/*
** $Id: ldebug.c $
** Debug Interface
** See Copyright Notice in lua.h
*/
#define ldebug_c
#define LUA_CORE
#include "lprefix.h"
#include <stdarg.h>
#include <stddef.h>
#include <string.h>
#include "lua.h"
#include "lapi.h"
#include "lcode.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"
#define noLuaClosure(f) ((f) == NULL || (f)->c.tt == LUA_VCCL)
static const char *funcnamefromcall (lua_State *L, CallInfo *ci,
const char **name);
static int currentpc (CallInfo *ci) {
lua_assert(isLua(ci));
return pcRel(ci->u.l.savedpc, ci_func(ci)->p);
}
/*
** Get a "base line" to find the line corresponding to an instruction.
** Base lines are regularly placed at MAXIWTHABS intervals, so usually
** an integer division gets the right place. When the source file has
** large sequences of empty/comment lines, it may need extra entries,
** so the original estimate needs a correction.
** If the original estimate is -1, the initial 'if' ensures that the
** 'while' will run at least once.
** The assertion that the estimate is a lower bound for the correct base
** is valid as long as the debug info has been generated with the same
** value for MAXIWTHABS or smaller. (Previous releases use a little
** smaller value.)
*/
static int getbaseline (const Proto *f, int pc, int *basepc) {
if (f->sizeabslineinfo == 0 || pc < f->abslineinfo[0].pc) {
*basepc = -1; /* start from the beginning */
return f->linedefined;
}
else {
int i = cast_uint(pc) / MAXIWTHABS - 1; /* get an estimate */
/* estimate must be a lower bound of the correct base */
lua_assert(i < 0 ||
(i < f->sizeabslineinfo && f->abslineinfo[i].pc <= pc));
while (i + 1 < f->sizeabslineinfo && pc >= f->abslineinfo[i + 1].pc)
i++; /* low estimate; adjust it */
*basepc = f->abslineinfo[i].pc;
return f->abslineinfo[i].line;
}
}
/*
** Get the line corresponding to instruction 'pc' in function 'f';
** first gets a base line and from there does the increments until
** the desired instruction.
*/
int luaG_getfuncline (const Proto *f, int pc) {
if (f->lineinfo == NULL) /* no debug information? */
return -1;
else {
int basepc;
int baseline = getbaseline(f, pc, &basepc);
while (basepc++ < pc) { /* walk until given instruction */
lua_assert(f->lineinfo[basepc] != ABSLINEINFO);
baseline += f->lineinfo[basepc]; /* correct line */
}
return baseline;
}
}
static int getcurrentline (CallInfo *ci) {
return luaG_getfuncline(ci_func(ci)->p, currentpc(ci));
}
/*
** Set 'trap' for all active Lua frames.
** This function can be called during a signal, under "reasonable"
** assumptions. A new 'ci' is completely linked in the list before it
** becomes part of the "active" list, and we assume that pointers are
** atomic; see comment in next function.
** (A compiler doing interprocedural optimizations could, theoretically,
** reorder memory writes in such a way that the list could be
** temporarily broken while inserting a new element. We simply assume it
** has no good reasons to do that.)
*/
static void settraps (CallInfo *ci) {
for (; ci != NULL; ci = ci->previous)
if (isLua(ci))
ci->u.l.trap = 1;
