->fs->freereg--;
          e.k = VRELOCABLE;
        } else {  /* Multiple call results. */
          e.u.s.info = e.u.s.aux;  /* Base of call is not relocatable. */
          e.k = VNONRELOC;
        }
      }
      bcemit_store(ls->fs, &lh->v, &e);
      return;
    }
    assign_adjust(ls, nvars, nexps, &e);
  }
  /* Assign RHS to LHS and recurse downwards. */
  expr_init(&e, VNONRELOC, ls->fs->freereg-1);
  bcemit_store(ls->fs, &lh->v, &e);
}

/* Parse call statement or assignment. */
static void parse_call_assign(LexState *ls)
{
  FuncState *fs = ls->fs;
  LHSVarList vl;
  expr_primary(ls, &vl.v);
  if (vl.v.k == VCALL) {  /* Function call statement. */
    setbc_b(bcptr(fs, &vl.v), 1);  /* No results. */
  } else {  /* Start of an assignment. */
    vl.prev = NULL;
    parse_assignment(ls, &vl, 1);
  }
}

/* Parse 'local' statement. */
static void parse_local(LexState *ls)
{
  if (lex_opt(ls, TK_function)) {  /* Local function declaration. */
    ExpDesc v, b;
    FuncState *fs = ls->fs;
    var_new(ls, 0, lex_str(ls));
    expr_init(&v, VLOCAL, fs->freereg);
    v.u.s.aux = fs->varmap[fs->freereg];
    bcreg_reserve(fs, 1);
    var_add(ls, 1);
    parse_body(ls, &b, 0, ls->linenumber);
    /* bcemit_store(fs, &v, &b) without setting VSTACK_VAR_RW. */
    expr_free(fs, &b);
    expr_toreg(fs, &b, v.u.s.info);
    /* The upvalue is in scope, but the local is only valid after the store. */
    var_get(ls, fs, fs->nactvar - 1).startpc = fs->pc;
  } else {  /* Local variable declaration. */
    ExpDesc e;
    BCReg nexps, nvars = 0;
    do {  /* Collect LHS. */
      var_new(ls, nvars++, lex_str(ls));
    } while (lex_opt(ls, ','));
    if (lex_opt(ls, '=')) {  /* Optional RHS. */
      nexps = expr_list(ls, &e);
    } else {  /* Or implicitly set to nil. */
      e.k = VVOID;
      nexps = 0;
    }
    assign_adjust(ls, nvars, nexps, &e);
    var_add(ls, nvars);
  }
}

/* Parse 'function' statement. */
static void parse_func(LexState *ls, BCLine line)
{
  FuncState *fs;
  ExpDesc v, b;
  int needself = 0;
  lj_lex_next(ls);  /* Skip 'function'. */
  /* Parse function name. */
  var_lookup(ls, &v);
  while (ls->tok == '.')  /* Multiple dot-separated fields. */
    expr_field(ls, &v);
  if (ls->tok == ':') {  /* Optional colon to signify method call. */
    needself = 1;
    expr_field(ls, &v);
  }
  parse_body(ls, &b, needself, line);
  fs = ls->fs;
  bcemit_store(fs, &v, &b);
  fs->bcbase[fs->pc - 1].line = line;  /* Set line for the store. */
}

/* -- Control transfer statements ----------------------------------------- */

/* Check for end of block. */
static int parse_isend(LexToken tok)
{
  switch (tok) {
  case TK_else: case TK_elseif: case TK_end: case TK_until: case TK_eof:
    return 1;
  default:
    return 0;
  }
}

