diff --git a/generated_for_cmake/google/protobuf/descriptor.upb.c b/generated_for_cmake/google/protobuf/descriptor.upb.c
index 471d12d327..3690b28bc8 100644
--- a/generated_for_cmake/google/protobuf/descriptor.upb.c
+++ b/generated_for_cmake/google/protobuf/descriptor.upb.c
@@ -23,8 +23,7 @@ static const upb_msglayout_field google_protobuf_FileDescriptorSet__fields[1] =
 const upb_msglayout google_protobuf_FileDescriptorSet_msginit = {
   &google_protobuf_FileDescriptorSet_submsgs[0],
   &google_protobuf_FileDescriptorSet__fields[0],
-  8,
-  UPB_SIZE(8, 8), 1, false,
+  UPB_SIZE(8, 8), 1, false, 8,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_prm_1bt_max192b, UPB_SIZE(10, 10)},
@@ -58,8 +57,7 @@ static const upb_msglayout_field google_protobuf_FileDescriptorProto__fields[12]
 const upb_msglayout google_protobuf_FileDescriptorProto_msginit = {
   &google_protobuf_FileDescriptorProto_submsgs[0],
   &google_protobuf_FileDescriptorProto__fields[0],
-  120,
-  UPB_SIZE(64, 128), 12, false,
+  UPB_SIZE(64, 128), 12, false, 120,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(1125899906973706, 2251799813816330)},
@@ -106,8 +104,7 @@ static const upb_msglayout_field google_protobuf_DescriptorProto__fields[10] = {
 const upb_msglayout google_protobuf_DescriptorProto_msginit = {
   &google_protobuf_DescriptorProto_submsgs[0],
   &google_protobuf_DescriptorProto__fields[0],
-  120,
-  UPB_SIZE(48, 96), 10, false,
+  UPB_SIZE(48, 96), 10, false, 120,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(1125899906973706, 2251799813816330)},
@@ -141,8 +138,7 @@ static const upb_msglayout_field google_protobuf_DescriptorProto_ExtensionRange_
 const upb_msglayout google_protobuf_DescriptorProto_ExtensionRange_msginit = {
   &google_protobuf_DescriptorProto_ExtensionRange_submsgs[0],
   &google_protobuf_DescriptorProto_ExtensionRange__fields[0],
-  24,
-  UPB_SIZE(16, 24), 3, false,
+  UPB_SIZE(16, 24), 3, false, 24,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_psv4_1bt, UPB_SIZE(1125899906973704, 1125899906973704)},
@@ -159,8 +155,7 @@ static const upb_msglayout_field google_protobuf_DescriptorProto_ReservedRange__
 const upb_msglayout google_protobuf_DescriptorProto_ReservedRange_msginit = {
   NULL,
   &google_protobuf_DescriptorProto_ReservedRange__fields[0],
-  24,
-  UPB_SIZE(16, 16), 2, false,
+  UPB_SIZE(16, 16), 2, false, 24,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_psv4_1bt, UPB_SIZE(1125899906973704, 1125899906973704)},
@@ -180,8 +175,7 @@ static const upb_msglayout_field google_protobuf_ExtensionRangeOptions__fields[1
 const upb_msglayout google_protobuf_ExtensionRangeOptions_msginit = {
   &google_protobuf_ExtensionRangeOptions_submsgs[0],
   &google_protobuf_ExtensionRangeOptions__fields[0],
-  0,
-  UPB_SIZE(8, 8), 1, false,
+  UPB_SIZE(8, 8), 1, false, 0,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
   },
@@ -208,8 +202,7 @@ static const upb_msglayout_field google_protobuf_FieldDescriptorProto__fields[11
 const upb_msglayout google_protobuf_FieldDescriptorProto_msginit = {
   &google_protobuf_FieldDescriptorProto_submsgs[0],
   &google_protobuf_FieldDescriptorProto__fields[0],
-  248,
-  UPB_SIZE(80, 128), 11, false,
