DrSocalkwe3n/luajit
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No longer let the GC replace dead keys with the LJ_TDEADKEY tag.

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Important: this changes the semantics of the write barrier!
Carefully read the big comment block in lj_obj.h
This helps HREFK key slot specialization and allows safely hoisting
HREF/HREFK across GC steps, too (fix for a barely reproducible bug).
Dead keys are only removed during a table resize (as before).
This commit is contained in:
Mike Pall
2010-04-21 01:45:58 +02:00
parent d8cb69ed07
commit ab45481199
13 changed files with 65 additions and 43 deletions
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9
src/lj_record.c
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@@ -994,6 +994,7 @@ static TRef rec_idx(jit_State *J, RecordIndex *ix)
return res;
} else { /* Indexed store. */
GCtab *mt = tabref(tabV(&ix->tabv)->metatable);
int keybarrier = tref_isgcv(ix->key) && !tref_isnil(ix->val);
if (tvisnil(oldv)) { /* Previous value was nil? */
/* Need to duplicate the hasmm check for the early guards. */
int hasmm = 0;
@@ -1004,7 +1005,8 @@ static TRef rec_idx(jit_State *J, RecordIndex *ix)
if (hasmm)
emitir(IRTG(loadop, IRT_NIL), xref, 0); /* Guard for nil value. */
else if (xrefop == IR_HREF)
emitir(IRTG(oldv == niltvg(J2G(J)) ? IR_EQ : IR_NE, IRT_PTR), xref, lj_ir_kptr(J, niltvg(J2G(J))));
emitir(IRTG(oldv == niltvg(J2G(J)) ? IR_EQ : IR_NE, IRT_PTR),
xref, lj_ir_kptr(J, niltvg(J2G(J))));
if (ix->idxchain && rec_mm_lookup(J, ix, MM_newindex)) { /* Metamethod? */
lua_assert(hasmm);
goto handlemm;
@@ -1015,6 +1017,7 @@ static TRef rec_idx(jit_State *J, RecordIndex *ix)
if (tref_isinteger(key)) /* NEWREF needs a TValue as a key. */
key = emitir(IRTN(IR_TONUM), key, 0);
xref = emitir(IRT(IR_NEWREF, IRT_PTR), ix->tab, key);
keybarrier = 0; /* NEWREF already takes care of the key barrier. */
}
} else if (!lj_opt_fwd_wasnonnil(J, loadop, tref_ref(xref))) {
/* Cannot derive that the previous value was non-nil, must do checks. */
@@ -1030,11 +1033,13 @@ static TRef rec_idx(jit_State *J, RecordIndex *ix)
emitir(IRTG(loadop, t), xref, 0); /* Guard for non-nil value. */
}
}
} else {
keybarrier = 0; /* Previous non-nil value kept the key alive. */
}
if (tref_isinteger(ix->val)) /* Convert int to number before storing. */
ix->val = emitir(IRTN(IR_TONUM), ix->val, 0);
emitir(IRT(loadop+IRDELTA_L2S, tref_type(ix->val)), xref, ix->val);
if (tref_isgcv(ix->val))
if (keybarrier || tref_isgcv(ix->val))
emitir(IRT(IR_TBAR, IRT_NIL), ix->tab, 0);
/* Invalidate neg. metamethod cache for stores with certain string keys. */
if (!nommstr(J, ix->key)) {