diff --git a/cmake/google/protobuf/descriptor.upb.c b/cmake/google/protobuf/descriptor.upb.c
index 932fbb3559..a6b9af9132 100644
--- a/cmake/google/protobuf/descriptor.upb.c
+++ b/cmake/google/protobuf/descriptor.upb.c
@@ -17,7 +17,7 @@ static const upb_msglayout *const google_protobuf_FileDescriptorSet_submsgs[1] =
 };
 
 static const upb_msglayout_field google_protobuf_FileDescriptorSet__fields[1] = {
-  {1, UPB_SIZE(0, 0), 0, 0, 11, 3},
+  {1, UPB_SIZE(0, 0), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_FileDescriptorSet_msginit = {
@@ -36,18 +36,18 @@ static const upb_msglayout *const google_protobuf_FileDescriptorProto_submsgs[6]
 };
 
 static const upb_msglayout_field google_protobuf_FileDescriptorProto__fields[12] = {
-  {1, UPB_SIZE(4, 8), 1, 0, 12, 1},
-  {2, UPB_SIZE(12, 24), 2, 0, 12, 1},
-  {3, UPB_SIZE(36, 72), 0, 0, 12, 3},
-  {4, UPB_SIZE(40, 80), 0, 0, 11, 3},
-  {5, UPB_SIZE(44, 88), 0, 1, 11, 3},
-  {6, UPB_SIZE(48, 96), 0, 4, 11, 3},
-  {7, UPB_SIZE(52, 104), 0, 2, 11, 3},
-  {8, UPB_SIZE(28, 56), 3, 3, 11, 1},
-  {9, UPB_SIZE(32, 64), 4, 5, 11, 1},
-  {10, UPB_SIZE(56, 112), 0, 0, 5, 3},
-  {11, UPB_SIZE(60, 120), 0, 0, 5, 3},
-  {12, UPB_SIZE(20, 40), 5, 0, 12, 1},
+  {1, UPB_SIZE(4, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(12, 24), 2, 0, 12, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(36, 72), 0, 0, 12, _UPB_MODE_ARRAY},
+  {4, UPB_SIZE(40, 80), 0, 0, 11, _UPB_MODE_ARRAY},
+  {5, UPB_SIZE(44, 88), 0, 1, 11, _UPB_MODE_ARRAY},
+  {6, UPB_SIZE(48, 96), 0, 4, 11, _UPB_MODE_ARRAY},
+  {7, UPB_SIZE(52, 104), 0, 2, 11, _UPB_MODE_ARRAY},
+  {8, UPB_SIZE(28, 56), 3, 3, 11, _UPB_MODE_SCALAR},
+  {9, UPB_SIZE(32, 64), 4, 5, 11, _UPB_MODE_SCALAR},
+  {10, UPB_SIZE(56, 112), 0, 0, 5, _UPB_MODE_ARRAY},
+  {11, UPB_SIZE(60, 120), 0, 0, 5, _UPB_MODE_ARRAY},
+  {12, UPB_SIZE(20, 40), 5, 0, 12, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_FileDescriptorProto_msginit = {
@@ -67,16 +67,16 @@ static const upb_msglayout *const google_protobuf_DescriptorProto_submsgs[7] = {
 };
 
 static const upb_msglayout_field google_protobuf_DescriptorProto__fields[10] = {
-  {1, UPB_SIZE(4, 8), 1, 0, 12, 1},
-  {2, UPB_SIZE(16, 32), 0, 4, 11, 3},
-  {3, UPB_SIZE(20, 40), 0, 0, 11, 3},
-  {4, UPB_SIZE(24, 48), 0, 3, 11, 3},
-  {5, UPB_SIZE(28, 56), 0, 1, 11, 3},
-  {6, UPB_SIZE(32, 64), 0, 4, 11, 3},
-  {7, UPB_SIZE(12, 24), 2, 5, 11, 1},
-  {8, UPB_SIZE(36, 72), 0, 6, 11, 3},
-  {9, UPB_SIZE(40, 80), 0, 2, 11, 3},
-  {10, UPB_SIZE(44, 88), 0, 0, 12, 3},
+  {1, UPB_SIZE(4, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(16, 32), 0, 4, 11, _UPB_MODE_ARRAY},
+  {3, UPB_SIZE(20, 40), 0, 0, 11, _UPB_MODE_ARRAY},
+  {4, UPB_SIZE(24, 48), 0, 3, 11, _UPB_MODE_ARRAY},
+  {5, UPB_SIZE(28, 56), 0, 1, 11, _UPB_MODE_ARRAY},
+  {6, UPB_SIZE(32, 64), 0, 4, 11, _UPB_MODE_ARRAY},
+  {7, UPB_SIZE(12, 24), 2, 5, 11, _UPB_MODE_SCALAR},
+  {8, UPB_SIZE(36, 72), 0, 6, 11, _UPB_MODE_ARRAY},
+  {9, UPB_SIZE(40, 80), 0, 2, 11, _UPB_MODE_ARRAY},
+  {10, UPB_SIZE(44, 88), 0, 0, 12, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_DescriptorProto_msginit = {
@@ -90,9 +90,9 @@ static const upb_msglayout *const google_protobuf_DescriptorProto_ExtensionRange
 };
 
