/*

** $Id: lcode.c $

** Code generator for Lua

** See Copyright Notice in lua.h

*/

#define lcode_c

#define LUA_CORE

#include "lprefix.h"

#include <limits.h>

#include <math.h>

#include <stdlib.h>

#include "lua.h"

#include "lcode.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"

/* Maximum number of registers in a Lua function (must fit in 8 bits) */

#define MAXREGS 255

#define hasjumps(e) ((e)->t != (e)->f)

static int codesJ (FuncState *fs, OpCode o, int sj, int k);

/* semantic error */

l_noret luaK_semerror (LexState *ls, const char *msg) {

ls->t.token = 0; /* remove "near <token>" from final message */

luaX_syntaxerror(ls, 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->k) {

case VKINT:

if (v) setivalue(v, e->u.ival);

return 1;

case VKFLT:

if (v) setfltvalue(v, e->u.nval);

return 1;

default: return 0;

}

}

/*

** If expression is a constant, fills 'v' with its value

** and returns 1. Otherwise, returns 0.

*/

int luaK_exp2const (FuncState *fs, const expdesc *e, TValue *v) {

if (hasjumps(e))

return 0; /* not a constant */

switch (e->k) {

case VFALSE: case VTRUE:

setbvalue(v, e->k == VTRUE);

return 1;

case VNIL:

setnilvalue(v);

return 1;

case VK: {

TValue *k = &fs->f->k[e->u.info];

setobj(fs->ls->L, v, k);

return 1;

}

default: return tonumeral(e, v);

}

}

/*

** 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).

*/

static Instruction *previousinstruction (FuncState *fs) {

static const Instruction invalidinstruction = -1;

if (fs->pc > fs->lasttarget)

return &fs->f->code[fs->pc - 1]; /* previous instruction */

else

return cast(Instruction*, &invalidinstruction);

}

/*

** Create a OP_LOADNIL instruction, but try to optimize: if the previous

** instruction is also OP_LOADNIL and ranges are compatible, adjust

** range of previous instruction instead of emitting a new one. (For

** instance, 'local a; local b' will generate a single opcode.)

*/

void luaK_nil (FuncState *fs, int from, int n) {

int l = from + n - 1; /* last register to set nil */

Instruction *previous = previousinstruction(fs);

if (GET_OPCODE(*previous) == OP_LOADNIL) { /* previous is LOADNIL? */

int pfrom = GETARG_A(*previous); /* get previous range */

int pl = pfrom + GETARG_B(*previous);

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, from);

SETARG_B(*previous, l - from);

return;

} /* else go through */

}

luaK_codeABC(fs, OP_LOADNIL, from, n - 1, 0); /* else no optimization */

}

/*

** Gets the destination address of a jump instruction. Used to traverse

** a list of jumps.

*/

static int getjump (FuncState *fs, int pc) {

int offset = GETARG_sJ(fs->f->code[pc]);

if (offset == NO_JUMP) /* point to itself represents end of list */

return NO_JUMP; /* end of list */

else

return (pc+1)+offset; /* turn offset into absolute position */

}

/*

** Fix jump instruction at position 'pc' to jump to 'dest'.

** (Jump addresses are relative in Lua)

*/

static void fixjump (FuncState *fs, int pc, int dest) {

Instruction *jmp = &fs->f->code[pc];

int offset = dest - (pc + 1);

lua_assert(dest != NO_JUMP);

if (!(-OFFSET_sJ <= offset && offset <= MAXARG_sJ - OFFSET_sJ))

luaX_syntaxerror(fs->ls, "control structure too long");

lua_assert(GET_OPCODE(*jmp) == OP_JMP);

SETARG_sJ(*jmp, offset);

}

/*

** Concatenate jump-list 'l2' into jump-list 'l1'

*/

void luaK_concat (FuncState *fs, 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(fs, list)) != NO_JUMP) /* find last element */

list = next;

fixjump(fs, list, l2); /* last element links to 'l2' */

}

}

/*

** Create a jump instruction and return its position, so its destination

** can be fixed later (with 'fixjump').

*/

int luaK_jump (FuncState *fs) {

return codesJ(fs, OP_JMP, NO_JUMP, 0);

}

/*

** Code a 'return' instruction

*/

void luaK_ret (FuncState *fs, 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;

}

luaK_codeABC(fs, op, first, nret + 1, 0);

}

/*

** Code a "conditional jump", that is, a test or comparison opcode

** followed by a jump. Return jump position.

*/

static int condjump (FuncState *fs, OpCode op, int A, int B, int C, int k) {

luaK_codeABCk(fs, op, A, B, C, k);

return luaK_jump(fs);

}

/*

** returns current 'pc' and marks it as a jump target (to avoid wrong

** optimizations with consecutive instructions not in the same basic block).

*/

int luaK_getlabel (FuncState *fs) {

fs->lasttarget = fs->pc;

return fs->pc;

}

/*

** Returns the position of the instruction "controlling" a given

** jump (that is, its condition), or the jump itself if it is

** unconditional.

*/

static Instruction *getjumpcontrol (FuncState *fs, int pc) {

Instruction *pi = &fs->f->code[pc];

if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))

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)

*/

static int patchtestreg (FuncState *fs, int node, int reg) {

Instruction *i = getjumpcontrol(fs, node);

if (GET_OPCODE(*i) != OP_TESTSET)

return 0; /* cannot patch other instructions */

if (reg != NO_REG && reg != GETARG_B(*i))

SETARG_A(*i, reg);

else {

/* no register to put value or register already has the value;

change instruction to simple test */

*i = CREATE_ABCk(OP_TEST, GETARG_B(*i), 0, 0, GETARG_k(*i));

}

return 1;

}

/*

** Traverse a list of tests ensuring no one produces a value

*/

static void removevalues (FuncState *fs, int list) {

for (; list != NO_JUMP; list = getjump(fs, list))

patchtestreg(fs, list, NO_REG);

}

/*

** 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'.

*/

static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,

int dtarget) {

while (list != NO_JUMP) {

int next = getjump(fs, list);

if (patchtestreg(fs, list, reg))

fixjump(fs, list, vtarget);

else

fixjump(fs, list, dtarget); /* jump to default target */

list = next;

}

}

/*

** Path all jumps in 'list' to jump to 'target'.

** (The assert means that we cannot fix a jump to a forward address

** because we only know addresses once code is generated.)

*/

void luaK_patchlist (FuncState *fs, int list, int target) {

lua_assert(target <= fs->pc);

patchlistaux(fs, list, target, NO_REG, target);

}

void luaK_patchtohere (FuncState *fs, int list) {

int hr = luaK_getlabel(fs); /* mark "here" as a jump target */

luaK_patchlist(fs, list, hr);

}

/*

** MAXimum number of successive Instructions WiTHout ABSolute line

** information.

*/

#if !defined(MAXIWTHABS)

#define MAXIWTHABS 120

#endif

/* 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'.

*/

static void savelineinfo (FuncState *fs, Proto *f, int line) {

int linedif = line - fs->previousline;

int pc = fs->pc - 1; /* last instruction coded */

if (abs(linedif) >= LIMLINEDIFF || fs->iwthabs++ > MAXIWTHABS) {

luaM_growvector(fs->ls->L, f->abslineinfo, fs->nabslineinfo,

f->sizeabslineinfo, AbsLineInfo, MAX_INT, "lines");

f->abslineinfo[fs->nabslineinfo].pc = pc;

f->abslineinfo[fs->nabslineinfo++].line = line;

linedif = ABSLINEINFO; /* signal that there is absolute information */

fs->iwthabs = 0; /* restart counter */

}

luaM_growvector(fs->ls->L, f->lineinfo, pc, f->sizelineinfo, ls_byte,

MAX_INT, "opcodes");

f->lineinfo[pc] = linedif;

fs->previousline = 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.

*/

static void removelastlineinfo (FuncState *fs) {

Proto *f = fs->f;

int pc = fs->pc - 1; /* last instruction coded */

if (f->lineinfo[pc] != ABSLINEINFO) { /* relative line info? */

fs->previousline -= f->lineinfo[pc]; /* last line saved */

fs->iwthabs--;

}

else { /* absolute line information */

fs->nabslineinfo--; /* remove it */

lua_assert(f->abslineinfo[fs->nabslineinfo].pc = pc);

fs->iwthabs = MAXIWTHABS + 1; /* force next line info to be absolute */

}

}

/*

** Remove the last instruction created, correcting line information

** accordingly.

*/

static void removelastinstruction (FuncState *fs) {

removelastlineinfo(fs);

fs->pc--;

}

/*

** Emit instruction 'i', checking for array sizes and saving also its

** line information. Return 'i' position.

*/

static int luaK_code (FuncState *fs, Instruction i) {

Proto *f = fs->f;

/* put new instruction in code array */

luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction,

MAX_INT, "opcodes");

f->code[fs->pc++] = i;

savelineinfo(fs, f, fs->ls->lastline);

return fs->pc - 1; /* index of new instruction */

}

/*

** Format and emit an 'iABC' instruction. (Assertions check consistency

** of parameters versus opcode.)

*/

int luaK_codeABCk (FuncState *fs, OpCode o, int a, int b, int c, int k) {

lua_assert(getOpMode(o) == iABC);

lua_assert(a <= MAXARG_A && b <= MAXARG_B &&

c <= MAXARG_C && (k & ~1) == 0);

return luaK_code(fs, CREATE_ABCk(o, a, b, c, k));

}

/*

** Format and emit an 'iABx' instruction.

*/

int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {

lua_assert(getOpMode(o) == iABx);

lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);

return luaK_code(fs, CREATE_ABx(o, a, bc));

}

/*

** Format and emit an 'iAsBx' instruction.

*/

int luaK_codeAsBx (FuncState *fs, OpCode o, int a, int bc) {

unsigned int b = bc + OFFSET_sBx;

lua_assert(getOpMode(o) == iAsBx);

lua_assert(a <= MAXARG_A && b <= MAXARG_Bx);

return luaK_code(fs, CREATE_ABx(o, a, b));

}

/*

** Format and emit an 'isJ' instruction.

*/

static int codesJ (FuncState *fs, OpCode o, int sj, int k) {

unsigned int j = sj + OFFSET_sJ;

lua_assert(getOpMode(o) == isJ);

lua_assert(j <= MAXARG_sJ && (k & ~1) == 0);

return luaK_code(fs, CREATE_sJ(o, j, k));

}

/*

** Emit an "extra argument" instruction (format 'iAx')

*/

int luaK_codeextraarg (FuncState *fs, int a) {

lua_assert(a <= MAXARG_Ax);

return luaK_code(fs, 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".

*/

static int luaK_codek (FuncState *fs, int reg, int k) {

if (k <= MAXARG_Bx)

return luaK_codeABx(fs, OP_LOADK, reg, k);

else {

int p = luaK_codeABx(fs, OP_LOADKX, reg, 0);

luaK_codeextraarg(fs, k);

return p;

}

}

/*

** Check register-stack level, keeping track of its maximum size

** in field 'maxstacksize'

*/

void luaK_checkstack (FuncState *fs, int n) {

int newstack = fs->freereg + n;

if (newstack > fs->f->maxstacksize) {

if (newstack >= MAXREGS)

luaX_syntaxerror(fs->ls,

"function or expression needs too many registers");

fs->f->maxstacksize = cast_byte(newstack);

}

}

/*

** Reserve 'n' registers in register stack

*/

void luaK_reserveregs (FuncState *fs, int n) {

luaK_checkstack(fs, n);

fs->freereg += n;

}

/*

** Free register 'reg', if it is neither a constant index nor

** a local variable.

)

*/

static void freereg (FuncState *fs, int reg) {

if (reg >= luaY_nvarstack(fs)) {

fs->freereg--;

lua_assert(reg == fs->freereg);

}

}

/*

** Free two registers in proper order

*/

static void freeregs (FuncState *fs, int r1, int r2) {

if (r1 > r2) {

freereg(fs, r1);

freereg(fs, r2);

}

else {

freereg(fs, r2);

freereg(fs, r1);

}

}

/*

** Free register used by expression 'e' (if any)

*/

static void freeexp (FuncState *fs, expdesc *e) {

if (e->k == VNONRELOC)

freereg(fs, e->u.info);

}

/*

** Free registers used by expressions 'e1' and 'e2' (if any) in proper

** order.

*/

static void freeexps (FuncState *fs, expdesc *e1, expdesc *e2) {

int r1 = (e1->k == VNONRELOC) ? e1->u.info : -1;

int r2 = (e2->k == VNONRELOC) ? e2->u.info : -1;

freeregs(fs, r1, r2);

}

/*

** Add constant 'v' to prototype's list of constants (field '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.

*/

static int addk (FuncState *fs, TValue *key, TValue *v) {

lua_State *L = fs->ls->L;

Proto *f = fs->f;

