Lua 5.3.4 里的 lvm.c
lvm.c 是 Lua virtual machine 的具体实现。
#ifndef lvm_h
#define lvm_h
#include "ldo.h"
#include "lobject.h"
#include "ltm.h"
#if !defined(LUA_NOCVTN2S)
#define cvt2str(o) ttisnumber(o)
#else
#define cvt2str(o) 0 /* no conversion from numbers to strings */
#endif
#if !defined(LUA_NOCVTS2N)
#define cvt2num(o) ttisstring(o)
#else
#define cvt2num(o) 0 /* no conversion from strings to numbers */
#endif
/*
** You can define LUA_FLOORN2I if you want to convert floats to integers
** by flooring them (instead of raising an error if they are not
** integral values)
*/
#if !defined(LUA_FLOORN2I)
#define LUA_FLOORN2I 0
#endif
#define tonumber(o,n) \
(ttisfloat(o) ? (*(n) = fltvalue(o), 1) : luaV_tonumber_(o,n))
#define tointeger(o,i) \
(ttisinteger(o) ? (*(i) = ivalue(o), 1) : luaV_tointeger(o,i,LUA_FLOORN2I))
#define intop(op,v1,v2) l_castU2S(l_castS2U(v1) op l_castS2U(v2))
#define luaV_rawequalobj(t1,t2) luaV_equalobj(NULL,t1,t2)
/*
** fast track for 'gettable': if 't' is a table and 't[k]' is not nil,
** return 1 with 'slot' pointing to 't[k]' (final result). Otherwise,
** return 0 (meaning it will have to check metamethod) with 'slot'
** pointing to a nil 't[k]' (if 't' is a table) or NULL (otherwise).
** 'f' is the raw get function to use.
*/
#define luaV_fastget(L,t,k,slot,f) \
(!ttistable(t) \
? (slot = NULL, 0) /* not a table; 'slot' is NULL and result is 0 */ \
: (slot = f(hvalue(t), k), /* else, do raw access */ \
!ttisnil(slot))) /* result not nil? */
/*
** standard implementation for 'gettable'
*/
#define luaV_gettable(L,t,k,v) { const TValue *slot; \
if (luaV_fastget(L,t,k,slot,luaH_get)) { setobj2s(L, v, slot); } \
else luaV_finishget(L,t,k,v,slot); }
/*
** Fast track for set table. If 't' is a table and 't[k]' is not nil,
** call GC barrier, do a raw 't[k]=v', and return true; otherwise,
** return false with 'slot' equal to NULL (if 't' is not a table) or
** 'nil'. (This is needed by 'luaV_finishget'.) Note that, if the macro
** returns true, there is no need to 'invalidateTMcache', because the
** call is not creating a new entry.
*/
#define luaV_fastset(L,t,k,slot,f,v) \
(!ttistable(t) \
? (slot = NULL, 0) \
: (slot = f(hvalue(t), k), \
ttisnil(slot) ? 0 \
: (luaC_barrierback(L, hvalue(t), v), \
setobj2t(L, cast(TValue *,slot), v), \
1)))
#define luaV_settable(L,t,k,v) { const TValue *slot; \
if (!luaV_fastset(L,t,k,slot,luaH_get,v)) \
luaV_finishset(L,t,k,v,slot); }
LUAI_FUNC int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2);
LUAI_FUNC int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r);
LUAI_FUNC int luaV_lessequal (lua_State *L, const TValue *l, const TValue *r);
LUAI_FUNC int luaV_tonumber_ (const TValue *obj, lua_Number *n);
LUAI_FUNC int luaV_tointeger (const TValue *obj, lua_Integer *p, int mode);
LUAI_FUNC void luaV_finishget (lua_State *L, const TValue *t, TValue *key,
StkId val, const TValue *slot);
LUAI_FUNC void luaV_finishset (lua_State *L, const TValue *t, TValue *key,
StkId val, const TValue *slot);
LUAI_FUNC void luaV_finishOp (lua_State *L);
LUAI_FUNC void luaV_execute (lua_State *L);
LUAI_FUNC void luaV_concat (lua_State *L, int total);
LUAI_FUNC lua_Integer luaV_div (lua_State *L, lua_Integer x, lua_Integer y);
LUAI_FUNC lua_Integer luaV_mod (lua_State *L, lua_Integer x, lua_Integer y);
LUAI_FUNC lua_Integer luaV_shiftl (lua_Integer x, lua_Integer y);
LUAI_FUNC void luaV_objlen (lua_State *L, StkId ra, const TValue *rb);
#endiflvm.h 定义了几个跟 table 相关的宏，还声明了些方法，最重要的应该是 luaV_execute 了吧，这个方法在 ldo.c 也调用到。
#define LUA_CORE
#include "lprefix.h"
#include <float.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lua.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"
/* limit for table tag-method chains (to avoid loops) */
#define MAXTAGLOOP 2000
/*
** 'l_intfitsf' checks whether a given integer can be converted to a
** float without rounding. Used in comparisons. Left undefined if
** all integers fit in a float precisely.
*/
#if !defined(l_intfitsf)
/* number of bits in the mantissa of a float */
#define NBM (l_mathlim(MANT_DIG))
/*
** Check whether some integers may not fit in a float, that is, whether
** (maxinteger >> NBM) > 0 (that implies (1 << NBM) <= maxinteger).
** (The shifts are done in parts to avoid shifting by more than the size
** of an integer. In a worst case, NBM == 113 for long double and
** sizeof(integer) == 32.)
*/
#if ((((LUA_MAXINTEGER >> (NBM / 4)) >> (NBM / 4)) >> (NBM / 4)) \
>> (NBM - (3 * (NBM / 4)))) > 0
#define l_intfitsf(i) \
(-((lua_Integer)1 << NBM) <= (i) && (i) <= ((lua_Integer)1 << NBM))
