Merge pull request #90 from haberman/gencode3

Added new encoder/decoder that operates on upb_msglayout.

17 files changed, 1484 insertions, 349 deletions

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..8b52c1d
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "third_party/protobuf"]
+	path = third_party/protobuf
+	url = https://github.com/google/protobuf.git
diff --git a/Makefile b/Makefile
index 597476c..390e7af 100644
--- a/Makefile
+++ b/Makefile
@@ -110,7 +110,7 @@ clean_leave_profile:
 	@rm -rf obj lib
 	@rm -f tests/google_message?.h
 	@rm -f tests/json/test.upbdefs.o
-	@rm -f $(TESTS) tests/testmain.o tests/t.*
+	@rm -f $(TESTS) tests/testmain.o tests/t.* tests/conformance_upb
 	@rm -rf tools/upbc deps
 	@rm -rf upb/bindings/python/build
 	@rm -f upb/bindings/ruby/Makefile
@@ -148,7 +148,9 @@ make_objs_cc = $$(patsubst upb/$$(pc).cc,obj/upb/$$(pc).$(1),$$($$(call to_srcs,
 # Core libraries (ie. not bindings). ###############################################################
 
 upb_SRCS = \
+  upb/decode.c \
   upb/def.c \
+  upb/encode.c \
   upb/handlers.c \
   upb/msg.c \
   upb/refcounted.c \
@@ -361,6 +363,21 @@ test:
 	done;
 	@echo "All tests passed!"
 
+obj/conformance_protos: obj/conformance_protos.pb tools/upbc
+	cd obj && ../tools/upbc conformance_protos.pb && touch conformance_protos
+
+obj/conformance_protos.pb: third_party/protobuf/autogen.sh
+	protoc -Ithird_party/protobuf/conformance -Ithird_party/protobuf/src --include_imports \
+	  third_party/protobuf/conformance/conformance.proto \
+	  third_party/protobuf/src/google/protobuf/test_messages_proto3.proto \
+	  -o obj/conformance_protos.pb
+
+third_party/protouf/autogen.sh: .gitmodules
+	git submodule init && git submodule update
+
+tests/conformance_upb: tests/conformance_upb.c lib/libupb.a obj/conformance_protos
+	$(CC) -o tests/conformance_upb tests/conformance_upb.c -Iobj -I. $(CPPFLAGS) $(CFLAGS) obj/conformance.upb.c obj/google/protobuf/*.upb.c lib/libupb.a
+
 
 # Google protobuf binding ######################################################
 
diff --git a/tests/conformance_upb.c b/tests/conformance_upb.c
index 1671409..70ea300 100644
--- a/tests/conformance_upb.c
+++ b/tests/conformance_upb.c
@@ -4,6 +4,7 @@
 
 #include <errno.h>
 #include <stdarg.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
@@ -32,7 +33,7 @@ bool CheckedRead(int fd, void *buf, size_t len) {
 }
 
 void CheckedWrite(int fd, const void *buf, size_t len) {
-  if (write(fd, buf, len) != len) {
+  if ((size_t)write(fd, buf, len) != len) {
     perror("writing to test runner");
     exit(1);
   }
@@ -52,7 +53,7 @@ void DoTest(
 
       if (!test_message) {
         /* TODO(haberman): return details. */
-        static char msg[] = "Parse error (no more details available).";
+        static const char msg[] = "Parse error (no more details available).";
         conformance_ConformanceResponse_set_parse_error(
             response, upb_stringview_make(msg, sizeof(msg)));
         return;
@@ -60,20 +61,20 @@ void DoTest(
       break;
 
     case conformance_ConformanceRequest_payload_json_payload: {
-      static char msg[] = "JSON support not yet implemented.";
+      static const char msg[] = "JSON support not yet implemented.";
       conformance_ConformanceResponse_set_skipped(
           response, upb_stringview_make(msg, sizeof(msg)));
       return;
     }
 
     case conformance_ConformanceRequest_payload_NOT_SET:
-      fprintf(stderr, "conformance_upb: Request didn't have payload.");
-      exit(1);
+      fprintf(stderr, "conformance_upb: Request didn't have payload.\n");
+      return;
   }
 
   switch (conformance_ConformanceRequest_requested_output_format(request)) {
     case conformance_UNSPECIFIED:
-      fprintf(stderr, "conformance_upb: Unspecified output format.");
+      fprintf(stderr, "conformance_upb: Unspecified output format.\n");
       exit(1);
 
     case conformance_PROTOBUF: {
@@ -81,8 +82,10 @@ void DoTest(
       char *serialized = protobuf_test_messages_proto3_TestAllTypes_serialize(
           test_message, env, &serialized_len);
       if (!serialized) {
-        fprintf(stderr, "conformance_upb: Error serializing.");
-        exit(1);
+        static const char msg[] = "Error serializing.";
+        conformance_ConformanceResponse_set_serialize_error(
+            response, upb_stringview_make(msg, sizeof(msg)));
+        return;
       }
       conformance_ConformanceResponse_set_protobuf_payload(
           response, upb_stringview_make(serialized, serialized_len));
@@ -90,14 +93,14 @@ void DoTest(
     }
 
     case conformance_JSON: {
-      static char msg[] = "JSON support not yet implemented.";
+      static const char msg[] = "JSON support not yet implemented.";
       conformance_ConformanceResponse_set_skipped(
           response, upb_stringview_make(msg, sizeof(msg)));
       break;
     }
 
     default:
-      fprintf(stderr, "conformance_upb: Unknown output format: %d",
+      fprintf(stderr, "conformance_upb: Unknown output format: %d\n",
               conformance_ConformanceRequest_requested_output_format(request));
       exit(1);
   }
diff --git a/tests/conformance_upb_failures.txt b/tests/conformance_upb_failures.txt
new file mode 100644
index 0000000..05aab58
--- /dev/null
+++ b/tests/conformance_upb_failures.txt
@@ -0,0 +1 @@
+Required.ProtobufInput.PrematureEofInSubmessageValue.MESSAGE
diff --git a/third_party/protobuf b/third_party/protobuf
new file mode 160000
+Subproject 6bd51a59df41b99058ec8c2b03a177a218267ce
diff --git a/tools/make_c_api.lua b/tools/make_c_api.lua
index c13f37c..d81ca6b 100644
--- a/tools/make_c_api.lua
+++ b/tools/make_c_api.lua
@@ -42,7 +42,6 @@ local function to_preproc(...)
   return string.upper(to_cident(...))
 end
 
-
 -- Strips away last path element, ie:
 --   foo.Bar.Baz -> foo.Bar
 local function remove_name(name)
@@ -55,6 +54,10 @@ local function remove_name(name)
   return string.sub(name, 1, package_end)
 end
 
+local function enum_value_symbol(enumdef, name)
+  return to_cident(remove_name(enumdef:full_name())) .. "_" .. name
+end
+
 local function dump_enum_vals(enumdef, append)
   local enum_vals = {}
 
@@ -91,7 +94,7 @@ local function dump_enum_vals(enumdef, append)
   local cident = to_cident(remove_name(enumdef:full_name()))
   for i, pair in ipairs(enum_vals) do
     k, v = pair[1], pair[2]
-    append('  %s = %d', cident .. "_" .. k, v)
+    append('  %s = %d', enum_value_symbol(enumdef, k), v)
     if i == #enum_vals then
       append('\n')
     else
@@ -100,6 +103,20 @@ local function dump_enum_vals(enumdef, append)
   end
 end
 
