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author | Roberto Ierusalimschy <roberto@inf.puc-rio.br> | 2021-02-09 14:00:05 -0300 |
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committer | Roberto Ierusalimschy <roberto@inf.puc-rio.br> | 2021-02-09 14:00:05 -0300 |
commit | 4e47f81188d37e29027158b76271d02a781242e2 (patch) | |
tree | c360912d1901acf8371390cc1f716278e5d91bb4 /lfunc.c | |
parent | c63e5d212bc5dec1b1c749e3f07b42cd83081826 (diff) | |
download | lua-4e47f81188d37e29027158b76271d02a781242e2.tar.gz lua-4e47f81188d37e29027158b76271d02a781242e2.tar.bz2 lua-4e47f81188d37e29027158b76271d02a781242e2.zip |
New implementation for to-be-closed variables
To-be-closed variables are linked in their own list, embedded into the
stack elements. (Due to alignment, this information does not change
the size of the stack elements in most architectures.) This new list
does not produce garbage and avoids memory errors when creating tbc
variables.
Diffstat (limited to 'lfunc.c')
-rw-r--r-- | lfunc.c | 66 |
1 files changed, 34 insertions, 32 deletions
@@ -120,11 +120,11 @@ static void callclosemethod (lua_State *L, TValue *obj, TValue *err, int yy) { | |||
120 | 120 | ||
121 | 121 | ||
122 | /* | 122 | /* |
123 | ** Check whether 'obj' has a close metamethod and raise an error | 123 | ** Check whether object at given level has a close metamethod and raise |
124 | ** if not. | 124 | ** an error if not. |
125 | */ | 125 | */ |
126 | static void checkclosemth (lua_State *L, StkId level, const TValue *obj) { | 126 | static void checkclosemth (lua_State *L, StkId level) { |
127 | const TValue *tm = luaT_gettmbyobj(L, obj, TM_CLOSE); | 127 | const TValue *tm = luaT_gettmbyobj(L, s2v(level), TM_CLOSE); |
128 | if (ttisnil(tm)) { /* no metamethod? */ | 128 | if (ttisnil(tm)) { /* no metamethod? */ |
129 | int idx = cast_int(level - L->ci->func); /* variable index */ | 129 | int idx = cast_int(level - L->ci->func); /* variable index */ |
130 | const char *vname = luaG_findlocal(L, L->ci, idx, NULL); | 130 | const char *vname = luaG_findlocal(L, L->ci, idx, NULL); |
@@ -155,20 +155,21 @@ static void prepcallclosemth (lua_State *L, StkId level, int status, int yy) { | |||
155 | 155 | ||
156 | 156 | ||
157 | /* | 157 | /* |
158 | ** Create a to-be-closed upvalue. If there is a memory allocation error, | 158 | ** Insert a variable in the list of to-be-closed variables. |
159 | ** 'ptbc' keeps the object so it can be closed as soon as possible. | ||
160 | ** (Since memory errors have no handler, that will happen before any | ||
161 | ** stack reallocation.) | ||
162 | */ | 159 | */ |
163 | void luaF_newtbcupval (lua_State *L, StkId level) { | 160 | void luaF_newtbcupval (lua_State *L, StkId level) { |
164 | TValue *obj = s2v(level); | 161 | lua_assert(level > L->tbclist); |
165 | lua_assert(L->openupval == NULL || uplevel(L->openupval) < level); | 162 | if (l_isfalse(s2v(level))) |
166 | if (!l_isfalse(obj)) { /* false doesn't need to be closed */ | 163 | return; /* false doesn't need to be closed */ |
167 | checkclosemth(L, level, obj); | 164 | checkclosemth(L, level); /* value must have a close method */ |
168 | L->ptbc = level; /* in case of allocation error */ | 165 | while (level - L->tbclist > USHRT_MAX) { /* is delta too large? */ |