#endif
#endif
/*
** Try to convert a value to a float. The float case is already handled
** by the macro 'tonumber'.
*/
int luaV_tonumber_ (const TValue *obj, lua_Number *n) {
TValue v;
if (ttisinteger(obj)) {
*n = cast_num(ivalue(obj));
return 1;
}
else if (cvt2num(obj) && /* string convertible to number? */
luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
*n = nvalue(&v); /* convert result of 'luaO_str2num' to a float */
return 1;
}
else
return 0; /* conversion failed */
}
/*
** try to convert a value to an integer, rounding according to 'mode':
** mode == 0: accepts only integral values
** mode == 1: takes the floor of the number
** mode == 2: takes the ceil of the number
*/
int luaV_tointeger (const TValue *obj, lua_Integer *p, int mode) {
TValue v;
again:
if (ttisfloat(obj)) {
lua_Number n = fltvalue(obj);
lua_Number f = l_floor(n);
if (n != f) { /* not an integral value? */
if (mode == 0) return 0; /* fails if mode demands integral value */
else if (mode > 1) /* needs ceil? */
f += 1; /* convert floor to ceil (remember: n != f) */
}
return lua_numbertointeger(f, p);
}
else if (ttisinteger(obj)) {
*p = ivalue(obj);
return 1;
}
else if (cvt2num(obj) &&
luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
obj = &v;
goto again; /* convert result from 'luaO_str2num' to an integer */
}
return 0; /* conversion failed */
}
/*
** Try to convert a 'for' limit to an integer, preserving the
** semantics of the loop.
** (The following explanation assumes a non-negative step; it is valid
** for negative steps mutatis mutandis.)
** If the limit can be converted to an integer, rounding down, that is
** it.
** Otherwise, check whether the limit can be converted to a number. If
** the number is too large, it is OK to set the limit as LUA_MAXINTEGER,
** which means no limit. If the number is too negative, the loop
** should not run, because any initial integer value is larger than the
** limit. So, it sets the limit to LUA_MININTEGER. 'stopnow' corrects
** the extreme case when the initial value is LUA_MININTEGER, in which
** case the LUA_MININTEGER limit would still run the loop once.
*/
static int forlimit (const TValue *obj, lua_Integer *p, lua_Integer step,
int *stopnow) {
*stopnow = 0; /* usually, let loops run */
if (!luaV_tointeger(obj, p, (step < 0 ? 2 : 1))) { /* not fit in integer? */
lua_Number n; /* try to convert to float */
if (!tonumber(obj, &n)) /* cannot convert to float? */
return 0; /* not a number */
if (luai_numlt(0, n)) { /* if true, float is larger than max integer */
*p = LUA_MAXINTEGER;
if (step < 0) *stopnow = 1;
}
else { /* float is smaller than min integer */
*p = LUA_MININTEGER;
if (step >= 0) *stopnow = 1;
}
}
return 1;
}
/*
** Finish the table access 'val = t[key]'.
** if 'slot' is NULL, 't' is not a table; otherwise, 'slot' points to
** t[k] entry (which must be nil).
*/
void luaV_finishget (lua_State *L, const TValue *t, TValue *key, StkId val,
const TValue *slot) {
int loop; /* counter to avoid infinite loops */
const TValue *tm; /* metamethod */
for (loop = 0; loop < MAXTAGLOOP; loop++) {
if (slot == NULL) { /* 't' is not a table? */
lua_assert(!ttistable(t));
tm = luaT_gettmbyobj(L, t, TM_INDEX);
if (ttisnil(tm))
luaG_typeerror(L, t, "index"); /* no metamethod */
/* else will try the metamethod */
}
else { /* 't' is a table */
lua_assert(ttisnil(slot));
tm = fasttm(L, hvalue(t)->metatable, TM_INDEX); /* table's metamethod */
if (tm == NULL) { /* no metamethod? */
setnilvalue(val); /* result is nil */
return;
}
/* else will try the metamethod */
}
if (ttisfunction(tm)) { /* is metamethod a function? */
luaT_callTM(L, tm, t, key, val, 1); /* call it */
return;
}
t = tm; /* else try to access 'tm[key]' */
if (luaV_fastget(L,t,key,slot,luaH_get)) { /* fast track? */
setobj2s(L, val, slot); /* done */
return;
}
/* else repeat (tail call 'luaV_finishget') */
}
luaG_runerror(L, "'__index' chain too long; possible loop");
}
/*
** Finish a table assignment 't[key] = val'.
** If 'slot' is NULL, 't' is not a table. Otherwise, 'slot' points
** to the entry 't[key]', or to 'luaO_nilobject' if there is no such
** entry. (The value at 'slot' must be nil, otherwise 'luaV_fastset'
** would have done the job.)
*/
void luaV_finishset (lua_State *L, const TValue *t, TValue *key,
StkId val, const TValue *slot) {
int loop; /* counter to avoid infinite loops */
for (loop = 0; loop < MAXTAGLOOP; loop++) {
const TValue *tm; /* '__newindex' metamethod */
if (slot != NULL) { /* is 't' a table? */
Table *h = hvalue(t); /* save 't' table */
lua_assert(ttisnil(slot)); /* old value must be nil */
tm = fasttm(L, h->metatable, TM_NEWINDEX); /* get metamethod */
if (tm == NULL) { /* no metamethod? */
if (slot == luaO_nilobject) /* no previous entry? */
slot = luaH_newkey(L, h, key); /* create one */
/* no metamethod and (now) there is an entry with given key */
setobj2t(L, cast(TValue *, slot), val); /* set its new value */
invalidateTMcache(h);
luaC_barrierback(L, h, val);
return;
}
/* else will try the metamethod */
}
else { /* not a table; check metamethod */
if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
luaG_typeerror(L, t, "index");
}
/* try the metamethod */
if (ttisfunction(tm)) {
luaT_callTM(L, tm, t, key, val, 0);
return;
}
t = tm; /* else repeat assignment over 'tm' */
if (luaV_fastset(L, t, key, slot, luaH_get, val))
return; /* done */
/* else loop */
}
luaG_runerror(L, "'__newindex' chain too long; possible loop");