+local function field_default(field)
+  if field:type() == upb.TYPE_MESSAGE then
+    return "NULL"
+  elseif field:type() == upb.TYPE_STRING or
+         field:type() == upb.TYPE_BYTES then
+    local default = field:default() or ""
+    return string.format('upb_stringview_make("%s", strlen("%s"))', field:default(), field:default())
+  elseif field:type() == upb.TYPE_ENUM then
+    return enum_value_symbol(field:subdef(), field:default())
+  else
+    return field:default();
+  end
+end
+
 local function ctype(field)
   if field:label() == upb.LABEL_REPEATED then
     return "upb_array*"
@@ -129,25 +146,26 @@ end
 local function field_layout_rank(field)
   -- Order:
   --   1, 2, 3. primitive fields (8, 4, 1 byte)
-  --   4. oneof fields
-  --   5. string fields
-  --   6. submessage fields
-  --   7. repeated fields
+  --   4. string fields
+  --   5. submessage fields
+  --   6. repeated fields
   --
   -- This has the following nice properties:
   --
   --  1. padding alignment is (nearly) minimized.
-  --  2. fields that might have defaults (1-5) are segregated
-  --     from fields that are always zero-initialized (6-7).
+  --  2. fields that might have defaults (1-4) are segregated
+  --     from fields that are always zero-initialized (5-7).
+  --
+  -- We skip oneof fields, because they are emitted in a separate pass.
   local rank
   if field:containing_oneof() then
-    rank = 4
+    rank = 100  -- These go last (actually we skip them).
   elseif field:label() == upb.LABEL_REPEATED then
-    rank = 7
-  elseif field:type() == upb.TYPE_MESSAGE then
     rank = 6
-  elseif field:type() == upb.TYPE_STRING or field:type() == upb.TYPE_BYTES then
+  elseif field:type() == upb.TYPE_MESSAGE then
     rank = 5
+  elseif field:type() == upb.TYPE_STRING or field:type() == upb.TYPE_BYTES then
+    rank = 4
   elseif field:type() == upb.TYPE_BOOL then
     rank = 3
   elseif field:type() == upb.TYPE_FLOAT or
@@ -258,6 +276,8 @@ local function write_c_file(filedef, hfilename, append)
   emit_file_warning(filedef, append)
 
   append('#include <stddef.h>\n')
+  append('#include "upb/decode.h"\n')
+  append('#include "upb/encode.h"\n')
   append('#include "upb/msg.h"\n')
   append('#include "upb/upb.h"\n')
   append('#include "%s"\n\n', hfilename)
@@ -274,13 +294,29 @@ local function write_c_file(filedef, hfilename, append)
 
     local fields_array_ref = "NULL"
     local submsgs_array_ref = "NULL"
+    local oneofs_array_ref = "NULL"
     local field_count = 0
     local submsg_count = 0
     local submsg_set = {}
     local submsg_indexes = {}
     local hasbit_count = 0
     local hasbit_indexes = {}
-    -- TODO(haberman): oneofs
+    local oneof_count = 0
+    local oneof_indexes = {}
+
+    -- Create a layout order for oneofs.
+    local oneofs_layout_order = {}
+    for oneof in msg:oneofs() do
+      table.insert(oneofs_layout_order, oneof)
+    end
+    table.sort(oneofs_layout_order, function(a, b)
+      return a:name() < b:name()
+    end)
+
+    for _, oneof in ipairs(oneofs_layout_order) do
+      oneof_indexes[oneof] = oneof_count
+      oneof_count = oneof_count + 1
+    end
 
     -- Create a layout order for fields.  We use this order for the struct and
     -- for offsets, but our list of fields we keep in field number order.
@@ -302,6 +338,8 @@ local function write_c_file(filedef, hfilename, append)
     end)
 
     append('struct %s {\n', msgname)
+
+    -- Non-oneof fields.
     for _, field in ipairs(fields_layout_order) do
       field_count = field_count + 1
 
@@ -310,15 +348,43 @@ local function write_c_file(filedef, hfilename, append)
         submsg_set[field:subdef()] = true
       end
 
-      if has_hasbit(field) then
-        hasbit_indexes[field] = hasbit_count
-        hasbit_count = hasbit_count + 1
+      if field:containing_oneof() then
+        -- Handled below.
+      else
+        if has_hasbit(field) then
+          hasbit_indexes[field] = hasbit_count
+          hasbit_count = hasbit_count + 1
+        end
+
+        append('  %s %s;\n', ctype(field), field:name())
       end
+    end
 
-      append('  %s %s;\n', ctype(field), field:name())
+    -- Oneof fields.
+    for oneof in msg:oneofs() do
+      local fullname = to_cident(oneof:containing_type():full_name() .. "." .. oneof:name())
+      append('  union {\n')
+      for field in oneof:fields() do
+        append('    %s %s;\n', ctype(field), field:name())
+      end
+      append('  } %s;\n', oneof:name())
+      append('  %s_oneofcases %s_case;\n', fullname, oneof:name())
     end
+
     append('};\n\n')
 
+    if oneof_count > 0 then
+      local oneofs_array_name = msgname .. "_oneofs"
+      oneofs_array_ref = "&" .. oneofs_array_name .. "[0]"
+      append('static const upb_msglayout_oneofinit_v1 %s[%s] = {\n',
+             oneofs_array_name, oneof_count)
+      for _, oneof in ipairs(oneofs_layout_order) do
+        append('  {offsetof(%s, %s), offsetof(%s, %s_case)},\n',
+               msgname, oneof:name(), msgname, oneof:name())
+      end
+      append('};\n\n')
+    end
+
     if submsg_count > 0 then
       -- TODO(haberman): could save a little bit of space by only generating a
       -- "submsgs" array for every strongly-connected component.
@@ -350,17 +416,19 @@ local function write_c_file(filedef, hfilename, append)
       append('static const upb_msglayout_fieldinit_v1 %s[%s] = {\n',
              fields_array_name, field_count)
       for _, field in ipairs(fields_number_order) do
-        local submsg_index = "-1"
+        local submsg_index = "UPB_NO_SUBMSG"
         local oneof_index = "UPB_NOT_IN_ONEOF"
         if field:type() == upb.TYPE_MESSAGE then
           submsg_index = submsg_indexes[field:subdef()]
         end
-        -- TODO(haberman): oneofs.
+        if field:containing_oneof() then
+          oneof_index = oneof_indexes[field:containing_oneof()]
+        end
         append('  {%s, offsetof(%s, %s), %s, %s, %s, %s, %s},\n',
                field:number(),
                msgname,
-               field:name(),
-               hasbit_indexes[field] or "-1",
+               (field:containing_oneof() and field:containing_oneof():name()) or field:name(),
+               hasbit_indexes[field] or "UPB_NO_HASBIT",
                oneof_index,
                submsg_index,
                field:descriptor_type(),
@@ -372,13 +440,13 @@ local function write_c_file(filedef, hfilename, append)
     append('const upb_msglayout_msginit_v1 %s_msginit = {\n', msgname)
     append('  %s,\n', submsgs_array_ref)
     append('  %s,\n', fields_array_ref)
-    append('  NULL, /* TODO. oneofs */\n')
+    append('  %s,\n', oneofs_array_ref)
     append('  NULL, /* TODO. default_msg */\n')
     append('  UPB_ALIGNED_SIZEOF(%s), %s, %s, %s, %s\n',
            msgname, field_count,
            0, -- TODO: oneof_count
            'false', -- TODO: extendable
-           'true' -- TODO: is_proto2
+          msg:file():syntax() == upb.SYNTAX_PROTO2
           )
     append('};\n\n')
 
