Remove DUALNUM mode

DUALNUM mode is a complex optional feature, disabled by default on
x86-64, that allows numbers to be stored on the heap either as doubles
(the usual) or as integers (the extension.)

This requires a _LOT_ of ifdef-style conditional logic throughout the
VM and runtime system. My tests have never found a verifiable benefit
to the dual number mode and since it is already disabled by default on
x86-64 I have simply removed it.

This change is a bit scary because it is large and I have mostly made
it manually. The conditional uses of DUALNUM were not ones that I
could remove automatically with 'unifdef'. I have surely made a
mistake in here somewhere and that will surely bit somebody on the
backside one day... Sorry in advance, but meanwhile, onward!

src/Makefile

@@ -391,9 +391,6 @@ endif
 ifneq (,$(findstring LJ_HASFFI 1,$(TARGET_TESTARCH)))
   DASM_AFLAGS+= -D FFI
 endif
-ifneq (,$(findstring LJ_DUALNUM 1,$(TARGET_TESTARCH)))
-  DASM_AFLAGS+= -D DUALNUM
-endif
 ifneq (,$(findstring LJ_ARCH_HASFPU 1,$(TARGET_TESTARCH)))
   DASM_AFLAGS+= -D FPU
   TARGET_ARCH+= -DLJ_ARCH_HASFPU=1

src/host/buildvm_lib.c

@@ -176,7 +176,7 @@ static void libdef_fixupbc(uint8_t *p)
     uint8_t ra = p[libbc_endian ? 2 : 1];
     uint8_t rc = p[libbc_endian ? 1 : 2];
     uint8_t rb = p[libbc_endian ? 0 : 3];
-    if (!LJ_DUALNUM && op == BC_ISTYPE && rc == ~LJ_TNUMX+1) {
+    if (op == BC_ISTYPE && rc == ~LJ_TNUMX+1) {
       op = BC_ISNUM; rc++;
     }
     p[LJ_ENDIAN_SELECT(0, 3)] = op;

src/ifdef-defile

@@ -18,6 +18,7 @@
 #define LJ_64 1
 #define LJ_ARCH_BITS 64
 #define LJ_ARCH_ENDIAN == LUAJIT_LE
+#define LJ_DUALNUM 0
 #define LJ_FR2 1
 #define LJ_NUMMODE LJ_NUMMODE_SINGLE_DUAL
 #define LJ_NUMMODE_DUAL		2
@@ -47,6 +48,7 @@
 #define LUAJIT_ARCH_x64		2
 #define LUAJIT_ARCH_x86		1
 #define LUAJIT_LE 1
+#define LUAJIT_NUMMODE=1
 #define LUAJIT_OS LUAJIT_OS_LINUX
 #define LUAJIT_OS_LINUX 2
 #define LUAJIT_OS_WINDOWS 3

src/lib_base.c

@@ -264,13 +264,6 @@ LJLIB_ASM(tonumber)		LJLIB_REC(.)
       CType *ct = lj_ctype_rawref(cts, cdataV(o)->ctypeid);
       if (ctype_isenum(ct->info)) ct = ctype_child(cts, ct);
       if (ctype_isnum(ct->info) || ctype_iscomplex(ct->info)) {
-	if (LJ_DUALNUM && ctype_isinteger_or_bool(ct->info) &&
-	    ct->size <= 4 && !(ct->size == 4 && (ct->info & CTF_UNSIGNED))) {
-	  int32_t i;
-	  lj_cconv_ct_tv(cts, ctype_get(cts, CTID_INT32), (uint8_t *)&i, o, 0);
-	  setintV(L->base-1-LJ_FR2, i);
-	  return FFH_RES(1);
-	}
 	lj_cconv_ct_tv(cts, ctype_get(cts, CTID_DOUBLE),
 		       (uint8_t *)&(L->base-1-LJ_FR2)->n, o, 0);
 	return FFH_RES(1);
@@ -286,10 +279,7 @@ LJLIB_ASM(tonumber)		LJLIB_REC(.)
     if (p != ep) {
       while (lj_char_isspace((unsigned char)(*ep))) ep++;
       if (*ep == '\0') {
-	if (LJ_DUALNUM && LJ_LIKELY(ul < 0x80000000u))
-	  setintV(L->base-1-LJ_FR2, (int32_t)ul);
-	else
-	  setnumV(L->base-1-LJ_FR2, (lua_Number)ul);
+        setnumV(L->base-1-LJ_FR2, (lua_Number)ul);
 	return FFH_RES(1);
       }
     }