 static const upb_msglayout_field google_protobuf_DescriptorProto_ExtensionRange__fields[3] = {
-  {1, UPB_SIZE(4, 4), 1, 0, 5, 1},
-  {2, UPB_SIZE(8, 8), 2, 0, 5, 1},
-  {3, UPB_SIZE(12, 16), 3, 0, 11, 1},
+  {1, UPB_SIZE(4, 4), 1, 0, 5, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(8, 8), 2, 0, 5, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(12, 16), 3, 0, 11, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_DescriptorProto_ExtensionRange_msginit = {
@@ -102,8 +102,8 @@ const upb_msglayout google_protobuf_DescriptorProto_ExtensionRange_msginit = {
 };
 
 static const upb_msglayout_field google_protobuf_DescriptorProto_ReservedRange__fields[2] = {
-  {1, UPB_SIZE(4, 4), 1, 0, 5, 1},
-  {2, UPB_SIZE(8, 8), 2, 0, 5, 1},
+  {1, UPB_SIZE(4, 4), 1, 0, 5, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(8, 8), 2, 0, 5, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_DescriptorProto_ReservedRange_msginit = {
@@ -117,7 +117,7 @@ static const upb_msglayout *const google_protobuf_ExtensionRangeOptions_submsgs[
 };
 
 static const upb_msglayout_field google_protobuf_ExtensionRangeOptions__fields[1] = {
-  {999, UPB_SIZE(0, 0), 0, 0, 11, 3},
+  {999, UPB_SIZE(0, 0), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_ExtensionRangeOptions_msginit = {
@@ -131,17 +131,17 @@ static const upb_msglayout *const google_protobuf_FieldDescriptorProto_submsgs[1
 };
 
 static const upb_msglayout_field google_protobuf_FieldDescriptorProto__fields[11] = {
-  {1, UPB_SIZE(24, 24), 1, 0, 12, 1},
-  {2, UPB_SIZE(32, 40), 2, 0, 12, 1},
-  {3, UPB_SIZE(12, 12), 3, 0, 5, 1},
-  {4, UPB_SIZE(4, 4), 4, 0, 14, 1},
-  {5, UPB_SIZE(8, 8), 5, 0, 14, 1},
-  {6, UPB_SIZE(40, 56), 6, 0, 12, 1},
-  {7, UPB_SIZE(48, 72), 7, 0, 12, 1},
-  {8, UPB_SIZE(64, 104), 8, 0, 11, 1},
-  {9, UPB_SIZE(16, 16), 9, 0, 5, 1},
-  {10, UPB_SIZE(56, 88), 10, 0, 12, 1},
-  {17, UPB_SIZE(20, 20), 11, 0, 8, 1},
+  {1, UPB_SIZE(24, 24), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(32, 40), 2, 0, 12, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(12, 12), 3, 0, 5, _UPB_MODE_SCALAR},
+  {4, UPB_SIZE(4, 4), 4, 0, 14, _UPB_MODE_SCALAR},
+  {5, UPB_SIZE(8, 8), 5, 0, 14, _UPB_MODE_SCALAR},
+  {6, UPB_SIZE(40, 56), 6, 0, 12, _UPB_MODE_SCALAR},
+  {7, UPB_SIZE(48, 72), 7, 0, 12, _UPB_MODE_SCALAR},
+  {8, UPB_SIZE(64, 104), 8, 0, 11, _UPB_MODE_SCALAR},
+  {9, UPB_SIZE(16, 16), 9, 0, 5, _UPB_MODE_SCALAR},
+  {10, UPB_SIZE(56, 88), 10, 0, 12, _UPB_MODE_SCALAR},
+  {17, UPB_SIZE(20, 20), 11, 0, 8, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_FieldDescriptorProto_msginit = {
@@ -155,8 +155,8 @@ static const upb_msglayout *const google_protobuf_OneofDescriptorProto_submsgs[1
 };
 
 static const upb_msglayout_field google_protobuf_OneofDescriptorProto__fields[2] = {
-  {1, UPB_SIZE(4, 8), 1, 0, 12, 1},
-  {2, UPB_SIZE(12, 24), 2, 0, 11, 1},
+  {1, UPB_SIZE(4, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(12, 24), 2, 0, 11, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_OneofDescriptorProto_msginit = {
@@ -172,11 +172,11 @@ static const upb_msglayout *const google_protobuf_EnumDescriptorProto_submsgs[3]
 };
 
 static const upb_msglayout_field google_protobuf_EnumDescriptorProto__fields[5] = {
-  {1, UPB_SIZE(4, 8), 1, 0, 12, 1},
-  {2, UPB_SIZE(16, 32), 0, 2, 11, 3},
-  {3, UPB_SIZE(12, 24), 2, 1, 11, 1},
-  {4, UPB_SIZE(20, 40), 0, 0, 11, 3},
-  {5, UPB_SIZE(24, 48), 0, 0, 12, 3},
+  {1, UPB_SIZE(4, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(16, 32), 0, 2, 11, _UPB_MODE_ARRAY},
+  {3, UPB_SIZE(12, 24), 2, 1, 11, _UPB_MODE_SCALAR},
+  {4, UPB_SIZE(20, 40), 0, 0, 11, _UPB_MODE_ARRAY},
+  {5, UPB_SIZE(24, 48), 0, 0, 12, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_EnumDescriptorProto_msginit = {
@@ -186,8 +186,8 @@ const upb_msglayout google_protobuf_EnumDescriptorProto_msginit = {
 };
 