@@ -391,36 +459,49 @@ local function write_c_file(filedef, hfilename, append)
 
     append('%s *%s_parsenew(upb_stringview buf, upb_env *env) {\n',
            msgname, msgname)
-    append('  UPB_UNUSED(buf);\n')
-    append('  UPB_UNUSED(env);\n')
-    append('  return NULL;\n')
+    append('  %s *msg = %s_new(env);\n', msgname, msgname)
+    append('  if (upb_decode(buf, msg, &%s_msginit, env)) {\n', msgname)
+    append('    return msg;\n')
+    append('  } else {\n')
+    append('    return NULL;\n')
+    append('  }\n')
     append('}\n')
 
     append('char *%s_serialize(%s *msg, upb_env *env, size_t *size) {\n',
            msgname, msgname)
-    append('  UPB_UNUSED(msg);\n')
-    append('  UPB_UNUSED(env);\n')
-    append('  UPB_UNUSED(size);\n')
-    append('  return NULL; /* TODO. */\n')
+    append('  return upb_encode(msg, &%s_msginit, env, size);\n', msgname)
     append('}\n')
 
     for field in msg:fields() do
       local typename = ctype(field)
       append('%s %s_%s(const %s *msg) {\n',
              typename, msgname, field:name(), msgname);
-      append('  return msg->%s;\n', field:name())
+      if field:containing_oneof() then
+        local oneof = field:containing_oneof()
+        append('  return msg->%s_case == %s ? msg->%s.%s : %s;\n',
+               oneof:name(), field:number(), oneof:name(), field:name(),
+               field_default(field))
+      else
+        append('  return msg->%s;\n', field:name())
+      end
       append('}\n')
       append('void %s_set_%s(%s *msg, %s value) {\n',
              msgname, field:name(), msgname, typename);
-      append('  msg->%s = value;\n', field:name())
+      if field:containing_oneof() then
+        local oneof = field:containing_oneof()
+        append('  msg->%s.%s = value;\n', oneof:name(), field:name())
+        append('  msg->%s_case = %s;\n', oneof:name(), field:number())
+      else
+        append('  msg->%s = value;\n', field:name())
+      end
       append('}\n')
     end
 
     for oneof in msg:oneofs() do
       local fullname = to_cident(oneof:containing_type():full_name() .. "." .. oneof:name())
       append('%s_oneofcases %s_case(const %s *msg) {\n', fullname, fullname, msgname)
-      append('  return 0;  /* TODO. */')
-      append('}')
+      append('  return msg->%s_case;\n', oneof:name())
+      append('}\n')
     end
   end
 end
diff --git a/tools/upbc.lua b/tools/upbc.lua
index bfd93f8..a538b1c 100644
--- a/tools/upbc.lua
+++ b/tools/upbc.lua
@@ -15,8 +15,13 @@ local upb = require "upb"
 local generate_upbdefs = false
 
