Third argument to __index handlers?

The original table triggering the MT call chain

Originally 6d84cd88d6c74289b1eaad4f94beb840ce16f945

Signed-off-by: Karel Tuma <kat@lua.cz>

src/lj_meta.c

@@ -135,6 +135,7 @@ static TValue *mmcall(lua_State *L, ASMFunction cont, cTValue *mo,
 cTValue *lj_meta_tget(lua_State *L, cTValue *o, cTValue *k)
 {
   int loop;
+  cTValue *origo = o;
   for (loop = 0; loop < LJ_MAX_IDXCHAIN; loop++) {
     cTValue *mo;
     if (LJ_LIKELY(tvistab(o))) {
@@ -149,6 +150,7 @@ cTValue *lj_meta_tget(lua_State *L, cTValue *o, cTValue *k)
     }
     if (tvisfunc(mo)) {
       L->top = mmcall(L, lj_cont_ra, mo, o, k);
+      copyTV(L, L->top+2, origo);
       return NULL;  /* Trigger metamethod call. */
     }
     o = mo;

src/lj_record.c

@@ -1301,6 +1301,10 @@ TRef lj_record_idx(jit_State *J, RecordIndex *ix)
   IRType1 rbguard;
   cTValue *oldv;
 
+  /* Remember original table before overwriting it. */
+  ix->otab = ix->tab;
+  ix->otabv = ix->tabv;
+
   while (!tref_istab(ix->tab)) { /* Handle non-table lookup. */
     /* Never call raw lj_record_idx() on non-table. */
     lua_assert(ix->idxchain != 0);
@@ -1322,7 +1326,9 @@ TRef lj_record_idx(jit_State *J, RecordIndex *ix)
 	lj_record_call(J, func, 3);  /* mobj(tab, key, val) */
 	return 0;
       } else {
-	lj_record_call(J, func, 2);  /* res = mobj(tab, key) */
+        base[3] = ix->otab;
+        copyTV(J->L, tv+3, &ix->otabv);
+        lj_record_call(J, func, 3);  /* res = mobj(tab, key, origtab) */
 	return 0;  /* No result yet. */
       }
     }

src/lj_record.h

@@ -12,12 +12,14 @@
 #if LJ_HASJIT
 /* Context for recording an indexed load/store. */
 typedef struct RecordIndex {
+  TValue otabv;         /* Original runtime value of table (or indexed object). */
   TValue tabv;		/* Runtime value of table (or indexed object). */
   TValue keyv;		/* Runtime value of key. */
   TValue valv;		/* Runtime value of stored value. */
   TValue mobjv;		/* Runtime value of metamethod object. */
   GCtab *mtv;		/* Runtime value of metatable object. */
   cTValue *oldv;	/* Runtime value of previously stored value. */
+  TRef otab;            /* Original table (or indexed object) reference. */
   TRef tab;		/* Table (or indexed object) reference. */
   TRef key;		/* Key reference. */
   TRef val;		/* Value reference for a store or 0 for a load. */

src/vm_x86.dasc

@@ -931,13 +931,13 @@ static void build_subroutines(BuildCtx *ctx)
   |  ins_next
   |
   |3:  // Call __index metamethod.
-  |  // BASE = base, L->top = new base, stack = cont/func/t/k
+  |  // BASE = base, L->top = new base, stack = cont/func/t/k/origt
   |  mov RA, L:RB->top
   |  mov [RA-12], PC			// [cont|PC]
   |  lea PC, [RA+FRAME_CONT]
   |  sub PC, BASE
   |  mov LFUNC:RB, [RA-8]		// Guaranteed to be a function here.
-  |  mov NARGS:RD, 2+1			// 2 args for func(t, k).
+  |  mov NARGS:RD, 3+1			// 2 args for func(t, k).
   |  jmp ->vm_call_dispatch_f
   |
   |->vmeta_tgetr: