lcode.cpp

/*
** $Id: lcode.c $
** Code generator for Lua
** See Copyright Notice in lua.h
*/

#define lcode_c
#define LUA_CORE

#include "lprefix.h"


#include <cfloat>
#include <climits>
#include <cmath>
#include <cstdlib>

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lgc.h"
#include "llex.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
#include "lstring.h"
#include "ltable.h"
#include "lvm.h"


/* (note that expressions VJMP also have jumps.) */
inline bool hasjumps(const expdesc* e) noexcept {
	return e->getTrueList() != e->getFalseList();
}

/* semantic error */
l_noret LexState::semerror(const char *fmt, ...) {
  const char *msg;
  va_list argp;
  pushvfstring(getLuaState(), argp, fmt, msg);
  getCurrentTokenRef().token = 0;  /* remove "near <token>" from final message */
  syntaxError(msg);
}

/*
** If expression is a numeric constant, fills 'v' with its value
** and returns 1. Otherwise, returns 0.
*/
static int tonumeral (const expdesc *e, TValue *v) {
  if (hasjumps(e))
    return 0;  /* not a numeral */
  switch (e->getKind()) {
    case VKINT:
      if (v) v->setInt(e->getIntValue());
      return 1;
    case VKFLT:
      if (v) v->setFloat(e->getFloatValue());
      return 1;
    default: return 0;
  }
}

/*
** Get the constant value from a constant expression
*/
TValue *FuncState::const2val(const expdesc *e) {
  lua_assert(e->getKind() == VCONST);
  return &getLexState()->getDyndata()->actvar()[e->getInfo()].k;
}

/*
** Return the previous instruction of the current code. If there
** may be a jump target between the current instruction and the
** previous one, return an invalid instruction (to avoid wrong
** optimizations).
*/
Instruction *FuncState::previousinstruction() {
  static const Instruction invalidinstruction = ~(Instruction)0;
  if (getPC() > getLastTarget())
    return &getProto()->getCode()[getPC() - 1];  /* previous instruction */
  else
    return const_cast<Instruction*>(&invalidinstruction);
}

/*
** Gets the destination address of a jump instruction. Used to traverse
** a list of jumps.
*/
int FuncState::getjump(int position) {
  int offset = InstructionView(getProto()->getCode()[position]).sj();
  if (offset == NO_JUMP)  /* point to itself represents end of list */
    return NO_JUMP;  /* end of list */
  else
    return (position+1)+offset;  /* turn offset into absolute position */
}

/*
** Fix jump instruction at position 'pc' to jump to 'dest'.
** (Jump addresses are relative in Lua)
*/
void FuncState::fixjump(int position, int dest) {
  Instruction *jmp = &getProto()->getCode()[position];
  int offset = dest - (position + 1);
  lua_assert(dest != NO_JUMP);
  if (!(-OFFSET_sJ <= offset && offset <= MAXARG_sJ - OFFSET_sJ))
    getLexState()->syntaxError("control structure too long");
  lua_assert(InstructionView(*jmp).opcode() == OP_JMP);
  SETARG_sJ(*jmp, offset);
}

/*
** Code a "conditional jump", that is, a test or comparison opcode
** followed by a jump. Return jump position.
*/
int FuncState::condjump(OpCode o, int A, int B, int C, int k) {
  codeABCk(o, A, B, C, k);
  return jump();
}

/*
** Returns the position of the instruction "controlling" a given
** jump (that is, its condition), or the jump itself if it is
** unconditional.
*/
Instruction *FuncState::getjumpcontrol(int position) {
  Instruction *pi = &getProto()->getCode()[position];
  if (position >= 1 && InstructionView(*(pi-1)).testTMode())
    return pi-1;
  else
    return pi;
}

/*
** Patch destination register for a TESTSET instruction.
** If instruction in position 'node' is not a TESTSET, return 0 ("fails").
** Otherwise, if 'reg' is not 'NO_REG', set it as the destination
** register. Otherwise, change instruction to a simple 'TEST' (produces
** no register value)
*/
int FuncState::patchtestreg(int node, int reg) {
  Instruction *i = getjumpcontrol(node);
  if (InstructionView(*i).opcode() != OP_TESTSET)
    return 0;  /* cannot patch other instructions */
  if (reg != NO_REG && reg != InstructionView(*i).b())
    SETARG_A(*i, static_cast<unsigned int>(reg));
  else {
     /* no register to put value or register already has the value;
        change instruction to simple test */
    *i = CREATE_ABCk(OP_TEST, InstructionView(*i).b(), 0, 0, InstructionView(*i).k());
  }
  return 1;
}

/*
** Traverse a list of tests ensuring no one produces a value
*/
int FuncState::removevalues(int list) {
  for (; list != NO_JUMP; list = getjump(list))
      patchtestreg(list, NO_REG);
  return list;
}

/*
** Traverse a list of tests, patching their destination address and
** registers: tests producing values jump to 'vtarget' (and put their
** values in 'reg'), other tests jump to 'dtarget'.
*/
void FuncState::patchlistaux(int list, int vtarget, int reg, int dtarget) {
  while (list != NO_JUMP) {
    int next = getjump(list);
    if (patchtestreg(list, reg))
      fixjump(list, vtarget);
    else
      fixjump(list, dtarget);  /* jump to default target */
    list = next;
  }
}

/* limit for difference between lines in relative line info. */
#define LIMLINEDIFF	0x80

/*
** Save line info for a new instruction. If difference from last line
** does not fit in a byte, of after that many instructions, save a new
** absolute line info; (in that case, the special value 'ABSLINEINFO'
** in 'lineinfo' signals the existence of this absolute information.)
** Otherwise, store the difference from last line in 'lineinfo'.
*/
void FuncState::savelineinfo(Proto *proto, int line) {
  int linedif = line - getPreviousLine();
  int pcval = getPC() - 1;  /* last instruction coded */
  if (abs(linedif) >= LIMLINEDIFF || postIncrementInstructionsWithAbs() >= MAXIWTHABS) {
    luaM_growvector(getLexState()->getLuaState(), proto->getAbsLineInfoRef(), getNAbsLineInfo(),
                    proto->getAbsLineInfoSizeRef(), AbsLineInfo, std::numeric_limits<int>::max(), "lines");
    proto->getAbsLineInfo()[getNAbsLineInfo()].setPC(pcval);
    proto->getAbsLineInfo()[postIncrementNAbsLineInfo()].setLine(line);
    linedif = ABSLINEINFO;  /* signal that there is absolute information */
    setInstructionsWithAbs(1);  /* restart counter */
  }
  luaM_growvector(getLexState()->getLuaState(), proto->getLineInfoRef(), pcval, proto->getLineInfoSizeRef(), ls_byte,
                  std::numeric_limits<int>::max(), "opcodes");
  proto->getLineInfo()[pcval] = static_cast<ls_byte>(linedif);
  setPreviousLine(line);  /* last line saved */
}

/*
** Remove line information from the last instruction.
** If line information for that instruction is absolute, set 'iwthabs'
** above its max to force the new (replacing) instruction to have
** absolute line info, too.
*/
void FuncState::removelastlineinfo() {
  Proto *proto = getProto();
  int pcval = getPC() - 1;  /* last instruction coded */
  if (proto->getLineInfo()[pcval] != ABSLINEINFO) {  /* relative line info? */
    setPreviousLine(getPreviousLine() - proto->getLineInfo()[pcval]);  /* correct last line saved */
    decrementInstructionsWithAbs();  /* undo previous increment */
  }
  else {  /* absolute line information */
    lua_assert(proto->getAbsLineInfo()[getNAbsLineInfo() - 1].getPC() == pcval);
    decrementNAbsLineInfo();  /* remove it */
    setInstructionsWithAbs(MAXIWTHABS + 1);  /* force next line info to be absolute */
  }
}