/* Parse 'return' statement. */
static void parse_return(LexState *ls)
{
  BCIns ins;
  FuncState *fs = ls->fs;
  lj_lex_next(ls);  /* Skip 'return'. */
  fs->flags |= PROTO_HAS_RETURN;
  if (parse_isend(ls->tok) || ls->tok == ';') {  /* Bare return. */
    ins = BCINS_AD(BC_RET0, 0, 1);
  } else {  /* Return with one or more values. */
    ExpDesc e;  /* Receives the _last_ expression in the list. */
    BCReg nret = expr_list(ls, &e);
    if (nret == 1) {  /* Return one result. */
      if (e.k == VCALL) {  /* Check for tail call. */
        BCIns *ip = bcptr(fs, &e);
        /* It doesn't pay off to add BC_VARGT just for 'return ...'. */
        if (bc_op(*ip) == BC_VARG) goto notailcall;
        fs->pc--;
        ins = BCINS_AD(bc_op(*ip)-BC_CALL+BC_CALLT, bc_a(*ip), bc_c(*ip));
      } else {  /* Can return the result from any register. */
        ins = BCINS_AD(BC_RET1, expr_toanyreg(fs, &e), 2);
      }
    } else {
      if (e.k == VCALL) {  /* Append all results from a call. */
      notailcall:
        setbc_b(bcptr(fs, &e), 0);
        ins = BCINS_AD(BC_RETM, fs->nactvar, e.u.s.aux - fs->nactvar);
      } else {
        expr_tonextreg(fs, &e);  /* Force contiguous registers. */
        ins = BCINS_AD(BC_RET, fs->nactvar, nret+1);
      }
    }
  }
  if (fs->flags & PROTO_CHILD)
    bcemit_AJ(fs, BC_UCLO, 0, 0);  /* May need to close upvalues first. */
  bcemit_INS(fs, ins);
}

/* Parse 'break' statement. */
static void parse_break(LexState *ls)
{
  ls->fs->bl->flags |= FSCOPE_BREAK;
  gola_new(ls, NAME_BREAK, VSTACK_GOTO, bcemit_jmp(ls->fs));
}

/* Parse 'goto' statement. */
static void parse_goto(LexState *ls)
{
  FuncState *fs = ls->fs;
  GCstr *name = lex_str(ls);
  VarInfo *vl = gola_findlabel(ls, name);
  if (vl)  /* Treat backwards goto within same scope like a loop. */
    bcemit_AJ(fs, BC_LOOP, vl->slot, -1);  /* No BC range check. */
  fs->bl->flags |= FSCOPE_GOLA;
  gola_new(ls, name, VSTACK_GOTO, bcemit_jmp(fs));
}

/* Parse label. */
static void parse_label(LexState *ls)
{
  FuncState *fs = ls->fs;
  GCstr *name;
  MSize idx;
  fs->lasttarget = fs->pc;
  fs->bl->flags |= FSCOPE_GOLA;
  lj_lex_next(ls);  /* Skip '::'. */
  name = lex_str(ls);
  if (gola_findlabel(ls, name))
    lj_lex_error(ls, 0, LJ_ERR_XLDUP, strdata(name));
  idx = gola_new(ls, name, VSTACK_LABEL, fs->pc);
  lex_check(ls, TK_label);
  /* Recursively parse trailing statements: labels and ';' (Lua 5.2 only). */
  for (;;) {
    if (ls->tok == TK_label) {
      synlevel_begin(ls);
      parse_label(ls);
      synlevel_end(ls);
    } else if (LJ_52 && ls->tok == ';') {
      lj_lex_next(ls);
    } else {
      break;
    }
  }
  /* Trailing label is considered to be outside of scope. */
  if (parse_isend(ls->tok) && ls->tok != TK_until)
    ls->vstack[idx].slot = fs->bl->nactvar;
  gola_resolve(ls, fs->bl, idx);
}

/* -- Blocks, loops and conditional statements ---------------------------- */

/* Parse a block. */
static void parse_block(LexState *ls)
{
  FuncState *fs = ls->fs;
  FuncScope bl;
  fscope_begin(fs, &bl, 0);
  parse_chunk(ls);
  fscope_end(fs);
}

/* Parse 'while' statement. */
static void parse_while(LexState *ls, BCLine line)
{
  FuncState *fs = ls->fs;
  BCPos start, loop, condexit;
  FuncScope bl;
  lj_lex_next(ls);  /* Skip 'while'. */
  start = fs->lasttarget = fs->pc;
  condexit = expr_cond(ls);
  fscope_begin(fs, &bl, FSCOPE_LOOP);
  lex_check(ls, TK_do);
  loop = bcemit_AD(fs, BC_LOOP, fs->nactvar, 0);
  parse_block(ls);
  jmp_patch(fs, bcemit_jmp(fs), start);
  lex_match(ls, TK_end, TK_while, line);
  fscope_end(fs);
  jmp_tohere(fs, condexit);
  jmp_patchins(fs, loop, fs->pc);
}