 static const upb_msglayout_field google_protobuf_EnumDescriptorProto_EnumReservedRange__fields[2] = {
-  {1, UPB_SIZE(4, 4), 1, 0, 5, 1},
-  {2, UPB_SIZE(8, 8), 2, 0, 5, 1},
+  {1, UPB_SIZE(4, 4), 1, 0, 5, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(8, 8), 2, 0, 5, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_EnumDescriptorProto_EnumReservedRange_msginit = {
@@ -201,9 +201,9 @@ static const upb_msglayout *const google_protobuf_EnumValueDescriptorProto_subms
 };
 
 static const upb_msglayout_field google_protobuf_EnumValueDescriptorProto__fields[3] = {
-  {1, UPB_SIZE(8, 8), 1, 0, 12, 1},
-  {2, UPB_SIZE(4, 4), 2, 0, 5, 1},
-  {3, UPB_SIZE(16, 24), 3, 0, 11, 1},
+  {1, UPB_SIZE(8, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(4, 4), 2, 0, 5, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(16, 24), 3, 0, 11, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_EnumValueDescriptorProto_msginit = {
@@ -218,9 +218,9 @@ static const upb_msglayout *const google_protobuf_ServiceDescriptorProto_submsgs
 };
 
 static const upb_msglayout_field google_protobuf_ServiceDescriptorProto__fields[3] = {
-  {1, UPB_SIZE(4, 8), 1, 0, 12, 1},
-  {2, UPB_SIZE(16, 32), 0, 0, 11, 3},
-  {3, UPB_SIZE(12, 24), 2, 1, 11, 1},
+  {1, UPB_SIZE(4, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(16, 32), 0, 0, 11, _UPB_MODE_ARRAY},
+  {3, UPB_SIZE(12, 24), 2, 1, 11, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_ServiceDescriptorProto_msginit = {
@@ -234,12 +234,12 @@ static const upb_msglayout *const google_protobuf_MethodDescriptorProto_submsgs[
 };
 
 static const upb_msglayout_field google_protobuf_MethodDescriptorProto__fields[6] = {
-  {1, UPB_SIZE(4, 8), 1, 0, 12, 1},
-  {2, UPB_SIZE(12, 24), 2, 0, 12, 1},
-  {3, UPB_SIZE(20, 40), 3, 0, 12, 1},
-  {4, UPB_SIZE(28, 56), 4, 0, 11, 1},
-  {5, UPB_SIZE(1, 1), 5, 0, 8, 1},
-  {6, UPB_SIZE(2, 2), 6, 0, 8, 1},
+  {1, UPB_SIZE(4, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(12, 24), 2, 0, 12, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(20, 40), 3, 0, 12, _UPB_MODE_SCALAR},
+  {4, UPB_SIZE(28, 56), 4, 0, 11, _UPB_MODE_SCALAR},
+  {5, UPB_SIZE(1, 1), 5, 0, 8, _UPB_MODE_SCALAR},
+  {6, UPB_SIZE(2, 2), 6, 0, 8, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_MethodDescriptorProto_msginit = {
@@ -253,27 +253,27 @@ static const upb_msglayout *const google_protobuf_FileOptions_submsgs[1] = {
 };
 