 for _, argument in ipairs(arg) do
-  if argument == "--generate-upbdefs" then
-    generate_upbdefs = true
+  if argument.sub(argument, 1, 2) == "--" then
+    if argument == "--generate-upbdefs" then
+      generate_upbdefs = true
+    else
+      print("Unknown flag: " .. argument)
+      return 1
+    end
   else
     if src then
       print("upbc can only handle one input file at a time.")
diff --git a/upb/decode.c b/upb/decode.c
new file mode 100644
index 0000000..3c76e0f
--- /dev/null
+++ b/upb/decode.c
@@ -0,0 +1,582 @@
+
+#include "upb/upb.h"
+#include "upb/decode.h"
+#include "upb/structs.int.h"
+
+/* Maps descriptor type -> upb field type.  */
+static const uint8_t upb_desctype_to_fieldtype[] = {
+  UPB_WIRE_TYPE_END_GROUP,  /* ENDGROUP */
+  UPB_TYPE_DOUBLE,          /* DOUBLE */
+  UPB_TYPE_FLOAT,           /* FLOAT */
+  UPB_TYPE_INT64,           /* INT64 */
+  UPB_TYPE_UINT64,          /* UINT64 */
+  UPB_TYPE_INT32,           /* INT32 */
+  UPB_TYPE_UINT64,          /* FIXED64 */
+  UPB_TYPE_UINT32,          /* FIXED32 */
+  UPB_TYPE_BOOL,            /* BOOL */
+  UPB_TYPE_STRING,          /* STRING */
+  UPB_TYPE_MESSAGE,         /* GROUP */
+  UPB_TYPE_MESSAGE,         /* MESSAGE */
+  UPB_TYPE_BYTES,           /* BYTES */
+  UPB_TYPE_UINT32,          /* UINT32 */
+  UPB_TYPE_ENUM,            /* ENUM */
+  UPB_TYPE_INT32,           /* SFIXED32 */
+  UPB_TYPE_INT64,           /* SFIXED64 */
+  UPB_TYPE_INT32,           /* SINT32 */
+  UPB_TYPE_INT64,           /* SINT64 */
+};
+
+/* Data pertaining to the parse. */
+typedef struct {
+  upb_env *env;
+  /* Current decoding pointer.  Points to the beginning of a field until we
+   * have finished decoding the whole field. */
+  const char *ptr;
+} upb_decstate;
+
+/* Data pertaining to a single message frame. */
+typedef struct {
+  const char *limit;
+  int32_t group_number;  /* 0 if we are not parsing a group. */
+
+  /* These members are unset for an unknown group frame. */
+  char *msg;
+  const upb_msglayout_msginit_v1 *m;
+} upb_decframe;
+
+#define CHK(x) if (!(x)) { return false; }
+
+static bool upb_skip_unknowngroup(upb_decstate *d, int field_number,
+                                  const char *limit);
+static bool upb_decode_message(upb_decstate *d, const char *limit,
+                               int group_number, char *msg,
+                               const upb_msglayout_msginit_v1 *l);
+
+static bool upb_decode_varint(const char **ptr, const char *limit,
+                              uint64_t *val) {
+  uint8_t byte;
+  int bitpos = 0;
+  const char *p = *ptr;
+  *val = 0;
+
+  do {
+    CHK(bitpos < 70 && p < limit);
+    byte = *p;
+    *val |= (uint64_t)(byte & 0x7F) << bitpos;
+    p++;
+    bitpos += 7;
+  } while (byte & 0x80);
+
+  *ptr = p;
+  return true;
+}
+
+static bool upb_decode_varint32(const char **ptr, const char *limit,
+                                uint32_t *val) {
+  uint64_t u64;
+  CHK(upb_decode_varint(ptr, limit, &u64) && u64 <= UINT32_MAX);
+  *val = u64;
+  return true;
+}
+
+static bool upb_decode_64bit(const char **ptr, const char *limit,
+                             uint64_t *val) {
+  CHK(limit - *ptr >= 8);
+  memcpy(val, *ptr, 8);
+  *ptr += 8;
+  return true;
+}
+
+static bool upb_decode_32bit(const char **ptr, const char *limit,
+                             uint32_t *val) {
+  CHK(limit - *ptr >= 4);
+  memcpy(val, *ptr, 4);
+  *ptr += 4;
+  return true;
+}
+
+static bool upb_decode_tag(const char **ptr, const char *limit,
+                           int *field_number, int *wire_type) {
+  uint32_t tag;
+  CHK(upb_decode_varint32(ptr, limit, &tag));
+  *field_number = tag >> 3;
+  *wire_type = tag & 7;
+  return true;
+}
+
+static int32_t upb_zzdecode_32(uint32_t n) {
+  return (n >> 1) ^ -(int32_t)(n & 1);
+}
+
+static int64_t upb_zzdecode_64(uint64_t n) {
+  return (n >> 1) ^ -(int64_t)(n & 1);
+}
+
+static bool upb_decode_string(const char **ptr, const char *limit,
+                              upb_stringview *val) {
+  uint32_t len;
+
+  CHK(upb_decode_varint32(ptr, limit, &len) &&
+      len < INT32_MAX &&
+      limit - *ptr >= (int32_t)len);
+
+  *val = upb_stringview_make(*ptr, len);
+  *ptr += len;
+  return true;
+}
+
+static void upb_set32(void *msg, size_t ofs, uint32_t val) {
+  memcpy((char*)msg + ofs, &val, sizeof(val));
+}
+
+static bool upb_append_unknown(upb_decstate *d, upb_decframe *frame,
+                               const char *start) {
+  UPB_UNUSED(d);
+  UPB_UNUSED(frame);
+  UPB_UNUSED(start);
+  return true;
+}
+
+static bool upb_skip_unknownfielddata(upb_decstate *d, upb_decframe *frame,
+                                      int field_number, int wire_type) {
+  switch (wire_type) {
+    case UPB_WIRE_TYPE_VARINT: {
+      uint64_t val;
+      return upb_decode_varint(&d->ptr, frame->limit, &val);
+    }
+    case UPB_WIRE_TYPE_32BIT: {
+      uint32_t val;
+      return upb_decode_32bit(&d->ptr, frame->limit, &val);
+    }
+    case UPB_WIRE_TYPE_64BIT: {
+      uint64_t val;
+      return upb_decode_64bit(&d->ptr, frame->limit, &val);
+    }
+    case UPB_WIRE_TYPE_DELIMITED: {
+      upb_stringview val;
+      return upb_decode_string(&d->ptr, frame->limit, &val);
+    }
+    case UPB_WIRE_TYPE_START_GROUP:
+      return upb_skip_unknowngroup(d, field_number, frame->limit);
+    case UPB_WIRE_TYPE_END_GROUP:
+      CHK(field_number == frame->group_number);
+      frame->limit = d->ptr;
+      return true;
+  }
+  return false;
+}
+
+static bool upb_array_grow(upb_array *arr, size_t elements) {
+  size_t needed = arr->len + elements;
+  size_t new_size = UPB_MAX(arr->size, 8);
+  size_t new_bytes;
+  size_t old_bytes;
+  void *new_data;
+
+  while (new_size < needed) {
+    new_size *= 2;
+  }
+
+  old_bytes = arr->len * arr->element_size;
+  new_bytes = new_size * arr->element_size;
+  new_data = upb_realloc(arr->alloc, arr->data, old_bytes, new_bytes);
+  CHK(new_data);
+
+  arr->data = new_data;
+  arr->size = new_size;
+  return true;
+}
+
+static void *upb_array_reserve(upb_array *arr, size_t elements) {
+  if (arr->size - arr->len < elements) {
+    CHK(upb_array_grow(arr, elements));
+  }
+  return (char*)arr->data + (arr->len * arr->element_size);
+}
+
+static void *upb_array_add(upb_array *arr, size_t elements) {
+  void *ret = upb_array_reserve(arr, elements);
+  arr->len += elements;
+  return ret;
+}
+
+static upb_array *upb_getarr(upb_decframe *frame,
+                             const upb_msglayout_fieldinit_v1 *field) {
