lua/lcode.c at master · lua/lua · GitHub

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** $Id: lcode.c $

** Code generator for Lua

** See Copyright Notice in lua.h

#define lcode_c

#define LUA_CORE

#include "lprefix.h"

#include <float.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"

/* (note that expressions VJMP also have jumps.) */

#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 *fmt, ...) {

const char *msg;

va_list argp;

pushvfstring(ls->L, argp, fmt, msg);

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

ls->linenumber = ls->lastline; /* back to line of last used token */

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;

}

** Get the constant value from a constant expression

static TValue *const2val (FuncState *fs, const expdesc *e) {

lua_assert(e->k == VCONST);

return &fs->ls->dyd->actvar.arr[e->u.info].k;

}

** 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:

setbfvalue(v);

return 1;

case VTRUE:

setbtvalue(v);

return 1;

case VNIL:

setnilvalue(v);

return 1;

case VKSTR: {

setsvalue(fs->ls->L, v, e->u.strval);

return 1;

}

case VCONST: {

setobj(fs->ls->L, v, const2val(fs, e));

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 = ~(Instruction)0;

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;

}

luaY_checklimit(fs, nret + 1, MAXARG_B, "returns");

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);

}

/* 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, INT_MAX, "lines");

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

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

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

fs->iwthabs = 1; /* restart counter */

}

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

INT_MAX, "opcodes");

f->lineinfo[pc] = cast(ls_byte, 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]; /* correct last line saved */

fs->iwthabs--; /* undo previous increment */

}

else { /* absolute line information */

lua_assert(f->abslineinfo[fs->nabslineinfo - 1].pc == pc);

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

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.

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,

INT_MAX, "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));

}

int luaK_codevABCk (FuncState *fs, OpCode o, int A, int B, int C, int k) {

lua_assert(getOpMode(o) == ivABC);

lua_assert(A <= MAXARG_A && B <= MAXARG_vB &&

C <= MAXARG_vC && (k & ~1) == 0);

return luaK_code(fs, CREATE_vABCk(o, A, B, C, k));

}

** Format and emit an 'iABx' instruction.

int luaK_codeABx (FuncState *fs, OpCode o, int A, 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.

static int codeAsBx (FuncState *fs, OpCode o, int A, int Bc) {

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) {

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')

static int 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);

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) {

luaY_checklimit(fs, newstack, MAX_FSTACK, "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 = cast_byte(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').

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

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

int oldsize = f->sizek;

int k = fs->nk;

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;

}

** 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 k2proto (FuncState *fs, TValue *key, TValue *v) {

TValue val;

Proto *f = fs->f;

int tag = luaH_get(fs->kcache, 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(&f->k[k], v));

return k; /* reuse index */

}

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

int k = addk(fs, f, 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 */

setivalue(&val, k);

luaH_set(fs->ls->L, fs->kcache, key, &val);

return k;

}

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

static int stringK (FuncState *fs, TString *s) {

TValue o;

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

return k2proto(fs, &o, &o); /* use string itself as key */

}

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

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

TValue o;

setivalue(&o, n);

return k2proto(fs, &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.

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

TValue o, kv;

setfltvalue(&o, r); /* value as a TValue */

if (r == 0) { /* handle zero as a special case */

setpvalue(&kv, fs); /* use FuncState as index */

return k2proto(fs, &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;

setfltvalue(&kv, k); /* key as a TValue */

if (!luaV_flttointeger(k, &ik, F2Ieq)) { /* not an integer value? */

int n = k2proto(fs, &kv, &o); /* use key */

if (luaV_rawequalobj(&fs->f->k[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(fs, fs->f, &o);

}

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

static int boolF (FuncState *fs) {

TValue o;

setbfvalue(&o);

return k2proto(fs, &o, &o); /* use boolean itself as key */

}

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

static int boolT (FuncState *fs) {

TValue o;

setbtvalue(&o);

return k2proto(fs, &o, &o); /* use boolean itself as key */

}

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

static int nilK (FuncState *fs) {

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

TValue k;

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

sethvalue(L, &k, fs->kcache);

return k2proto(fs, &k, &G(L)->nilvalue);

}

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

if (fitsBx(i))

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

else

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

}

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

lua_Integer fi;

if (luaV_flttointeger(f, &fi, F2Ieq) && fitsBx(fi))

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

else

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

}

** Get the value of 'var' in a register and generate an opcode to check

** whether that register is nil. 'k' is the index of the variable name

** in the list of constants. If its value cannot be encoded in Bx, a 0

** will use '?' for the name.

void luaK_codecheckglobal (FuncState *fs, expdesc *var, int k, int line) {

luaK_exp2anyreg(fs, var);

luaK_fixline(fs, line);

k = (k >= MAXARG_Bx) ? 0 : k + 1;

luaK_codeABx(fs, OP_ERRNNIL, var->u.info, k);

luaK_fixline(fs, line);

freeexp(fs, var);

}

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

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

switch (ttypetag(v)) {

case LUA_VNUMINT:

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

break;

case LUA_VNUMFLT:

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

break;

case LUA_VFALSE:

e->k = VFALSE;

break;

case LUA_VTRUE:

e->k = VTRUE;

break;

case LUA_VNIL:

e->k = VNIL;

break;

case LUA_VSHRSTR: case LUA_VLNGSTR:

e->k = VKSTR; e->u.strval = tsvalue(v);

break;

default: lua_assert(0);

}

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

** 'e' must be a multi-ret expression (function call or vararg).

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

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

luaY_checklimit(fs, nresults + 1, MAXARG_C, "multiple results");

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

SETARG_C(*pc, nresults + 1);

else {

lua_assert(e->k == VVARARG);

SETARG_C(*pc, nresults + 1);

SETARG_A(*pc, fs->freereg);

luaK_reserveregs(fs, 1);

}

** Convert a VKSTR to a VK

static int str2K (FuncState *fs, expdesc *e) {

lua_assert(e->k == VKSTR);

e->u.info = stringK(fs, e->u.strval);

e->k = VK;

return e->u.info;

}

** 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 */

}

** Change a vararg parameter into a regular local variable

void luaK_vapar2local (FuncState *fs, expdesc *var) {

needvatab(fs->f); /* function will need a vararg table */

/* now a vararg parameter is equivalent to a regular local variable */

var->k = VLOCAL;

}

** Ensure that expression 'e' is not a variable (nor a <const>).

** (Expression still may have jump lists.)

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

switch (e->k) {

case VCONST: {

const2exp(const2val(fs, e), e);

break;

}

case VVARGVAR: {

luaK_vapar2local(fs, e); /* turn it into a local variable */

} /* FALLTHROUGH */

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

int temp = e->u.var.ridx;

e->u.info = temp; /* (avoid a direct assignment; values overlap) */

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 VVARGIND: {

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

e->u.info = luaK_codeABC(fs, OP_GETVARG, 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) */

}

** Ensure expression value is in register 'reg', making 'e' 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: {

luaK_codeABC(fs, OP_LOADFALSE, reg, 0, 0);

break;

}

case VTRUE: {

luaK_codeABC(fs, OP_LOADTRUE, reg, 0, 0);

break;

}

case VKSTR: {

str2K(fs, e);

} /* FALLTHROUGH */

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;

}

** Ensure expression value is in a register, making 'e' a

** non-relocatable expression.

** (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, OpCode op) {

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

return luaK_codeABC(fs, op, A, 0, 0);

}

** 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, OP_LFALSESKIP); /* skip next inst. */

p_t = code_loadbool(fs, reg, OP_LOADTRUE);

/* 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);

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