}
/*
** This function can be called during a signal, under "reasonable"
** assumptions.
** Fields 'basehookcount' and 'hookcount' (set by 'resethookcount')
** are for debug only, and it is no problem if they get arbitrary
** values (causes at most one wrong hook call). 'hookmask' is an atomic
** value. We assume that pointers are atomic too (e.g., gcc ensures that
** for all platforms where it runs). Moreover, 'hook' is always checked
** before being called (see 'luaD_hook').
*/
LUA_API void lua_sethook (lua_State *L, lua_Hook func, int mask, int count) {
if (func == NULL || mask == 0) { /* turn off hooks? */
mask = 0;
func = NULL;
}
L->hook = func;
L->basehookcount = count;
resethookcount(L);
L->hookmask = cast_byte(mask);
if (mask)
settraps(L->ci); /* to trace inside 'luaV_execute' */
}
LUA_API lua_Hook lua_gethook (lua_State *L) {
return L->hook;
}
LUA_API int lua_gethookmask (lua_State *L) {
return L->hookmask;
}
LUA_API int lua_gethookcount (lua_State *L) {
return L->basehookcount;
}
LUA_API int lua_getstack (lua_State *L, int level, lua_Debug *ar) {
int status;
CallInfo *ci;
if (level < 0) return 0; /* invalid (negative) level */
lua_lock(L);
for (ci = L->ci; level > 0 && ci != &L->base_ci; ci = ci->previous)
level--;
if (level == 0 && ci != &L->base_ci) { /* level found? */
status = 1;
ar->i_ci = ci;
}
else status = 0; /* no such level */
lua_unlock(L);
return status;
}
static const char *upvalname (const Proto *p, int uv) {
TString *s = check_exp(uv < p->sizeupvalues, p->upvalues[uv].name);
if (s == NULL) return "?";
else return getstr(s);
}
static const char *findvararg (CallInfo *ci, int n, StkId *pos) {
if (clLvalue(s2v(ci->func))->p->is_vararg) {
int nextra = ci->u.l.nextraargs;
if (n >= -nextra) { /* 'n' is negative */
*pos = ci->func - nextra - (n + 1);
return "(vararg)"; /* generic name for any vararg */
}
}
return NULL; /* no such vararg */
}
const char *luaG_findlocal (lua_State *L, CallInfo *ci, int n, StkId *pos) {
StkId base = ci->func + 1;
const char *name = NULL;
if (isLua(ci)) {
if (n < 0) /* access to vararg values? */
return findvararg(ci, n, pos);
else
name = luaF_getlocalname(ci_func(ci)->p, n, currentpc(ci));
}
if (name == NULL) { /* no 'standard' name? */
StkId limit = (ci == L->ci) ? L->top : ci->next->func;
if (limit - base >= n && n > 0) { /* is 'n' inside 'ci' stack? */
/* generic name for any valid slot */
name = isLua(ci) ? "(temporary)" : "(C temporary)";
}
else
return NULL; /* no name */
}
if (pos)
*pos = base + (n - 1);
return name;
}
LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
const char *name;
lua_lock(L);
if (ar == NULL) { /* information about non-active function? */
if (!isLfunction(s2v(L->top - 1))) /* not a Lua function? */
name = NULL;
else /* consider live variables at function start (parameters) */
name = luaF_getlocalname(clLvalue(s2v(L->top - 1))->p, n, 0);
}
else { /* active function; get information through 'ar' */
StkId pos = NULL; /* to avoid warnings */
name = luaG_findlocal(L, ar->i_ci, n, &pos);
if (name) {
setobjs2s(L, L->top, pos);
api_incr_top(L);
}
}
lua_unlock(L);
return name;
}
LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
StkId pos = NULL; /* to avoid warnings */
const char *name;
lua_lock(L);
name = luaG_findlocal(L, ar->i_ci, n, &pos);
if (name) {
setobjs2s(L, pos, L->top - 1);
L->top--; /* pop value */
}
lua_unlock(L);
return name;
}
static void funcinfo (lua_Debug *ar, Closure *cl) {
if (noLuaClosure(cl)) {
ar->source = "=[C]";
ar->srclen = LL("=[C]");
ar->linedefined = -1;
ar->lastlinedefined = -1;
ar->what = "C";
}
else {
const Proto *p = cl->l.p;
if (p->source) {
ar->source = getstr(p->source);
ar->srclen = tsslen(p->source);
}
else {
ar->source = "=?";
ar->srclen = LL("=?");
}