+  UPB_ASSERT(field->label == UPB_LABEL_REPEATED);
+  return *(upb_array**)&frame->msg[field->offset];
+}
+
+static upb_array *upb_getorcreatearr(upb_decstate *d,
+                                     upb_decframe *frame,
+                                     const upb_msglayout_fieldinit_v1 *field) {
+  upb_array *arr = upb_getarr(frame, field);
+
+  if (!arr) {
+    arr = upb_env_malloc(d->env, sizeof(*arr));
+    if (!arr) {
+      return NULL;
+    }
+    upb_array_init(arr, upb_desctype_to_fieldtype[field->type],
+                   upb_arena_alloc(upb_env_arena(d->env)));
+    *(upb_array**)&frame->msg[field->offset] = arr;
+  }
+
+  return arr;
+}
+
+static void upb_sethasbit(upb_decframe *frame,
+                          const upb_msglayout_fieldinit_v1 *field) {
+  UPB_ASSERT(field->hasbit != UPB_NO_HASBIT);
+  frame->msg[field->hasbit / 8] |= (1 << (field->hasbit % 8));
+}
+
+static void upb_setoneofcase(upb_decframe *frame,
+                             const upb_msglayout_fieldinit_v1 *field) {
+  UPB_ASSERT(field->oneof_index != UPB_NOT_IN_ONEOF);
+  upb_set32(frame->msg, frame->m->oneofs[field->oneof_index].case_offset,
+            field->number);
+}
+
+static char *upb_decode_prepareslot(upb_decstate *d,
+                                    upb_decframe *frame,
+                                    const upb_msglayout_fieldinit_v1 *field) {
+  char *field_mem = frame->msg + field->offset;
+  upb_array *arr;
+
+  if (field->label == UPB_LABEL_REPEATED) {
+    arr = upb_getorcreatearr(d, frame, field);
+    field_mem = upb_array_reserve(arr, 1);
+  }
+
+  return field_mem;
+}
+
+static void upb_decode_setpresent(upb_decframe *frame,
+                                  const upb_msglayout_fieldinit_v1 *field) {
+  if (field->label == UPB_LABEL_REPEATED) {
+   upb_array *arr = upb_getarr(frame, field);
+   UPB_ASSERT(arr->len < arr->size);
+   arr->len++;
+  } else if (field->oneof_index != UPB_NOT_IN_ONEOF) {
+    upb_setoneofcase(frame, field);
+  } else if (field->hasbit != UPB_NO_HASBIT) {
+    upb_sethasbit(frame, field);
+  }
+}
+
+static bool upb_decode_submsg(upb_decstate *d,
+                              upb_decframe *frame,
+                              const char *limit,
+                              const upb_msglayout_fieldinit_v1 *field,
+                              int group_number) {
+  char *submsg = *(void**)&frame->msg[field->offset];
+  const upb_msglayout_msginit_v1 *subm;
+
+  UPB_ASSERT(field->submsg_index != UPB_NO_SUBMSG);
+  subm = frame->m->submsgs[field->submsg_index];
+  UPB_ASSERT(subm);
+
+  if (!submsg) {
+    submsg = upb_env_malloc(d->env, upb_msg_sizeof((upb_msglayout *)subm));
+    CHK(submsg);
+    submsg = upb_msg_init(
+        submsg, (upb_msglayout*)subm, upb_arena_alloc(upb_env_arena(d->env)));
+    *(void**)&frame->msg[field->offset] = submsg;
+  }
+
+  upb_decode_message(d, limit, group_number, submsg, subm);
+
+  return true;
+}
+
+static bool upb_decode_varintfield(upb_decstate *d, upb_decframe *frame,
+                                   const char *field_start,
+                                   const upb_msglayout_fieldinit_v1 *field) {
+  uint64_t val;
+  void *field_mem;
+
+  field_mem = upb_decode_prepareslot(d, frame, field);
+  CHK(field_mem);
+  CHK(upb_decode_varint(&d->ptr, frame->limit, &val));
+
+  switch ((upb_descriptortype_t)field->type) {
+    case UPB_DESCRIPTOR_TYPE_INT64:
+    case UPB_DESCRIPTOR_TYPE_UINT64:
+      memcpy(field_mem, &val, sizeof(val));
+      break;
+    case UPB_DESCRIPTOR_TYPE_INT32:
+    case UPB_DESCRIPTOR_TYPE_UINT32:
+    case UPB_DESCRIPTOR_TYPE_ENUM: {
+      uint32_t val32 = val;
+      memcpy(field_mem, &val32, sizeof(val32));
+      break;
+    }
+    case UPB_DESCRIPTOR_TYPE_BOOL: {
+      bool valbool = val != 0;
+      memcpy(field_mem, &valbool, sizeof(valbool));
+      break;
+    }
+    case UPB_DESCRIPTOR_TYPE_SINT32: {
+      int32_t decoded = upb_zzdecode_32(val);
+      memcpy(field_mem, &decoded, sizeof(decoded));
+      break;
+    }
+    case UPB_DESCRIPTOR_TYPE_SINT64: {
+      int64_t decoded = upb_zzdecode_64(val);
+      memcpy(field_mem, &decoded, sizeof(decoded));
+      break;
+    }
+    default:
+      return upb_append_unknown(d, frame, field_start);
+  }
+
+  upb_decode_setpresent(frame, field);
+  return true;
+}
+
+static bool upb_decode_64bitfield(upb_decstate *d, upb_decframe *frame,
+                                  const char *field_start,
+                                  const upb_msglayout_fieldinit_v1 *field) {
+  void *field_mem;
+  uint64_t val;
+
+  field_mem = upb_decode_prepareslot(d, frame, field);
+  CHK(field_mem);
+  CHK(upb_decode_64bit(&d->ptr, frame->limit, &val));
+
+  switch ((upb_descriptortype_t)field->type) {
+    case UPB_DESCRIPTOR_TYPE_DOUBLE:
+    case UPB_DESCRIPTOR_TYPE_FIXED64:
+    case UPB_DESCRIPTOR_TYPE_SFIXED64:
+      memcpy(field_mem, &val, sizeof(val));
+      break;
+    default:
+      return upb_append_unknown(d, frame, field_start);
+  }
+
+  upb_decode_setpresent(frame, field);
+  return true;
+}
+
+static bool upb_decode_32bitfield(upb_decstate *d, upb_decframe *frame,
+                                  const char *field_start,
+                                  const upb_msglayout_fieldinit_v1 *field) {
+  void *field_mem;
+  uint32_t val;
+
+  field_mem = upb_decode_prepareslot(d, frame, field);
+  CHK(field_mem);
+  CHK(upb_decode_32bit(&d->ptr, frame->limit, &val));
+
+  switch ((upb_descriptortype_t)field->type) {
+    case UPB_DESCRIPTOR_TYPE_FLOAT:
+    case UPB_DESCRIPTOR_TYPE_FIXED32:
+    case UPB_DESCRIPTOR_TYPE_SFIXED32:
+      memcpy(field_mem, &val, sizeof(val));
+      break;
+    default:
+      return upb_append_unknown(d, frame, field_start);
+  }
+
+  upb_decode_setpresent(frame, field);
+  return true;
+}
+
+static bool upb_decode_fixedpacked(upb_array *arr, upb_stringview data,
+                                   int elem_size) {
+  int elements = data.size / elem_size;
+  void *field_mem;
+
+  CHK((size_t)(elements * elem_size) == data.size);
+  field_mem = upb_array_add(arr, elements);
+  CHK(field_mem);
+  memcpy(field_mem, data.data, data.size);
+  return true;
+}
+
+static bool upb_decode_toarray(upb_decstate *d, upb_decframe *frame,
+                               const char *field_start,
+                               const upb_msglayout_fieldinit_v1 *field,
+                               upb_stringview val) {
+  upb_array *arr = upb_getorcreatearr(d, frame, field);
+
+#define VARINT_CASE(ctype, decode) { \
+  const char *ptr = val.data; \
