Add LJ_GC64 mode: 64 bit GC object references.

Actually NaN tagging with 47 bit pointers and 13+4 bit tags.

src/lj_ir.h

@@ -320,6 +320,7 @@ IRTDEF(IRTENUM)
   IRT_PTR = LJ_64 ? IRT_P64 : IRT_P32,
   IRT_INTP = LJ_64 ? IRT_I64 : IRT_INT,
   IRT_UINTP = LJ_64 ? IRT_U64 : IRT_U32,
+  /* TODO_GC64: major changes required for all uses of IRT_P32. */
 
   /* Additional flags. */
   IRT_MARK = 0x20,	/* Marker for misc. purposes. */
@@ -371,7 +372,12 @@ typedef struct IRType1 { uint8_t irt; } IRType1;
 #define irt_isaddr(t)		(irt_typerange((t), IRT_LIGHTUD, IRT_UDATA))
 #define irt_isint64(t)		(irt_typerange((t), IRT_I64, IRT_U64))
 
-#if LJ_64
+#if LJ_GC64
+#define IRT_IS64 \
+  ((1u<<IRT_NUM)|(1u<<IRT_I64)|(1u<<IRT_U64)|(1u<<IRT_P64)|\
+   (1u<<IRT_LIGHTUD)|(1u<<IRT_STR)|(1u<<IRT_THREAD)|(1u<<IRT_PROTO)|\
+   (1u<<IRT_FUNC)|(1u<<IRT_CDATA)|(1u<<IRT_TAB)|(1u<<IRT_UDATA))
+#elif LJ_64
 #define IRT_IS64 \
   ((1u<<IRT_NUM)|(1u<<IRT_I64)|(1u<<IRT_U64)|(1u<<IRT_P64)|(1u<<IRT_LIGHTUD))
 #else
@@ -392,7 +398,7 @@ static LJ_AINLINE IRType itype2irt(const TValue *tv)
     return IRT_INT;
   else if (tvisnum(tv))
     return IRT_NUM;
-#if LJ_64
+#if LJ_64 && !LJ_GC64
   else if (tvislightud(tv))
     return IRT_LIGHTUD;
 #endif
@@ -547,6 +553,7 @@ typedef union IRIns {
   MRef ptr;		/* Pointer constant (overlaps op12). */
 } IRIns;
 
+/* TODO_GC64: major changes required. */
 #define ir_kgc(ir)	check_exp((ir)->o == IR_KGC, gcref((ir)->gcr))
 #define ir_kstr(ir)	(gco2str(ir_kgc((ir))))
 #define ir_ktab(ir)	(gco2tab(ir_kgc((ir))))