/*
** Remove the last instruction created, correcting line information
** accordingly.
*/
void FuncState::removelastinstruction() {
  removelastlineinfo();
  decrementPC();
}

/*
** Format and emit an 'iAsBx' instruction.
*/
int FuncState::codeAsBx(OpCode o, int A, int Bc) {
  int b = Bc + OFFSET_sBx;
  lua_assert(getOpMode(o) == OpMode::iAsBx);
  lua_assert(A <= MAXARG_A && b <= MAXARG_Bx);
  return code(CREATE_ABx(o, A, b));
}

/*
** Emit an "extra argument" instruction (format 'iAx')
*/
int FuncState::codeextraarg(int A) {
  lua_assert(A <= MAXARG_Ax);
  return code(CREATE_Ax(OP_EXTRAARG, A));
}

/*
** Emit a "load constant" instruction, using either 'OP_LOADK'
** (if constant index 'k' fits in 18 bits) or an 'OP_LOADKX'
** instruction with "extra argument".
*/
int FuncState::codek(int reg, int k) {
  if (k <= MAXARG_Bx)
    return codeABx(OP_LOADK, reg, k);
  else {
    int p = codeABx(OP_LOADKX, reg, 0);
    codeextraarg(k);
    return p;
  }
}

/*
** Free register 'reg', if it is neither a constant index nor
** a local variable.
)
*/
void FuncState::freeRegister(int reg) {
  if (reg >= luaY_nvarstack(this)) {
    decrementFreeReg();
    lua_assert(reg == getFreeReg());
  }
}

/*
** Free two registers in proper order
*/
void FuncState::freeRegisters(int r1, int r2) {
  if (r1 > r2) {
    freeRegister(r1);
    freeRegister(r2);
  }
  else {
    freeRegister(r2);
    freeRegister(r1);
  }
}

/*
** Free register used by expression 'e' (if any)
*/
void FuncState::freeExpression(expdesc *e) {
  if (e->getKind() == VNONRELOC)
    freeRegister(e->getInfo());
}

/*
** Free registers used by expressions 'e1' and 'e2' (if any) in proper
** order.
*/
void FuncState::freeExpressions(expdesc *e1, expdesc *e2) {
  int r1 = (e1->getKind() == VNONRELOC) ? e1->getInfo() : -1;
  int r2 = (e2->getKind() == VNONRELOC) ? e2->getInfo() : -1;
  freeRegisters(r1, r2);
}

/*
** Add constant 'v' to prototype's list of constants (field 'k').
*/
int FuncState::addk(Proto *proto, TValue *v) {
  lua_State *L = getLexState()->getLuaState();
  int oldsize = proto->getConstantsSize();
  int k = getNK();
  luaM_growvector(L, proto->getConstantsRef(), k, proto->getConstantsSizeRef(), TValue, MAXARG_Ax, "constants");
  auto constantsSpan = proto->getConstantsSpan();
  while (oldsize < static_cast<int>(constantsSpan.size()))
    setnilvalue(&constantsSpan[oldsize++]);
  constantsSpan[k] = *v;
  incrementNK();
  luaC_barrier(L, proto, v);
  return k;
}

/*
** Use scanner's table to cache position of constants in constant list
** and try to reuse constants. Because some values should not be used
** as keys (nil cannot be a key, integer keys can collapse with float
** keys), the caller must provide a useful 'key' for indexing the cache.
*/
int FuncState::k2proto(TValue *key, TValue *v) {
  TValue val;
  Proto *proto = getProto();
  LuaT tag = luaH_get(getKCache(), key, &val);  /* query scanner table */
  if (!tagisempty(tag)) {  /* is there an index there? */
    int k = cast_int(ivalue(&val));
    /* collisions can happen only for float keys */
    lua_assert(ttisfloat(key) || luaV_rawequalobj(&proto->getConstants()[k], v));
    return k;  /* reuse index */
  }
  else {  /* constant not found; create a new entry */
    int k = addk(proto, v);
    /* cache it for reuse; numerical value does not need GC barrier;
       table is not a metatable, so it does not need to invalidate cache */
    val.setInt(k);
    luaH_set(getLexState()->getLuaState(), getKCache(), key, &val);
    return k;
  }
}

/*
** Add a string to list of constants and return its index.
*/
int FuncState::stringK(TString *s) {
  TValue o;
  setsvalue(getLexState()->getLuaState(), &o, s);
  return k2proto(&o, &o);  /* use string itself as key */
}

/*
** Add an integer to list of constants and return its index.
*/
int FuncState::intK(lua_Integer n) {
  TValue o;
  o.setInt(n);
  return k2proto(&o, &o);  /* use integer itself as key */
}

/*
** Add a float to list of constants and return its index. Floats
** with integral values need a different key, to avoid collision
** with actual integers. To that end, we add to the number its smaller
** power-of-two fraction that is still significant in its scale.
** (For doubles, the fraction would be 2^-52).
** This method is not bulletproof: different numbers may generate the
** same key (e.g., very large numbers will overflow to 'inf') and for
** floats larger than 2^53 the result is still an integer. For those
** cases, just generate a new entry. At worst, this only wastes an entry
** with a duplicate.
*/
int FuncState::numberK(lua_Number r) {
  TValue o, kv;
  o.setFloat(r);  /* value as a TValue */
  if (r == 0) {  /* handle zero as a special case */
    setpvalue(&kv, this);  /* use FuncState as index */
    return k2proto(&kv, &o);  /* cannot collide */
  }
  else {
    const int nbm = l_floatatt(MANT_DIG);
    const lua_Number q = l_mathop(ldexp)(l_mathop(1.0), -nbm + 1);
    const lua_Number k =  r * (1 + q);  /* key */
    lua_Integer ik;
    kv.setFloat(k);  /* key as a TValue */
    if (!luaV_flttointeger(k, &ik, F2Imod::F2Ieq)) {  /* not an integer value? */
      int n = k2proto(&kv, &o);  /* use key */
      if (luaV_rawequalobj(&getProto()->getConstants()[n], &o))  /* correct value? */
        return n;
    }
    /* else, either key is still an integer or there was a collision;
       anyway, do not try to reuse constant; instead, create a new one */
    return addk(getProto(), &o);
  }
}

/*
** Add a false to list of constants and return its index.
*/
int FuncState::boolF() {
  TValue o;
  setbfvalue(&o);
  return k2proto(&o, &o);  /* use boolean itself as key */
}

/*
** Add a true to list of constants and return its index.
*/
int FuncState::boolT() {
  TValue o;
  setbtvalue(&o);
  return k2proto(&o, &o);  /* use boolean itself as key */
}

/*
** Add nil to list of constants and return its index.
*/
int FuncState::nilK() {
  TValue k, v;
  setnilvalue(&v);
  /* cannot use nil as key; instead use table itself */
  sethvalue(getLexState()->getLuaState(), &k, getKCache());
  return k2proto(&k, &v);
}

/*
** Check whether 'i' can be stored in an 'sC' operand. Equivalent to
** (0 <= int2sC(i) && int2sC(i) <= MAXARG_C) but without risk of
** overflows in the hidden addition inside 'int2sC'.
*/
static int fitsC (lua_Integer i) {
  return (l_castS2U(i) + OFFSET_sC <= cast_uint(MAXARG_C));
}

/*
** Check whether 'i' can be stored in an 'sBx' operand.
*/
static int fitsBx (lua_Integer i) {
  return (-OFFSET_sBx <= i && i <= MAXARG_Bx - OFFSET_sBx);
}

void FuncState::floatCode(int reg, lua_Number flt) {
  lua_Integer fi;
  if (luaV_flttointeger(flt, &fi, F2Imod::F2Ieq) && fitsBx(fi))
    codeAsBx(OP_LOADF, reg, cast_int(fi));
  else
    codek(reg, numberK(flt));
}