TValue *idx = luaH_set(L, fs->ls->h, key); /* index scanner table */

int k, oldsize;

if (ttisinteger(idx)) { /* is there an index there? */

k = cast_int(ivalue(idx));

/* correct value? (warning: must distinguish floats from integers!) */

if (k < fs->nk && ttypetag(&f->k[k]) == ttypetag(v) &&

luaV_rawequalobj(&f->k[k], v))

return k; /* reuse index */

}

/* constant not found; create a new entry */

oldsize = f->sizek;

k = fs->nk;

/* numerical value does not need GC barrier;

table has no metatable, so it does not need to invalidate cache */

setivalue(idx, k);

luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants");

while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);

setobj(L, &f->k[k], v);

fs->nk++;

luaC_barrier(L, f, v);

return k;

}

/*

** Add a string to list of constants and return its index.

*/

int luaK_stringK (FuncState *fs, TString *s) {

TValue o;

setsvalue(fs->ls->L, &o, s);

return addk(fs, &o, &o); /* use string itself as key */

}

/*

** Add an integer to list of constants and return its index.

** Integers use userdata as keys to avoid collision with floats with

** same value; conversion to 'void*' is used only for hashing, so there

** are no "precision" problems.

*/

static int luaK_intK (FuncState *fs, lua_Integer n) {

TValue k, o;

setpvalue(&k, cast_voidp(cast_sizet(n)));

setivalue(&o, n);

return addk(fs, &k, &o);

}

/*

** Add a float to list of constants and return its index.

*/

static int luaK_numberK (FuncState *fs, lua_Number r) {

TValue o;

setfltvalue(&o, r);

return addk(fs, &o, &o); /* use number itself as key */

}

/*

** Add a boolean to list of constants and return its index.

*/

static int boolK (FuncState *fs, int b) {

TValue o;

setbvalue(&o, b);

return addk(fs, &o, &o); /* use boolean itself as key */

}

/*

** Add nil to list of constants and return its index.

*/

static int nilK (FuncState *fs) {

TValue k, v;

setnilvalue(&v);

/* cannot use nil as key; instead use table itself to represent nil */

sethvalue(fs->ls->L, &k, fs->ls->h);

return addk(fs, &k, &v);

}

/*

** Check whether 'i' can be stored in an 'sC' operand.

** Equivalent to (0 <= i + OFFSET_sC && i + OFFSET_sC <= MAXARG_C)

** but without risk of overflows in the addition.

*/

static int fitsC (lua_Integer i) {

return (-OFFSET_sC <= i && i <= MAXARG_C - OFFSET_sC);

}

/*

** 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 luaK_int (FuncState *fs, int reg, lua_Integer i) {

if (fitsBx(i))

luaK_codeAsBx(fs, OP_LOADI, reg, cast_int(i));

else

luaK_codek(fs, reg, luaK_intK(fs, i));

}

static int floatI (lua_Number f, lua_Integer *fi) {

return (luaV_flttointeger(f, fi, 0) && fitsBx(*fi));

}

static void luaK_float (FuncState *fs, int reg, lua_Number f) {

lua_Integer fi;

if (floatI(f, &fi))

luaK_codeAsBx(fs, OP_LOADF, reg, cast_int(fi));

else

luaK_codek(fs, reg, luaK_numberK(fs, f));

}

/*

** Convert a constant in 'v' into an expression description 'e'

*/

static void const2exp (FuncState *fs, TValue *v, expdesc *e) {

switch (ttypetag(v)) {

case LUA_TNUMINT:

e->k = VKINT; e->u.ival = ivalue(v);

break;

case LUA_TNUMFLT:

e->k = VKFLT; e->u.nval = fltvalue(v);

break;

case LUA_TBOOLEAN:

e->k = bvalue(v) ? VTRUE : VFALSE;

break;

case LUA_TNIL:

e->k = VNIL;

break;

case LUA_TSHRSTR: case LUA_TLNGSTR:

e->k = VK; e->u.info = luaK_stringK(fs, tsvalue(v));

break;

default: lua_assert(0);

}

}

/*

** Fix an expression to return the number of results 'nresults'.

** Either 'e' is a multi-ret expression (function call or vararg)

** or 'nresults' is LUA_MULTRET (as any expression can satisfy that).

*/

void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {

Instruction *pc = &getinstruction(fs, e);

if (e->k == VCALL) /* expression is an open function call? */

SETARG_C(*pc, nresults + 1);

else if (e->k == VVARARG) {

SETARG_C(*pc, nresults + 1);