+  UPB_SIZE(80, 128), 11, false, 248,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(10133099165777930, 11258999072620554)},
@@ -258,8 +251,7 @@ static const upb_msglayout_field google_protobuf_OneofDescriptorProto__fields[2]
 const upb_msglayout google_protobuf_OneofDescriptorProto_msginit = {
   &google_protobuf_OneofDescriptorProto_submsgs[0],
   &google_protobuf_OneofDescriptorProto__fields[0],
-  24,
-  UPB_SIZE(16, 32), 2, false,
+  UPB_SIZE(16, 32), 2, false, 24,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(1125899906973706, 2251799813816330)},
@@ -285,8 +277,7 @@ static const upb_msglayout_field google_protobuf_EnumDescriptorProto__fields[5]
 const upb_msglayout google_protobuf_EnumDescriptorProto_msginit = {
   &google_protobuf_EnumDescriptorProto_submsgs[0],
   &google_protobuf_EnumDescriptorProto__fields[0],
-  56,
-  UPB_SIZE(32, 64), 5, false,
+  UPB_SIZE(32, 64), 5, false, 56,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(1125899906973706, 2251799813816330)},
@@ -307,8 +298,7 @@ static const upb_msglayout_field google_protobuf_EnumDescriptorProto_EnumReserve
 const upb_msglayout google_protobuf_EnumDescriptorProto_EnumReservedRange_msginit = {
   NULL,
   &google_protobuf_EnumDescriptorProto_EnumReservedRange__fields[0],
-  24,
-  UPB_SIZE(16, 16), 2, false,
+  UPB_SIZE(16, 16), 2, false, 24,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_psv4_1bt, UPB_SIZE(1125899906973704, 1125899906973704)},
@@ -330,8 +320,7 @@ static const upb_msglayout_field google_protobuf_EnumValueDescriptorProto__field
 const upb_msglayout google_protobuf_EnumValueDescriptorProto_msginit = {
   &google_protobuf_EnumValueDescriptorProto_submsgs[0],
   &google_protobuf_EnumValueDescriptorProto__fields[0],
-  24,
-  UPB_SIZE(24, 32), 3, false,
+  UPB_SIZE(24, 32), 3, false, 24,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(2251799813947402, 2251799813947402)},
@@ -354,8 +343,7 @@ static const upb_msglayout_field google_protobuf_ServiceDescriptorProto__fields[
 const upb_msglayout google_protobuf_ServiceDescriptorProto_msginit = {
   &google_protobuf_ServiceDescriptorProto_submsgs[0],
   &google_protobuf_ServiceDescriptorProto__fields[0],
-  24,
-  UPB_SIZE(24, 48), 3, false,
+  UPB_SIZE(24, 48), 3, false, 24,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(1125899906973706, 2251799813816330)},
@@ -380,8 +368,7 @@ static const upb_msglayout_field google_protobuf_MethodDescriptorProto__fields[6
 const upb_msglayout google_protobuf_MethodDescriptorProto_msginit = {
   &google_protobuf_MethodDescriptorProto_submsgs[0],
   &google_protobuf_MethodDescriptorProto__fields[0],
-  56,
-  UPB_SIZE(32, 64), 6, false,
+  UPB_SIZE(32, 64), 6, false, 56,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(1125899907366922, 2251799814209546)},
@@ -425,8 +412,7 @@ static const upb_msglayout_field google_protobuf_FileOptions__fields[21] = {
 const upb_msglayout google_protobuf_FileOptions_msginit = {
   &google_protobuf_FileOptions_submsgs[0],
   &google_protobuf_FileOptions__fields[0],
-  248,
-  UPB_SIZE(112, 208), 21, false,
+  UPB_SIZE(112, 208), 21, false, 248,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(7881299482116106, 9007199388958730)},
@@ -478,8 +464,7 @@ static const upb_msglayout_field google_protobuf_MessageOptions__fields[5] = {