}
/*
** Compare two strings 'ls' x 'rs', returning an integer smaller-equal-
** -larger than zero if 'ls' is smaller-equal-larger than 'rs'.
** The code is a little tricky because it allows '\0' in the strings
** and it uses 'strcoll' (to respect locales) for each segments
** of the strings.
*/
static int l_strcmp (const TString *ls, const TString *rs) {
const char *l = getstr(ls);
size_t ll = tsslen(ls);
const char *r = getstr(rs);
size_t lr = tsslen(rs);
for (;;) { /* for each segment */
int temp = strcoll(l, r);
if (temp != 0) /* not equal? */
return temp; /* done */
else { /* strings are equal up to a '\0' */
size_t len = strlen(l); /* index of first '\0' in both strings */
if (len == lr) /* 'rs' is finished? */
return (len == ll) ? 0 : 1; /* check 'ls' */
else if (len == ll) /* 'ls' is finished? */
return -1; /* 'ls' is smaller than 'rs' ('rs' is not finished) */
/* both strings longer than 'len'; go on comparing after the '\0' */
len++;
l += len; ll -= len; r += len; lr -= len;
}
}
}
/*
** Check whether integer 'i' is less than float 'f'. If 'i' has an
** exact representation as a float ('l_intfitsf'), compare numbers as
** floats. Otherwise, if 'f' is outside the range for integers, result
** is trivial. Otherwise, compare them as integers. (When 'i' has no
** float representation, either 'f' is "far away" from 'i' or 'f' has
** no precision left for a fractional part; either way, how 'f' is
** truncated is irrelevant.) When 'f' is NaN, comparisons must result
** in false.
*/
static int LTintfloat (lua_Integer i, lua_Number f) {
#if defined(l_intfitsf)
if (!l_intfitsf(i)) {
if (f >= -cast_num(LUA_MININTEGER)) /* -minint == maxint + 1 */
return 1; /* f >= maxint + 1 > i */
else if (f > cast_num(LUA_MININTEGER)) /* minint < f <= maxint ? */
return (i < cast(lua_Integer, f)); /* compare them as integers */
else /* f <= minint <= i (or 'f' is NaN) --> not(i < f) */
return 0;
}
#endif
return luai_numlt(cast_num(i), f); /* compare them as floats */
}
/*
** Check whether integer 'i' is less than or equal to float 'f'.
** See comments on previous function.
*/
static int LEintfloat (lua_Integer i, lua_Number f) {
#if defined(l_intfitsf)
if (!l_intfitsf(i)) {
if (f >= -cast_num(LUA_MININTEGER)) /* -minint == maxint + 1 */
return 1; /* f >= maxint + 1 > i */
else if (f >= cast_num(LUA_MININTEGER)) /* minint <= f <= maxint ? */
return (i <= cast(lua_Integer, f)); /* compare them as integers */
else /* f < minint <= i (or 'f' is NaN) --> not(i <= f) */
return 0;
}
#endif
return luai_numle(cast_num(i), f); /* compare them as floats */
}
/*
** Return 'l < r', for numbers.
*/
static int LTnum (const TValue *l, const TValue *r) {
if (ttisinteger(l)) {
lua_Integer li = ivalue(l);
if (ttisinteger(r))
return li < ivalue(r); /* both are integers */
else /* 'l' is int and 'r' is float */
return LTintfloat(li, fltvalue(r)); /* l < r ? */
}
else {
lua_Number lf = fltvalue(l); /* 'l' must be float */
if (ttisfloat(r))
return luai_numlt(lf, fltvalue(r)); /* both are float */
else if (luai_numisnan(lf)) /* 'r' is int and 'l' is float */
return 0; /* NaN < i is always false */
else /* without NaN, (l < r) <--> not(r <= l) */
return !LEintfloat(ivalue(r), lf); /* not (r <= l) ? */
}
}
/*
** Return 'l <= r', for numbers.
*/
static int LEnum (const TValue *l, const TValue *r) {
if (ttisinteger(l)) {
lua_Integer li = ivalue(l);
if (ttisinteger(r))
return li <= ivalue(r); /* both are integers */
else /* 'l' is int and 'r' is float */
return LEintfloat(li, fltvalue(r)); /* l <= r ? */
}
else {
lua_Number lf = fltvalue(l); /* 'l' must be float */
if (ttisfloat(r))
return luai_numle(lf, fltvalue(r)); /* both are float */
else if (luai_numisnan(lf)) /* 'r' is int and 'l' is float */
return 0; /* NaN <= i is always false */
else /* without NaN, (l <= r) <--> not(r < l) */
return !LTintfloat(ivalue(r), lf); /* not (r < l) ? */
}
}
/*
** Main operation less than; return 'l < r'.
*/
int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r) {
int res;
if (ttisnumber(l) && ttisnumber(r)) /* both operands are numbers? */
return LTnum(l, r);
else if (ttisstring(l) && ttisstring(r)) /* both are strings? */
return l_strcmp(tsvalue(l), tsvalue(r)) < 0;
else if ((res = luaT_callorderTM(L, l, r, TM_LT)) < 0) /* no metamethod? */
luaG_ordererror(L, l, r); /* error */
return res;
}
/*
** Main operation less than or equal to; return 'l <= r'. If it needs
** a metamethod and there is no '__le', try '__lt', based on
** l <= r iff !(r < l) (assuming a total order). If the metamethod
** yields during this substitution, the continuation has to know
** about it (to negate the result of r<l); bit CIST_LEQ in the call
** status keeps that information.
*/
int luaV_lessequal (lua_State *L, const TValue *l, const TValue *r) {
int res;
if (ttisnumber(l) && ttisnumber(r)) /* both operands are numbers? */
return LEnum(l, r);
else if (ttisstring(l) && ttisstring(r)) /* both are strings? */
return l_strcmp(tsvalue(l), tsvalue(r)) <= 0;
else if ((res = luaT_callorderTM(L, l, r, TM_LE)) >= 0) /* try 'le' */
return res;
else { /* try 'lt': */
L->ci->callstatus |= CIST_LEQ; /* mark it is doing 'lt' for 'le' */
res = luaT_callorderTM(L, r, l, TM_LT);
L->ci->callstatus ^= CIST_LEQ; /* clear mark */
if (res < 0)
luaG_ordererror(L, l, r);