 static const upb_msglayout_field google_protobuf_FileOptions__fields[21] = {
-  {1, UPB_SIZE(20, 24), 1, 0, 12, 1},
-  {8, UPB_SIZE(28, 40), 2, 0, 12, 1},
-  {9, UPB_SIZE(4, 4), 3, 0, 14, 1},
-  {10, UPB_SIZE(8, 8), 4, 0, 8, 1},
-  {11, UPB_SIZE(36, 56), 5, 0, 12, 1},
-  {16, UPB_SIZE(9, 9), 6, 0, 8, 1},
-  {17, UPB_SIZE(10, 10), 7, 0, 8, 1},
-  {18, UPB_SIZE(11, 11), 8, 0, 8, 1},
-  {20, UPB_SIZE(12, 12), 9, 0, 8, 1},
-  {23, UPB_SIZE(13, 13), 10, 0, 8, 1},
-  {27, UPB_SIZE(14, 14), 11, 0, 8, 1},
-  {31, UPB_SIZE(15, 15), 12, 0, 8, 1},
-  {36, UPB_SIZE(44, 72), 13, 0, 12, 1},
-  {37, UPB_SIZE(52, 88), 14, 0, 12, 1},
-  {39, UPB_SIZE(60, 104), 15, 0, 12, 1},
-  {40, UPB_SIZE(68, 120), 16, 0, 12, 1},
-  {41, UPB_SIZE(76, 136), 17, 0, 12, 1},
-  {42, UPB_SIZE(16, 16), 18, 0, 8, 1},
-  {44, UPB_SIZE(84, 152), 19, 0, 12, 1},
-  {45, UPB_SIZE(92, 168), 20, 0, 12, 1},
-  {999, UPB_SIZE(100, 184), 0, 0, 11, 3},
+  {1, UPB_SIZE(20, 24), 1, 0, 12, _UPB_MODE_SCALAR},
+  {8, UPB_SIZE(28, 40), 2, 0, 12, _UPB_MODE_SCALAR},
+  {9, UPB_SIZE(4, 4), 3, 0, 14, _UPB_MODE_SCALAR},
+  {10, UPB_SIZE(8, 8), 4, 0, 8, _UPB_MODE_SCALAR},
+  {11, UPB_SIZE(36, 56), 5, 0, 12, _UPB_MODE_SCALAR},
+  {16, UPB_SIZE(9, 9), 6, 0, 8, _UPB_MODE_SCALAR},
+  {17, UPB_SIZE(10, 10), 7, 0, 8, _UPB_MODE_SCALAR},
+  {18, UPB_SIZE(11, 11), 8, 0, 8, _UPB_MODE_SCALAR},
+  {20, UPB_SIZE(12, 12), 9, 0, 8, _UPB_MODE_SCALAR},
+  {23, UPB_SIZE(13, 13), 10, 0, 8, _UPB_MODE_SCALAR},
+  {27, UPB_SIZE(14, 14), 11, 0, 8, _UPB_MODE_SCALAR},
+  {31, UPB_SIZE(15, 15), 12, 0, 8, _UPB_MODE_SCALAR},
+  {36, UPB_SIZE(44, 72), 13, 0, 12, _UPB_MODE_SCALAR},
+  {37, UPB_SIZE(52, 88), 14, 0, 12, _UPB_MODE_SCALAR},
+  {39, UPB_SIZE(60, 104), 15, 0, 12, _UPB_MODE_SCALAR},
+  {40, UPB_SIZE(68, 120), 16, 0, 12, _UPB_MODE_SCALAR},
+  {41, UPB_SIZE(76, 136), 17, 0, 12, _UPB_MODE_SCALAR},
+  {42, UPB_SIZE(16, 16), 18, 0, 8, _UPB_MODE_SCALAR},
+  {44, UPB_SIZE(84, 152), 19, 0, 12, _UPB_MODE_SCALAR},
+  {45, UPB_SIZE(92, 168), 20, 0, 12, _UPB_MODE_SCALAR},
+  {999, UPB_SIZE(100, 184), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_FileOptions_msginit = {
@@ -287,11 +287,11 @@ static const upb_msglayout *const google_protobuf_MessageOptions_submsgs[1] = {
 };
 
 static const upb_msglayout_field google_protobuf_MessageOptions__fields[5] = {
-  {1, UPB_SIZE(1, 1), 1, 0, 8, 1},
-  {2, UPB_SIZE(2, 2), 2, 0, 8, 1},
-  {3, UPB_SIZE(3, 3), 3, 0, 8, 1},
-  {7, UPB_SIZE(4, 4), 4, 0, 8, 1},
-  {999, UPB_SIZE(8, 8), 0, 0, 11, 3},
+  {1, UPB_SIZE(1, 1), 1, 0, 8, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(2, 2), 2, 0, 8, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(3, 3), 3, 0, 8, _UPB_MODE_SCALAR},
+  {7, UPB_SIZE(4, 4), 4, 0, 8, _UPB_MODE_SCALAR},
+  {999, UPB_SIZE(8, 8), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_MessageOptions_msginit = {
@@ -305,13 +305,13 @@ static const upb_msglayout *const google_protobuf_FieldOptions_submsgs[1] = {
 };
 
 static const upb_msglayout_field google_protobuf_FieldOptions__fields[7] = {
-  {1, UPB_SIZE(4, 4), 1, 0, 14, 1},
-  {2, UPB_SIZE(12, 12), 2, 0, 8, 1},
-  {3, UPB_SIZE(13, 13), 3, 0, 8, 1},
-  {5, UPB_SIZE(14, 14), 4, 0, 8, 1},
-  {6, UPB_SIZE(8, 8), 5, 0, 14, 1},
-  {10, UPB_SIZE(15, 15), 6, 0, 8, 1},
-  {999, UPB_SIZE(16, 16), 0, 0, 11, 3},
+  {1, UPB_SIZE(4, 4), 1, 0, 14, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(12, 12), 2, 0, 8, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(13, 13), 3, 0, 8, _UPB_MODE_SCALAR},
+  {5, UPB_SIZE(14, 14), 4, 0, 8, _UPB_MODE_SCALAR},
+  {6, UPB_SIZE(8, 8), 5, 0, 14, _UPB_MODE_SCALAR},
+  {10, UPB_SIZE(15, 15), 6, 0, 8, _UPB_MODE_SCALAR},
+  {999, UPB_SIZE(16, 16), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_FieldOptions_msginit = {
@@ -325,7 +325,7 @@ static const upb_msglayout *const google_protobuf_OneofOptions_submsgs[1] = {
 };
 