+  const char *limit = ptr + val.size; \
+  while (ptr < limit) { \
+    uint64_t val; \
+    void *field_mem; \
+    ctype decoded; \
+    CHK(upb_decode_varint(&ptr, limit, &val)); \
+    decoded = (decode)(val); \
+    field_mem = upb_array_add(arr, 1); \
+    CHK(field_mem); \
+    memcpy(field_mem, &decoded, sizeof(ctype)); \
+  } \
+  return true; \
+}
+
+  switch ((upb_descriptortype_t)field->type) {
+    case UPB_DESCRIPTOR_TYPE_STRING:
+    case UPB_DESCRIPTOR_TYPE_BYTES: {
+      void *field_mem = upb_array_add(arr, 1);
+      CHK(field_mem);
+      memcpy(field_mem, &val, sizeof(val));
+      return true;
+    }
+    case UPB_DESCRIPTOR_TYPE_FLOAT:
+    case UPB_DESCRIPTOR_TYPE_FIXED32:
+    case UPB_DESCRIPTOR_TYPE_SFIXED32:
+      return upb_decode_fixedpacked(arr, val, sizeof(int32_t));
+    case UPB_DESCRIPTOR_TYPE_DOUBLE:
+    case UPB_DESCRIPTOR_TYPE_FIXED64:
+    case UPB_DESCRIPTOR_TYPE_SFIXED64:
+      return upb_decode_fixedpacked(arr, val, sizeof(int64_t));
+    case UPB_DESCRIPTOR_TYPE_INT32:
+    case UPB_DESCRIPTOR_TYPE_UINT32:
+    case UPB_DESCRIPTOR_TYPE_ENUM:
+      /* TODO: proto2 enum field that isn't in the enum. */
+      VARINT_CASE(uint32_t, uint32_t);
+    case UPB_DESCRIPTOR_TYPE_INT64:
+    case UPB_DESCRIPTOR_TYPE_UINT64:
+      VARINT_CASE(uint64_t, uint64_t);
+    case UPB_DESCRIPTOR_TYPE_BOOL:
+      VARINT_CASE(bool, bool);
+    case UPB_DESCRIPTOR_TYPE_SINT32:
+      VARINT_CASE(int32_t, upb_zzdecode_32);
+    case UPB_DESCRIPTOR_TYPE_SINT64:
+      VARINT_CASE(int64_t, upb_zzdecode_64);
+    case UPB_DESCRIPTOR_TYPE_MESSAGE:
+      CHK(val.size <= (size_t)(frame->limit - val.data));
+      return upb_decode_submsg(d, frame, val.data + val.size, field, 0);
+    case UPB_DESCRIPTOR_TYPE_GROUP:
+      return upb_append_unknown(d, frame, field_start);
+  }
+#undef VARINT_CASE
+  UPB_UNREACHABLE();
+}
+
+static bool upb_decode_delimitedfield(upb_decstate *d, upb_decframe *frame,
+                                      const char *field_start,
+                                      const upb_msglayout_fieldinit_v1 *field) {
+  upb_stringview val;
+
+  CHK(upb_decode_string(&d->ptr, frame->limit, &val));
+
+  if (field->label == UPB_LABEL_REPEATED) {
+    return upb_decode_toarray(d, frame, field_start, field, val);
+  } else {
+    switch ((upb_descriptortype_t)field->type) {
+      case UPB_DESCRIPTOR_TYPE_STRING:
+      case UPB_DESCRIPTOR_TYPE_BYTES: {
+        void *field_mem = upb_decode_prepareslot(d, frame, field);
+        CHK(field_mem);
+        memcpy(field_mem, &val, sizeof(val));
+        break;
+      }
+      case UPB_DESCRIPTOR_TYPE_MESSAGE:
+        CHK(val.size <= (size_t)(frame->limit - val.data));
+        CHK(upb_decode_submsg(d, frame, val.data + val.size, field, 0));
+        break;
+      default:
+        /* TODO(haberman): should we accept the last element of a packed? */
+        return upb_append_unknown(d, frame, field_start);
+    }
+    upb_decode_setpresent(frame, field);
+    return true;
+  }
+}
+
+static const upb_msglayout_fieldinit_v1 *upb_find_field(
+    const upb_msglayout_msginit_v1 *l, uint32_t field_number) {
+  /* Lots of optimization opportunities here. */
+  int i;
+  for (i = 0; i < l->field_count; i++) {
+    if (l->fields[i].number == field_number) {
+      return &l->fields[i];
+    }
+  }
+
+  return NULL;  /* Unknown field. */
+}
+
+static bool upb_decode_field(upb_decstate *d, upb_decframe *frame) {
+  int field_number;
+  int wire_type;
+  const char *field_start = d->ptr;
+  const upb_msglayout_fieldinit_v1 *field;
+
+  CHK(upb_decode_tag(&d->ptr, frame->limit, &field_number, &wire_type));
+  field = upb_find_field(frame->m, field_number);
+
+  if (field) {
+    switch (wire_type) {
+      case UPB_WIRE_TYPE_VARINT:
+        return upb_decode_varintfield(d, frame, field_start, field);
+      case UPB_WIRE_TYPE_32BIT:
+        return upb_decode_32bitfield(d, frame, field_start, field);
+      case UPB_WIRE_TYPE_64BIT:
+        return upb_decode_64bitfield(d, frame, field_start, field);
+      case UPB_WIRE_TYPE_DELIMITED:
+        return upb_decode_delimitedfield(d, frame, field_start, field);
+      case UPB_WIRE_TYPE_START_GROUP:
+        CHK(field->type == UPB_DESCRIPTOR_TYPE_GROUP);
+        return upb_decode_submsg(d, frame, frame->limit, field, field_number);
+      case UPB_WIRE_TYPE_END_GROUP:
+        CHK(frame->group_number == field_number)
+        frame->limit = d->ptr;
+        return true;
+      default:
+        return false;
+    }
+  } else {
+    CHK(field_number != 0);
+    return upb_skip_unknownfielddata(d, frame, field_number, wire_type);
+  }
+}
+
+static bool upb_skip_unknowngroup(upb_decstate *d, int field_number,
+                                  const char *limit) {
+  upb_decframe frame;
+  frame.msg = NULL;
+  frame.m = NULL;
+  frame.group_number = field_number;
+  frame.limit = limit;
+
+  while (d->ptr < frame.limit) {
+    int wire_type;
+    int field_number;
+
+    CHK(upb_decode_tag(&d->ptr, frame.limit, &field_number, &wire_type));
+    CHK(upb_skip_unknownfielddata(d, &frame, field_number, wire_type));
+  }
+
+  return true;
+}
+
+static bool upb_decode_message(upb_decstate *d, const char *limit,
+                               int group_number, char *msg,
+                               const upb_msglayout_msginit_v1 *l) {
+  upb_decframe frame;
+  frame.group_number = group_number;
+  frame.limit = limit;
+  frame.msg = msg;
+  frame.m = l;
+
+  while (d->ptr < frame.limit) {
+    CHK(upb_decode_field(d, &frame));
+  }
+
+  return true;
+}
+
+bool upb_decode(upb_stringview buf, void *msg,
+                const upb_msglayout_msginit_v1 *l, upb_env *env) {
+  upb_decstate state;
+  state.ptr = buf.data;
+  state.env = env;
+
+  return upb_decode_message(&state, buf.data + buf.size, 0, msg, l);
+}
+
+#undef CHK
diff --git a/upb/decode.h b/upb/decode.h
new file mode 100644
index 0000000..2a9e39e
--- /dev/null
+++ b/upb/decode.h
@@ -0,0 +1,17 @@
+/*
+** upb_decode: parsing into a upb_msg using a upb_msglayout.
+*/
+
+#ifndef UPB_DECODE_H_
+#define UPB_DECODE_H_
+
+#include "upb/msg.h"
+
+UPB_BEGIN_EXTERN_C
+
+bool upb_decode(upb_stringview buf, void *msg,
+                const upb_msglayout_msginit_v1 *l, upb_env *env);
+
+UPB_END_EXTERN_C
+
+#endif  /* UPB_DECODE_H_ */
diff --git a/upb/descriptor/descriptor.upb.c b/upb/descriptor/descriptor.upb.c
index c0b537c..f388cfd 100644
--- a/upb/descriptor/descriptor.upb.c
+++ b/upb/descriptor/descriptor.upb.c
@@ -7,6 +7,8 @@
  * regenerated. */
 