return !res; /* result is negated */
}
}
/*
** Main operation for equality of Lua values; return 't1 == t2'.
** L == NULL means raw equality (no metamethods)
*/
int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2) {
const TValue *tm;
if (ttype(t1) != ttype(t2)) { /* not the same variant? */
if (ttnov(t1) != ttnov(t2) || ttnov(t1) != LUA_TNUMBER)
return 0; /* only numbers can be equal with different variants */
else { /* two numbers with different variants */
lua_Integer i1, i2; /* compare them as integers */
return (tointeger(t1, &i1) && tointeger(t2, &i2) && i1 == i2);
}
}
/* values have same type and same variant */
switch (ttype(t1)) {
case LUA_TNIL: return 1;
case LUA_TNUMINT: return (ivalue(t1) == ivalue(t2));
case LUA_TNUMFLT: return luai_numeq(fltvalue(t1), fltvalue(t2));
case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2); /* true must be 1 !! */
case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);
case LUA_TLCF: return fvalue(t1) == fvalue(t2);
case LUA_TSHRSTR: return eqshrstr(tsvalue(t1), tsvalue(t2));
case LUA_TLNGSTR: return luaS_eqlngstr(tsvalue(t1), tsvalue(t2));
case LUA_TUSERDATA: {
if (uvalue(t1) == uvalue(t2)) return 1;
else if (L == NULL) return 0;
tm = fasttm(L, uvalue(t1)->metatable, TM_EQ);
if (tm == NULL)
tm = fasttm(L, uvalue(t2)->metatable, TM_EQ);
break; /* will try TM */
}
case LUA_TTABLE: {
if (hvalue(t1) == hvalue(t2)) return 1;
else if (L == NULL) return 0;
tm = fasttm(L, hvalue(t1)->metatable, TM_EQ);
if (tm == NULL)
tm = fasttm(L, hvalue(t2)->metatable, TM_EQ);
break; /* will try TM */
}
default:
return gcvalue(t1) == gcvalue(t2);
}
if (tm == NULL) /* no TM? */
return 0; /* objects are different */
luaT_callTM(L, tm, t1, t2, L->top, 1); /* call TM */
return !l_isfalse(L->top);
}
/* macro used by 'luaV_concat' to ensure that element at 'o' is a string */
#define tostring(L,o) \
(ttisstring(o) || (cvt2str(o) && (luaO_tostring(L, o), 1)))
#define isemptystr(o) (ttisshrstring(o) && tsvalue(o)->shrlen == 0)
/* copy strings in stack from top - n up to top - 1 to buffer */
static void copy2buff (StkId top, int n, char *buff) {
size_t tl = 0; /* size already copied */
do {
size_t l = vslen(top - n); /* length of string being copied */
memcpy(buff + tl, svalue(top - n), l * sizeof(char));
tl += l;
} while (--n > 0);
}
/*
** Main operation for concatenation: concat 'total' values in the stack,
** from 'L->top - total' up to 'L->top - 1'.
*/
void luaV_concat (lua_State *L, int total) {
lua_assert(total >= 2);
do {
StkId top = L->top;
int n = 2; /* number of elements handled in this pass (at least 2) */
if (!(ttisstring(top-2) || cvt2str(top-2)) || !tostring(L, top-1))
luaT_trybinTM(L, top-2, top-1, top-2, TM_CONCAT);
else if (isemptystr(top - 1)) /* second operand is empty? */
cast_void(tostring(L, top - 2)); /* result is first operand */
else if (isemptystr(top - 2)) { /* first operand is an empty string? */
setobjs2s(L, top - 2, top - 1); /* result is second op. */
}
else {
/* at least two non-empty string values; get as many as possible */
size_t tl = vslen(top - 1);
TString *ts;
/* collect total length and number of strings */
for (n = 1; n < total && tostring(L, top - n - 1); n++) {
size_t l = vslen(top - n - 1);
if (l >= (MAX_SIZE/sizeof(char)) - tl)
luaG_runerror(L, "string length overflow");
tl += l;
}
if (tl <= LUAI_MAXSHORTLEN) { /* is result a short string? */
char buff[LUAI_MAXSHORTLEN];
copy2buff(top, n, buff); /* copy strings to buffer */
ts = luaS_newlstr(L, buff, tl);
}
else { /* long string; copy strings directly to final result */
ts = luaS_createlngstrobj(L, tl);
copy2buff(top, n, getstr(ts));
}
setsvalue2s(L, top - n, ts); /* create result */
}
total -= n-1; /* got 'n' strings to create 1 new */
L->top -= n-1; /* popped 'n' strings and pushed one */
} while (total > 1); /* repeat until only 1 result left */
}
/*
** Main operation 'ra' = #rb'.
*/
void luaV_objlen (lua_State *L, StkId ra, const TValue *rb) {
const TValue *tm;
switch (ttype(rb)) {
case LUA_TTABLE: {
Table *h = hvalue(rb);
tm = fasttm(L, h->metatable, TM_LEN);
if (tm) break; /* metamethod? break switch to call it */
setivalue(ra, luaH_getn(h)); /* else primitive len */
return;
}
case LUA_TSHRSTR: {
setivalue(ra, tsvalue(rb)->shrlen);
return;
}
case LUA_TLNGSTR: {
setivalue(ra, tsvalue(rb)->u.lnglen);
return;
}
default: { /* try metamethod */
tm = luaT_gettmbyobj(L, rb, TM_LEN);
if (ttisnil(tm)) /* no metamethod? */
luaG_typeerror(L, rb, "get length of");
break;
}
}
luaT_callTM(L, tm, rb, rb, ra, 1);
}
/*
** Integer division; return 'm // n', that is, floor(m/n).
** C division truncates its result (rounds towards zero).
** 'floor(q) == trunc(q)' when 'q >= 0' or when 'q' is integer,
** otherwise 'floor(q) == trunc(q) - 1'.
*/
lua_Integer luaV_div (lua_State *L, lua_Integer m, lua_Integer n) {
if (l_castS2U(n) + 1u <= 1u) { /* special cases: -1 or 0 */
if (n == 0)
luaG_runerror(L, "attempt to divide by zero");
return intop(-, 0, m); /* n==-1; avoid overflow with 0x80000...//-1 */
}
else {
lua_Integer q = m / n; /* perform C division */
if ((m ^ n) < 0 && m % n != 0) /* 'm/n' would be negative non-integer? */
q -= 1; /* correct result for different rounding */
return q;