src/lib_io.c

@@ -120,13 +120,6 @@ static int io_file_readnum(lua_State *L, FILE *fp)
 {
   lua_Number d;
   if (fscanf(fp, LUA_NUMBER_SCAN, &d) == 1) {
-    if (LJ_DUALNUM) {
-      int32_t i = lj_num2int(d);
-      if (d == (lua_Number)i && !tvismzero((cTValue *)&d)) {
-	setintV(L->top++, i);
-	return 1;
-      }
-    }
     setnumV(L->top++, d);
     return 1;
   } else {
@@ -311,9 +304,7 @@ LJLIB_CF(io_method_seek)
   else if (opt == 2) opt = SEEK_END;
   o = L->base+2;
   if (o < L->top) {
-    if (tvisint(o))
-      ofs = (int64_t)intV(o);
-    else if (tvisnum(o))
+    if (tvisnum(o))
       ofs = (int64_t)numV(o);
     else if (!tvisnil(o))
       lj_err_argt(L, 3, LUA_TNUMBER);

src/lib_math.c

@@ -157,42 +157,13 @@ LJLIB_CF(math_random)		LJLIB_REC(.)
   u.u64 = lj_math_random_step(rs);
   d = u.d - 1.0;
   if (n > 0) {
-#if LJ_DUALNUM
-    int isint = 1;
-    double r1;
-    lj_lib_checknumber(L, 1);
-    if (tvisint(L->base)) {
-      r1 = (lua_Number)intV(L->base);
-    } else {
-      isint = 0;
-      r1 = numV(L->base);
-    }
-#else
     double r1 = lj_lib_checknum(L, 1);
-#endif
     if (n == 1) {
       d = lj_vm_floor(d*r1) + 1.0;  /* d is an int in range [1, r1] */
     } else {
-#if LJ_DUALNUM
-      double r2;
-      lj_lib_checknumber(L, 2);
-      if (tvisint(L->base+1)) {
-	r2 = (lua_Number)intV(L->base+1);
-      } else {
-	isint = 0;
-	r2 = numV(L->base+1);
-      }
-#else
       double r2 = lj_lib_checknum(L, 2);
-#endif
       d = lj_vm_floor(d*(r2-r1+1.0)) + r1;  /* d is an int in range [r1, r2] */
     }
-#if LJ_DUALNUM
-    if (isint) {
-      setintV(L->top-1, lj_num2int(d));
-      return 1;
-    }
-#endif
   }  /* else: d is a double in range [0, 1] */
   setnumV(L->top++, d);
   return 1;

src/lib_string.c

@@ -681,21 +681,10 @@ LJLIB_CF(string_format)		LJLIB_REC(.)
 	luaL_argerror(L, arg, lj_obj_typename[0]);
       switch (STRFMT_TYPE(sf)) {
       case STRFMT_INT:
-	if (tvisint(L->base+arg-1)) {
-	  int32_t k = intV(L->base+arg-1);
-	  if (sf == STRFMT_INT)
-	    lj_strfmt_putint(sb, k);  /* Shortcut for plain %d. */
-	  else
-	    lj_strfmt_putfxint(sb, sf, k);
-	} else {
-	  lj_strfmt_putfnum_int(sb, sf, lj_lib_checknum(L, arg));
-	}
+        lj_strfmt_putfnum_int(sb, sf, lj_lib_checknum(L, arg));
 	break;
       case STRFMT_UINT:
-	if (tvisint(L->base+arg-1))
-	  lj_strfmt_putfxint(sb, sf, intV(L->base+arg-1));
-	else
-	  lj_strfmt_putfnum_uint(sb, sf, lj_lib_checknum(L, arg));
+        lj_strfmt_putfnum_uint(sb, sf, lj_lib_checknum(L, arg));
 	break;
       case STRFMT_NUM:
 	lj_strfmt_putfnum(sb, sf, lj_lib_checknum(L, arg));