/* Parse 'repeat' statement. */
static void parse_repeat(LexState *ls, BCLine line)
{
  FuncState *fs = ls->fs;
  BCPos loop = fs->lasttarget = fs->pc;
  BCPos condexit;
  FuncScope bl1, bl2;
  fscope_begin(fs, &bl1, FSCOPE_LOOP);  /* Breakable loop scope. */
  fscope_begin(fs, &bl2, 0);  /* Inner scope. */
  lj_lex_next(ls);  /* Skip 'repeat'. */
  bcemit_AD(fs, BC_LOOP, fs->nactvar, 0);
  parse_chunk(ls);
  lex_match(ls, TK_until, TK_repeat, line);
  condexit = expr_cond(ls);  /* Parse condition (still inside inner scope). */
  if (!(bl2.flags & FSCOPE_UPVAL)) {  /* No upvalues? Just end inner scope. */
    fscope_end(fs);
  } else {  /* Otherwise generate: cond: UCLO+JMP out, !cond: UCLO+JMP loop. */
    parse_break(ls);  /* Break from loop and close upvalues. */
    jmp_tohere(fs, condexit);
    fscope_end(fs);  /* End inner scope and close upvalues. */
    condexit = bcemit_jmp(fs);
  }
  jmp_patch(fs, condexit, loop);  /* Jump backwards if !cond. */
  jmp_patchins(fs, loop, fs->pc);
  fscope_end(fs);  /* End loop scope. */
}

/* Parse numeric 'for'. */
static void parse_for_num(LexState *ls, GCstr *varname, BCLine line)
{
  FuncState *fs = ls->fs;
  BCReg base = fs->freereg;
  FuncScope bl;
  BCPos loop, loopend;
  /* Hidden control variables. */
  var_new_fixed(ls, FORL_IDX, VARNAME_FOR_IDX);
  var_new_fixed(ls, FORL_STOP, VARNAME_FOR_STOP);
  var_new_fixed(ls, FORL_STEP, VARNAME_FOR_STEP);
  /* Visible copy of index variable. */
  var_new(ls, FORL_EXT, varname);
  lex_check(ls, '=');
  expr_next(ls);
  lex_check(ls, ',');
  expr_next(ls);
  if (lex_opt(ls, ',')) {
    expr_next(ls);
  } else {
    bcemit_AD(fs, BC_KSHORT, fs->freereg, 1);  /* Default step is 1. */
    bcreg_reserve(fs, 1);
  }
  var_add(ls, 3);  /* Hidden control variables. */
  lex_check(ls, TK_do);
  loop = bcemit_AJ(fs, BC_FORI, base, NO_JMP);
  fscope_begin(fs, &bl, 0);  /* Scope for visible variables. */
  var_add(ls, 1);
  bcreg_reserve(fs, 1);
  parse_block(ls);
  fscope_end(fs);
  /* Perform loop inversion. Loop control instructions are at the end. */
  loopend = bcemit_AJ(fs, BC_FORL, base, NO_JMP);
  fs->bcbase[loopend].line = line;  /* Fix line for control ins. */
  jmp_patchins(fs, loopend, loop+1);
  jmp_patchins(fs, loop, fs->pc);
}

/* Try to predict whether the iterator is next() and specialize the bytecode.
** Detecting next() and pairs() by name is simplistic, but quite effective.
** The interpreter backs off if the check for the closure fails at runtime.
*/
static int predict_next(LexState *ls, FuncState *fs, BCPos pc)
{
  BCIns ins = fs->bcbase[pc].ins;
  GCstr *name;
  cTValue *o;
  switch (bc_op(ins)) {
  case BC_MOV:
    if (bc_d(ins) >= fs->nactvar) return 0;
    name = gco2str(gcref(var_get(ls, fs, bc_d(ins)).name));
    break;
  case BC_UGET:
    name = gco2str(gcref(ls->vstack[fs->uvmap[bc_d(ins)]].name));
    break;
  case BC_GGET:
    /* There's no inverse index (yet), so lookup the strings. */
    o = lj_tab_getstr(fs->kt, lj_str_newlit(ls->L, "pairs"));
    if (o && tvhaskslot(o) && tvkslot(o) == bc_d(ins))
      return 1;
    o = lj_tab_getstr(fs->kt, lj_str_newlit(ls->L, "next"));
    if (o && tvhaskslot(o) && tvkslot(o) == bc_d(ins))
      return 1;
    return 0;
  default:
    return 0;
  }
  return (name->len == 5 && !strcmp(strdata(name), "pairs")) ||
         (name->len == 4 && !strcmp(strdata(name), "next"));
}