}
}
/*
** Integer modulus; return 'm % n'. (Assume that C '%' with
** negative operands follows C99 behavior. See previous comment
** about luaV_div.)
*/
lua_Integer luaV_mod (lua_State *L, lua_Integer m, lua_Integer n) {
if (l_castS2U(n) + 1u <= 1u) { /* special cases: -1 or 0 */
if (n == 0)
luaG_runerror(L, "attempt to perform 'n%%0'");
return 0; /* m % -1 == 0; avoid overflow with 0x80000...%-1 */
}
else {
lua_Integer r = m % n;
if (r != 0 && (m ^ n) < 0) /* 'm/n' would be non-integer negative? */
r += n; /* correct result for different rounding */
return r;
}
}
/* number of bits in an integer */
#define NBITS cast_int(sizeof(lua_Integer) * CHAR_BIT)
/*
** Shift left operation. (Shift right just negates 'y'.)
*/
lua_Integer luaV_shiftl (lua_Integer x, lua_Integer y) {
if (y < 0) { /* shift right? */
if (y <= -NBITS) return 0;
else return intop(>>, x, -y);
}
else { /* shift left */
if (y >= NBITS) return 0;
else return intop(<<, x, y);
}
}
/*
** check whether cached closure in prototype 'p' may be reused, that is,
** whether there is a cached closure with the same upvalues needed by
** new closure to be created.
*/
static LClosure *getcached (Proto *p, UpVal **encup, StkId base) {
LClosure *c = p->cache;
if (c != NULL) { /* is there a cached closure? */
int nup = p->sizeupvalues;
Upvaldesc *uv = p->upvalues;
int i;
for (i = 0; i < nup; i++) { /* check whether it has right upvalues */
TValue *v = uv[i].instack ? base + uv[i].idx : encup[uv[i].idx]->v;
if (c->upvals[i]->v != v)
return NULL; /* wrong upvalue; cannot reuse closure */
}
}
return c; /* return cached closure (or NULL if no cached closure) */
}
/*
** create a new Lua closure, push it in the stack, and initialize
** its upvalues. Note that the closure is not cached if prototype is
** already black (which means that 'cache' was already cleared by the
** GC).
*/
static void pushclosure (lua_State *L, Proto *p, UpVal **encup, StkId base,
StkId ra) {
int nup = p->sizeupvalues;
Upvaldesc *uv = p->upvalues;
int i;
LClosure *ncl = luaF_newLclosure(L, nup);
ncl->p = p;
setclLvalue(L, ra, ncl); /* anchor new closure in stack */
for (i = 0; i < nup; i++) { /* fill in its upvalues */
if (uv[i].instack) /* upvalue refers to local variable? */
ncl->upvals[i] = luaF_findupval(L, base + uv[i].idx);
else /* get upvalue from enclosing function */
ncl->upvals[i] = encup[uv[i].idx];
ncl->upvals[i]->refcount++;
/* new closure is white, so we do not need a barrier here */
}
if (!isblack(p)) /* cache will not break GC invariant? */
p->cache = ncl; /* save it on cache for reuse */
}
/*
** finish execution of an opcode interrupted by an yield
*/
void luaV_finishOp (lua_State *L) {
CallInfo *ci = L->ci;
StkId base = ci->u.l.base;
Instruction inst = *(ci->u.l.savedpc - 1); /* interrupted instruction */
OpCode op = GET_OPCODE(inst);
switch (op) { /* finish its execution */
case OP_ADD: case OP_SUB: case OP_MUL: case OP_DIV: case OP_IDIV:
case OP_BAND: case OP_BOR: case OP_BXOR: case OP_SHL: case OP_SHR:
case OP_MOD: case OP_POW:
case OP_UNM: case OP_BNOT: case OP_LEN:
case OP_GETTABUP: case OP_GETTABLE: case OP_SELF: {
setobjs2s(L, base + GETARG_A(inst), --L->top);
break;
}
case OP_LE: case OP_LT: case OP_EQ: {
int res = !l_isfalse(L->top - 1);
L->top--;
if (ci->callstatus & CIST_LEQ) { /* "<=" using "<" instead? */
lua_assert(op == OP_LE);
ci->callstatus ^= CIST_LEQ; /* clear mark */
res = !res; /* negate result */
}
lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_JMP);
if (res != GETARG_A(inst)) /* condition failed? */
ci->u.l.savedpc++; /* skip jump instruction */
break;
}
case OP_CONCAT: {
StkId top = L->top - 1; /* top when 'luaT_trybinTM' was called */
int b = GETARG_B(inst); /* first element to concatenate */
int total = cast_int(top - 1 - (base + b)); /* yet to concatenate */
setobj2s(L, top - 2, top); /* put TM result in proper position */
if (total > 1) { /* are there elements to concat? */
L->top = top - 1; /* top is one after last element (at top-2) */
luaV_concat(L, total); /* concat them (may yield again) */
}
/* move final result to final position */
setobj2s(L, ci->u.l.base + GETARG_A(inst), L->top - 1);
L->top = ci->top; /* restore top */
break;
}
case OP_TFORCALL: {
lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_TFORLOOP);
L->top = ci->top; /* correct top */
break;
}
case OP_CALL: {
if (GETARG_C(inst) - 1 >= 0) /* nresults >= 0? */
L->top = ci->top; /* adjust results */
break;
}
case OP_TAILCALL: case OP_SETTABUP: case OP_SETTABLE:
break;
default: lua_assert(0);
}
}lvm.c 的前部分定义了一些在 luaV_execute 使用的函数，简单是那些 number 的对比函数，复杂的就是跟执行相关了。
/*
** some macros for common tasks in 'luaV_execute'
*/
#define RA(i) (base+GETARG_A(i))
#define RB(i) check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
#define RC(i) check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
#define RKB(i) check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
#define RKC(i) check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
/* execute a jump instruction */
#define dojump(ci,i,e) \
{ int a = GETARG_A(i); \
if (a != 0) luaF_close(L, ci->u.l.base + a - 1); \
