Fixed bugs of stack reallocation x GC
Macro 'checkstackGC' was doing a GC step after resizing the stack;
the GC could shrink the stack and undo the resize. Moreover, macro
'checkstackp' also does a GC step, which could remove the preallocated
CallInfo when calling a function. (Its name has been changed to
'checkstackGCp' to emphasize that it calls the GC.)
diff --git a/ldo.c b/ldo.c
index 66217a4..e3db1f7 100644
--- a/ldo.c
+++ b/ldo.c
@@ -465,13 +465,13 @@
f = fvalue(s2v(func));
Cfunc: {
int n; /* number of returns */
- CallInfo *ci = next_ci(L);
- checkstackp(L, LUA_MINSTACK, func); /* ensure minimum stack size */
+ CallInfo *ci;
+ checkstackGCp(L, LUA_MINSTACK, func); /* ensure minimum stack size */
+ L->ci = ci = next_ci(L);
ci->nresults = nresults;
ci->callstatus = CIST_C;
ci->top = L->top + LUA_MINSTACK;
ci->func = func;
- L->ci = ci;
lua_assert(ci->top <= L->stack_last);
if (L->hookmask & LUA_MASKCALL) {
int narg = cast_int(L->top - func) - 1;
@@ -485,12 +485,13 @@
break;
}
case LUA_VLCL: { /* Lua function */
- CallInfo *ci = next_ci(L);
+ CallInfo *ci;
Proto *p = clLvalue(s2v(func))->p;
int narg = cast_int(L->top - func) - 1; /* number of real arguments */
int nfixparams = p->numparams;
int fsize = p->maxstacksize; /* frame size */
- checkstackp(L, fsize, func);
+ checkstackGCp(L, fsize, func);
+ L->ci = ci = next_ci(L);
ci->nresults = nresults;
ci->u.l.savedpc = p->code; /* starting point */
ci->callstatus = 0;
@@ -504,7 +505,7 @@
break;
}
default: { /* not a function */
- checkstackp(L, 1, func); /* space for metamethod */
+ checkstackGCp(L, 1, func); /* space for metamethod */
luaD_tryfuncTM(L, func); /* try to get '__call' metamethod */
goto retry; /* try again with metamethod */
}
diff --git a/ldo.h b/ldo.h
index 7760f85..6c6cb28 100644
--- a/ldo.h
+++ b/ldo.h
@@ -17,6 +17,8 @@
** Macro to check stack size and grow stack if needed. Parameters
** 'pre'/'pos' allow the macro to preserve a pointer into the
** stack across reallocations, doing the work only when needed.
+** It also allows the running of one GC step when the stack is
+** reallocated.
** 'condmovestack' is used in heavy tests to force a stack reallocation
** at every check.
*/
@@ -35,7 +37,7 @@
/* macro to check stack size, preserving 'p' */
-#define checkstackp(L,n,p) \
+#define checkstackGCp(L,n,p) \
luaD_checkstackaux(L, n, \
ptrdiff_t t__ = savestack(L, p); /* save 'p' */ \
luaC_checkGC(L), /* stack grow uses memory */ \
@@ -44,7 +46,7 @@
/* macro to check stack size and GC */
#define checkstackGC(L,fsize) \
- luaD_checkstackaux(L, (fsize), (void)0, luaC_checkGC(L))
+ luaD_checkstackaux(L, (fsize), luaC_checkGC(L), (void)0)
/* type of protected functions, to be ran by 'runprotected' */
diff --git a/ltm.c b/ltm.c
index ae60983..4770f96 100644
--- a/ltm.c
+++ b/ltm.c
@@ -240,7 +240,7 @@
int actual = cast_int(L->top - ci->func) - 1; /* number of arguments */
int nextra = actual - nfixparams; /* number of extra arguments */
ci->u.l.nextraargs = nextra;
- checkstackGC(L, p->maxstacksize + 1);
+ luaD_checkstack(L, p->maxstacksize + 1);
/* copy function to the top of the stack */
setobjs2s(L, L->top++, ci->func);
/* move fixed parameters to the top of the stack */
@@ -259,7 +259,7 @@
int nextra = ci->u.l.nextraargs;
if (wanted < 0) {
wanted = nextra; /* get all extra arguments available */
- checkstackp(L, nextra, where); /* ensure stack space */
+ checkstackGCp(L, nextra, where); /* ensure stack space */
L->top = where + nextra; /* next instruction will need top */
}
for (i = 0; i < wanted && i < nextra; i++)
diff --git a/lvm.c b/lvm.c
index ccbfbab..d78d6be 100644
--- a/lvm.c
+++ b/lvm.c
@@ -1634,7 +1634,7 @@
while (!ttisfunction(s2v(ra))) { /* not a function? */
luaD_tryfuncTM(L, ra); /* try '__call' metamethod */
b++; /* there is now one extra argument */
- checkstackp(L, 1, ra);
+ checkstackGCp(L, 1, ra);
}
if (!ttisLclosure(s2v(ra))) { /* C function? */
luaD_call(L, ra, LUA_MULTRET); /* call it */
