Simplify handling of instable types in TNEW/TDUP load forwarding.

Thanks to Peter Cawley. #994

diff --git a/src/lj_opt_mem.c b/src/lj_opt_mem.c
index dc74a06de3fef6b5a4afd3360cd4daf6ab6e1b76..04b95a6f6ae3c223c3562cad70fdde867a17874e 100644 (file)
--- a/src/lj_opt_mem.c
+++ b/src/lj_opt_mem.c
@@ -185,25 +185,23 @@ static TRef fwd_ahload(jit_State *J, IRRef xref)
        }
        ref = store->prev;
       }
-      if (ir->o == IR_TNEW && !irt_isnil(fins->t))
-       return 0;  /* Type instability in loop-carried dependency. */
-      if (irt_ispri(fins->t)) {
-       return TREF_PRI(irt_type(fins->t));
-      } else if (irt_isnum(fins->t) || (LJ_DUALNUM && irt_isint(fins->t)) ||
-                irt_isstr(fins->t)) {
+      /* Simplified here: let loop_unroll() figure out any type instability. */
+      if (ir->o == IR_TNEW) {
+       return TREF_NIL;
+      } else {
        TValue keyv;
        cTValue *tv;
        IRIns *key = IR(xr->op2);
        if (key->o == IR_KSLOT) key = IR(key->op1);
        lj_ir_kvalue(J->L, &keyv, key);
        tv = lj_tab_get(J->L, ir_ktab(IR(ir->op1)), &keyv);
-       if (itype2irt(tv) != irt_type(fins->t))
-         return 0;  /* Type instability in loop-carried dependency. */
-       if (irt_isnum(fins->t))
+       if (tvispri(tv))
+         return TREF_PRI(itype2irt(tv));
+       else if (tvisnum(tv))
          return lj_ir_knum_u64(J, tv->u64);
-       else if (LJ_DUALNUM && irt_isint(fins->t))
+       else if (tvisint(tv))
          return lj_ir_kint(J, intV(tv));
-       else
+       else if (tvisgcv(tv))
          return lj_ir_kstr(J, strV(tv));
       }
       /* Othwerwise: don't intern as a constant. */