 static const upb_msglayout_field google_protobuf_OneofOptions__fields[1] = {
-  {999, UPB_SIZE(0, 0), 0, 0, 11, 3},
+  {999, UPB_SIZE(0, 0), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_OneofOptions_msginit = {
@@ -339,9 +339,9 @@ static const upb_msglayout *const google_protobuf_EnumOptions_submsgs[1] = {
 };
 
 static const upb_msglayout_field google_protobuf_EnumOptions__fields[3] = {
-  {2, UPB_SIZE(1, 1), 1, 0, 8, 1},
-  {3, UPB_SIZE(2, 2), 2, 0, 8, 1},
-  {999, UPB_SIZE(4, 8), 0, 0, 11, 3},
+  {2, UPB_SIZE(1, 1), 1, 0, 8, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(2, 2), 2, 0, 8, _UPB_MODE_SCALAR},
+  {999, UPB_SIZE(4, 8), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_EnumOptions_msginit = {
@@ -355,8 +355,8 @@ static const upb_msglayout *const google_protobuf_EnumValueOptions_submsgs[1] =
 };
 
 static const upb_msglayout_field google_protobuf_EnumValueOptions__fields[2] = {
-  {1, UPB_SIZE(1, 1), 1, 0, 8, 1},
-  {999, UPB_SIZE(4, 8), 0, 0, 11, 3},
+  {1, UPB_SIZE(1, 1), 1, 0, 8, _UPB_MODE_SCALAR},
+  {999, UPB_SIZE(4, 8), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_EnumValueOptions_msginit = {
@@ -370,8 +370,8 @@ static const upb_msglayout *const google_protobuf_ServiceOptions_submsgs[1] = {
 };
 
 static const upb_msglayout_field google_protobuf_ServiceOptions__fields[2] = {
-  {33, UPB_SIZE(1, 1), 1, 0, 8, 1},
-  {999, UPB_SIZE(4, 8), 0, 0, 11, 3},
+  {33, UPB_SIZE(1, 1), 1, 0, 8, _UPB_MODE_SCALAR},
+  {999, UPB_SIZE(4, 8), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_ServiceOptions_msginit = {
@@ -385,9 +385,9 @@ static const upb_msglayout *const google_protobuf_MethodOptions_submsgs[1] = {
 };
 
 static const upb_msglayout_field google_protobuf_MethodOptions__fields[3] = {
-  {33, UPB_SIZE(8, 8), 1, 0, 8, 1},
-  {34, UPB_SIZE(4, 4), 2, 0, 14, 1},
-  {999, UPB_SIZE(12, 16), 0, 0, 11, 3},
+  {33, UPB_SIZE(8, 8), 1, 0, 8, _UPB_MODE_SCALAR},
+  {34, UPB_SIZE(4, 4), 2, 0, 14, _UPB_MODE_SCALAR},
+  {999, UPB_SIZE(12, 16), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_MethodOptions_msginit = {
@@ -401,13 +401,13 @@ static const upb_msglayout *const google_protobuf_UninterpretedOption_submsgs[1]
 };
 
 static const upb_msglayout_field google_protobuf_UninterpretedOption__fields[7] = {
-  {2, UPB_SIZE(56, 80), 0, 0, 11, 3},
-  {3, UPB_SIZE(32, 32), 1, 0, 12, 1},
-  {4, UPB_SIZE(8, 8), 2, 0, 4, 1},
-  {5, UPB_SIZE(16, 16), 3, 0, 3, 1},
-  {6, UPB_SIZE(24, 24), 4, 0, 1, 1},
-  {7, UPB_SIZE(40, 48), 5, 0, 12, 1},
-  {8, UPB_SIZE(48, 64), 6, 0, 12, 1},
+  {2, UPB_SIZE(56, 80), 0, 0, 11, _UPB_MODE_ARRAY},
+  {3, UPB_SIZE(32, 32), 1, 0, 12, _UPB_MODE_SCALAR},
+  {4, UPB_SIZE(8, 8), 2, 0, 4, _UPB_MODE_SCALAR},
+  {5, UPB_SIZE(16, 16), 3, 0, 3, _UPB_MODE_SCALAR},
+  {6, UPB_SIZE(24, 24), 4, 0, 1, _UPB_MODE_SCALAR},
+  {7, UPB_SIZE(40, 48), 5, 0, 12, _UPB_MODE_SCALAR},
+  {8, UPB_SIZE(48, 64), 6, 0, 12, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_UninterpretedOption_msginit = {
@@ -417,8 +417,8 @@ const upb_msglayout google_protobuf_UninterpretedOption_msginit = {
 };
 
 static const upb_msglayout_field google_protobuf_UninterpretedOption_NamePart__fields[2] = {
-  {1, UPB_SIZE(4, 8), 1, 0, 12, 2},
-  {2, UPB_SIZE(1, 1), 2, 0, 8, 2},
+  {1, UPB_SIZE(4, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {2, UPB_SIZE(1, 1), 2, 0, 8, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_UninterpretedOption_NamePart_msginit = {
@@ -432,7 +432,7 @@ static const upb_msglayout *const google_protobuf_SourceCodeInfo_submsgs[1] = {
 };
 