ar->linedefined = p->linedefined;
ar->lastlinedefined = p->lastlinedefined;
ar->what = (ar->linedefined == 0) ? "main" : "Lua";
}
luaO_chunkid(ar->short_src, ar->source, ar->srclen);
}
static int nextline (const Proto *p, int currentline, int pc) {
if (p->lineinfo[pc] != ABSLINEINFO)
return currentline + p->lineinfo[pc];
else
return luaG_getfuncline(p, pc);
}
static void collectvalidlines (lua_State *L, Closure *f) {
if (noLuaClosure(f)) {
setnilvalue(s2v(L->top));
api_incr_top(L);
}
else {
int i;
TValue v;
const Proto *p = f->l.p;
int currentline = p->linedefined;
Table *t = luaH_new(L); /* new table to store active lines */
sethvalue2s(L, L->top, t); /* push it on stack */
api_incr_top(L);
setbtvalue(&v); /* boolean 'true' to be the value of all indices */
if (!p->is_vararg) /* regular function? */
i = 0; /* consider all instructions */
else { /* vararg function */
lua_assert(GET_OPCODE(p->code[0]) == OP_VARARGPREP);
currentline = nextline(p, currentline, 0);
i = 1; /* skip first instruction (OP_VARARGPREP) */
}
for (; i < p->sizelineinfo; i++) { /* for each instruction */
currentline = nextline(p, currentline, i); /* get its line */
luaH_setint(L, t, currentline, &v); /* table[line] = true */
}
}
}
static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
/* calling function is a known function? */
if (ci != NULL && !(ci->callstatus & CIST_TAIL))
return funcnamefromcall(L, ci->previous, name);
else return NULL; /* no way to find a name */
}
static int auxgetinfo (lua_State *L, const char *what, lua_Debug *ar,
Closure *f, CallInfo *ci) {
int status = 1;
for (; *what; what++) {
switch (*what) {
case 'S': {
funcinfo(ar, f);
break;
}
case 'l': {
ar->currentline = (ci && isLua(ci)) ? getcurrentline(ci) : -1;
break;
}
case 'u': {
ar->nups = (f == NULL) ? 0 : f->c.nupvalues;
if (noLuaClosure(f)) {
ar->isvararg = 1;
ar->nparams = 0;
}
else {
ar->isvararg = f->l.p->is_vararg;
ar->nparams = f->l.p->numparams;
}
break;
}
case 't': {
ar->istailcall = (ci) ? ci->callstatus & CIST_TAIL : 0;
break;
}
case 'n': {
ar->namewhat = getfuncname(L, ci, &ar->name);
if (ar->namewhat == NULL) {
ar->namewhat = ""; /* not found */
ar->name = NULL;
}
break;
}
case 'r': {
if (ci == NULL || !(ci->callstatus & CIST_TRAN))
ar->ftransfer = ar->ntransfer = 0;
else {
ar->ftransfer = ci->u2.transferinfo.ftransfer;
ar->ntransfer = ci->u2.transferinfo.ntransfer;
}
break;
}
case 'L':
case 'f': /* handled by lua_getinfo */
break;
default: status = 0; /* invalid option */
}
}
return status;
}
LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
int status;
Closure *cl;
CallInfo *ci;
TValue *func;
lua_lock(L);
if (*what == '>') {
ci = NULL;
func = s2v(L->top - 1);
api_check(L, ttisfunction(func), "function expected");
what++; /* skip the '>' */
L->top--; /* pop function */
}
else {
ci = ar->i_ci;
func = s2v(ci->func);
lua_assert(ttisfunction(func));
}
cl = ttisclosure(func) ? clvalue(func) : NULL;
status = auxgetinfo(L, what, ar, cl, ci);
setobj2s(L, L->top, func);
api_incr_top(L);
}
collectvalidlines(L, cl);
lua_unlock(L);
return status;
}
/*
** {======================================================
** Symbolic Execution
** =======================================================
*/
static const char *getobjname (const Proto *p, int lastpc, int reg,
const char **name);
/*
** Find a "name" for the constant 'c'.
*/
static void kname (const Proto *p, int c, const char **name) {
TValue *kvalue = &p->k[c];
*name = (ttisstring(kvalue)) ? svalue(kvalue) : "?";
}
/*
** Find a "name" for the register 'c'.
*/
static void rname (const Proto *p, int pc, int c, const char **name) {
const char *what = getobjname(p, pc, c, name); /* search for 'c' */
if (!(what && *what == 'c')) /* did not find a constant name? */
*name = "?";