 #include <stddef.h>
+#include "upb/decode.h"
+#include "upb/encode.h"
 #include "upb/msg.h"
 #include "upb/upb.h"
 #include "upb/descriptor/descriptor.upb.h"
@@ -21,13 +23,13 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_FileDescriptorSet_s
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_FileDescriptorSet__fields[1] = {
-  {1, offsetof(google_protobuf_FileDescriptorSet, file), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {1, offsetof(google_protobuf_FileDescriptorSet, file), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_FileDescriptorSet_msginit = {
   &google_protobuf_FileDescriptorSet_submsgs[0],
   &google_protobuf_FileDescriptorSet__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_FileDescriptorSet), 1, 0, false, true
 };
@@ -38,15 +40,15 @@ google_protobuf_FileDescriptorSet *google_protobuf_FileDescriptorSet_new(upb_env
   return msg;
 }
 google_protobuf_FileDescriptorSet *google_protobuf_FileDescriptorSet_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_FileDescriptorSet *msg = google_protobuf_FileDescriptorSet_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_FileDescriptorSet_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_FileDescriptorSet_serialize(google_protobuf_FileDescriptorSet *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_FileDescriptorSet_msginit, env, size);
 }
 upb_array* google_protobuf_FileDescriptorSet_file(const google_protobuf_FileDescriptorSet *msg) {
   return msg->file;
@@ -79,24 +81,24 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_FileDescriptorProto
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_FileDescriptorProto__fields[12] = {
-  {1, offsetof(google_protobuf_FileDescriptorProto, name), 0, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {2, offsetof(google_protobuf_FileDescriptorProto, package), 1, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {3, offsetof(google_protobuf_FileDescriptorProto, dependency), -1, UPB_NOT_IN_ONEOF, -1, 9, 3},
-  {4, offsetof(google_protobuf_FileDescriptorProto, message_type), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
-  {5, offsetof(google_protobuf_FileDescriptorProto, enum_type), -1, UPB_NOT_IN_ONEOF, 1, 11, 3},
-  {6, offsetof(google_protobuf_FileDescriptorProto, service), -1, UPB_NOT_IN_ONEOF, 4, 11, 3},
-  {7, offsetof(google_protobuf_FileDescriptorProto, extension), -1, UPB_NOT_IN_ONEOF, 2, 11, 3},
+  {1, offsetof(google_protobuf_FileDescriptorProto, name), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {2, offsetof(google_protobuf_FileDescriptorProto, package), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {3, offsetof(google_protobuf_FileDescriptorProto, dependency), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 3},
+  {4, offsetof(google_protobuf_FileDescriptorProto, message_type), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {5, offsetof(google_protobuf_FileDescriptorProto, enum_type), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 1, 11, 3},
+  {6, offsetof(google_protobuf_FileDescriptorProto, service), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 4, 11, 3},
+  {7, offsetof(google_protobuf_FileDescriptorProto, extension), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 2, 11, 3},
   {8, offsetof(google_protobuf_FileDescriptorProto, options), 3, UPB_NOT_IN_ONEOF, 3, 11, 1},
   {9, offsetof(google_protobuf_FileDescriptorProto, source_code_info), 4, UPB_NOT_IN_ONEOF, 5, 11, 1},
-  {10, offsetof(google_protobuf_FileDescriptorProto, public_dependency), -1, UPB_NOT_IN_ONEOF, -1, 5, 3},
-  {11, offsetof(google_protobuf_FileDescriptorProto, weak_dependency), -1, UPB_NOT_IN_ONEOF, -1, 5, 3},
-  {12, offsetof(google_protobuf_FileDescriptorProto, syntax), 2, UPB_NOT_IN_ONEOF, -1, 9, 1},
+  {10, offsetof(google_protobuf_FileDescriptorProto, public_dependency), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 3},
+  {11, offsetof(google_protobuf_FileDescriptorProto, weak_dependency), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 3},
+  {12, offsetof(google_protobuf_FileDescriptorProto, syntax), 2, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_FileDescriptorProto_msginit = {
   &google_protobuf_FileDescriptorProto_submsgs[0],
   &google_protobuf_FileDescriptorProto__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_FileDescriptorProto), 12, 0, false, true
 };
@@ -107,15 +109,15 @@ google_protobuf_FileDescriptorProto *google_protobuf_FileDescriptorProto_new(upb
   return msg;
 }
 google_protobuf_FileDescriptorProto *google_protobuf_FileDescriptorProto_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_FileDescriptorProto *msg = google_protobuf_FileDescriptorProto_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_FileDescriptorProto_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_FileDescriptorProto_serialize(google_protobuf_FileDescriptorProto *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_FileDescriptorProto_msginit, env, size);
 }
 upb_stringview google_protobuf_FileDescriptorProto_name(const google_protobuf_FileDescriptorProto *msg) {
   return msg->name;
@@ -213,22 +215,22 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_DescriptorProto_sub
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_DescriptorProto__fields[10] = {
-  {1, offsetof(google_protobuf_DescriptorProto, name), 0, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {2, offsetof(google_protobuf_DescriptorProto, field), -1, UPB_NOT_IN_ONEOF, 4, 11, 3},
-  {3, offsetof(google_protobuf_DescriptorProto, nested_type), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
-  {4, offsetof(google_protobuf_DescriptorProto, enum_type), -1, UPB_NOT_IN_ONEOF, 3, 11, 3},
-  {5, offsetof(google_protobuf_DescriptorProto, extension_range), -1, UPB_NOT_IN_ONEOF, 1, 11, 3},
-  {6, offsetof(google_protobuf_DescriptorProto, extension), -1, UPB_NOT_IN_ONEOF, 4, 11, 3},
+  {1, offsetof(google_protobuf_DescriptorProto, name), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {2, offsetof(google_protobuf_DescriptorProto, field), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 4, 11, 3},
+  {3, offsetof(google_protobuf_DescriptorProto, nested_type), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {4, offsetof(google_protobuf_DescriptorProto, enum_type), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 3, 11, 3},
+  {5, offsetof(google_protobuf_DescriptorProto, extension_range), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 1, 11, 3},
+  {6, offsetof(google_protobuf_DescriptorProto, extension), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 4, 11, 3},
   {7, offsetof(google_protobuf_DescriptorProto, options), 1, UPB_NOT_IN_ONEOF, 5, 11, 1},
-  {8, offsetof(google_protobuf_DescriptorProto, oneof_decl), -1, UPB_NOT_IN_ONEOF, 6, 11, 3},
-  {9, offsetof(google_protobuf_DescriptorProto, reserved_range), -1, UPB_NOT_IN_ONEOF, 2, 11, 3},
-  {10, offsetof(google_protobuf_DescriptorProto, reserved_name), -1, UPB_NOT_IN_ONEOF, -1, 9, 3},
+  {8, offsetof(google_protobuf_DescriptorProto, oneof_decl), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 6, 11, 3},
+  {9, offsetof(google_protobuf_DescriptorProto, reserved_range), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 2, 11, 3},
+  {10, offsetof(google_protobuf_DescriptorProto, reserved_name), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_DescriptorProto_msginit = {
   &google_protobuf_DescriptorProto_submsgs[0],
   &google_protobuf_DescriptorProto__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_DescriptorProto), 10, 0, false, true
 };
@@ -239,15 +241,15 @@ google_protobuf_DescriptorProto *google_protobuf_DescriptorProto_new(upb_env *en
   return msg;
 }
 google_protobuf_DescriptorProto *google_protobuf_DescriptorProto_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_DescriptorProto *msg = google_protobuf_DescriptorProto_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_DescriptorProto_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_DescriptorProto_serialize(google_protobuf_DescriptorProto *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_DescriptorProto_msginit, env, size);
 }
 upb_stringview google_protobuf_DescriptorProto_name(const google_protobuf_DescriptorProto *msg) {
   return msg->name;
@@ -315,14 +317,14 @@ struct google_protobuf_DescriptorProto_ExtensionRange {
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_DescriptorProto_ExtensionRange__fields[2] = {
-  {1, offsetof(google_protobuf_DescriptorProto_ExtensionRange, start), 0, UPB_NOT_IN_ONEOF, -1, 5, 1},
-  {2, offsetof(google_protobuf_DescriptorProto_ExtensionRange, end), 1, UPB_NOT_IN_ONEOF, -1, 5, 1},
+  {1, offsetof(google_protobuf_DescriptorProto_ExtensionRange, start), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 1},
+  {2, offsetof(google_protobuf_DescriptorProto_ExtensionRange, end), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_DescriptorProto_ExtensionRange_msginit = {
   NULL,
   &google_protobuf_DescriptorProto_ExtensionRange__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_DescriptorProto_ExtensionRange), 2, 0, false, true
 };
@@ -333,15 +335,15 @@ google_protobuf_DescriptorProto_ExtensionRange *google_protobuf_DescriptorProto_
   return msg;
 }
 google_protobuf_DescriptorProto_ExtensionRange *google_protobuf_DescriptorProto_ExtensionRange_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_DescriptorProto_ExtensionRange *msg = google_protobuf_DescriptorProto_ExtensionRange_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_DescriptorProto_ExtensionRange_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_DescriptorProto_ExtensionRange_serialize(google_protobuf_DescriptorProto_ExtensionRange *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_DescriptorProto_ExtensionRange_msginit, env, size);
 }
 int32_t google_protobuf_DescriptorProto_ExtensionRange_start(const google_protobuf_DescriptorProto_ExtensionRange *msg) {
   return msg->start;
@@ -361,14 +363,14 @@ struct google_protobuf_DescriptorProto_ReservedRange {
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_DescriptorProto_ReservedRange__fields[2] = {
-  {1, offsetof(google_protobuf_DescriptorProto_ReservedRange, start), 0, UPB_NOT_IN_ONEOF, -1, 5, 1},
-  {2, offsetof(google_protobuf_DescriptorProto_ReservedRange, end), 1, UPB_NOT_IN_ONEOF, -1, 5, 1},
+  {1, offsetof(google_protobuf_DescriptorProto_ReservedRange, start), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 1},
+  {2, offsetof(google_protobuf_DescriptorProto_ReservedRange, end), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_DescriptorProto_ReservedRange_msginit = {
   NULL,
   &google_protobuf_DescriptorProto_ReservedRange__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_DescriptorProto_ReservedRange), 2, 0, false, true
 };
@@ -379,15 +381,15 @@ google_protobuf_DescriptorProto_ReservedRange *google_protobuf_DescriptorProto_R
   return msg;
 }
 google_protobuf_DescriptorProto_ReservedRange *google_protobuf_DescriptorProto_ReservedRange_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_DescriptorProto_ReservedRange *msg = google_protobuf_DescriptorProto_ReservedRange_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_DescriptorProto_ReservedRange_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_DescriptorProto_ReservedRange_serialize(google_protobuf_DescriptorProto_ReservedRange *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_DescriptorProto_ReservedRange_msginit, env, size);
 }
 int32_t google_protobuf_DescriptorProto_ReservedRange_start(const google_protobuf_DescriptorProto_ReservedRange *msg) {
   return msg->start;
@@ -419,22 +421,22 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_FieldDescriptorProt
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_FieldDescriptorProto__fields[10] = {
-  {1, offsetof(google_protobuf_FieldDescriptorProto, name), 4, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {2, offsetof(google_protobuf_FieldDescriptorProto, extendee), 5, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {3, offsetof(google_protobuf_FieldDescriptorProto, number), 2, UPB_NOT_IN_ONEOF, -1, 5, 1},
-  {4, offsetof(google_protobuf_FieldDescriptorProto, label), 0, UPB_NOT_IN_ONEOF, -1, 14, 1},