 static const upb_msglayout_field google_protobuf_SourceCodeInfo__fields[1] = {
-  {1, UPB_SIZE(0, 0), 0, 0, 11, 3},
+  {1, UPB_SIZE(0, 0), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_SourceCodeInfo_msginit = {
@@ -442,11 +442,11 @@ const upb_msglayout google_protobuf_SourceCodeInfo_msginit = {
 };
 
 static const upb_msglayout_field google_protobuf_SourceCodeInfo_Location__fields[5] = {
-  {1, UPB_SIZE(20, 40), 0, 0, 5, _UPB_LABEL_PACKED},
-  {2, UPB_SIZE(24, 48), 0, 0, 5, _UPB_LABEL_PACKED},
-  {3, UPB_SIZE(4, 8), 1, 0, 12, 1},
-  {4, UPB_SIZE(12, 24), 2, 0, 12, 1},
-  {6, UPB_SIZE(28, 56), 0, 0, 12, 3},
+  {1, UPB_SIZE(20, 40), 0, 0, 5, _UPB_MODE_ARRAY | _UPB_MODE_IS_PACKED},
+  {2, UPB_SIZE(24, 48), 0, 0, 5, _UPB_MODE_ARRAY | _UPB_MODE_IS_PACKED},
+  {3, UPB_SIZE(4, 8), 1, 0, 12, _UPB_MODE_SCALAR},
+  {4, UPB_SIZE(12, 24), 2, 0, 12, _UPB_MODE_SCALAR},
+  {6, UPB_SIZE(28, 56), 0, 0, 12, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_SourceCodeInfo_Location_msginit = {
@@ -460,7 +460,7 @@ static const upb_msglayout *const google_protobuf_GeneratedCodeInfo_submsgs[1] =
 };
 
 static const upb_msglayout_field google_protobuf_GeneratedCodeInfo__fields[1] = {
-  {1, UPB_SIZE(0, 0), 0, 0, 11, 3},
+  {1, UPB_SIZE(0, 0), 0, 0, 11, _UPB_MODE_ARRAY},
 };
 
 const upb_msglayout google_protobuf_GeneratedCodeInfo_msginit = {
@@ -470,10 +470,10 @@ const upb_msglayout google_protobuf_GeneratedCodeInfo_msginit = {
 };
 
 static const upb_msglayout_field google_protobuf_GeneratedCodeInfo_Annotation__fields[4] = {
-  {1, UPB_SIZE(20, 32), 0, 0, 5, _UPB_LABEL_PACKED},
-  {2, UPB_SIZE(12, 16), 1, 0, 12, 1},
-  {3, UPB_SIZE(4, 4), 2, 0, 5, 1},
-  {4, UPB_SIZE(8, 8), 3, 0, 5, 1},
+  {1, UPB_SIZE(20, 32), 0, 0, 5, _UPB_MODE_ARRAY | _UPB_MODE_IS_PACKED},
+  {2, UPB_SIZE(12, 16), 1, 0, 12, _UPB_MODE_SCALAR},
+  {3, UPB_SIZE(4, 4), 2, 0, 5, _UPB_MODE_SCALAR},
+  {4, UPB_SIZE(8, 8), 3, 0, 5, _UPB_MODE_SCALAR},
 };
 
 const upb_msglayout google_protobuf_GeneratedCodeInfo_Annotation_msginit = {
diff --git a/upb/decode.c b/upb/decode.c
index 56aef0afda..1bd091ec9f 100644
--- a/upb/decode.c
+++ b/upb/decode.c
@@ -641,7 +641,7 @@ static const char *decode_msg(upb_decstate *d, const char *ptr, upb_msg *msg,
       case UPB_WIRE_TYPE_DELIMITED: {
         int ndx = field->descriptortype;
         uint64_t size;
-        if (_upb_isrepeated(field)) ndx += 18;
+        if (_upb_getmode(field) == _UPB_MODE_ARRAY) ndx += 18;
         ptr = decode_varint64(d, ptr, &size);
         if (size >= INT32_MAX ||
             ptr - d->end + (int32_t)size > d->limit) {
@@ -665,17 +665,18 @@ static const char *decode_msg(upb_decstate *d, const char *ptr, upb_msg *msg,
 
     if (op >= 0) {
       /* Parse, using op for dispatch. */
-      switch (field->label) {
-        case UPB_LABEL_REPEATED:
-        case _UPB_LABEL_PACKED:
+      switch (_upb_getmode(field)) {
+        case _UPB_MODE_ARRAY:
           ptr = decode_toarray(d, ptr, msg, layout->submsgs, field, &val, op);
           break;
-        case _UPB_LABEL_MAP:
+        case _UPB_MODE_MAP:
           ptr = decode_tomap(d, ptr, msg, layout->submsgs, field, &val);
           break;
-        default:
+        case _UPB_MODE_SCALAR:
           ptr = decode_tomsg(d, ptr, msg, layout->submsgs, field, &val, op);
           break;
+        default:
+          UPB_UNREACHABLE();
       }
     } else {
     unknown:
diff --git a/upb/def.c b/upb/def.c
index 5394955b12..599f42e5be 100644
--- a/upb/def.c
+++ b/upb/def.c
@@ -1035,6 +1035,30 @@ static void assign_layout_indices(const upb_msgdef *m, upb_msglayout *l,
   l->dense_below = dense_below;
 }
 