 const upb_msglayout google_protobuf_MessageOptions_msginit = {
   &google_protobuf_MessageOptions_submsgs[0],
   &google_protobuf_MessageOptions__fields[0],
-  56,
-  UPB_SIZE(16, 16), 5, false,
+  UPB_SIZE(16, 16), 5, false, 56,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_psb1_1bt, UPB_SIZE(281474976841736, 281474976841736)},
@@ -509,8 +494,7 @@ static const upb_msglayout_field google_protobuf_FieldOptions__fields[7] = {
 const upb_msglayout google_protobuf_FieldOptions_msginit = {
   &google_protobuf_FieldOptions_submsgs[0],
   &google_protobuf_FieldOptions__fields[0],
-  120,
-  UPB_SIZE(32, 40), 7, false,
+  UPB_SIZE(32, 40), 7, false, 120,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_psv4_1bt, UPB_SIZE(2251799813816328, 2251799813816328)},
@@ -542,8 +526,7 @@ static const upb_msglayout_field google_protobuf_OneofOptions__fields[1] = {
 const upb_msglayout google_protobuf_OneofOptions_msginit = {
   &google_protobuf_OneofOptions_submsgs[0],
   &google_protobuf_OneofOptions__fields[0],
-  0,
-  UPB_SIZE(8, 8), 1, false,
+  UPB_SIZE(8, 8), 1, false, 0,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
   },
@@ -562,8 +545,7 @@ static const upb_msglayout_field google_protobuf_EnumOptions__fields[3] = {
 const upb_msglayout google_protobuf_EnumOptions_msginit = {
   &google_protobuf_EnumOptions_submsgs[0],
   &google_protobuf_EnumOptions__fields[0],
-  24,
-  UPB_SIZE(8, 16), 3, false,
+  UPB_SIZE(8, 16), 3, false, 24,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&fastdecode_generic, UPB_SIZE(0, 0)},
@@ -584,8 +566,7 @@ static const upb_msglayout_field google_protobuf_EnumValueOptions__fields[2] = {
 const upb_msglayout google_protobuf_EnumValueOptions_msginit = {
   &google_protobuf_EnumValueOptions_submsgs[0],
   &google_protobuf_EnumValueOptions__fields[0],
-  8,
-  UPB_SIZE(8, 16), 2, false,
+  UPB_SIZE(8, 16), 2, false, 8,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_psb1_1bt, UPB_SIZE(281474976841736, 281474976841736)},
@@ -604,8 +585,7 @@ static const upb_msglayout_field google_protobuf_ServiceOptions__fields[2] = {
 const upb_msglayout google_protobuf_ServiceOptions_msginit = {
   &google_protobuf_ServiceOptions_submsgs[0],
   &google_protobuf_ServiceOptions__fields[0],
-  0,
-  UPB_SIZE(8, 16), 2, false,
+  UPB_SIZE(8, 16), 2, false, 0,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
   },
@@ -624,8 +604,7 @@ static const upb_msglayout_field google_protobuf_MethodOptions__fields[3] = {
 const upb_msglayout google_protobuf_MethodOptions_msginit = {
   &google_protobuf_MethodOptions_submsgs[0],
   &google_protobuf_MethodOptions__fields[0],
-  0,
-  UPB_SIZE(24, 32), 3, false,
+  UPB_SIZE(24, 32), 3, false, 0,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
   },
@@ -648,8 +627,7 @@ static const upb_msglayout_field google_protobuf_UninterpretedOption__fields[7]
 const upb_msglayout google_protobuf_UninterpretedOption_msginit = {
   &google_protobuf_UninterpretedOption_submsgs[0],
   &google_protobuf_UninterpretedOption__fields[0],
-  120,
-  UPB_SIZE(64, 96), 7, false,
+  UPB_SIZE(64, 96), 7, false, 120,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&fastdecode_generic, UPB_SIZE(0, 0)},