src/lj_api.c

@@ -253,9 +253,7 @@ LUA_API int lua_equal(lua_State *L, int idx1, int idx2)
 {
   cTValue *o1 = index2adr(L, idx1);
   cTValue *o2 = index2adr(L, idx2);
-  if (tvisint(o1) && tvisint(o2)) {
-    return intV(o1) == intV(o2);
-  } else if (tvisnumber(o1) && tvisnumber(o2)) {
+  if (tvisnumber(o1) && tvisnumber(o2)) {
     return numberVnum(o1) == numberVnum(o2);
   } else if (itype(o1) != itype(o2)) {
     return 0;
@@ -284,8 +282,6 @@ LUA_API int lua_lessthan(lua_State *L, int idx1, int idx2)
   cTValue *o2 = index2adr(L, idx2);
   if (o1 == niltv(L) || o2 == niltv(L)) {
     return 0;
-  } else if (tvisint(o1) && tvisint(o2)) {
-    return intV(o1) < intV(o2);
   } else if (tvisnumber(o1) && tvisnumber(o2)) {
     return numberVnum(o1) < numberVnum(o2);
   } else {
@@ -342,15 +338,11 @@ LUA_API lua_Integer lua_tointeger(lua_State *L, int idx)
   cTValue *o = index2adr(L, idx);
   TValue tmp;
   lua_Number n;
-  if (LJ_LIKELY(tvisint(o))) {
-    return intV(o);
-  } else if (LJ_LIKELY(tvisnum(o))) {
+  if (LJ_LIKELY(tvisnum(o))) {
     n = numV(o);
   } else {
     if (!(tvisstr(o) && lj_strscan_number(strV(o), &tmp)))
       return 0;
-    if (tvisint(&tmp))
-      return (lua_Integer)intV(&tmp);
     n = numV(&tmp);
   }
   return (lua_Integer)n;
@@ -361,15 +353,11 @@ LUALIB_API lua_Integer luaL_checkinteger(lua_State *L, int idx)
   cTValue *o = index2adr(L, idx);
   TValue tmp;
   lua_Number n;
-  if (LJ_LIKELY(tvisint(o))) {
-    return intV(o);
-  } else if (LJ_LIKELY(tvisnum(o))) {
+  if (LJ_LIKELY(tvisnum(o))) {
     n = numV(o);
   } else {
     if (!(tvisstr(o) && lj_strscan_number(strV(o), &tmp)))
       lj_err_argt(L, idx, LUA_TNUMBER);
-    if (tvisint(&tmp))
-      return (lua_Integer)intV(&tmp);
     n = numV(&tmp);
   }
   return (lua_Integer)n;
@@ -380,17 +368,13 @@ LUALIB_API lua_Integer luaL_optinteger(lua_State *L, int idx, lua_Integer def)
   cTValue *o = index2adr(L, idx);
   TValue tmp;
   lua_Number n;
-  if (LJ_LIKELY(tvisint(o))) {
-    return intV(o);
-  } else if (LJ_LIKELY(tvisnum(o))) {
+  if (LJ_LIKELY(tvisnum(o))) {
     n = numV(o);
   } else if (tvisnil(o)) {
     return def;
   } else {
     if (!(tvisstr(o) && lj_strscan_number(strV(o), &tmp)))
       lj_err_argt(L, idx, LUA_TNUMBER);
-    if (tvisint(&tmp))
-      return (lua_Integer)intV(&tmp);
     n = numV(&tmp);
   }
   return (lua_Integer)n;

src/lj_arch.h

@@ -57,11 +57,6 @@
 
 
 
-#define LJ_NUMMODE_SINGLE	0	/* Single-number mode only. */
-#define LJ_NUMMODE_SINGLE_DUAL	1	/* Default to single-number mode. */
-#define LJ_NUMMODE_DUAL		2	/* Dual-number mode only. */
-#define LJ_NUMMODE_DUAL_SINGLE	3	/* Default to dual-number mode. */
-
 /* Set target architecture properties. */
 
 #define LJ_ARCH_NAME		"x64"
@@ -75,7 +70,6 @@
 #define LJ_TARGET_MASKSHIFT	1
 #define LJ_TARGET_MASKROT	1
 #define LJ_TARGET_UNALIGNED	1
-#define LJ_ARCH_NUMMODE		LJ_NUMMODE_SINGLE_DUAL
 #define LJ_TARGET_GC64		1
 