/*
** Convert a constant in 'v' into an expression description 'e'
*/
static void const2exp (TValue *v, expdesc *e) {
  switch (ttypetag(v)) {
    case LuaT::NUMINT:
      e->setKind(VKINT); e->setIntValue(ivalue(v));
      break;
    case LuaT::NUMFLT:
      e->setKind(VKFLT); e->setFloatValue(fltvalue(v));
      break;
    case LuaT::VFALSE:
      e->setKind(VFALSE);
      break;
    case LuaT::VTRUE:
      e->setKind(VTRUE);
      break;
    case LuaT::NIL:
      e->setKind(VNIL);
      break;
    case LuaT::SHRSTR:  case LuaT::LNGSTR:
      e->setKind(VKSTR); e->setStringValue(tsvalue(v));
      break;
    default: lua_assert(0);
  }
}

/*
** Convert a VKSTR to a VK
*/
int FuncState::str2K(expdesc *e) {
  lua_assert(e->getKind() == VKSTR);
  e->setInfo(stringK(e->getStringValue()));
  e->setKind(VK);
  return e->getInfo();
}

/*
** Ensure expression value is in register 'reg', making 'e' a
** non-relocatable expression.
** (Expression still may have jump lists.)
*/
void FuncState::discharge2reg(expdesc *e, int reg) {
  dischargevars(e);
  switch (e->getKind()) {
    case VNIL: {
      nil(reg, 1);
      break;
    }
    case VFALSE: {
      codeABC(OP_LOADFALSE, reg, 0, 0);
      break;
    }
    case VTRUE: {
      codeABC(OP_LOADTRUE, reg, 0, 0);
      break;
    }
    case VKSTR: {
      str2K(e);
    }  /* FALLTHROUGH */
    case VK: {
      codek(reg, e->getInfo());
      break;
    }
    case VKFLT: {
      floatCode(reg, e->getFloatValue());
      break;
    }
    case VKINT: {
      intCode(reg, e->getIntValue());
      break;
    }
    case VRELOC: {
      Instruction *instr = &getinstruction(this, e);
      SETARG_A(*instr, static_cast<unsigned int>(reg));  /* instruction will put result in 'reg' */
      break;
    }
    case VNONRELOC: {
      if (reg != e->getInfo())
        codeABC(OP_MOVE, reg, e->getInfo(), 0);
      break;
    }
    default: {
      lua_assert(e->getKind() == VJMP);
      return;  /* nothing to do... */
    }
  }
  e->setInfo(reg);
  e->setKind(VNONRELOC);
}

/*
** Ensure expression value is in a register, making 'e' a
** non-relocatable expression.
** (Expression still may have jump lists.)
*/
void FuncState::discharge2anyreg(expdesc *e) {
  if (e->getKind() != VNONRELOC) {  /* no fixed register yet? */
    reserveregs(1);  /* get a register */
    discharge2reg(e, getFreeReg()-1);  /* put value there */
  }
}

int FuncState::code_loadbool(int A, OpCode op) {
  getlabel();  /* those instructions may be jump targets */
  return codeABC(op, A, 0, 0);
}

/*
** check whether list has any jump that do not produce a value
** or produce an inverted value
*/
int FuncState::need_value(int list) {
  for (; list != NO_JUMP; list = getjump(list)) {
    Instruction i = *getjumpcontrol(list);
    if (InstructionView(i).opcode() != OP_TESTSET) return 1;
  }
  return 0;  /* not found */
}

/*
** Ensures final expression result (which includes results from its
** jump lists) is in register 'reg'.
** If expression has jumps, need to patch these jumps either to
** its final position or to "load" instructions (for those tests
** that do not produce values).
*/
void FuncState::exp2reg(expdesc *e, int reg) {
  discharge2reg(e, reg);
  if (e->getKind() == VJMP)  /* expression itself is a test? */
    concat(e->getTrueListRef(), e->getInfo());  /* put this jump in 't' list */
  if (hasjumps(e)) {
    int p_f = NO_JUMP;  /* position of an eventual LOAD false */
    int p_t = NO_JUMP;  /* position of an eventual LOAD true */
    if (need_value(e->getTrueList()) || need_value(e->getFalseList())) {
      int fj = (e->getKind() == VJMP) ? NO_JUMP : jump();
      p_f = code_loadbool(reg, OP_LFALSESKIP);  /* skip next inst. */
      p_t = code_loadbool(reg, OP_LOADTRUE);
      /* jump around these booleans if 'e' is not a test */
      patchtohere(fj);
    }
    int final = getlabel();  /* position after whole expression */
    patchlistaux(e->getFalseList(), final, reg, p_f);
    patchlistaux(e->getTrueList(), final, reg, p_t);
  }
  e->setFalseList(NO_JUMP); e->setTrueList(NO_JUMP);
  e->setInfo(reg);
  e->setKind(VNONRELOC);
}

/*
** Try to make 'e' a K expression with an index in the range of R/K
** indices. Return true iff succeeded.
*/
int FuncState::exp2K(expdesc *e) {
  if (!hasjumps(e)) {
    int info;
    switch (e->getKind()) {  /* move constants to 'k' */
      case VTRUE: info = boolT(); break;
      case VFALSE: info = boolF(); break;
      case VNIL: info = nilK(); break;
      case VKINT: info = intK(e->getIntValue()); break;
      case VKFLT: info = numberK(e->getFloatValue()); break;
      case VKSTR: info = stringK(e->getStringValue()); break;
      case VK: info = e->getInfo(); break;
      default: return 0;  /* not a constant */
    }
    if (info <= MAXINDEXRK) {  /* does constant fit in 'argC'? */
      e->setKind(VK);  /* make expression a 'K' expression */
      e->setInfo(info);
      return 1;
    }
  }
  /* else, expression doesn't fit; leave it unchanged */
  return 0;
}

/*
** Ensures final expression result is in a valid R/K index
** (that is, it is either in a register or in 'k' with an index
** in the range of R/K indices).
** Returns 1 iff expression is K.
*/
int FuncState::exp2RK(expdesc *e) {
  if (exp2K(e))
    return 1;
  else {  /* not a constant in the right range: put it in a register */
    exp2anyreg(e);
    return 0;
  }
}

void FuncState::codeABRK(OpCode o, int A, int B, expdesc *ec) {
  int k = exp2RK(ec);
  codeABCk(o, A, B, ec->getInfo(), k);
}

/*
** Negate condition 'e' (where 'e' is a comparison).
*/
void FuncState::negatecondition(expdesc *e) {
  Instruction *instr = getjumpcontrol(e->getInfo());
  InstructionView view(*instr);
  lua_assert(view.testTMode() && view.opcode() != OP_TESTSET &&
                                  view.opcode() != OP_TEST);
  SETARG_k(*instr, static_cast<unsigned int>(view.k() ^ 1));
}

/*
** Emit instruction to jump if 'e' is 'cond' (that is, if 'cond'
** is true, code will jump if 'e' is true.) Return jump position.
** Optimize when 'e' is 'not' something, inverting the condition
** and removing the 'not'.
*/
int FuncState::jumponcond(expdesc *e, int cond) {
  if (e->getKind() == VRELOC) {
    Instruction ie = getinstruction(this, e);
    if (InstructionView(ie).opcode() == OP_NOT) {
      removelastinstruction();  /* remove previous OP_NOT */
      return condjump(OP_TEST, InstructionView(ie).b(), 0, 0, !cond);
    }
    /* else go through */
  }
  discharge2anyreg(e);
  freeExpression(e);
  return condjump(OP_TESTSET, NO_REG, e->getInfo(), 0, cond);
}