ci->u.l.savedpc += GETARG_sBx(i) + e; }
/* for test instructions, execute the jump instruction that follows it */
#define donextjump(ci) { i = *ci->u.l.savedpc; dojump(ci, i, 1); }
#define Protect(x) { {x;}; base = ci->u.l.base; }
#define checkGC(L,c) \
{ luaC_condGC(L, L->top = (c), /* limit of live values */ \
Protect(L->top = ci->top)); /* restore top */ \
luai_threadyield(L); }
/* fetch an instruction and prepare its execution */
#define vmfetch() { \
i = *(ci->u.l.savedpc++); \
if (L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) \
Protect(luaG_traceexec(L)); \
ra = RA(i); /* WARNING: any stack reallocation invalidates 'ra' */ \
lua_assert(base == ci->u.l.base); \
lua_assert(base <= L->top && L->top < L->stack + L->stacksize); \
}
#define vmdispatch(o) switch(o)
#define vmcase(l) case l:
#define vmbreak break
/*
** copy of 'luaV_gettable', but protecting the call to potential
** metamethod (which can reallocate the stack)
*/
#define gettableProtected(L,t,k,v) { const TValue *slot; \
if (luaV_fastget(L,t,k,slot,luaH_get)) { setobj2s(L, v, slot); } \
else Protect(luaV_finishget(L,t,k,v,slot)); }
/* same for 'luaV_settable' */
#define settableProtected(L,t,k,v) { const TValue *slot; \
if (!luaV_fastset(L,t,k,slot,luaH_get,v)) \
Protect(luaV_finishset(L,t,k,v,slot)); }
void luaV_execute (lua_State *L) {
CallInfo *ci = L->ci;
LClosure *cl;
TValue *k;
StkId base;
ci->callstatus |= CIST_FRESH; /* fresh invocation of 'luaV_execute" */
newframe: /* reentry point when frame changes (call/return) */
lua_assert(ci == L->ci);
cl = clLvalue(ci->func); /* local reference to function's closure */
k = cl->p->k; /* local reference to function's constant table */
base = ci->u.l.base; /* local copy of function's base */
/* main loop of interpreter */
for (;;) {
Instruction i;
StkId ra;
vmfetch();
vmdispatch (GET_OPCODE(i)) {
vmcase(OP_MOVE) {
setobjs2s(L, ra, RB(i));
vmbreak;
}
vmcase(OP_LOADK) {
TValue *rb = k + GETARG_Bx(i);
setobj2s(L, ra, rb);
vmbreak;
}
vmcase(OP_LOADKX) {
TValue *rb;
lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
rb = k + GETARG_Ax(*ci->u.l.savedpc++);
setobj2s(L, ra, rb);
vmbreak;
}
vmcase(OP_LOADBOOL) {
setbvalue(ra, GETARG_B(i));
if (GETARG_C(i)) ci->u.l.savedpc++; /* skip next instruction (if C) */
vmbreak;
}
vmcase(OP_LOADNIL) {
int b = GETARG_B(i);
do {
setnilvalue(ra++);
} while (b--);
vmbreak;
}
vmcase(OP_GETUPVAL) {
int b = GETARG_B(i);
setobj2s(L, ra, cl->upvals[b]->v);
vmbreak;
}
vmcase(OP_GETTABUP) {
TValue *upval = cl->upvals[GETARG_B(i)]->v;
TValue *rc = RKC(i);
gettableProtected(L, upval, rc, ra);
vmbreak;
}
vmcase(OP_GETTABLE) {
StkId rb = RB(i);
TValue *rc = RKC(i);
gettableProtected(L, rb, rc, ra);
vmbreak;
}
vmcase(OP_SETTABUP) {
TValue *upval = cl->upvals[GETARG_A(i)]->v;
TValue *rb = RKB(i);
TValue *rc = RKC(i);
settableProtected(L, upval, rb, rc);
vmbreak;
}
vmcase(OP_SETUPVAL) {
UpVal *uv = cl->upvals[GETARG_B(i)];
setobj(L, uv->v, ra);
luaC_upvalbarrier(L, uv);
vmbreak;
}
vmcase(OP_SETTABLE) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
settableProtected(L, ra, rb, rc);
vmbreak;
}
vmcase(OP_NEWTABLE) {
int b = GETARG_B(i);
int c = GETARG_C(i);
Table *t = luaH_new(L);
sethvalue(L, ra, t);
if (b != 0 || c != 0)
luaH_resize(L, t, luaO_fb2int(b), luaO_fb2int(c));
checkGC(L, ra + 1);
vmbreak;
}
vmcase(OP_SELF) {
const TValue *aux;
StkId rb = RB(i);
TValue *rc = RKC(i);
TString *key = tsvalue(rc); /* key must be a string */
setobjs2s(L, ra + 1, rb);
if (luaV_fastget(L, rb, key, aux, luaH_getstr)) {
setobj2s(L, ra, aux);
}
else Protect(luaV_finishget(L, rb, rc, ra, aux));
vmbreak;
}
vmcase(OP_ADD) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Number nb; lua_Number nc;
if (ttisinteger(rb) && ttisinteger(rc)) {
lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
setivalue(ra, intop(+, ib, ic));
}
else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
setfltvalue(ra, luai_numadd(L, nb, nc));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_ADD)); }
vmbreak;
}
vmcase(OP_SUB) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Number nb; lua_Number nc;
if (ttisinteger(rb) && ttisinteger(rc)) {
lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
setivalue(ra, intop(-, ib, ic));
}
else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
setfltvalue(ra, luai_numsub(L, nb, nc));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SUB)); }
vmbreak;
}
vmcase(OP_MUL) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Number nb; lua_Number nc;
if (ttisinteger(rb) && ttisinteger(rc)) {
lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
setivalue(ra, intop(*, ib, ic));
}
else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
setfltvalue(ra, luai_nummul(L, nb, nc));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_MUL)); }
vmbreak;
}
vmcase(OP_DIV) { /* float division (always with floats) */
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Number nb; lua_Number nc;
if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
setfltvalue(ra, luai_numdiv(L, nb, nc));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_DIV)); }
vmbreak;
}
