/*

** $Id: lcode.c,v 2.112 2016/12/22 13:08:50 roberto Exp $

** Code generator for Lua

** See Copyright Notice in lua.h

*/

#define lcode_c

#define LUA_CORE

#include "lprefix.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)

/*

** 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;

}

}

/*

** 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) {

Instruction *previous;

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

if (fs->pc > fs->lasttarget) { /* no jumps to current position? */

previous = &fs->f->code[fs->pc-1];

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_sBx(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 (abs(offset) > MAXARG_sBx)

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

SETARG_sBx(*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'). If there are jumps to

** this position (kept in 'jpc'), link them all together so that

** 'patchlistaux' will fix all them directly to the final destination.

*/

int luaK_jump (FuncState *fs) {

int jpc = fs->jpc; /* save list of jumps to here */

int j;

fs->jpc = NO_JUMP; /* no more jumps to here */

j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);

luaK_concat(fs, &j, jpc); /* keep them on hold */

return j;

}

/*

** Code a 'return' instruction

*/

void luaK_ret (FuncState *fs, int first, int nret) {

luaK_codeABC(fs, OP_RETURN, 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) {

luaK_codeABC(fs, op, A, B, C);

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_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*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;

}

}

/*

** Ensure all pending jumps to current position are fixed (jumping

** to current position with no values) and reset list of pending

** jumps

*/

static void dischargejpc (FuncState *fs) {

patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);

fs->jpc = NO_JUMP;

}

/*

** Add elements in 'list' to list of pending jumps to "here"

** (current position)

*/

void luaK_patchtohere (FuncState *fs, int list) {

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

luaK_concat(fs, &fs->jpc, list);

}

/*

** 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) {

if (target == fs->pc) /* 'target' is current position? */

luaK_patchtohere(fs, list); /* add list to pending jumps */

else {

lua_assert(target < fs->pc);

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

}

}

/*

** Path all jumps in 'list' to close upvalues up to given 'level'

** (The assertion checks that jumps either were closing nothing

** or were closing higher levels, from inner blocks.)

*/

void luaK_patchclose (FuncState *fs, int list, int level) {

level++; /* argument is +1 to reserve 0 as non-op */

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

lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP &&

(GETARG_A(fs->f->code[list]) == 0 ||

GETARG_A(fs->f->code[list]) >= level));

SETARG_A(fs->f->code[list], level);

}

}

/*

** 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;

dischargejpc(fs); /* 'pc' will change */

/* 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;

/* save corresponding line information */

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

MAX_INT, "opcodes");

f->lineinfo[fs->pc] = fs->ls->lastline;

return fs->pc++;

}

/*

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

** of parameters versus opcode.)

*/

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

lua_assert(getOpMode(o) == iABC);

lua_assert(getBMode(o) != OpArgN || b == 0);

lua_assert(getCMode(o) != OpArgN || c == 0);

lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C);

return luaK_code(fs, CREATE_ABC(o, a, b, c));

}

/*

** Format and emit an 'iABx' instruction.

*/

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

lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);

lua_assert(getCMode(o) == OpArgN);

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

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

}

/*

** 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".

*/

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) {

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 (!ISK(reg) && reg >= fs->nactvar) {

fs->freereg--;

lua_assert(reg == fs->freereg);

}

}

/*

** 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;

if (r1 > r2) {

freereg(fs, r1);

freereg(fs, r2);

}

else {

freereg(fs, r2);

freereg(fs, r1);

}

}

/*

** 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 && ttype(&f->k[k]) == ttype(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.

*/

int luaK_intK (FuncState *fs, lua_Integer n) {

TValue k, o;

setpvalue(&k, cast(void*, cast(size_t, 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);

}

/*

** 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) {

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

SETARG_C(getinstruction(fs, e), nresults + 1);

}

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

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

SETARG_B(*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 VRELOCABLE (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_B(getinstruction(fs, e), 2);

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

}

}

/*

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

*/

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

switch (e->k) {

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

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 = VRELOCABLE;

break;

}

case VINDEXED: {

OpCode op;

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

if (e->u.ind.vt == VLOCAL) { /* is 't' in a register? */

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

op = OP_GETTABLE;

}

else {

lua_assert(e->u.ind.vt == VUPVAL);

op = OP_GETTABUP; /* 't' is in an upvalue */

}

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

e->k = VRELOCABLE;

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).

*/

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

break;

}

case VKINT: {

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

break;

}

case VRELOCABLE: {

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.

*/

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 (including 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);

p_t = code_loadbool(fs, reg, 1, 0);

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 (including results from its jump

** lists) 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 (including results from its jump

** lists) 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 >= fs->nactvar) { /* 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);

}

/*

** 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 R/K index.

*/

int luaK_exp2RK (FuncState *fs, expdesc *e) {

luaK_exp2val(fs, e);

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

case VTRUE: e->u.info = boolK(fs, 1); goto vk;

case VFALSE: e->u.info = boolK(fs, 0); goto vk;

case VNIL: e->u.info = nilK(fs); goto vk;

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

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

case VK:

vk:

e->k = VK;

if (e->u.info <= MAXINDEXRK) /* constant fits in 'argC'? */

return RKASK(e->u.info);

else break;

default: break;

}

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

return luaK_exp2anyreg(fs, e);