/*
** Code 'not e', doing constant folding.
*/
void FuncState::codenot(expdesc *e) {
  switch (e->getKind()) {
    case VNIL: case VFALSE: {
      e->setKind(VTRUE);  /* true == not nil == not false */
      break;
    }
    case VK: case VKFLT: case VKINT: case VKSTR: case VTRUE: {
      e->setKind(VFALSE);  /* false == not "x" == not 0.5 == not 1 == not true */
      break;
    }
    case VJMP: {
      negatecondition(e);
      break;
    }
    case VRELOC:
    case VNONRELOC: {
      discharge2anyreg(e);
      freeExpression(e);
      e->setInfo(codeABC(OP_NOT, 0, e->getInfo(), 0));
      e->setKind(VRELOC);
      break;
    }
    default: lua_assert(0);  /* cannot happen */
  }
  /* interchange true and false lists */
  { int temp = e->getFalseList(); e->setFalseList(e->getTrueList()); e->setTrueList(temp); }
  removevalues(e->getFalseList());  /* values are useless when negated */
  removevalues(e->getTrueList());
}

/*
** Check whether expression 'e' is a short literal string
*/
int FuncState::isKstr(expdesc *e) {
  return (e->getKind() == VK && !hasjumps(e) && e->getInfo() <= MAXARG_B &&
          ttisshrstring(&getProto()->getConstants()[e->getInfo()]));
}

/*
** Check whether expression 'e' is a literal integer.
*/
static bool isKint (expdesc *e) {
  return (e->getKind() == VKINT && !hasjumps(e));
}

/*
** Check whether expression 'e' is a literal integer in
** proper range to fit in register C
*/
static bool isCint (expdesc *e) {
  return isKint(e) && (l_castS2U(e->getIntValue()) <= l_castS2U(MAXARG_C));
}

/*
** Check whether expression 'e' is a literal integer in
** proper range to fit in register sC
*/
static bool isSCint (expdesc *e) {
  return isKint(e) && fitsC(e->getIntValue());
}

/*
** Check whether expression 'e' is a literal integer or float in
** proper range to fit in a register (sB or sC).
*/
static bool isSCnumber (expdesc *e, int *pi, int *isfloat) {
  lua_Integer i;
  if (e->getKind() == VKINT)
    i = e->getIntValue();
  else if (e->getKind() == VKFLT && luaV_flttointeger(e->getFloatValue(), &i, F2Imod::F2Ieq))
    *isfloat = 1;
  else
    return false;  /* not a number */
  if (!hasjumps(e) && fitsC(i)) {
    *pi = int2sC(cast_int(i));
    return true;
  }
  else
    return false;
}

/*
** Return false if folding can raise an error.
** Bitwise operations need operands convertible to integers; division
** operations cannot have 0 as divisor.
*/
static bool validop (int op, TValue *v1, TValue *v2) {
  switch (op) {
    case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
    case LUA_OPSHL: case LUA_OPSHR: case LUA_OPBNOT: {  /* conversion errors */
      lua_Integer i;
      return (luaV_tointegerns(v1, &i, LUA_FLOORN2I) &&
              luaV_tointegerns(v2, &i, LUA_FLOORN2I));
    }
    case LUA_OPDIV: case LUA_OPIDIV: case LUA_OPMOD:  /* division by 0 */
      return (nvalue(v2) != 0);
    default: return true;  /* everything else is valid */
  }
}

/*
** Try to "constant-fold" an operation; return 1 iff successful.
** (In this case, 'e1' has the final result.)
*/
int FuncState::constfolding(int op, expdesc *e1, const expdesc *e2) {
  TValue v1, v2, res;
  if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2) || !validop(op, &v1, &v2))
    return 0;  /* non-numeric operands or not safe to fold */
  if (!luaO_rawarith(getLexState()->getLuaState(), op, &v1, &v2, &res))
    return 0;  /* operation failed */
  if (ttisinteger(&res)) {
    e1->setKind(VKINT);
    e1->setIntValue(ivalue(&res));
  }
  else {  /* folds neither NaN nor 0.0 (to avoid problems with -0.0) */
    lua_Number n = fltvalue(&res);
    if (luai_numisnan(n) || n == 0)
      return 0;
    e1->setKind(VKFLT);
    e1->setFloatValue(n);
  }
  return 1;
}

/*
** Convert a BinOpr to an OpCode  (ORDER OPR - ORDER OP)
*/
static inline OpCode binopr2op (BinOpr opr, BinOpr baser, OpCode base) {
  lua_assert(baser <= opr &&
            ((baser == BinOpr::OPR_ADD && opr <= BinOpr::OPR_SHR) ||
             (baser == BinOpr::OPR_LT && opr <= BinOpr::OPR_LE)));
  return static_cast<OpCode>((cast_int(opr) - cast_int(baser)) + cast_int(base));
}

/*
** Convert a UnOpr to an OpCode  (ORDER OPR - ORDER OP)
*/
static inline OpCode unopr2op (UnOpr opr) {
  return static_cast<OpCode>((cast_int(opr) - cast_int(UnOpr::OPR_MINUS)) +
                                       cast_int(OP_UNM));
}

/*
** Convert a BinOpr to a tag method  (ORDER OPR - ORDER TM)
*/
static inline TMS binopr2TM (BinOpr opr) {
  lua_assert(BinOpr::OPR_ADD <= opr && opr <= BinOpr::OPR_SHR);
  return static_cast<TMS>((cast_int(opr) - cast_int(BinOpr::OPR_ADD)) + cast_int(TMS::TM_ADD));
}

/*
** Emit code for unary expressions that "produce values"
** (everything but 'not').
** Expression to produce final result will be encoded in 'e'.
*/
void FuncState::codeunexpval(OpCode op, expdesc *e, int line) {
  int r = exp2anyreg(e);  /* opcodes operate only on registers */
  freeExpression(e);
  e->setInfo(codeABC(op, 0, r, 0));  /* generate opcode */
  e->setKind(VRELOC);  /* all those operations are relocatable */
  fixline(line);
}

/*
** Emit code for binary expressions that "produce values"
** (everything but logical operators 'and'/'or' and comparison
** operators).
** Expression to produce final result will be encoded in 'e1'.
*/
void FuncState::finishbinexpval(expdesc *e1, expdesc *e2, OpCode op, int v2,
                                 int flip, int line, OpCode mmop, TMS event) {
  int v1 = exp2anyreg(e1);
  int instrPos = codeABCk(op, 0, v1, v2, 0);
  freeExpressions(e1, e2);
  e1->setInfo(instrPos);
  e1->setKind(VRELOC);  /* all those operations are relocatable */
  fixline(line);
  codeABCk(mmop, v1, v2, cast_int(event), flip);  /* metamethod */
  fixline(line);
}

/*
** Emit code for binary expressions that "produce values" over
** two registers.
*/
void FuncState::codebinexpval(BinOpr opr, expdesc *e1, expdesc *e2, int line) {
  OpCode op = binopr2op(opr, BinOpr::OPR_ADD, OP_ADD);
  int v2 = exp2anyreg(e2);  /* make sure 'e2' is in a register */
  /* 'e1' must be already in a register or it is a constant */
  lua_assert((VNIL <= e1->getKind() && e1->getKind() <= VKSTR) ||
             e1->getKind() == VNONRELOC || e1->getKind() == VRELOC);
  lua_assert(OP_ADD <= op && op <= OP_SHR);
  finishbinexpval(e1, e2, op, v2, 0, line, OP_MMBIN, binopr2TM(opr));
}

/*
** Code binary operators with immediate operands.
*/
void FuncState::codebini(OpCode op, expdesc *e1, expdesc *e2, int flip,
                          int line, TMS event) {
  int v2 = int2sC(cast_int(e2->getIntValue()));  /* immediate operand */
  lua_assert(e2->getKind() == VKINT);
  finishbinexpval(e1, e2, op, v2, flip, line, OP_MMBINI, event);
}