}
/*
** Find a "name" for a 'C' value in an RK instruction.
*/
static void rkname (const Proto *p, int pc, Instruction i, const char **name) {
int c = GETARG_C(i); /* key index */
if (GETARG_k(i)) /* is 'c' a constant? */
kname(p, c, name);
else /* 'c' is a register */
rname(p, pc, c, name);
}
static int filterpc (int pc, int jmptarget) {
if (pc < jmptarget) /* is code conditional (inside a jump)? */
return -1; /* cannot know who sets that register */
else return pc; /* current position sets that register */
}
/*
** Try to find last instruction before 'lastpc' that modified register 'reg'.
*/
static int findsetreg (const Proto *p, int lastpc, int reg) {
int pc;
int setreg = -1; /* keep last instruction that changed 'reg' */
int jmptarget = 0; /* any code before this address is conditional */
if (testMMMode(GET_OPCODE(p->code[lastpc])))
lastpc--; /* previous instruction was not actually executed */
for (pc = 0; pc < lastpc; pc++) {
Instruction i = p->code[pc];
OpCode op = GET_OPCODE(i);
int a = GETARG_A(i);
int change; /* true if current instruction changed 'reg' */
switch (op) {
case OP_LOADNIL: { /* set registers from 'a' to 'a+b' */
int b = GETARG_B(i);
change = (a <= reg && reg <= a + b);
break;
}
case OP_TFORCALL: { /* affect all regs above its base */
change = (reg >= a + 2);
break;
}
case OP_CALL:
case OP_TAILCALL: { /* affect all registers above base */
change = (reg >= a);
break;
}
case OP_JMP: { /* doesn't change registers, but changes 'jmptarget' */
int b = GETARG_sJ(i);
int dest = pc + 1 + b;
/* jump does not skip 'lastpc' and is larger than current one? */
if (dest <= lastpc && dest > jmptarget)
jmptarget = dest; /* update 'jmptarget' */
change = 0;
break;
}
default: /* any instruction that sets A */
change = (testAMode(op) && reg == a);
break;
}
if (change)
setreg = filterpc(pc, jmptarget);
}
return setreg;
}
/*
** Check whether table being indexed by instruction 'i' is the
** environment '_ENV'
*/
static const char *gxf (const Proto *p, int pc, Instruction i, int isup) {
int t = GETARG_B(i); /* table index */
const char *name; /* name of indexed variable */
if (isup) /* is an upvalue? */
name = upvalname(p, t);
else
getobjname(p, pc, t, &name);
return (name
&& strcmp(name
, LUA_ENV
) == 0) ? "global" : "field"; }
static const char *getobjname (const Proto *p, int lastpc, int reg,
const char **name) {
int pc;
*name = luaF_getlocalname(p, reg + 1, lastpc);
if (*name) /* is a local? */
return "local";
/* else try symbolic execution */
pc = findsetreg(p, lastpc, reg);
if (pc != -1) { /* could find instruction? */
Instruction i = p->code[pc];
OpCode op = GET_OPCODE(i);
switch (op) {
case OP_MOVE: {
int b = GETARG_B(i); /* move from 'b' to 'a' */
if (b < GETARG_A(i))
return getobjname(p, pc, b, name); /* get name for 'b' */
break;
}
case OP_GETTABUP: {
int k = GETARG_C(i); /* key index */
kname(p, k, name);
return gxf(p, pc, i, 1);
}
case OP_GETTABLE: {
int k = GETARG_C(i); /* key index */
rname(p, pc, k, name);
return gxf(p, pc, i, 0);
}
case OP_GETI: {
*name = "integer index";
return "field";
}
case OP_GETFIELD: {
int k = GETARG_C(i); /* key index */
kname(p, k, name);
return gxf(p, pc, i, 0);
}
case OP_GETUPVAL: {
*name = upvalname(p, GETARG_B(i));
return "upvalue";
}
case OP_LOADK:
case OP_LOADKX: {
int b = (op == OP_LOADK) ? GETARG_Bx(i)
: GETARG_Ax(p->code[pc + 1]);
if (ttisstring(&p->k[b])) {
*name = svalue(&p->k[b]);
return "constant";
}
break;
}
case OP_SELF: {
rkname(p, pc, i, name);
return "method";