 
@@ -97,20 +91,6 @@
 #endif
 #endif
 
-/* Enable or disable the dual-number mode for the VM. */
-#if (LJ_ARCH_NUMMODE == LJ_NUMMODE_SINGLE && LUAJIT_NUMMODE == 2) || \
-    (LJ_ARCH_NUMMODE == LJ_NUMMODE_DUAL && LUAJIT_NUMMODE == 1)
-#error "No support for this number mode on this architecture"
-#endif
-#if LJ_ARCH_NUMMODE == LJ_NUMMODE_DUAL || \
-    (LJ_ARCH_NUMMODE == LJ_NUMMODE_DUAL_SINGLE && LUAJIT_NUMMODE != 1) || \
-    (LJ_ARCH_NUMMODE == LJ_NUMMODE_SINGLE_DUAL && LUAJIT_NUMMODE == 2)
-#define LJ_DUALNUM		1
-#else
-#define LJ_DUALNUM		0
-#endif
-
-
 /* 64 bit GC references. */
 #define LJ_GC64			1
 

src/lj_asm_x86.h

@@ -1160,8 +1160,7 @@ static void asm_fxstore(ASMState *as, IRIns *ir)
 static void asm_ahuvload(ASMState *as, IRIns *ir)
 {
   Reg tmp = RID_NONE;
-  lua_assert(irt_isnum(ir->t) || irt_ispri(ir->t) || irt_isaddr(ir->t) ||
-	     (LJ_DUALNUM && irt_isint(ir->t)));
+  lua_assert(irt_isnum(ir->t) || irt_ispri(ir->t) || irt_isaddr(ir->t));
   if (ra_used(ir)) {
     RegSet allow = irt_isnum(ir->t) ? RSET_FPR : RSET_GPR;
     Reg dest = ra_dest(as, ir, allow);
@@ -1245,25 +1244,17 @@ static void asm_ahustore(ASMState *as, IRIns *ir)
     }
     asm_fuseahuref(as, ir->op1, allow);
     if (ra_hasreg(src)) {
-      if (!(LJ_DUALNUM && irt_isinteger(ir->t))) {
-	/* TODO: 64 bit store + 32 bit load-modify-store is suboptimal. */
-	as->mrm.ofs += 4;
-	emit_u32(as, irt_toitype(ir->t) << 15);
-	emit_mrm(as, XO_ARITHi, XOg_OR, RID_MRM);
-	as->mrm.ofs -= 4;
-	emit_mrm(as, XO_MOVto, src|REX_64, RID_MRM);
-	return;
-      }
-      emit_mrm(as, XO_MOVto, src, RID_MRM);
-    } else if (!irt_ispri(irr->t)) {
-      lua_assert(irt_isaddr(ir->t) || (LJ_DUALNUM && irt_isinteger(ir->t)));
+      /* TODO: 64 bit store + 32 bit load-modify-store is suboptimal. */
+      as->mrm.ofs += 4;
+      emit_u32(as, irt_toitype(ir->t) << 15);
+      emit_mrm(as, XO_ARITHi, XOg_OR, RID_MRM);
+      as->mrm.ofs -= 4;
+      emit_mrm(as, XO_MOVto, src|REX_64, RID_MRM);
+    } else {
+      lua_assert(!irt_ispri(irr->t) && irt_isaddr(ir->t));
       emit_i32(as, irr->i);
       emit_mrm(as, XO_MOVmi, 0, RID_MRM);
     }
-    as->mrm.ofs += 4;
-    lua_assert(LJ_DUALNUM && irt_isinteger(ir->t));
-    emit_i32(as, LJ_TNUMX << 15);
-    emit_mrm(as, XO_MOVmi, 0, RID_MRM);
   }
 }
 