/*
** Code binary operators with K operand.
*/
void FuncState::codebinK(BinOpr opr, expdesc *e1, expdesc *e2, int flip, int line) {
  TMS event = binopr2TM(opr);
  int v2 = e2->getInfo();  /* K index */
  OpCode op = binopr2op(opr, BinOpr::OPR_ADD, OP_ADDK);
  finishbinexpval(e1, e2, op, v2, flip, line, OP_MMBINK, event);
}

/* Try to code a binary operator negating its second operand.
** For the metamethod, 2nd operand must keep its original value.
*/
int FuncState::finishbinexpneg(expdesc *e1, expdesc *e2, OpCode op, int line, TMS event) {
  if (!isKint(e2))
    return 0;  /* not an integer constant */
  else {
    lua_Integer i2 = e2->getIntValue();
    if (!(fitsC(i2) && fitsC(-i2)))
      return 0;  /* not in the proper range */
    else {  /* operating a small integer constant */
      int v2 = cast_int(i2);
      finishbinexpval(e1, e2, op, int2sC(-v2), 0, line, OP_MMBINI, event);
      /* correct metamethod argument */
      SETARG_B(getProto()->getCode()[getPC() - 1], static_cast<unsigned int>(int2sC(v2)));
      return 1;  /* successfully coded */
    }
  }
}

static void swapexps (expdesc *e1, expdesc *e2) {
  expdesc temp = *e1; *e1 = *e2; *e2 = temp;  /* swap 'e1' and 'e2' */
}

/*
** Code binary operators with no constant operand.
*/
void FuncState::codebinNoK(BinOpr opr, expdesc *e1, expdesc *e2, int flip, int line) {
  if (flip)
    swapexps(e1, e2);  /* back to original order */
  codebinexpval(opr, e1, e2, line);  /* use standard operators */
}

/*
** Code arithmetic operators ('+', '-', ...). If second operand is a
** constant in the proper range, use variant opcodes with K operands.
*/
void FuncState::codearith(BinOpr opr, expdesc *e1, expdesc *e2, int flip, int line) {
  if (tonumeral(e2, nullptr) && exp2K(e2))  /* K operand? */
    codebinK(opr, e1, e2, flip, line);
  else  /* 'e2' is neither an immediate nor a K operand */
    codebinNoK(opr, e1, e2, flip, line);
}

/*
** Code commutative operators ('+', '*'). If first operand is a
** numeric constant, change order of operands to try to use an
** immediate or K operator.
*/
void FuncState::codecommutative(BinOpr op, expdesc *e1, expdesc *e2, int line) {
  int flip = 0;
  if (tonumeral(e1, nullptr)) {  /* is first operand a numeric constant? */
    swapexps(e1, e2);  /* change order */
    flip = 1;
  }
  if (op == BinOpr::OPR_ADD && isSCint(e2))  /* immediate operand? */
    codebini(OP_ADDI, e1, e2, flip, line, TMS::TM_ADD);
  else
    codearith(op, e1, e2, flip, line);
}

/*
** Code bitwise operations; they are all commutative, so the function
** tries to put an integer constant as the 2nd operand (a K operand).
*/
void FuncState::codebitwise(BinOpr opr, expdesc *e1, expdesc *e2, int line) {
  int flip = 0;
  if (e1->getKind() == VKINT) {
    swapexps(e1, e2);  /* 'e2' will be the constant operand */
    flip = 1;
  }
  if (e2->getKind() == VKINT && exp2K(e2))  /* K operand? */
    codebinK(opr, e1, e2, flip, line);
  else  /* no constants */
    codebinNoK(opr, e1, e2, flip, line);
}

/*
** Emit code for order comparisons. When using an immediate operand,
** 'isfloat' tells whether the original value was a float.
*/
void FuncState::codeorder(BinOpr opr, expdesc *e1, expdesc *e2) {
  int r1, r2;
  int im;
  int isfloat = 0;
  OpCode op;
  if (isSCnumber(e2, &im, &isfloat)) {
    /* use immediate operand */
    r1 = exp2anyreg(e1);
    r2 = im;
    op = binopr2op(opr, BinOpr::OPR_LT, OP_LTI);
  }
  else if (isSCnumber(e1, &im, &isfloat)) {
    /* transform (A < B) to (B > A) and (A <= B) to (B >= A) */
    r1 = exp2anyreg(e2);
    r2 = im;
    op = binopr2op(opr, BinOpr::OPR_LT, OP_GTI);
  }
  else {  /* regular case, compare two registers */
    r1 = exp2anyreg(e1);
    r2 = exp2anyreg(e2);
    op = binopr2op(opr, BinOpr::OPR_LT, OP_LT);
  }
  freeExpressions(e1, e2);
  e1->setInfo(condjump(op, r1, r2, isfloat, 1));
  e1->setKind(VJMP);
}

/*
** Emit code for equality comparisons ('==', '~=').
** 'e1' was already put as RK by 'luaK_infix'.
*/
void FuncState::codeeq(BinOpr opr, expdesc *e1, expdesc *e2) {
  int r1, r2;
  int im;
  int isfloat = 0;  /* not needed here, but kept for symmetry */
  OpCode op;
  if (e1->getKind() != VNONRELOC) {
    lua_assert(e1->getKind() == VK || e1->getKind() == VKINT || e1->getKind() == VKFLT);
    swapexps(e1, e2);
  }
  r1 = exp2anyreg(e1);  /* 1st expression must be in register */
  if (isSCnumber(e2, &im, &isfloat)) {
    op = OP_EQI;
    r2 = im;  /* immediate operand */
  }
  else if (exp2RK(e2)) {  /* 2nd expression is constant? */
    op = OP_EQK;
    r2 = e2->getInfo();  /* constant index */
  }
  else {
    op = OP_EQ;  /* will compare two registers */
    r2 = exp2anyreg(e2);
  }
  freeExpressions(e1, e2);
  e1->setInfo(condjump(op, r1, r2, isfloat, (opr == BinOpr::OPR_EQ)));
  e1->setKind(VJMP);
}

/*
** Create code for '(e1 .. e2)'.
** For '(e1 .. e2.1 .. e2.2)' (which is '(e1 .. (e2.1 .. e2.2))',
** because concatenation is right associative), merge both CONCATs.
*/
void FuncState::codeconcat(expdesc *e1, expdesc *e2, int line) {
  Instruction *ie2 = previousinstruction();
  if (InstructionView(*ie2).opcode() == OP_CONCAT) {  /* is 'e2' a concatenation? */
    int n = InstructionView(*ie2).b();  /* # of elements concatenated in 'e2' */
    lua_assert(e1->getInfo() + 1 == InstructionView(*ie2).a());
    freeExpression(e2);
    SETARG_A(*ie2, static_cast<unsigned int>(e1->getInfo()));  /* correct first element ('e1') */
    SETARG_B(*ie2, static_cast<unsigned int>(n + 1));  /* will concatenate one more element */
  }
  else {  /* 'e2' is not a concatenation */
    codeABC(OP_CONCAT, e1->getInfo(), 2, 0);  /* new concat opcode */
    freeExpression(e2);
    fixline(line);
  }
}

/*
** return the final target of a jump (skipping jumps to jumps)
*/
int FuncState::finaltarget(int i) {
  auto codeSpan = getProto()->getCodeSpan();
  for (int count = 0; count < 100; count++) {  /* avoid infinite loops */
    Instruction instr = codeSpan[i];
    if (InstructionView(instr).opcode() != OP_JMP)
      break;
    else
      i += InstructionView(instr).sj() + 1;
  }
  return i;
}