}
default: break; /* go through to return NULL */
}
}
return NULL; /* could not find reasonable name */
}
/*
** Try to find a name for a function based on the code that called it.
** (Only works when function was called by a Lua function.)
** Returns what the name is (e.g., "for iterator", "method",
** "metamethod") and sets '*name' to point to the name.
*/
static const char *funcnamefromcode (lua_State *L, const Proto *p,
int pc, const char **name) {
TMS tm = (TMS)0; /* (initial value avoids warnings) */
Instruction i = p->code[pc]; /* calling instruction */
switch (GET_OPCODE(i)) {
case OP_CALL:
case OP_TAILCALL:
return getobjname(p, pc, GETARG_A(i), name); /* get function name */
case OP_TFORCALL: { /* for iterator */
*name = "for iterator";
return "for iterator";
}
/* other instructions can do calls through metamethods */
case OP_SELF: case OP_GETTABUP: case OP_GETTABLE:
case OP_GETI: case OP_GETFIELD:
tm = TM_INDEX;
break;
case OP_SETTABUP: case OP_SETTABLE: case OP_SETI: case OP_SETFIELD:
tm = TM_NEWINDEX;
break;
case OP_MMBIN: case OP_MMBINI: case OP_MMBINK: {
tm = cast(TMS, GETARG_C(i));
break;
}
case OP_UNM: tm = TM_UNM; break;
case OP_BNOT: tm = TM_BNOT; break;
case OP_LEN: tm = TM_LEN; break;
case OP_CONCAT: tm = TM_CONCAT; break;
case OP_EQ: tm = TM_EQ; break;
/* no cases for OP_EQI and OP_EQK, as they don't call metamethods */
case OP_LT: case OP_LTI: case OP_GTI: tm = TM_LT; break;
case OP_LE: case OP_LEI: case OP_GEI: tm = TM_LE; break;
case OP_CLOSE: case OP_RETURN: tm = TM_CLOSE; break;
default:
return NULL; /* cannot find a reasonable name */
}
*name = getstr(G(L)->tmname[tm]) + 2;
return "metamethod";
}
/*
** Try to find a name for a function based on how it was called.
*/
static const char *funcnamefromcall (lua_State *L, CallInfo *ci,
const char **name) {
if (ci->callstatus & CIST_HOOKED) { /* was it called inside a hook? */
*name = "?";
return "hook";
}
else if (ci->callstatus & CIST_FIN) { /* was it called as a finalizer? */
*name = "__gc";
return "metamethod"; /* report it as such */
}
else if (isLua(ci))
return funcnamefromcode(L, ci_func(ci)->p, currentpc(ci), name);
else
return NULL;
}
/* }====================================================== */
/*
** Check whether pointer 'o' points to some value in the stack
** frame of the current function. Because 'o' may not point to a
** value in this stack, we cannot compare it with the region
** boundaries (undefined behaviour in ISO C).
*/
static int isinstack (CallInfo *ci, const TValue *o) {
StkId pos;
for (pos = ci->func + 1; pos < ci->top; pos++) {
if (o == s2v(pos))
return 1;
}
return 0; /* not found */
}
/*
** Checks whether value 'o' came from an upvalue. (That can only happen
** with instructions OP_GETTABUP/OP_SETTABUP, which operate directly on
** upvalues.)
*/
static const char *getupvalname (CallInfo *ci, const TValue *o,
const char **name) {
LClosure *c = ci_func(ci);
int i;
for (i = 0; i < c->nupvalues; i++) {
if (c->upvals[i]->v == o) {
*name = upvalname(c->p, i);
return "upvalue";
}
}
return NULL;
}
static const char *formatvarinfo (lua_State *L, const char *kind,
const char *name) {
if (kind == NULL)
return ""; /* no information */
else
return luaO_pushfstring(L, " (%s '%s')", kind, name);