169 | newupval(L, 1, level, &L->openupval); | 166 | L->tbclist += USHRT_MAX; /* create a dummy node at maximum delta */ |
170 | L->ptbc = NULL; /* no errors */ | 167 | L->tbclist->tbclist.delta = USHRT_MAX; |
168 | L->tbclist->tbclist.isdummy = 1; | ||
171 | } | 169 | } |
170 | level->tbclist.delta = level - L->tbclist; | ||
171 | level->tbclist.isdummy = 0; | ||
172 | L->tbclist = level; | ||
172 | } | 173 | } |
173 | 174 | ||
174 | 175 | ||
@@ -181,23 +182,11 @@ void luaF_unlinkupval (UpVal *uv) { | |||
181 | 182 | ||
182 | 183 | ||
183 | /* | 184 | /* |
184 | ** Close all upvalues up to the given stack level. A 'status' equal | 185 | ** Close all upvalues up to the given stack level. |
185 | ** to NOCLOSINGMETH closes upvalues without running any __close | ||
186 | ** metamethods. If there is a pending to-be-closed value, close | ||
187 | ** it before anything else. | ||
188 | */ | 186 | */ |
189 | void luaF_close (lua_State *L, StkId level, int status, int yy) { | 187 | void luaF_closeupval (lua_State *L, StkId level) { |
190 | UpVal *uv; | 188 | UpVal *uv; |
191 | StkId upl; /* stack index pointed by 'uv' */ | 189 | StkId upl; /* stack index pointed by 'uv' */ |
192 | if (unlikely(status == LUA_ERRMEM && L->ptbc != NULL)) { | ||
193 | ptrdiff_t levelrel = savestack(L, level); | ||
194 | upl = L->ptbc; | ||
195 | L->ptbc = NULL; /* remove from "list" before closing */ | ||
196 | prepcallclosemth(L, upl, status, yy); | ||
197 | level = restorestack(L, levelrel); | ||
198 | } | ||
199 | else | ||
200 | lua_assert(L->ptbc == NULL); /* must be empty for other status */ | ||
201 | while ((uv = L->openupval) != NULL && (upl = uplevel(uv)) >= level) { | 190 | while ((uv = L->openupval) != NULL && (upl = uplevel(uv)) >= level) { |
202 | TValue *slot = &uv->u.value; /* new position for value */ | 191 | TValue *slot = &uv->u.value; /* new position for value */ |
203 | lua_assert(uplevel(uv) < L->top); | 192 | lua_assert(uplevel(uv) < L->top); |
@@ -208,9 +197,22 @@ void luaF_close (lua_State *L, StkId level, int status, int yy) { | |||
208 | nw2black(uv); /* closed upvalues cannot be gray */ | 197 | nw2black(uv); /* closed upvalues cannot be gray */ |
209 | luaC_barrier(L, uv, slot); | 198 | luaC_barrier(L, uv, slot); |
210 | } | 199 | } |
211 | if (uv->tbc && status != NOCLOSINGMETH) { | 200 | } |
212 | ptrdiff_t levelrel = savestack(L, level); | 201 | } |
213 | prepcallclosemth(L, upl, status, yy); /* may change the stack */ | 202 | |
203 | |||
204 | /* | ||
205 | ** Close all upvalues and to-be-closed variables up to the given stack | ||
206 | ** level. | ||
207 | */ | ||
208 | void luaF_close (lua_State *L, StkId level, int status, int yy) { | ||
209 | ptrdiff_t levelrel = savestack(L, level); | ||
210 | luaF_closeupval(L, level); /* first, close the upvalues */ | ||
211 | while (L->tbclist >= level) { /* traverse tbc's down to that level */ | ||
212 | StkId tbc = L->tbclist; /* get variable index */ | ||
213 | L->tbclist -= tbc->tbclist.delta; /* remove it from list */ | ||
214 | if (!tbc->tbclist.isdummy) { /* not a dummy entry? */ | ||
215 | prepcallclosemth(L, tbc, status, yy); /* close variable */ | ||
214 | level = restorestack(L, levelrel); | 216 | level = restorestack(L, levelrel); |
215 | } | 217 | } |
216 | } | 218 | } |