/*
** =====================================================================
** FuncState Method Implementations (Phase 27c)
** Simple wrappers that forward to existing luaK_* functions
** =====================================================================
*/

int FuncState::code(Instruction i) {
  Proto *proto = getProto();
  /* put new instruction in code array */
  luaM_growvector(getLexState()->getLuaState(), proto->getCodeRef(), getPC(), proto->getCodeSizeRef(), Instruction,
                  std::numeric_limits<int>::max(), "opcodes");
  proto->getCode()[postIncrementPC()] = i;
  savelineinfo(proto, getLexState()->getLastLine());
  return getPC() - 1;  /* index of new instruction */
}

int FuncState::codeABx(int o, int A, int Bx) {
  OpCode op = static_cast<OpCode>(o);
  lua_assert(getOpMode(op) == OpMode::iABx);
  lua_assert(A <= MAXARG_A && Bx <= MAXARG_Bx);
  return code(CREATE_ABx(op, A, Bx));
}

int FuncState::codeABCk(int o, int A, int B, int C, int k) {
  OpCode op = static_cast<OpCode>(o);
  lua_assert(getOpMode(op) == OpMode::iABC);
  lua_assert(A <= MAXARG_A && B <= MAXARG_B &&
             C <= MAXARG_C && (k & ~1) == 0);
  return code(CREATE_ABCk(op, A, B, C, k));
}

int FuncState::codevABCk(int o, int A, int B, int C, int k) {
  OpCode op = static_cast<OpCode>(o);
  lua_assert(getOpMode(op) == OpMode::ivABC);
  lua_assert(A <= MAXARG_A && B <= MAXARG_vB &&
             C <= MAXARG_vC && (k & ~1) == 0);
  return code(CREATE_vABCk(op, A, B, C, k));
}

int FuncState::codesJ(int o, int sj, int k) {
  int j = sj + OFFSET_sJ;
  lua_assert(getOpMode(static_cast<OpCode>(o)) == OpMode::isJ);
  lua_assert(j <= MAXARG_sJ && (k & ~1) == 0);
  return code(CREATE_sJ(static_cast<OpCode>(o), j, k));
}

int FuncState::exp2const(const expdesc *e, TValue *v) {
  if (hasjumps(e))
    return 0;  /* not a constant */
  switch (e->getKind()) {
    case VFALSE:
      setbfvalue(v);
      return 1;
    case VTRUE:
      setbtvalue(v);
      return 1;
    case VNIL:
      setnilvalue(v);
      return 1;
    case VKSTR: {
      setsvalue(getLexState()->getLuaState(), v, e->getStringValue());
      return 1;
    }
    case VCONST: {
      *v = *const2val(e);
      return 1;
    }
    default: return tonumeral(e, v);
  }
}

void FuncState::fixline(int line) {
  removelastlineinfo();
  savelineinfo(getProto(), line);
}

void FuncState::nil(int from, int n) {
  int l = from + n - 1;  /* last register to set nil */
  Instruction *previous = previousinstruction();
  if (InstructionView(*previous).opcode() == OP_LOADNIL) {  /* previous is LOADNIL? */
    int pfrom = InstructionView(*previous).a();  /* get previous range */
    int pl = pfrom + InstructionView(*previous).b();
    if ((pfrom <= from && from <= pl + 1) ||
        (from <= pfrom && pfrom <= l + 1)) {  /* can connect both? */
      if (pfrom < from) from = pfrom;  /* from = min(from, pfrom) */
      if (pl > l) l = pl;  /* l = max(l, pl) */
      SETARG_A(*previous, static_cast<unsigned int>(from));
      SETARG_B(*previous, static_cast<unsigned int>(l - from));
      return;
    }  /* else go through */
  }
  codeABC(OP_LOADNIL, from, n - 1, 0);  /* else no optimization */
}

void FuncState::reserveregs(int n) {
  checkstack(n);
  setFreeReg(cast_byte(getFreeReg() + n));
}

void FuncState::checkstack(int n) {
  int newstack = getFreeReg() + n;
  if (newstack > getProto()->getMaxStackSize()) {
    luaY_checklimit(this, newstack, MAX_FSTACK, "registers");
    getProto()->setMaxStackSize(cast_byte(newstack));
  }
}

void FuncState::intCode(int reg, lua_Integer i) {
  if (fitsBx(i))
    codeAsBx(OP_LOADI, reg, cast_int(i));
  else
    codek(reg, intK(i));
}

void FuncState::dischargevars(expdesc *e) {
  switch (e->getKind()) {
    case VCONST: {
      const2exp(const2val(e), e);
      break;
    }
    case VLOCAL: {  /* already in a register */
      int temp = e->getLocalRegister();
      e->setInfo(temp);  /* (can't do a direct assignment; values overlap) */
      e->setKind(VNONRELOC);  /* becomes a non-relocatable value */
      break;
    }
    case VUPVAL: {  /* move value to some (pending) register */
      e->setInfo(codeABC(OP_GETUPVAL, 0, e->getInfo(), 0));
      e->setKind(VRELOC);
      break;
    }
    case VINDEXUP: {
      e->setInfo(codeABC(OP_GETTABUP, 0, e->getIndexedTableReg(), e->getIndexedKeyIndex()));
      e->setKind(VRELOC);
      break;
    }
    case VINDEXI: {
      freeRegister(e->getIndexedTableReg());
      e->setInfo(codeABC(OP_GETI, 0, e->getIndexedTableReg(), e->getIndexedKeyIndex()));
      e->setKind(VRELOC);
      break;
    }
    case VINDEXSTR: {
      freeRegister(e->getIndexedTableReg());
      e->setInfo(codeABC(OP_GETFIELD, 0, e->getIndexedTableReg(), e->getIndexedKeyIndex()));
      e->setKind(VRELOC);
      break;
    }
    case VINDEXED: {
      freeRegisters(e->getIndexedTableReg(), e->getIndexedKeyIndex());
      e->setInfo(codeABC(OP_GETTABLE, 0, e->getIndexedTableReg(), e->getIndexedKeyIndex()));
      e->setKind(VRELOC);
      break;
    }
    case VVARARG: case VCALL: {
      setoneret(e);
      break;
    }
    default: break;  /* there is one value available (somewhere) */
  }
}

int FuncState::exp2anyreg(expdesc *e) {
  dischargevars(e);
  if (e->getKind() == VNONRELOC) {  /* expression already has a register? */
    if (!hasjumps(e))  /* no jumps? */
      return e->getInfo();  /* result is already in a register */
    if (e->getInfo() >= luaY_nvarstack(this)) {  /* reg. is not a local? */
      exp2reg(e, e->getInfo());  /* put final result in it */
      return e->getInfo();
    }
    /* else expression has jumps and cannot change its register
       to hold the jump values, because it is a local variable.
       Go through to the default case. */
  }
  exp2nextreg(e);  /* default: use next available register */
  return e->getInfo();
}

void FuncState::exp2anyregup(expdesc *e) {
  if (e->getKind() != VUPVAL || hasjumps(e))
    exp2anyreg(e);
}

void FuncState::exp2nextreg(expdesc *e) {
  dischargevars(e);
  freeExpression(e);
  reserveregs(1);
  exp2reg(e, getFreeReg() - 1);
}

void FuncState::exp2val(expdesc *e) {
  if (e->getKind() == VJMP || hasjumps(e))
    exp2anyreg(e);
  else
    dischargevars(e);
}

void FuncState::self(expdesc *e, expdesc *key) {
  exp2anyreg(e);
  int ereg = e->getInfo();  /* register where 'e' (the receiver) was placed */
  freeExpression(e);
  int base = getFreeReg();
  e->setInfo(base);  /* base register for op_self */
  e->setKind(VNONRELOC);  /* self expression has a fixed register */
  reserveregs(2);  /* method and 'self' produced by op_self */
  lua_assert(key->getKind() == VKSTR);
  /* is method name a short string in a valid K index? */
  if (strisshr(key->getStringValue()) && exp2K(key)) {
    /* can use 'self' opcode */
    codeABCk(OP_SELF, base, ereg, key->getInfo(), 0);
  }
  else {  /* cannot use 'self' opcode; use move+gettable */
    exp2anyreg(key);  /* put method name in a register */
    codeABC(OP_MOVE, base + 1, ereg, 0);  /* copy self to base+1 */
    codeABC(OP_GETTABLE, base, ereg, key->getInfo());  /* get method */
  }
  freeExpression(key);
}