@@ -678,8 +656,7 @@ static const upb_msglayout_field google_protobuf_UninterpretedOption_NamePart__f
 const upb_msglayout google_protobuf_UninterpretedOption_NamePart_msginit = {
   NULL,
   &google_protobuf_UninterpretedOption_NamePart__fields[0],
-  24,
-  UPB_SIZE(16, 32), 2, false,
+  UPB_SIZE(16, 32), 2, false, 24,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_pss_1bt, UPB_SIZE(1125899907104778, 2251799813947402)},
@@ -699,8 +676,7 @@ static const upb_msglayout_field google_protobuf_SourceCodeInfo__fields[1] = {
 const upb_msglayout google_protobuf_SourceCodeInfo_msginit = {
   &google_protobuf_SourceCodeInfo_submsgs[0],
   &google_protobuf_SourceCodeInfo__fields[0],
-  8,
-  UPB_SIZE(8, 8), 1, false,
+  UPB_SIZE(8, 8), 1, false, 8,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_prm_1bt_max128b, UPB_SIZE(10, 10)},
@@ -718,8 +694,7 @@ static const upb_msglayout_field google_protobuf_SourceCodeInfo_Location__fields
 const upb_msglayout google_protobuf_SourceCodeInfo_Location_msginit = {
   NULL,
   &google_protobuf_SourceCodeInfo_Location__fields[0],
-  56,
-  UPB_SIZE(32, 64), 5, false,
+  UPB_SIZE(32, 64), 5, false, 56,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&fastdecode_generic, UPB_SIZE(0, 0)},
@@ -743,8 +718,7 @@ static const upb_msglayout_field google_protobuf_GeneratedCodeInfo__fields[1] =
 const upb_msglayout google_protobuf_GeneratedCodeInfo_msginit = {
   &google_protobuf_GeneratedCodeInfo_submsgs[0],
   &google_protobuf_GeneratedCodeInfo__fields[0],
-  8,
-  UPB_SIZE(8, 8), 1, false,
+  UPB_SIZE(8, 8), 1, false, 8,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&upb_prm_1bt_max64b, UPB_SIZE(10, 10)},
@@ -761,8 +735,7 @@ static const upb_msglayout_field google_protobuf_GeneratedCodeInfo_Annotation__f
 const upb_msglayout google_protobuf_GeneratedCodeInfo_Annotation_msginit = {
   NULL,
   &google_protobuf_GeneratedCodeInfo_Annotation__fields[0],
-  56,
-  UPB_SIZE(24, 48), 4, false,
+  UPB_SIZE(24, 48), 4, false, 56,
   {
     {&fastdecode_generic, UPB_SIZE(0, 0)},
     {&fastdecode_generic, UPB_SIZE(0, 0)},
diff --git a/upb/decode.c b/upb/decode.c
index 11a30faa38..eb40f67ca9 100644
--- a/upb/decode.c
+++ b/upb/decode.c
@@ -619,7 +619,7 @@ const char *fastdecode_generic(upb_decstate *d, const char *ptr, upb_msg *msg,
   *(uint32_t*)msg |= hasbits >> 16;  /* Sync hasbits. */
   (void)data;
   if (ptr == d->limit) return ptr;
-  ret = decode_field(d, ptr, msg, (const upb_msglayout *)(table >> 8));
+  ret = decode_field(d, ptr, msg, decode_totablep(table));
   if (ret.group_end) return ptr;
   return fastdecode_dispatch(d, ret.ptr, msg, table, hasbits);
 }
@@ -628,8 +628,7 @@ UPB_NOINLINE
 static const char *decode_msg(upb_decstate *d, const char *ptr, upb_msg *msg,
                               const upb_msglayout *layout) {
   if (msg) {
-    ptr = fastdecode_dispatch(d, ptr, msg,
-                              ((intptr_t)layout << 8) | layout->table_mask, 0);
+    ptr = fastdecode_dispatch(d, ptr, msg, decode_totable(layout), 0);
   } else {
     while (ptr < d->limit) {
       decode_parseret ret = decode_field(d, ptr, msg, layout);
diff --git a/upb/decode.int.h b/upb/decode.int.h
index f35066a47a..2b881bdc06 100644
--- a/upb/decode.int.h