}

/*

** 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.info); /* compute 'ex' into proper place */

return;

}

case VUPVAL: {

int e = luaK_exp2anyreg(fs, ex);

luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);

break;

}

case VINDEXED: {

OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP;

int e = luaK_exp2RK(fs, ex);

luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, e);

break;

}

default: lua_assert(0); /* invalid var kind to store */

}

freeexp(fs, ex);

}

/*

** Emit SELF instruction (convert expression 'e' into 'e:key(e,').

*/

void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {

int ereg;

luaK_exp2anyreg(fs, e);

ereg = e->u.info; /* register where 'e' was placed */

freeexp(fs, e);

e->u.info = fs->freereg; /* base register for op_self */

e->k = VNONRELOC; /* self expression has a fixed register */

luaK_reserveregs(fs, 2); /* function and 'self' produced by op_self */

luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key));

freeexp(fs, key);

}

/*

** Negate condition 'e' (where 'e' is a comparison).

*/

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

Instruction *pc = getjumpcontrol(fs, e->u.info);

lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&

GET_OPCODE(*pc) != OP_TEST);

SETARG_A(*pc, !(GETARG_A(*pc)));

}

/*

** 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'.

*/

static int jumponcond (FuncState *fs, expdesc *e, int cond) {

if (e->k == VRELOCABLE) {

Instruction ie = getinstruction(fs, e);

if (GET_OPCODE(ie) == OP_NOT) {

fs->pc--; /* remove previous OP_NOT */

return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);

}

/* else go through */

}

discharge2anyreg(fs, e);

freeexp(fs, e);

return condjump(fs, OP_TESTSET, NO_REG, e->u.info, cond);

}

/*

** Emit code to go through if 'e' is true, jump otherwise.

*/

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

int pc; /* pc of new jump */

luaK_dischargevars(fs, e);

switch (e->k) {

case VJMP: { /* condition? */

negatecondition(fs, e); /* jump when it is false */

pc = e->u.info; /* save jump position */

break;

}

case VK: case VKFLT: case VKINT: case VTRUE: {

pc = NO_JUMP; /* always true; do nothing */

break;

}

default: {

pc = jumponcond(fs, e, 0); /* jump when false */

break;

}

}

luaK_concat(fs, &e->f, pc); /* insert new jump in false list */

luaK_patchtohere(fs, e->t); /* true list jumps to here (to go through) */

e->t = NO_JUMP;

}

/*

** Emit code to go through if 'e' is false, jump otherwise.

*/

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

int pc; /* pc of new jump */

luaK_dischargevars(fs, e);

switch (e->k) {

case VJMP: {

pc = e->u.info; /* already jump if true */

break;

}

case VNIL: case VFALSE: {

pc = NO_JUMP; /* always false; do nothing */

break;

}

default: {

pc = jumponcond(fs, e, 1); /* jump if true */

break;

}

}

luaK_concat(fs, &e->t, pc); /* insert new jump in 't' list */

luaK_patchtohere(fs, e->f); /* false list jumps to here (to go through) */

e->f = NO_JUMP;

}

/*

** Code 'not e', doing constant folding.

*/

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

luaK_dischargevars(fs, e);

switch (e->k) {

case VNIL: case VFALSE: {

e->k = VTRUE; /* true == not nil == not false */

break;

}

case VK: case VKFLT: case VKINT: case VTRUE: {

e->k = VFALSE; /* false == not "x" == not 0.5 == not 1 == not true */

break;

}

case VJMP: {

negatecondition(fs, e);

break;

}

case VRELOCABLE:

case VNONRELOC: {

discharge2anyreg(fs, e);

freeexp(fs, e);

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

e->k = VRELOCABLE;

break;

}

default: lua_assert(0); /* cannot happen */

}

/* interchange true and false lists */

{ int temp = e->f; e->f = e->t; e->t = temp; }

removevalues(fs, e->f); /* values are useless when negated */

removevalues(fs, e->t);

}

/*

** Create expression 't[k]'. 't' must have its final result already in a

** register or upvalue.

*/

void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {

lua_assert(!hasjumps(t) && (vkisinreg(t->k) || t->k == VUPVAL));

t->u.ind.t = t->u.info; /* register or upvalue index */

t->u.ind.idx = luaK_exp2RK(fs, k); /* R/K index for key */

t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL : VLOCAL;

t->k = VINDEXED;

}

/*

** Return false if folding can raise an error.

** Bitwise operations need operands convertible to integers; division

** operations cannot have 0 as divisor.

*/

static int 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 (tointeger(v1, &i) && tointeger(v2, &i));

}

case LUA_OPDIV: case LUA_OPIDIV: case LUA_OPMOD: /* division by 0 */

return (nvalue(v2) != 0);

default: return 1; /* everything else is valid */

}

}

/*

** Try to "constant-fold" an operation; return 1 iff successful.

** (In this case, 'e1' has the final result.)

*/

static int constfolding (FuncState *fs, 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 */

luaO_arith(fs->ls->L, op, &v1, &v2, &res); /* does operation */

if (ttisinteger(&res)) {

e1->k = VKINT;

e1->u.ival = 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->k = VKFLT;

e1->u.nval = n;

}

return 1;

}

/*

** Emit code for unary expressions that "produce values"