/* Parse 'for' iterator. */
static void parse_for_iter(LexState *ls, GCstr *indexname)
{
  FuncState *fs = ls->fs;
  ExpDesc e;
  BCReg nvars = 0;
  BCLine line;
  BCReg base = fs->freereg + 3;
  BCPos loop, loopend, exprpc = fs->pc;
  FuncScope bl;
  int isnext;
  /* Hidden control variables. */
  var_new_fixed(ls, nvars++, VARNAME_FOR_GEN);
  var_new_fixed(ls, nvars++, VARNAME_FOR_STATE);
  var_new_fixed(ls, nvars++, VARNAME_FOR_CTL);
  /* Visible variables returned from iterator. */
  var_new(ls, nvars++, indexname);
  while (lex_opt(ls, ','))
    var_new(ls, nvars++, lex_str(ls));
  lex_check(ls, TK_in);
  line = ls->linenumber;
  assign_adjust(ls, 3, expr_list(ls, &e), &e);
  /* The iterator needs another 3 [4] slots (func [pc] | state ctl). */
  bcreg_bump(fs, 3+LJ_FR2);
  isnext = (nvars <= 5 && predict_next(ls, fs, exprpc));
  var_add(ls, 3);  /* Hidden control variables. */
  lex_check(ls, TK_do);
  loop = bcemit_AJ(fs, isnext ? BC_ISNEXT : BC_JMP, base, NO_JMP);
  fscope_begin(fs, &bl, 0);  /* Scope for visible variables. */
  var_add(ls, nvars-3);
  bcreg_reserve(fs, nvars-3);
  parse_block(ls);
  fscope_end(fs);
  /* Perform loop inversion. Loop control instructions are at the end. */
  jmp_patchins(fs, loop, fs->pc);
  bcemit_ABC(fs, isnext ? BC_ITERN : BC_ITERC, base, nvars-3+1, 2+1);
  loopend = bcemit_AJ(fs, BC_ITERL, base, NO_JMP);
  fs->bcbase[loopend-1].line = line;  /* Fix line for control ins. */
  fs->bcbase[loopend].line = line;
  jmp_patchins(fs, loopend, loop+1);
}

/* Parse 'for' statement. */
static void parse_for(LexState *ls, BCLine line)
{
  FuncState *fs = ls->fs;
  GCstr *varname;
  FuncScope bl;
  fscope_begin(fs, &bl, FSCOPE_LOOP);
  lj_lex_next(ls);  /* Skip 'for'. */
  varname = lex_str(ls);  /* Get first variable name. */
  if (ls->tok == '=')
    parse_for_num(ls, varname, line);
  else if (ls->tok == ',' || ls->tok == TK_in)
    parse_for_iter(ls, varname);
  else
    err_syntax(ls, LJ_ERR_XFOR);
  lex_match(ls, TK_end, TK_for, line);
  fscope_end(fs);  /* Resolve break list. */
}

/* Parse condition and 'then' block. */
static BCPos parse_then(LexState *ls)
{
  BCPos condexit;
  lj_lex_next(ls);  /* Skip 'if' or 'elseif'. */
  condexit = expr_cond(ls);
  lex_check(ls, TK_then);
  parse_block(ls);
  return condexit;
}