+static void fill_fieldlayout(upb_msglayout_field *field, const upb_fielddef *f) {
+  field->number = upb_fielddef_number(f);
+  field->descriptortype = upb_fielddef_descriptortype(f);
+
+  if (field->descriptortype == UPB_DTYPE_STRING &&
+      f->file->syntax == UPB_SYNTAX_PROTO2) {
+    /* See TableDescriptorType() in upbc/generator.cc for details and
+     * rationale. */
+    field->descriptortype = UPB_DTYPE_BYTES;
+  }
+
+  if (upb_fielddef_ismap(f)) {
+    field->mode = _UPB_MODE_MAP;
+  } else if (upb_fielddef_isseq(f)) {
+    field->mode = _UPB_MODE_ARRAY;
+  } else {
+    field->mode = _UPB_MODE_SCALAR;
+  }
+
+  if (upb_fielddef_packed(f)) {
+    field->mode |= _UPB_MODE_IS_PACKED;
+  }
+}
+
 /* This function is the dynamic equivalent of message_layout.{cc,h} in upbc.
  * It computes a dynamic layout for all of the fields in |m|. */
 static void make_layout(symtab_addctx *ctx, const upb_msgdef *m) {
@@ -1076,8 +1100,8 @@ static void make_layout(symtab_addctx *ctx, const upb_msgdef *m) {
     const upb_fielddef *val = upb_msgdef_itof(m, 2);
     fields[0].number = 1;
     fields[1].number = 2;
-    fields[0].label = UPB_LABEL_OPTIONAL;
-    fields[1].label = UPB_LABEL_OPTIONAL;
+    fields[0].mode = _UPB_MODE_SCALAR;
+    fields[1].mode = _UPB_MODE_SCALAR;
     fields[0].presence = 0;
     fields[1].presence = 0;
     fields[0].descriptortype = upb_fielddef_descriptortype(key);
@@ -1113,22 +1137,7 @@ static void make_layout(symtab_addctx *ctx, const upb_msgdef *m) {
     upb_fielddef* f = upb_msg_iter_field(&it);
     upb_msglayout_field *field = &fields[upb_fielddef_index(f)];
 
-    field->number = upb_fielddef_number(f);
-    field->descriptortype = upb_fielddef_descriptortype(f);
-    field->label = upb_fielddef_label(f);
-
-    if (field->descriptortype == UPB_DTYPE_STRING &&
-        f->file->syntax == UPB_SYNTAX_PROTO2) {
-      /* See TableDescriptorType() in upbc/generator.cc for details and
-       * rationale. */
-      field->descriptortype = UPB_DTYPE_BYTES;
-    }
-
-    if (upb_fielddef_ismap(f)) {
-      field->label = _UPB_LABEL_MAP;
-    } else if (upb_fielddef_packed(f)) {
-      field->label = _UPB_LABEL_PACKED;
-    }
+    fill_fieldlayout(field, f);
 
     if (upb_fielddef_issubmsg(f)) {
       const upb_msgdef *subm = upb_fielddef_msgsubdef(f);
diff --git a/upb/encode.c b/upb/encode.c
index f3149f2b31..6c5bfaf6ff 100644
--- a/upb/encode.c
+++ b/upb/encode.c
@@ -183,7 +183,7 @@ static void encode_fixedarray(upb_encstate *e, const upb_array *arr,
   }
 }
 
-static void encode_message(upb_encstate *e, const char *msg,
+static void encode_message(upb_encstate *e, const upb_msg *msg,
                            const upb_msglayout *m, size_t *size);
 
 static void encode_scalar(upb_encstate *e, const void *_field_mem,
@@ -275,10 +275,10 @@ static void encode_scalar(upb_encstate *e, const void *_field_mem,
   encode_tag(e, f->number, wire_type);
 }
 
-static void encode_array(upb_encstate *e, const char *field_mem,
+static void encode_array(upb_encstate *e, const upb_msg *msg,
                          const upb_msglayout *m, const upb_msglayout_field *f) {
-  const upb_array *arr = *(const upb_array**)field_mem;
-  bool packed = f->label == _UPB_LABEL_PACKED;
+  const upb_array *arr = *UPB_PTR_AT(msg, f->offset, upb_array*);
+  bool packed = f->mode & _UPB_MODE_IS_PACKED;
   size_t pre_len = e->limit - e->ptr;
 
   if (arr == NULL || arr->len == 0) {
@@ -394,9 +394,9 @@ static void encode_mapentry(upb_encstate *e, uint32_t number,
   encode_tag(e, number, UPB_WIRE_TYPE_DELIMITED);
 }
 
-static void encode_map(upb_encstate *e, const char *field_mem,
+static void encode_map(upb_encstate *e, const upb_msg *msg,
                        const upb_msglayout *m, const upb_msglayout_field *f) {
-  const upb_map *map = *(const upb_map**)field_mem;
+  const upb_map *map = *UPB_PTR_AT(msg, f->offset, const upb_map*);
   const upb_msglayout *layout = m->submsgs[f->submsg_index];
   UPB_ASSERT(layout->field_count == 2);
 