void FuncState::indexed(expdesc *t, expdesc *k) {
  int keystr = (k->getKind() == VKSTR) ? str2K(k) : -1;
  lua_assert(!hasjumps(t) &&
             (t->getKind() == VLOCAL || t->getKind() == VNONRELOC || t->getKind() == VUPVAL));
  if (t->getKind() == VUPVAL && !isKstr(k))  /* upvalue indexed by non 'Kstr'? */
    exp2anyreg(t);  /* put it in a register */
  if (t->getKind() == VUPVAL) {
    lu_byte temp = cast_byte(t->getInfo());  /* upvalue index */
    t->setIndexedTableReg(temp);  /* (can't do a direct assignment; values overlap) */
    lua_assert(isKstr(k));
    t->setIndexedKeyIndex(cast_short(k->getInfo()));  /* literal short string */
    t->setKind(VINDEXUP);
  }
  else {
    /* register index of the table */
    t->setIndexedTableReg(cast_byte((t->getKind() == VLOCAL) ? t->getLocalRegister(): t->getInfo()));
    if (isKstr(k)) {
      t->setIndexedKeyIndex(cast_short(k->getInfo()));  /* literal short string */
      t->setKind(VINDEXSTR);
    }
    else if (isCint(k)) {  /* int. constant in proper range? */
      t->setIndexedKeyIndex(cast_short(k->getIntValue()));
      t->setKind(VINDEXI);
    }
    else {
      t->setIndexedKeyIndex(cast_short(exp2anyreg(k)));  /* register */
      t->setKind(VINDEXED);
    }
  }
  t->setIndexedStringKeyIndex(keystr);  /* string index in 'k' */
  t->setIndexedReadOnly(0);  /* by default, not read-only */
}

void FuncState::goiftrue(expdesc *e) {
  dischargevars(e);
  int pcpos;  /* pc of new jump */
  switch (e->getKind()) {
    case VJMP: {  /* condition? */
      negatecondition(e);  /* jump when it is false */
      pcpos = e->getInfo();  /* save jump position */
      break;
    }
    case VK: case VKFLT: case VKINT: case VKSTR: case VTRUE: {
      pcpos = NO_JUMP;  /* always true; do nothing */
      break;
    }
    default: {
      pcpos = jumponcond(e, 0);  /* jump when false */
      break;
    }
  }
  concat(e->getFalseListRef(), pcpos);  /* insert new jump in false list */
  patchtohere(e->getTrueList());  /* true list jumps to here (to go through) */
  e->setTrueList(NO_JUMP);
}

void FuncState::goiffalse(expdesc *e) {
  dischargevars(e);
  int pcpos;  /* pc of new jump */
  switch (e->getKind()) {
    case VJMP: {
      pcpos = e->getInfo();  /* already jump if true */
      break;
    }
    case VNIL: case VFALSE: {
      pcpos = NO_JUMP;  /* always false; do nothing */
      break;
    }
    default: {
      pcpos = jumponcond(e, 1);  /* jump if true */
      break;
    }
  }
  concat(e->getTrueListRef(), pcpos);  /* insert new jump in 't' list */
  patchtohere(e->getFalseList());  /* false list jumps to here (to go through) */
  e->setFalseList(NO_JUMP);
}

void FuncState::storevar(expdesc *var, expdesc *ex) {
  switch (var->getKind()) {
    case VLOCAL: {
      freeExpression(ex);
      exp2reg(ex, var->getLocalRegister());  /* compute 'ex' into proper place */
      return;
    }
    case VUPVAL: {
      int e = exp2anyreg(ex);
      codeABC(OP_SETUPVAL, e, var->getInfo(), 0);
      break;
    }
    case VINDEXUP: {
      codeABRK(OP_SETTABUP, var->getIndexedTableReg(), var->getIndexedKeyIndex(), ex);
      break;
    }
    case VINDEXI: {
      codeABRK(OP_SETI, var->getIndexedTableReg(), var->getIndexedKeyIndex(), ex);
      break;
    }
    case VINDEXSTR: {
      codeABRK(OP_SETFIELD, var->getIndexedTableReg(), var->getIndexedKeyIndex(), ex);
      break;
    }
    case VINDEXED: {
      codeABRK(OP_SETTABLE, var->getIndexedTableReg(), var->getIndexedKeyIndex(), ex);
      break;
    }
    default: lua_assert(0);  /* invalid var kind to store */
  }
  freeExpression(ex);
}

void FuncState::setreturns(expdesc *e, int nresults) {
  Instruction *instr = &getinstruction(this, e);
  luaY_checklimit(this, nresults + 1, MAXARG_C, "multiple results");
  if (e->getKind() == VCALL)  /* expression is an open function call? */
    SETARG_C(*instr, static_cast<unsigned int>(nresults + 1));
  else {
    lua_assert(e->getKind() == VVARARG);
    SETARG_C(*instr, static_cast<unsigned int>(nresults + 1));
    SETARG_A(*instr, static_cast<unsigned int>(getFreeReg()));
    reserveregs(1);
  }
}

void FuncState::setoneret(expdesc *e) {
  if (e->getKind() == VCALL) {  /* expression is an open function call? */
    /* already returns 1 value */
    lua_assert(InstructionView(getinstruction(this, e)).c() == 2);
    e->setKind(VNONRELOC);  /* result has fixed position */
    e->setInfo(InstructionView(getinstruction(this, e)).a());
  }
  else if (e->getKind() == VVARARG) {
    SETARG_C(getinstruction(this, e), 2);
    e->setKind(VRELOC);  /* can relocate its simple result */
  }
}

int FuncState::jump() {
  return codesJ(OP_JMP, NO_JUMP, 0);
}

void FuncState::ret(int first, int nret) {
  OpCode op;
  switch (nret) {
    case 0: op = OP_RETURN0; break;
    case 1: op = OP_RETURN1; break;
    default: op = OP_RETURN; break;
  }
  luaY_checklimit(this, nret + 1, MAXARG_B, "returns");
  codeABC(op, first, nret + 1, 0);
}

void FuncState::patchlist(int list, int target) {
  lua_assert(target <= getPC());
  patchlistaux(list, target, NO_REG, target);
}

void FuncState::patchtohere(int list) {
  int hr = getlabel();  /* mark "here" as a jump target */
  patchlist(list, hr);
}

void FuncState::concat(int *l1, int l2) {
  if (l2 == NO_JUMP) return;  /* nothing to concatenate? */
  else if (*l1 == NO_JUMP)  /* no original list? */
    *l1 = l2;  /* 'l1' points to 'l2' */
  else {
    int list = *l1;
    int next;
    while ((next = getjump(list)) != NO_JUMP)  /* find last element */
      list = next;
    fixjump(list, l2);  /* last element links to 'l2' */
  }
}

int FuncState::getlabel() {
  setLastTarget(getPC());
  return getPC();
}

void FuncState::prefix(UnOpr op, expdesc *e, int line) {
  expdesc ef;
  ef.setKind(VKINT);
  ef.setIntValue(0);
  ef.setFalseList(NO_JUMP);
  ef.setTrueList(NO_JUMP);
  dischargevars(e);
  switch (op) {
    case UnOpr::OPR_MINUS: case UnOpr::OPR_BNOT:  /* use 'ef' as fake 2nd operand */
      if (constfolding(cast_int(op) + LUA_OPUNM, e, &ef))
        break;
      /* else */ /* FALLTHROUGH */
    case UnOpr::OPR_LEN:
      codeunexpval(unopr2op(op), e, line);
      break;
    case UnOpr::OPR_NOT: codenot(e); break;
    default: lua_assert(0);
  }
}