}
/*
** Build a string with a "description" for the value 'o', such as
** "variable 'x'" or "upvalue 'y'".
*/
static const char *varinfo (lua_State *L, const TValue *o) {
CallInfo *ci = L->ci;
const char *name = NULL; /* to avoid warnings */
const char *kind = NULL;
if (isLua(ci)) {
kind = getupvalname(ci, o, &name); /* check whether 'o' is an upvalue */
if (!kind && isinstack(ci, o)) /* no? try a register */
kind = getobjname(ci_func(ci)->p, currentpc(ci),
cast_int(cast(StkId, o) - (ci->func + 1)), &name);
}
return formatvarinfo(L, kind, name);
}
/*
** Raise a type error
*/
static l_noret typeerror (lua_State *L, const TValue *o, const char *op,
const char *extra) {
const char *t = luaT_objtypename(L, o);
luaG_runerror(L, "attempt to %s a %s value%s", op, t, extra);
}
/*
** Raise a type error with "standard" information about the faulty
** object 'o' (using 'varinfo').
*/
l_noret luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
typeerror(L, o, op, varinfo(L, o));
}
/*
** Raise an error for calling a non-callable object. Try to find a name
** for the object based on how it was called ('funcnamefromcall'); if it
** cannot get a name there, try 'varinfo'.
*/
l_noret luaG_callerror (lua_State *L, const TValue *o) {
CallInfo *ci = L->ci;
const char *name = NULL; /* to avoid warnings */
const char *kind = funcnamefromcall(L, ci, &name);
const char *extra = kind ? formatvarinfo(L, kind, name) : varinfo(L, o);
typeerror(L, o, "call", extra);
}
l_noret luaG_forerror (lua_State *L, const TValue *o, const char *what) {
luaG_runerror(L, "bad 'for' %s (number expected, got %s)",
what, luaT_objtypename(L, o));
}
l_noret luaG_concaterror (lua_State *L, const TValue *p1, const TValue *p2) {
if (ttisstring(p1) || cvt2str(p1)) p1 = p2;
luaG_typeerror(L, p1, "concatenate");
}
l_noret luaG_opinterror (lua_State *L, const TValue *p1,
const TValue *p2, const char *msg) {
if (!ttisnumber(p1)) /* first operand is wrong? */
p2 = p1; /* now second is wrong */
luaG_typeerror(L, p2, msg);
}
/*
** Error when both values are convertible to numbers, but not to integers
*/
l_noret luaG_tointerror (lua_State *L, const TValue *p1, const TValue *p2) {
lua_Integer temp;
if (!luaV_tointegerns(p1, &temp, LUA_FLOORN2I))
p2 = p1;
luaG_runerror(L, "number%s has no integer representation", varinfo(L, p2));
}
l_noret luaG_ordererror (lua_State *L, const TValue *p1, const TValue *p2) {
const char *t1 = luaT_objtypename(L, p1);
const char *t2 = luaT_objtypename(L, p2);
luaG_runerror(L, "attempt to compare two %s values", t1);
else
luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
}
/* add src:line information to 'msg' */
const char *luaG_addinfo (lua_State *L, const char *msg, TString *src,
int line) {
char buff[LUA_IDSIZE];
if (src)
luaO_chunkid(buff, getstr(src), tsslen(src));
else { /* no source available; use "?" instead */
buff[0] = '?'; buff[1] = '\0';
}
return luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
}
l_noret luaG_errormsg (lua_State *L) {
if (L->errfunc != 0) { /* is there an error handling function? */
StkId errfunc = restorestack(L, L->errfunc);
lua_assert(ttisfunction(s2v(errfunc)));
setobjs2s(L, L->top, L->top - 1); /* move argument */
setobjs2s(L, L->top - 1, errfunc); /* push function */
L->top++; /* assume EXTRA_STACK */
luaD_callnoyield(L, L->top - 2, 1); /* call it */
}
luaD_throw(L, LUA_ERRRUN);
}
l_noret luaG_runerror (lua_State *L, const char *fmt, ...) {
CallInfo *ci = L->ci;
const char *msg;
va_list argp;
luaC_checkGC(L); /* error message uses memory */
msg = luaO_pushvfstring(L, fmt, argp); /* format message */
if (isLua(ci)) /* if Lua function, add source:line information */
luaG_addinfo(L, msg, ci_func(ci)->p->source, getcurrentline(ci));
luaG_errormsg(L);