SETARG_A(*pc, fs->freereg);

luaK_reserveregs(fs, 1);

}

else lua_assert(nresults == LUA_MULTRET);

}

/*

** Fix an expression to return one result.

** If expression is not a multi-ret expression (function call or

** vararg), it already returns one result, so nothing needs to be done.

** Function calls become VNONRELOC expressions (as its result comes

** fixed in the base register of the call), while vararg expressions

** become VRELOC (as OP_VARARG puts its results where it wants).

** (Calls are created returning one result, so that does not need

** to be fixed.)

*/

void luaK_setoneret (FuncState *fs, expdesc *e) {

if (e->k == VCALL) { /* expression is an open function call? */

/* already returns 1 value */

lua_assert(GETARG_C(getinstruction(fs, e)) == 2);

e->k = VNONRELOC; /* result has fixed position */

e->u.info = GETARG_A(getinstruction(fs, e));

}

else if (e->k == VVARARG) {

SETARG_C(getinstruction(fs, e), 2);

e->k = VRELOC; /* can relocate its simple result */

}

}

/*

** Ensure that expression 'e' is not a variable.

** (Expression still may have jump lists.)

*/

void luaK_dischargevars (FuncState *fs, expdesc *e) {

switch (e->k) {

case VCONST: {

TValue *val = &fs->ls->dyd->actvar.arr[e->u.info].k;

const2exp(fs, val, e);

break;

}

case VLOCAL: { /* already in a register */

e->u.info = e->u.var.sidx;

e->k = VNONRELOC; /* becomes a non-relocatable value */

break;

}

case VUPVAL: { /* move value to some (pending) register */

e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);

e->k = VRELOC;

break;

}

case VINDEXUP: {

e->u.info = luaK_codeABC(fs, OP_GETTABUP, 0, e->u.ind.t, e->u.ind.idx);

e->k = VRELOC;

break;

}

case VINDEXI: {

freereg(fs, e->u.ind.t);

e->u.info = luaK_codeABC(fs, OP_GETI, 0, e->u.ind.t, e->u.ind.idx);

e->k = VRELOC;

break;

}

case VINDEXSTR: {

freereg(fs, e->u.ind.t);

e->u.info = luaK_codeABC(fs, OP_GETFIELD, 0, e->u.ind.t, e->u.ind.idx);

e->k = VRELOC;

break;

}

case VINDEXED: {

freeregs(fs, e->u.ind.t, e->u.ind.idx);

e->u.info = luaK_codeABC(fs, OP_GETTABLE, 0, e->u.ind.t, e->u.ind.idx);

e->k = VRELOC;

break;

}

case VVARARG: case VCALL: {

luaK_setoneret(fs, e);

break;

}

default: break; /* there is one value available (somewhere) */

}

}

/*

** Ensures expression value is in register 'reg' (and therefore

** 'e' will become a non-relocatable expression).

** (Expression still may have jump lists.)

*/

static void discharge2reg (FuncState *fs, expdesc *e, int reg) {

luaK_dischargevars(fs, e);

switch (e->k) {

case VNIL: {

luaK_nil(fs, reg, 1);

break;

}

case VFALSE: case VTRUE: {

luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);

break;

}

case VK: {

luaK_codek(fs, reg, e->u.info);

break;

}

case VKFLT: {

luaK_float(fs, reg, e->u.nval);

break;

}

case VKINT: {

luaK_int(fs, reg, e->u.ival);

break;

}

case VRELOC: {

Instruction *pc = &getinstruction(fs, e);

SETARG_A(*pc, reg); /* instruction will put result in 'reg' */

break;

}

case VNONRELOC: {

if (reg != e->u.info)

luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);

break;

}

default: {

lua_assert(e->k == VJMP);

return; /* nothing to do... */

}

}

e->u.info = reg;

e->k = VNONRELOC;

}

/*

** Ensures expression value is in any register.

** (Expression still may have jump lists.)

*/

static void discharge2anyreg (FuncState *fs, expdesc *e) {

if (e->k != VNONRELOC) { /* no fixed register yet? */

luaK_reserveregs(fs, 1); /* get a register */

discharge2reg(fs, e, fs->freereg-1); /* put value there */

}

}

static int code_loadbool (FuncState *fs, int A, int b, int jump) {

luaK_getlabel(fs); /* those instructions may be jump targets */

return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);

}

/*

** check whether list has any jump that do not produce a value

** or produce an inverted value

*/

static int need_value (FuncState *fs, int list) {

for (; list != NO_JUMP; list = getjump(fs, list)) {

Instruction i = *getjumpcontrol(fs, list);

if (GET_OPCODE(i) != 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).