@@ -442,7 +442,7 @@ static void encode_scalarfield(upb_encstate *e, const char *msg,
   encode_scalar(e, msg + f->offset, m, f, skip_empty);
 }
 
-static void encode_message(upb_encstate *e, const char *msg,
+static void encode_message(upb_encstate *e, const upb_msg *msg,
                            const upb_msglayout *m, size_t *size) {
   size_t pre_len = e->limit - e->ptr;
   const upb_msglayout_field *f = &m->fields[m->field_count];
@@ -459,12 +459,18 @@ static void encode_message(upb_encstate *e, const char *msg,
 
   while (f != first) {
     f--;
-    if (_upb_isrepeated(f)) {
-      encode_array(e, msg + f->offset, m, f);
-    } else if (f->label == _UPB_LABEL_MAP) {
-      encode_map(e, msg + f->offset, m, f);
-    } else {
-      encode_scalarfield(e, msg, m, f);
+    switch (_upb_getmode(f)) {
+      case _UPB_MODE_ARRAY:
+        encode_array(e, msg, m, f);
+        break;
+      case _UPB_MODE_MAP:
+        encode_map(e, msg, m, f);
+        break;
+      case _UPB_MODE_SCALAR:
+        encode_scalarfield(e, msg, m, f);
+        break;
+      default:
+        UPB_UNREACHABLE();
     }
   }
 
diff --git a/upb/msg_internal.h b/upb/msg_internal.h
index 9fefd53fb4..08af923734 100644
--- a/upb/msg_internal.h
+++ b/upb/msg_internal.h
@@ -42,9 +42,34 @@ typedef struct {
   int16_t presence;       /* If >0, hasbit_index.  If <0, ~oneof_index. */
   uint16_t submsg_index;  /* undefined if descriptortype != MESSAGE or GROUP. */
   uint8_t descriptortype;
-  uint8_t label;          /* google.protobuf.Label or _UPB_LABEL_* above. */
+  int8_t mode;            /* upb_fieldmode, with flags from upb_labelflags */
 } upb_msglayout_field;
 
+typedef enum {
+  _UPB_MODE_MAP = 0,
+  _UPB_MODE_ARRAY = 1,
+  _UPB_MODE_SCALAR = 2,
+} upb_fieldmode;
+
+/* Extra flags on the mode field. */
+enum upb_labelflags {
+  _UPB_MODE_IS_PACKED = 4,
+};
+
+UPB_INLINE upb_fieldmode _upb_getmode(const upb_msglayout_field *field) {
+  return (upb_fieldmode)(field->mode & 3);
+}
+
+UPB_INLINE bool _upb_repeated_or_map(const upb_msglayout_field *field) {
+  /* This works because upb_fieldmode has no value 3. */
+  return !(field->mode & _UPB_MODE_SCALAR);
+}
+
+UPB_INLINE bool _upb_issubmsg(const upb_msglayout_field *field) {
+  return field->descriptortype == UPB_DTYPE_MESSAGE ||
+         field->descriptortype == UPB_DTYPE_GROUP;
+}
+
 struct upb_decstate;
 struct upb_msglayout;
 
@@ -188,14 +213,6 @@ UPB_INLINE bool _upb_has_submsg_nohasbit(const upb_msg *msg, size_t ofs) {
   return *UPB_PTR_AT(msg, ofs, const upb_msg*) != NULL;
 }
 
-UPB_INLINE bool _upb_isrepeated(const upb_msglayout_field *field) {
-  return (field->label & 3) == UPB_LABEL_REPEATED;
-}
-
-UPB_INLINE bool _upb_repeated_or_map(const upb_msglayout_field *field) {
-  return field->label >= UPB_LABEL_REPEATED;
-}
-
 /** upb_array *****************************************************************/
 
 /* Our internal representation for repeated fields.  */
diff --git a/upbc/protoc-gen-upb.cc b/upbc/protoc-gen-upb.cc
index e809fa66c2..79db357dd3 100644
--- a/upbc/protoc-gen-upb.cc
+++ b/upbc/protoc-gen-upb.cc
@@ -846,18 +846,21 @@ std::vector<TableEntry> FastDecodeTable(const protobuf::Descriptor* message,
 void WriteField(const protobuf::FieldDescriptor* field,
                 absl::string_view offset, absl::string_view presence,
                 int submsg_index, Output& output) {
-
-  std::string label;
+  std::string mode;
   if (field->is_map()) {
-    label = "_UPB_LABEL_MAP";
-  } else if (field->is_packed()) {
-    label = "_UPB_LABEL_PACKED";
+    mode = "_UPB_MODE_MAP";
+  } else if (field->is_repeated()) {
+    mode = "_UPB_MODE_ARRAY";
   } else {
-    label = absl::StrCat(field->label());
+    mode = "_UPB_MODE_SCALAR";
+  }
+
+  if (field->is_packed()) {
+    absl::StrAppend(&mode, " | _UPB_MODE_IS_PACKED");
   }
 
   output("{$0, $1, $2, $3, $4, $5}", field->number(), offset, presence,
-         submsg_index, TableDescriptorType(field), label);
+         submsg_index, TableDescriptorType(field), mode);
 }
 
 // Writes a single field into a .upb.c source file.