@@ -1275,8 +1266,7 @@ static void asm_sload(ASMState *as, IRIns *ir)
   Reg base;
   lua_assert(!(ir->op2 & IRSLOAD_PARENT));  /* Handled by asm_head_side(). */
   lua_assert(irt_isguard(t) || !(ir->op2 & IRSLOAD_TYPECHECK));
-  lua_assert(LJ_DUALNUM ||
-	     !irt_isint(t) || (ir->op2 & (IRSLOAD_CONVERT|IRSLOAD_FRAME)));
+  lua_assert(!irt_isint(t) || (ir->op2 & (IRSLOAD_CONVERT|IRSLOAD_FRAME)));
   if ((ir->op2 & IRSLOAD_CONVERT) && irt_isguard(t) && irt_isint(t)) {
     Reg left = ra_scratch(as, RSET_FPR);
     asm_tointg(as, ir, left);  /* Frees dest reg. Do this before base alloc. */
@@ -2150,16 +2140,13 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
       Reg src = ra_alloc1(as, ref, RSET_FPR);
       emit_rmro(as, XO_MOVSDto, src, RID_BASE, ofs);
     } else {
-      lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t) ||
-		 (LJ_DUALNUM && irt_isinteger(ir->t)));
+      lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t));
       if (!irref_isk(ref)) {
 	Reg src = ra_alloc1(as, ref, rset_exclude(RSET_GPR, RID_BASE));
 	if (irt_is64(ir->t)) {
 	  /* TODO: 64 bit store + 32 bit load-modify-store is suboptimal. */
 	  emit_u32(as, irt_toitype(ir->t) << 15);
 	  emit_rmro(as, XO_ARITHi, XOg_OR, RID_BASE, ofs+4);
-	} else if (LJ_DUALNUM && irt_isinteger(ir->t)) {
-	  emit_movmroi(as, RID_BASE, ofs+4, LJ_TISNUM << 15);
 	} else {
 	  emit_movmroi(as, RID_BASE, ofs+4, (irt_toitype(ir->t)<<15)|0x7fff);
 	}

src/lj_bcwrite.c

@@ -39,11 +39,8 @@ static void bcwrite_ktabk(BCWriteCtx *ctx, cTValue *o, int narrow)
     p = lj_buf_more(&ctx->sb, 5+len);
     p = lj_strfmt_wuleb128(p, BCDUMP_KTAB_STR+len);
     p = lj_buf_wmem(p, strdata(str), len);
-  } else if (tvisint(o)) {
-    *p++ = BCDUMP_KTAB_INT;
-    p = lj_strfmt_wuleb128(p, intV(o));
   } else if (tvisnum(o)) {
-    if (!LJ_DUALNUM && narrow) {  /* Narrow number constants to integers. */
+    if (narrow) {  /* Narrow number constants to integers. */
       lua_Number num = numV(o);
       int32_t k = lj_num2int(num);
       if (num == (lua_Number)k) {  /* -0 is never a constant. */
@@ -165,27 +162,19 @@ static void bcwrite_knum(BCWriteCtx *ctx, GCproto *pt)
   char *p = lj_buf_more(&ctx->sb, 10*sizekn);
   for (i = 0; i < sizekn; i++, o++) {
     int32_t k;
-    if (tvisint(o)) {
-      k = intV(o);
-      goto save_int;
-    } else {
-      /* Write a 33 bit ULEB128 for the int (lsb=0) or loword (lsb=1). */
-      if (!LJ_DUALNUM) {  /* Narrow number constants to integers. */
-	lua_Number num = numV(o);
-	k = lj_num2int(num);
-	if (num == (lua_Number)k) {  /* -0 is never a constant. */
-	save_int:
-	  p = lj_strfmt_wuleb128(p, 2*(uint32_t)k | ((uint32_t)k&0x80000000u));
-	  if (k < 0)
-	    p[-1] = (p[-1] & 7) | ((k>>27) & 0x18);
-	  continue;
-	}
-      }
-      p = lj_strfmt_wuleb128(p, 1+(2*o->u32.lo | (o->u32.lo & 0x80000000u)));
-      if (o->u32.lo >= 0x80000000u)
-	p[-1] = (p[-1] & 7) | ((o->u32.lo>>27) & 0x18);
-      p = lj_strfmt_wuleb128(p, o->u32.hi);
+    /* Write a 33 bit ULEB128 for the int (lsb=0) or loword (lsb=1). */
+    lua_Number num = numV(o);
+    k = lj_num2int(num);
+    if (num == (lua_Number)k) {  /* -0 is never a constant. */
+      p = lj_strfmt_wuleb128(p, 2*(uint32_t)k | ((uint32_t)k&0x80000000u));
+      if (k < 0)
+        p[-1] = (p[-1] & 7) | ((k>>27) & 0x18);
+      continue;
     }
+    p = lj_strfmt_wuleb128(p, 1+(2*o->u32.lo | (o->u32.lo & 0x80000000u)));
+    if (o->u32.lo >= 0x80000000u)
+      p[-1] = (p[-1] & 7) | ((o->u32.lo>>27) & 0x18);
+    p = lj_strfmt_wuleb128(p, o->u32.hi);
   }
   setsbufP(&ctx->sb, p);
 }