vmcase(OP_BAND) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Integer ib; lua_Integer ic;
if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
setivalue(ra, intop(&, ib, ic));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BAND)); }
vmbreak;
}
vmcase(OP_BOR) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Integer ib; lua_Integer ic;
if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
setivalue(ra, intop(|, ib, ic));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BOR)); }
vmbreak;
}
vmcase(OP_BXOR) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Integer ib; lua_Integer ic;
if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
setivalue(ra, intop(^, ib, ic));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BXOR)); }
vmbreak;
}
vmcase(OP_SHL) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Integer ib; lua_Integer ic;
if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
setivalue(ra, luaV_shiftl(ib, ic));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SHL)); }
vmbreak;
}
vmcase(OP_SHR) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Integer ib; lua_Integer ic;
if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
setivalue(ra, luaV_shiftl(ib, -ic));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SHR)); }
vmbreak;
}
vmcase(OP_MOD) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Number nb; lua_Number nc;
if (ttisinteger(rb) && ttisinteger(rc)) {
lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
setivalue(ra, luaV_mod(L, ib, ic));
}
else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
lua_Number m;
luai_nummod(L, nb, nc, m);
setfltvalue(ra, m);
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_MOD)); }
vmbreak;
}
vmcase(OP_IDIV) { /* floor division */
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Number nb; lua_Number nc;
if (ttisinteger(rb) && ttisinteger(rc)) {
lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
setivalue(ra, luaV_div(L, ib, ic));
}
else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
setfltvalue(ra, luai_numidiv(L, nb, nc));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_IDIV)); }
vmbreak;
}
vmcase(OP_POW) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Number nb; lua_Number nc;
if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
setfltvalue(ra, luai_numpow(L, nb, nc));
}
else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_POW)); }
vmbreak;
}
vmcase(OP_UNM) {
TValue *rb = RB(i);
lua_Number nb;
if (ttisinteger(rb)) {
lua_Integer ib = ivalue(rb);
setivalue(ra, intop(-, 0, ib));
}
else if (tonumber(rb, &nb)) {
setfltvalue(ra, luai_numunm(L, nb));
}
else {
Protect(luaT_trybinTM(L, rb, rb, ra, TM_UNM));
}
vmbreak;
}
vmcase(OP_BNOT) {
TValue *rb = RB(i);
lua_Integer ib;
if (tointeger(rb, &ib)) {
setivalue(ra, intop(^, ~l_castS2U(0), ib));
}
else {
Protect(luaT_trybinTM(L, rb, rb, ra, TM_BNOT));
}
vmbreak;
}
vmcase(OP_NOT) {
TValue *rb = RB(i);
int res = l_isfalse(rb); /* next assignment may change this value */
setbvalue(ra, res);
vmbreak;
}
vmcase(OP_LEN) {
Protect(luaV_objlen(L, ra, RB(i)));
vmbreak;
}
vmcase(OP_CONCAT) {
int b = GETARG_B(i);
int c = GETARG_C(i);
StkId rb;
L->top = base + c + 1; /* mark the end of concat operands */
Protect(luaV_concat(L, c - b + 1));
ra = RA(i); /* 'luaV_concat' may invoke TMs and move the stack */
rb = base + b;
setobjs2s(L, ra, rb);
checkGC(L, (ra >= rb ? ra + 1 : rb));
L->top = ci->top; /* restore top */
vmbreak;
}
vmcase(OP_JMP) {
dojump(ci, i, 0);
vmbreak;
}
vmcase(OP_EQ) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
Protect(
if (luaV_equalobj(L, rb, rc) != GETARG_A(i))
ci->u.l.savedpc++;
else
donextjump(ci);
)
vmbreak;
}
vmcase(OP_LT) {
Protect(
if (luaV_lessthan(L, RKB(i), RKC(i)) != GETARG_A(i))
ci->u.l.savedpc++;
else
donextjump(ci);
)
vmbreak;
}
vmcase(OP_LE) {
Protect(
if (luaV_lessequal(L, RKB(i), RKC(i)) != GETARG_A(i))
ci->u.l.savedpc++;
else
donextjump(ci);
)
vmbreak;
}
vmcase(OP_TEST) {
if (GETARG_C(i) ? l_isfalse(ra) : !l_isfalse(ra))
ci->u.l.savedpc++;
else
donextjump(ci);
vmbreak;
}
vmcase(OP_TESTSET) {
TValue *rb = RB(i);
if (GETARG_C(i) ? l_isfalse(rb) : !l_isfalse(rb))
ci->u.l.savedpc++;
else {
setobjs2s(L, ra, rb);
donextjump(ci);
}
vmbreak;
}
vmcase(OP_CALL) {
int b = GETARG_B(i);
int nresults = GETARG_C(i) - 1;
if (b != 0) L->top = ra+b; /* else previous instruction set top */
if (luaD_precall(L, ra, nresults)) { /* C function? */
if (nresults >= 0)
L->top = ci->top; /* adjust results */
Protect((void)0); /* update 'base' */
}
else { /* Lua function */
ci = L->ci;
goto newframe; /* restart luaV_execute over new Lua function */
}
vmbreak;
}
vmcase(OP_TAILCALL) {
int b = GETARG_B(i);
if (b != 0) L->top = ra+b; /* else previous instruction set top */
lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
if (luaD_precall(L, ra, LUA_MULTRET)) { /* C function? */
Protect((void)0); /* update 'base' */
}
else {
/* tail call: put called frame (n) in place of caller one (o) */
CallInfo *nci = L->ci; /* called frame */
CallInfo *oci = nci->previous; /* caller frame */
StkId nfunc = nci->func; /* called function */