}
/*
** Check whether new instruction 'newpc' is in a different line from
** previous instruction 'oldpc'. More often than not, 'newpc' is only
** one or a few instructions after 'oldpc' (it must be after, see
** caller), so try to avoid calling 'luaG_getfuncline'. If they are
** too far apart, there is a good chance of a ABSLINEINFO in the way,
** so it goes directly to 'luaG_getfuncline'.
*/
static int changedline (const Proto *p, int oldpc, int newpc) {
if (p->lineinfo == NULL) /* no debug information? */
return 0;
if (newpc - oldpc < MAXIWTHABS / 2) { /* not too far apart? */
int delta = 0; /* line diference */
int pc = oldpc;
for (;;) {
int lineinfo = p->lineinfo[++pc];
if (lineinfo == ABSLINEINFO)
break; /* cannot compute delta; fall through */
delta += lineinfo;
if (pc == newpc)
return (delta != 0); /* delta computed successfully */
}
}
/* either instructions are too far apart or there is an absolute line
info in the way; compute line difference explicitly */
return (luaG_getfuncline(p, oldpc) != luaG_getfuncline(p, newpc));
}
/*
** Traces the execution of a Lua function. Called before the execution
** of each opcode, when debug is on. 'L->oldpc' stores the last
** instruction traced, to detect line changes. When entering a new
** function, 'npci' will be zero and will test as a new line whatever
** the value of 'oldpc'. Some exceptional conditions may return to
** a function without setting 'oldpc'. In that case, 'oldpc' may be
** invalid; if so, use zero as a valid value. (A wrong but valid 'oldpc'
** at most causes an extra call to a line hook.)
** This function is not "Protected" when called, so it should correct
** 'L->top' before calling anything that can run the GC.
*/
int luaG_traceexec (lua_State *L, const Instruction *pc) {
CallInfo *ci = L->ci;
lu_byte mask = L->hookmask;
const Proto *p = ci_func(ci)->p;
int counthook;
if (!(mask & (LUA_MASKLINE | LUA_MASKCOUNT))) { /* no hooks? */
ci->u.l.trap = 0; /* don't need to stop again */
return 0; /* turn off 'trap' */
}
pc++; /* reference is always next instruction */
ci->u.l.savedpc = pc; /* save 'pc' */
counthook = (--L->hookcount == 0 && (mask & LUA_MASKCOUNT));
if (counthook)
resethookcount(L); /* reset count */
else if (!(mask & LUA_MASKLINE))
return 1; /* no line hook and count != 0; nothing to be done now */
if (ci->callstatus & CIST_HOOKYIELD) { /* called hook last time? */
ci->callstatus &= ~CIST_HOOKYIELD; /* erase mark */
return 1; /* do not call hook again (VM yielded, so it did not move) */
}
if (!isIT(*(ci->u.l.savedpc - 1))) /* top not being used? */
L->top = ci->top; /* correct top */
if (counthook)
luaD_hook(L, LUA_HOOKCOUNT, -1, 0, 0); /* call count hook */
if (mask & LUA_MASKLINE) {
/* 'L->oldpc' may be invalid; use zero in this case */
int oldpc = (L->oldpc < p->sizecode) ? L->oldpc : 0;
int npci = pcRel(pc, p);
if (npci <= oldpc || /* call hook when jump back (loop), */
changedline(p, oldpc, npci)) { /* or when enter new line */
int newline = luaG_getfuncline(p, npci);
luaD_hook(L, LUA_HOOKLINE, newline, 0, 0); /* call line hook */
}
L->oldpc = npci; /* 'pc' of last call to line hook */
}
if (L->status == LUA_YIELD) { /* did hook yield? */
if (counthook)
L->hookcount = 1; /* undo decrement to zero */
ci->u.l.savedpc--; /* undo increment (resume will increment it again) */
ci->callstatus |= CIST_HOOKYIELD; /* mark that it yielded */
luaD_throw(L, LUA_YIELD);
}
return 1; /* keep 'trap' on */
}