void FuncState::infix(BinOpr op, expdesc *v) {
  dischargevars(v);
  switch (op) {
    case BinOpr::OPR_AND: {
      goiftrue(v);  /* go ahead only if 'v' is true */
      break;
    }
    case BinOpr::OPR_OR: {
      goiffalse(v);  /* go ahead only if 'v' is false */
      break;
    }
    case BinOpr::OPR_CONCAT: {
      exp2nextreg(v);  /* operand must be on the stack */
      break;
    }
    case BinOpr::OPR_ADD: case BinOpr::OPR_SUB:
    case BinOpr::OPR_MUL: case BinOpr::OPR_DIV: case BinOpr::OPR_IDIV:
    case BinOpr::OPR_MOD: case BinOpr::OPR_POW:
    case BinOpr::OPR_BAND: case BinOpr::OPR_BOR: case BinOpr::OPR_BXOR:
    case BinOpr::OPR_SHL: case BinOpr::OPR_SHR: {
      if (!tonumeral(v, nullptr))
        exp2anyreg(v);
      /* else keep numeral, which may be folded or used as an immediate
         operand */
      break;
    }
    case BinOpr::OPR_EQ: case BinOpr::OPR_NE: {
      if (!tonumeral(v, nullptr))
        exp2RK(v);
      /* else keep numeral, which may be an immediate operand */
      break;
    }
    case BinOpr::OPR_LT: case BinOpr::OPR_LE:
    case BinOpr::OPR_GT: case BinOpr::OPR_GE: {
      int dummy, dummy2;
      if (!isSCnumber(v, &dummy, &dummy2))
        exp2anyreg(v);
      /* else keep numeral, which may be an immediate operand */
      break;
    }
    default: lua_assert(0);
  }
}

void FuncState::posfix(BinOpr op, expdesc *e1, expdesc *e2, int line) {
  dischargevars(e2);
  if (foldbinop(op) && constfolding(cast_int(op) + LUA_OPADD, e1, e2))
    return;  /* done by folding */
  switch (op) {
    case BinOpr::OPR_AND: {
      lua_assert(e1->getTrueList() == NO_JUMP);  /* list closed by 'luaK_infix' */
      concat(e2->getFalseListRef(), e1->getFalseList());
      *e1 = *e2;
      break;
    }
    case BinOpr::OPR_OR: {
      lua_assert(e1->getFalseList() == NO_JUMP);  /* list closed by 'luaK_infix' */
      concat(e2->getTrueListRef(), e1->getTrueList());
      *e1 = *e2;
      break;
    }
    case BinOpr::OPR_CONCAT: {  /* e1 .. e2 */
      exp2nextreg(e2);
      codeconcat(e1, e2, line);
      break;
    }
    case BinOpr::OPR_ADD: case BinOpr::OPR_MUL: {
      codecommutative(op, e1, e2, line);
      break;
    }
    case BinOpr::OPR_SUB: {
      if (finishbinexpneg(e1, e2, OP_ADDI, line, TMS::TM_SUB))
        break; /* coded as (r1 + -I) */
      /* ELSE */
    }  /* FALLTHROUGH */
    case BinOpr::OPR_DIV: case BinOpr::OPR_IDIV: case BinOpr::OPR_MOD: case BinOpr::OPR_POW: {
      codearith(op, e1, e2, 0, line);
      break;
    }
    case BinOpr::OPR_BAND: case BinOpr::OPR_BOR: case BinOpr::OPR_BXOR: {
      codebitwise(op, e1, e2, line);
      break;
    }
    case BinOpr::OPR_SHL: {
      if (isSCint(e1)) {
        swapexps(e1, e2);
        codebini(OP_SHLI, e1, e2, 1, line, TMS::TM_SHL);  /* I << r2 */
      }
      else if (finishbinexpneg(e1, e2, OP_SHRI, line, TMS::TM_SHL)) {
        /* coded as (r1 >> -I) */;
      }
      else  /* regular case (two registers) */
       codebinexpval(op, e1, e2, line);
      break;
    }
    case BinOpr::OPR_SHR: {
      if (isSCint(e2))
        codebini(OP_SHRI, e1, e2, 0, line, TMS::TM_SHR);  /* r1 >> I */
      else  /* regular case (two registers) */
        codebinexpval(op, e1, e2, line);
      break;
    }
    case BinOpr::OPR_EQ: case BinOpr::OPR_NE: {
      codeeq(op, e1, e2);
      break;
    }
    case BinOpr::OPR_GT: case BinOpr::OPR_GE: {
      /* '(a > b)' <=> '(b < a)';  '(a >= b)' <=> '(b <= a)' */
      swapexps(e1, e2);
      op = static_cast<BinOpr>((cast_int(op) - cast_int(BinOpr::OPR_GT)) + cast_int(BinOpr::OPR_LT));
    }  /* FALLTHROUGH */
    case BinOpr::OPR_LT: case BinOpr::OPR_LE: {
      codeorder(op, e1, e2);
      break;
    }
    default: lua_assert(0);
  }
}

void FuncState::settablesize(int pcpos, unsigned ra, unsigned asize, unsigned hsize) {
  Instruction *inst = &getProto()->getCode()[pcpos];
  int extra = asize / (MAXARG_vC + 1);  /* higher bits of array size */
  int rc = asize % (MAXARG_vC + 1);  /* lower bits of array size */
  int k = (extra > 0);  /* true iff needs extra argument */
  int hsize_coded = (hsize != 0) ? luaO_ceillog2(cast_uint(hsize)) + 1 : 0;
  *inst = CREATE_vABCk(OP_NEWTABLE, static_cast<int>(ra), hsize_coded, rc, k);
  *(inst + 1) = CREATE_Ax(OP_EXTRAARG, extra);
}

void FuncState::setlist(int base, int nelems, int tostore) {
  lua_assert(tostore != 0);
  if (tostore == LUA_MULTRET)
    tostore = 0;
  if (nelems <= MAXARG_vC)
    codevABCk(OP_SETLIST, base, tostore, nelems, 0);
  else {
    int extra = nelems / (MAXARG_vC + 1);
    nelems %= (MAXARG_vC + 1);
    codevABCk(OP_SETLIST, base, tostore, nelems, 1);
    codeextraarg(extra);
  }
  setFreeReg(cast_byte(base + 1));  /* free registers with list values */
}

void FuncState::finish() {
  Proto *p = getProto();
  auto codeSpan = p->getCodeSpan();
  for (int i = 0; i < getPC(); i++) {
    Instruction *instr = &codeSpan[i];
    /* avoid "not used" warnings when assert is off (for 'onelua.c') */
    (void)luaP_isOT; (void)luaP_isIT;
    lua_assert(i == 0 || luaP_isOT(*(instr - 1)) == luaP_isIT(*instr));
    switch (InstructionView(*instr).opcode()) {
      case OP_RETURN0: case OP_RETURN1: {
        if (!(getNeedClose() || (p->getFlag() & PF_ISVARARG)))
          break;  /* no extra work */
        /* else use OP_RETURN to do the extra work */
        SET_OPCODE(*instr, OP_RETURN);
      }  /* FALLTHROUGH */
      case OP_RETURN: case OP_TAILCALL: {
        if (getNeedClose())
          SETARG_k(*instr, 1);  /* signal that it needs to close */
        if (p->getFlag() & PF_ISVARARG)
          SETARG_C(*instr, static_cast<unsigned int>(p->getNumParams()) + 1);  /* signal that it is vararg */
        break;
      }
      case OP_JMP: {
        int target = finaltarget(i);
        fixjump(i, target);
        break;
      }
      default: break;
    }
  }
}