*/

static void exp2reg (FuncState *fs, expdesc *e, int reg) {

discharge2reg(fs, e, reg);

if (e->k == VJMP) /* expression itself is a test? */

luaK_concat(fs, &e->t, e->u.info); /* put this jump in 't' list */

if (hasjumps(e)) {

int final; /* position after whole expression */

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(fs, e->t) || need_value(fs, e->f)) {

int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);

p_f = code_loadbool(fs, reg, 0, 1); /* load false and skip next i. */

p_t = code_loadbool(fs, reg, 1, 0); /* load true */

/* jump around these booleans if 'e' is not a test */

luaK_patchtohere(fs, fj);

}

final = luaK_getlabel(fs);

patchlistaux(fs, e->f, final, reg, p_f);

patchlistaux(fs, e->t, final, reg, p_t);

}

e->f = e->t = NO_JUMP;

e->u.info = reg;

e->k = VNONRELOC;

}

/*

** Ensures final expression result is in next available register.

*/

void luaK_exp2nextreg (FuncState *fs, expdesc *e) {

luaK_dischargevars(fs, e);

freeexp(fs, e);

luaK_reserveregs(fs, 1);

exp2reg(fs, e, fs->freereg - 1);

}

/*

** Ensures final expression result is in some (any) register

** and return that register.

*/

int luaK_exp2anyreg (FuncState *fs, expdesc *e) {

luaK_dischargevars(fs, e);

if (e->k == VNONRELOC) { /* expression already has a register? */

if (!hasjumps(e)) /* no jumps? */

return e->u.info; /* result is already in a register */

if (e->u.info >= luaY_nvarstack(fs)) { /* reg. is not a local? */

exp2reg(fs, e, e->u.info); /* put final result in it */

return e->u.info;

}

}

luaK_exp2nextreg(fs, e); /* otherwise, use next available register */

return e->u.info;

}

/*

** Ensures final expression result is either in a register

** or in an upvalue.

*/

void luaK_exp2anyregup (FuncState *fs, expdesc *e) {

if (e->k != VUPVAL || hasjumps(e))

luaK_exp2anyreg(fs, e);

}

/*

** Ensures final expression result is either in a register

** or it is a constant.

*/

void luaK_exp2val (FuncState *fs, expdesc *e) {

if (hasjumps(e))

luaK_exp2anyreg(fs, e);

else

luaK_dischargevars(fs, e);

}

/*

** Try to make 'e' a K expression with an index in the range of R/K

** indices. Return true iff succeeded.

*/

static int luaK_exp2K (FuncState *fs, expdesc *e) {

if (!hasjumps(e)) {

int info;

switch (e->k) { /* move constants to 'k' */

case VTRUE: info = boolK(fs, 1); break;

case VFALSE: info = boolK(fs, 0); break;

case VNIL: info = nilK(fs); break;

case VKINT: info = luaK_intK(fs, e->u.ival); break;

case VKFLT: info = luaK_numberK(fs, e->u.nval); break;

case VK: info = e->u.info; break;

default: return 0; /* not a constant */

}

if (info <= MAXINDEXRK) { /* does constant fit in 'argC'? */

e->k = VK; /* make expression a 'K' expression */

e->u.info = 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 luaK_exp2RK (FuncState *fs, expdesc *e) {

if (luaK_exp2K(fs, e))

return 1;

else { /* not a constant in the right range: put it in a register */

luaK_exp2anyreg(fs, e);

return 0;

}

}

static void codeABRK (FuncState *fs, OpCode o, int a, int b,

expdesc *ec) {

int k = luaK_exp2RK(fs, ec);

luaK_codeABCk(fs, o, a, b, ec->u.info, k);

}

/*

** Generate code to store result of expression 'ex' into variable 'var'.

*/

void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {

switch (var->k) {

case VLOCAL: {

freeexp(fs, ex);

exp2reg(fs, ex, var->u.var.sidx); /* compute 'ex' into proper place */

return;

}

case VUPVAL: {

int e = luaK_exp2anyreg(fs, ex);