StkId ofunc = oci->func; /* caller function */
/* last stack slot filled by 'precall' */
StkId lim = nci->u.l.base + getproto(nfunc)->numparams;
int aux;
/* close all upvalues from previous call */
if (cl->p->sizep > 0) luaF_close(L, oci->u.l.base);
/* move new frame into old one */
for (aux = 0; nfunc + aux < lim; aux++)
setobjs2s(L, ofunc + aux, nfunc + aux);
oci->u.l.base = ofunc + (nci->u.l.base - nfunc); /* correct base */
oci->top = L->top = ofunc + (L->top - nfunc); /* correct top */
oci->u.l.savedpc = nci->u.l.savedpc;
oci->callstatus |= CIST_TAIL; /* function was tail called */
ci = L->ci = oci; /* remove new frame */
lua_assert(L->top == oci->u.l.base + getproto(ofunc)->maxstacksize);
goto newframe; /* restart luaV_execute over new Lua function */
}
vmbreak;
}
vmcase(OP_RETURN) {
int b = GETARG_B(i);
if (cl->p->sizep > 0) luaF_close(L, base);
b = luaD_poscall(L, ci, ra, (b != 0 ? b - 1 : cast_int(L->top - ra)));
if (ci->callstatus & CIST_FRESH) /* local 'ci' still from callee */
return; /* external invocation: return */
else { /* invocation via reentry: continue execution */
ci = L->ci;
if (b) L->top = ci->top;
lua_assert(isLua(ci));
lua_assert(GET_OPCODE(*((ci)->u.l.savedpc - 1)) == OP_CALL);
goto newframe; /* restart luaV_execute over new Lua function */
}
}
vmcase(OP_FORLOOP) {
if (ttisinteger(ra)) { /* integer loop? */
lua_Integer step = ivalue(ra + 2);
lua_Integer idx = intop(+, ivalue(ra), step); /* increment index */
lua_Integer limit = ivalue(ra + 1);
if ((0 < step) ? (idx <= limit) : (limit <= idx)) {
ci->u.l.savedpc += GETARG_sBx(i); /* jump back */
chgivalue(ra, idx); /* update internal index... */
setivalue(ra + 3, idx); /* ...and external index */
}
}
else { /* floating loop */
lua_Number step = fltvalue(ra + 2);
lua_Number idx = luai_numadd(L, fltvalue(ra), step); /* inc. index */
lua_Number limit = fltvalue(ra + 1);
if (luai_numlt(0, step) ? luai_numle(idx, limit)
: luai_numle(limit, idx)) {
ci->u.l.savedpc += GETARG_sBx(i); /* jump back */
chgfltvalue(ra, idx); /* update internal index... */
setfltvalue(ra + 3, idx); /* ...and external index */
}
}
vmbreak;
}
vmcase(OP_FORPREP) {
TValue *init = ra;
TValue *plimit = ra + 1;
TValue *pstep = ra + 2;
lua_Integer ilimit;
int stopnow;
if (ttisinteger(init) && ttisinteger(pstep) &&
forlimit(plimit, &ilimit, ivalue(pstep), &stopnow)) {
/* all values are integer */
lua_Integer initv = (stopnow ? 0 : ivalue(init));
setivalue(plimit, ilimit);
setivalue(init, intop(-, initv, ivalue(pstep)));
}
else { /* try making all values floats */
lua_Number ninit; lua_Number nlimit; lua_Number nstep;
if (!tonumber(plimit, &nlimit))
luaG_runerror(L, "'for' limit must be a number");
setfltvalue(plimit, nlimit);
if (!tonumber(pstep, &nstep))
luaG_runerror(L, "'for' step must be a number");
setfltvalue(pstep, nstep);
if (!tonumber(init, &ninit))
luaG_runerror(L, "'for' initial value must be a number");
setfltvalue(init, luai_numsub(L, ninit, nstep));
}
ci->u.l.savedpc += GETARG_sBx(i);
vmbreak;
}
vmcase(OP_TFORCALL) {
StkId cb = ra + 3; /* call base */
setobjs2s(L, cb+2, ra+2);
setobjs2s(L, cb+1, ra+1);
setobjs2s(L, cb, ra);
L->top = cb + 3; /* func. + 2 args (state and index) */
Protect(luaD_call(L, cb, GETARG_C(i)));
L->top = ci->top;
i = *(ci->u.l.savedpc++); /* go to next instruction */
ra = RA(i);
lua_assert(GET_OPCODE(i) == OP_TFORLOOP);
goto l_tforloop;
}
vmcase(OP_TFORLOOP) {
l_tforloop:
if (!ttisnil(ra + 1)) { /* continue loop? */
setobjs2s(L, ra, ra + 1); /* save control variable */
ci->u.l.savedpc += GETARG_sBx(i); /* jump back */
}
vmbreak;
}
vmcase(OP_SETLIST) {
int n = GETARG_B(i);
int c = GETARG_C(i);
unsigned int last;
Table *h;
if (n == 0) n = cast_int(L->top - ra) - 1;
if (c == 0) {
lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
c = GETARG_Ax(*ci->u.l.savedpc++);
}
h = hvalue(ra);
last = ((c-1)*LFIELDS_PER_FLUSH) + n;
if (last > h->sizearray) /* needs more space? */
luaH_resizearray(L, h, last); /* preallocate it at once */
for (; n > 0; n--) {
TValue *val = ra+n;
luaH_setint(L, h, last--, val);
luaC_barrierback(L, h, val);
}
L->top = ci->top; /* correct top (in case of previous open call) */
vmbreak;
}
vmcase(OP_CLOSURE) {
Proto *p = cl->p->p[GETARG_Bx(i)];
LClosure *ncl = getcached(p, cl->upvals, base); /* cached closure */
if (ncl == NULL) /* no match? */
pushclosure(L, p, cl->upvals, base, ra); /* create a new one */
else
setclLvalue(L, ra, ncl); /* push cashed closure */
checkGC(L, ra + 1);
vmbreak;
}
vmcase(OP_VARARG) {
int b = GETARG_B(i) - 1; /* required results */
int j;
int n = cast_int(base - ci->func) - cl->p->numparams - 1;
if (n < 0) /* less arguments than parameters? */
n = 0; /* no vararg arguments */
if (b < 0) { /* B == 0? */
b = n; /* get all var. arguments */
Protect(luaD_checkstack(L, n));
ra = RA(i); /* previous call may change the stack */
L->top = ra + n;
}
for (j = 0; j < b && j < n; j++)
setobjs2s(L, ra + j, base - n + j);
for (; j < b; j++) /* complete required results with nil */
setnilvalue(ra + j);
vmbreak;
}
vmcase(OP_EXTRAARG) {
lua_assert(0);
vmbreak;
}
}
}
}lvm.c 的后半部分主要就是 luaV_execute 函数，里面就是 switch…case… 的内容。