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1875 lines (1657 loc) · 52 KB
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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"
/* Maximum number of registers in a Lua function (must fit in 8 bits) */
#define MAXREGS 255
/* (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 *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;
}
}
/*
** 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;
}
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, 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 = 1; /* 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]; /* 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,
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.
*/
static int 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')
*/
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) {
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.
** Note that all functions share the same table, so entering or exiting
** a function can make some indices wrong.
*/
static int addk (FuncState *fs, TValue *key, TValue *v) {
TValue val;
lua_State *L = fs->ls->L;
Proto *f = fs->f;
const TValue *idx = luaH_get(fs->ls->h, key); /* query 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(&val, k);
luaH_finishset(L, fs->ls->h, key, idx, &val);
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.
*/
static int 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.
*/
static int luaK_intK (FuncState *fs, lua_Integer n) {
TValue o;
setivalue(&o, n);
return addk(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, we add to the number its smaller
** power-of-two fraction that is still significant in its scale.
** For doubles, that would be 1/2^52.
** (This method is not bulletproof: there may be another float
** with that value, and for floats larger than 2^53 the result is
** still an integer. At worst, this only wastes an entry with
** a duplicate.)
*/
static int luaK_numberK (FuncState *fs, lua_Number r) {
TValue o;
lua_Integer ik;
setfltvalue(&o, r);
if (!luaV_flttointeger(r, &ik, F2Ieq)) /* not an integral value? */
return addk(fs, &o, &o); /* use number itself as key */
else { /* must build an alternative key */
const int nbm = l_floatatt(MANT_DIG);
const lua_Number q = l_mathop(ldexp)(l_mathop(1.0), -nbm + 1);
const lua_Number k = (ik == 0) ? q : r + r*q; /* new key */
TValue kv;
setfltvalue(&kv, k);
/* result is not an integral value, unless value is too large */
lua_assert(!luaV_flttointeger(k, &ik, F2Ieq) ||
l_mathop(fabs)(r) >= l_mathop(1e6));
return addk(fs, &kv, &o);
}
}
/*
** Add a false to list of constants and return its index.
*/
static int boolF (FuncState *fs) {
TValue o;
setbfvalue(&o);
return addk(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 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 <= 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));
}
/*
** 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);
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 void str2K (FuncState *fs, expdesc *e) {
lua_assert(e->k == VKSTR);
e->u.info = stringK(fs, e->u.strval);
e->k = VK;
}
/*
** 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 (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 VLOCAL: { /* already in a register */
int temp = e->u.var.ridx;
e->u.info = temp; /* (can't do 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 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);
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;
}
/* 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. */
}
luaK_exp2nextreg(fs, e); /* default: 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 (e->k == VJMP || 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) {