/* Parse 'if' statement. */
static void parse_if(LexState *ls, BCLine line)
{
  FuncState *fs = ls->fs;
  BCPos flist;
  BCPos escapelist = NO_JMP;
  flist = parse_then(ls);
  while (ls->tok == TK_elseif) {  /* Parse multiple 'elseif' blocks. */
    jmp_append(fs, &escapelist, bcemit_jmp(fs));
    jmp_tohere(fs, flist);
    flist = parse_then(ls);
  }
  if (ls->tok == TK_else) {  /* Parse optional 'else' block. */
    jmp_append(fs, &escapelist, bcemit_jmp(fs));
    jmp_tohere(fs, flist);
    lj_lex_next(ls);  /* Skip 'else'. */
    parse_block(ls);
  } else {
    jmp_append(fs, &escapelist, flist);
  }
  jmp_tohere(fs, escapelist);
  lex_match(ls, TK_end, TK_if, line);
}

/* -- Parse statements ---------------------------------------------------- */

/* Parse a statement. Returns 1 if it must be the last one in a chunk. */
static int parse_stmt(LexState *ls)
{
  BCLine line = ls->linenumber;
  switch (ls->tok) {
  case TK_if:
    parse_if(ls, line);
    break;
  case TK_while:
    parse_while(ls, line);
    break;
  case TK_do:
    lj_lex_next(ls);
    parse_block(ls);
    lex_match(ls, TK_end, TK_do, line);
    break;
  case TK_for:
    parse_for(ls, line);
    break;
  case TK_repeat:
    parse_repeat(ls, line);
    break;
  case TK_function:
    parse_func(ls, line);
    break;
  case TK_local:
    lj_lex_next(ls);
    parse_local(ls);
    break;
  case TK_return:
    parse_return(ls);
    return 1;  /* Must be last. */
  case TK_break:
    lj_lex_next(ls);
    parse_break(ls);
    return !LJ_52;  /* Must be last in Lua 5.1. */
#if LJ_52
  case ';':
    lj_lex_next(ls);
    break;
#endif
  case TK_label:
    parse_label(ls);
    break;
  case TK_goto:
    if (LJ_52 || lj_lex_lookahead(ls) == TK_name) {
      lj_lex_next(ls);
      parse_goto(ls);
      break;
    }
    /* fallthrough */
  default:
    parse_call_assign(ls);
    break;
  }
  return 0;
}

/* A chunk is a list of statements optionally separated by semicolons. */
static void parse_chunk(LexState *ls)
{
  int islast = 0;
  synlevel_begin(ls);
  while (!islast && !parse_isend(ls->tok)) {
    islast = parse_stmt(ls);
    lex_opt(ls, ';');
    lj_assertLS(ls->fs->framesize >= ls->fs->freereg &&
                ls->fs->freereg >= ls->fs->nactvar,
                "bad regalloc");
    ls->fs->freereg = ls->fs->nactvar;  /* Free registers after each stmt. */
  }
  synlevel_end(ls);
}

/* Entry point of bytecode parser. */
GCproto *lj_parse(LexState *ls)
{
  FuncState fs;
  FuncScope bl;
  GCproto *pt;
  lua_State *L = ls->L;
#ifdef LUAJIT_DISABLE_DEBUGINFO
  ls->chunkname = lj_str_newlit(L, "=");
#else
  ls->chunkname = lj_str_newz(L, ls->chunkarg);
#endif
  setstrV(L, L->top, ls->chunkname);  /* Anchor chunkname string. */
  incr_top(L);
  ls->level = 0;
  fs_init(ls, &fs);
  fs.linedefined = 0;
  fs.numparams = 0;
  fs.bcbase = NULL;
  fs.bclim = 0;
  fs.flags |= PROTO_VARARG;  /* Main chunk is always a vararg func. */
  fscope_begin(&fs, &bl, 0);
  bcemit_AD(&fs, BC_FUNCV, 0, 0);  /* Placeholder. */
  lj_lex_next(ls);  /* Read-ahead first token. */
  parse_chunk(ls);
  if (ls->tok != TK_eof)
    err_token(ls, TK_eof);
  pt = fs_finish(ls, ls->linenumber);
  L->top--;  /* Drop chunkname. */
  lj_assertL(fs.prev == NULL && ls->fs == NULL, "mismatched frame nesting");
  lj_assertL(pt->sizeuv == 0, "toplevel proto has upvalues");
  return pt;
}


tarantool / luajit / 6035198545

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