+++ b/upb/decode.int.h
@@ -21,6 +21,15 @@ const char *fastdecode_dispatch(upb_decstate *d, const char *ptr, upb_msg *msg,
                                 intptr_t table, uint64_t hasbits);
 const char *fastdecode_err(upb_decstate *d);
 
+/* x86-64 pointers always have the high 16 bits matching. So we can shift
+ * left 8 and right 8 without loss of information. */
+UPB_INLINE intptr_t decode_totable(const upb_msglayout *tablep) {
+  return ((intptr_t)tablep << 8) | tablep->table_mask;
+}
+
+UPB_INLINE const upb_msglayout *decode_totablep(intptr_t table) {
+  return (void*)(table >> 8);
+}
 
 UPB_INLINE
 upb_msg *decode_newmsg_ceil(upb_decstate *d, size_t size, int msg_ceil_bytes) {
diff --git a/upb/decode_fast.c b/upb/decode_fast.c
index 4d133b2531..3ab1023b96 100644
--- a/upb/decode_fast.c
+++ b/upb/decode_fast.c
@@ -27,7 +27,7 @@ UPB_FORCEINLINE
 const char *fastdecode_tag_dispatch(upb_decstate *d, const char *ptr,
                                     upb_msg *msg, intptr_t table,
                                     uint64_t hasbits, uint32_t tag) {
-  const upb_msglayout *table_p = (void*)(table >> 8);
+  const upb_msglayout *table_p = decode_totablep(table);
   uint8_t mask = table;
   uint64_t data;
   size_t idx = tag & mask;
@@ -310,9 +310,9 @@ static const char *fastdecode_submsg(UPB_PARSE_PARAMS, int tagbytes,
   void *end;
   uint32_t submsg_idx = data;
   submsg_idx >>= 16;
-  const upb_msglayout *table_p = (void*)(table >> 8);
+  const upb_msglayout *table_p = decode_totablep(table);
   const upb_msglayout *subl = table_p->submsgs[submsg_idx];
-  intptr_t subt = (intptr_t)subl << 8 | subl->table_mask;
+  intptr_t subt = decode_totable(subl);
   size_t submsg_size = subl->size + sizeof(upb_msg_internal);
   submsg = fastdecode_getfield_ofs(d, ptr, msg, &data, &hasbits, &arr, &end,
                                    sizeof(upb_msg *), card, true);
diff --git a/upb/msg.h b/upb/msg.h
index a6ae8aea9c..8a542842e1 100644
--- a/upb/msg.h
+++ b/upb/msg.h
@@ -61,12 +61,12 @@ typedef struct {
 typedef struct upb_msglayout {
   const struct upb_msglayout *const* submsgs;
   const upb_msglayout_field *fields;
-  uint8_t table_mask;
   /* Must be aligned to sizeof(void*).  Doesn't include internal members like
    * unknown fields, extension dict, pointer to msglayout, etc. */
   uint16_t size;
   uint16_t field_count;
   bool extendable;
+  uint8_t table_mask;
   _upb_fasttable_entry fasttable[];
 } upb_msglayout;
 
diff --git a/upbc/generator.cc b/upbc/generator.cc
index 0bd474cd41..13f41d151d 100644
--- a/upbc/generator.cc
+++ b/upbc/generator.cc
@@ -973,10 +973,10 @@ void WriteSource(const protobuf::FileDescriptor* file, Output& output) {
     output("const upb_msglayout $0 = {\n", MessageInit(message));
     output("  $0,\n", submsgs_array_ref);
     output("  $0,\n", fields_array_ref);
-    output("  $0,\n", (table.size() - 1) << 3);
-    output("  $0, $1, $2,\n", GetSizeInit(layout.message_size()),
+    output("  $0, $1, $2, $3,\n", GetSizeInit(layout.message_size()),
            field_number_order.size(),
-           "false"  // TODO: extendable
+           "false",  // TODO: extendable
+           (table.size() - 1) << 3
     );
     output("  {\n");
     for (const auto& ent : table) {