-  {5, offsetof(google_protobuf_FieldDescriptorProto, type), 1, UPB_NOT_IN_ONEOF, -1, 14, 1},
-  {6, offsetof(google_protobuf_FieldDescriptorProto, type_name), 6, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {7, offsetof(google_protobuf_FieldDescriptorProto, default_value), 7, UPB_NOT_IN_ONEOF, -1, 9, 1},
+  {1, offsetof(google_protobuf_FieldDescriptorProto, name), 4, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {2, offsetof(google_protobuf_FieldDescriptorProto, extendee), 5, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {3, offsetof(google_protobuf_FieldDescriptorProto, number), 2, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 1},
+  {4, offsetof(google_protobuf_FieldDescriptorProto, label), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 14, 1},
+  {5, offsetof(google_protobuf_FieldDescriptorProto, type), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 14, 1},
+  {6, offsetof(google_protobuf_FieldDescriptorProto, type_name), 6, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {7, offsetof(google_protobuf_FieldDescriptorProto, default_value), 7, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
   {8, offsetof(google_protobuf_FieldDescriptorProto, options), 9, UPB_NOT_IN_ONEOF, 0, 11, 1},
-  {9, offsetof(google_protobuf_FieldDescriptorProto, oneof_index), 3, UPB_NOT_IN_ONEOF, -1, 5, 1},
-  {10, offsetof(google_protobuf_FieldDescriptorProto, json_name), 8, UPB_NOT_IN_ONEOF, -1, 9, 1},
+  {9, offsetof(google_protobuf_FieldDescriptorProto, oneof_index), 3, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 1},
+  {10, offsetof(google_protobuf_FieldDescriptorProto, json_name), 8, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_FieldDescriptorProto_msginit = {
   &google_protobuf_FieldDescriptorProto_submsgs[0],
   &google_protobuf_FieldDescriptorProto__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_FieldDescriptorProto), 10, 0, false, true
 };
@@ -445,15 +447,15 @@ google_protobuf_FieldDescriptorProto *google_protobuf_FieldDescriptorProto_new(u
   return msg;
 }
 google_protobuf_FieldDescriptorProto *google_protobuf_FieldDescriptorProto_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_FieldDescriptorProto *msg = google_protobuf_FieldDescriptorProto_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_FieldDescriptorProto_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_FieldDescriptorProto_serialize(google_protobuf_FieldDescriptorProto *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_FieldDescriptorProto_msginit, env, size);
 }
 upb_stringview google_protobuf_FieldDescriptorProto_name(const google_protobuf_FieldDescriptorProto *msg) {
   return msg->name;
@@ -520,13 +522,13 @@ struct google_protobuf_OneofDescriptorProto {
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_OneofDescriptorProto__fields[1] = {
-  {1, offsetof(google_protobuf_OneofDescriptorProto, name), 0, UPB_NOT_IN_ONEOF, -1, 9, 1},
+  {1, offsetof(google_protobuf_OneofDescriptorProto, name), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_OneofDescriptorProto_msginit = {
   NULL,
   &google_protobuf_OneofDescriptorProto__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_OneofDescriptorProto), 1, 0, false, true
 };
@@ -537,15 +539,15 @@ google_protobuf_OneofDescriptorProto *google_protobuf_OneofDescriptorProto_new(u
   return msg;
 }
 google_protobuf_OneofDescriptorProto *google_protobuf_OneofDescriptorProto_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_OneofDescriptorProto *msg = google_protobuf_OneofDescriptorProto_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_OneofDescriptorProto_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_OneofDescriptorProto_serialize(google_protobuf_OneofDescriptorProto *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_OneofDescriptorProto_msginit, env, size);
 }
 upb_stringview google_protobuf_OneofDescriptorProto_name(const google_protobuf_OneofDescriptorProto *msg) {
   return msg->name;
@@ -565,15 +567,15 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_EnumDescriptorProto
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_EnumDescriptorProto__fields[3] = {
-  {1, offsetof(google_protobuf_EnumDescriptorProto, name), 0, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {2, offsetof(google_protobuf_EnumDescriptorProto, value), -1, UPB_NOT_IN_ONEOF, 1, 11, 3},
+  {1, offsetof(google_protobuf_EnumDescriptorProto, name), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {2, offsetof(google_protobuf_EnumDescriptorProto, value), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 1, 11, 3},
   {3, offsetof(google_protobuf_EnumDescriptorProto, options), 1, UPB_NOT_IN_ONEOF, 0, 11, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_EnumDescriptorProto_msginit = {
   &google_protobuf_EnumDescriptorProto_submsgs[0],
   &google_protobuf_EnumDescriptorProto__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_EnumDescriptorProto), 3, 0, false, true
 };
@@ -584,15 +586,15 @@ google_protobuf_EnumDescriptorProto *google_protobuf_EnumDescriptorProto_new(upb
   return msg;
 }
 google_protobuf_EnumDescriptorProto *google_protobuf_EnumDescriptorProto_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_EnumDescriptorProto *msg = google_protobuf_EnumDescriptorProto_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_EnumDescriptorProto_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_EnumDescriptorProto_serialize(google_protobuf_EnumDescriptorProto *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_EnumDescriptorProto_msginit, env, size);
 }
 upb_stringview google_protobuf_EnumDescriptorProto_name(const google_protobuf_EnumDescriptorProto *msg) {
   return msg->name;
@@ -623,15 +625,15 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_EnumValueDescriptor
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_EnumValueDescriptorProto__fields[3] = {
-  {1, offsetof(google_protobuf_EnumValueDescriptorProto, name), 1, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {2, offsetof(google_protobuf_EnumValueDescriptorProto, number), 0, UPB_NOT_IN_ONEOF, -1, 5, 1},
+  {1, offsetof(google_protobuf_EnumValueDescriptorProto, name), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {2, offsetof(google_protobuf_EnumValueDescriptorProto, number), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 1},
   {3, offsetof(google_protobuf_EnumValueDescriptorProto, options), 2, UPB_NOT_IN_ONEOF, 0, 11, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_EnumValueDescriptorProto_msginit = {
   &google_protobuf_EnumValueDescriptorProto_submsgs[0],
   &google_protobuf_EnumValueDescriptorProto__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_EnumValueDescriptorProto), 3, 0, false, true
 };
@@ -642,15 +644,15 @@ google_protobuf_EnumValueDescriptorProto *google_protobuf_EnumValueDescriptorPro
   return msg;
 }
 google_protobuf_EnumValueDescriptorProto *google_protobuf_EnumValueDescriptorProto_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_EnumValueDescriptorProto *msg = google_protobuf_EnumValueDescriptorProto_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_EnumValueDescriptorProto_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_EnumValueDescriptorProto_serialize(google_protobuf_EnumValueDescriptorProto *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_EnumValueDescriptorProto_msginit, env, size);
 }
 upb_stringview google_protobuf_EnumValueDescriptorProto_name(const google_protobuf_EnumValueDescriptorProto *msg) {
   return msg->name;
@@ -682,15 +684,15 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_ServiceDescriptorPr
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_ServiceDescriptorProto__fields[3] = {
-  {1, offsetof(google_protobuf_ServiceDescriptorProto, name), 0, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {2, offsetof(google_protobuf_ServiceDescriptorProto, method), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {1, offsetof(google_protobuf_ServiceDescriptorProto, name), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {2, offsetof(google_protobuf_ServiceDescriptorProto, method), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
   {3, offsetof(google_protobuf_ServiceDescriptorProto, options), 1, UPB_NOT_IN_ONEOF, 1, 11, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_ServiceDescriptorProto_msginit = {
   &google_protobuf_ServiceDescriptorProto_submsgs[0],
   &google_protobuf_ServiceDescriptorProto__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_ServiceDescriptorProto), 3, 0, false, true
 };
@@ -701,15 +703,15 @@ google_protobuf_ServiceDescriptorProto *google_protobuf_ServiceDescriptorProto_n
   return msg;
 }
 google_protobuf_ServiceDescriptorProto *google_protobuf_ServiceDescriptorProto_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_ServiceDescriptorProto *msg = google_protobuf_ServiceDescriptorProto_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_ServiceDescriptorProto_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_ServiceDescriptorProto_serialize(google_protobuf_ServiceDescriptorProto *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_ServiceDescriptorProto_msginit, env, size);
 }
 upb_stringview google_protobuf_ServiceDescriptorProto_name(const google_protobuf_ServiceDescriptorProto *msg) {
   return msg->name;
@@ -743,18 +745,18 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_MethodDescriptorPro
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_MethodDescriptorProto__fields[6] = {
-  {1, offsetof(google_protobuf_MethodDescriptorProto, name), 2, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {2, offsetof(google_protobuf_MethodDescriptorProto, input_type), 3, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {3, offsetof(google_protobuf_MethodDescriptorProto, output_type), 4, UPB_NOT_IN_ONEOF, -1, 9, 1},
+  {1, offsetof(google_protobuf_MethodDescriptorProto, name), 2, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {2, offsetof(google_protobuf_MethodDescriptorProto, input_type), 3, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {3, offsetof(google_protobuf_MethodDescriptorProto, output_type), 4, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
   {4, offsetof(google_protobuf_MethodDescriptorProto, options), 5, UPB_NOT_IN_ONEOF, 0, 11, 1},
-  {5, offsetof(google_protobuf_MethodDescriptorProto, client_streaming), 0, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {6, offsetof(google_protobuf_MethodDescriptorProto, server_streaming), 1, UPB_NOT_IN_ONEOF, -1, 8, 1},
+  {5, offsetof(google_protobuf_MethodDescriptorProto, client_streaming), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {6, offsetof(google_protobuf_MethodDescriptorProto, server_streaming), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_MethodDescriptorProto_msginit = {
   &google_protobuf_MethodDescriptorProto_submsgs[0],
   &google_protobuf_MethodDescriptorProto__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_MethodDescriptorProto), 6, 0, false, true
 };
@@ -765,15 +767,15 @@ google_protobuf_MethodDescriptorProto *google_protobuf_MethodDescriptorProto_new
   return msg;
 }
 google_protobuf_MethodDescriptorProto *google_protobuf_MethodDescriptorProto_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_MethodDescriptorProto *msg = google_protobuf_MethodDescriptorProto_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_MethodDescriptorProto_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_MethodDescriptorProto_serialize(google_protobuf_MethodDescriptorProto *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_MethodDescriptorProto_msginit, env, size);
 }
 upb_stringview google_protobuf_MethodDescriptorProto_name(const google_protobuf_MethodDescriptorProto *msg) {
   return msg->name;
@@ -837,30 +839,30 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_FileOptions_submsgs
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_FileOptions__fields[18] = {
-  {1, offsetof(google_protobuf_FileOptions, java_package), 10, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {8, offsetof(google_protobuf_FileOptions, java_outer_classname), 11, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {9, offsetof(google_protobuf_FileOptions, optimize_for), 0, UPB_NOT_IN_ONEOF, -1, 14, 1},
-  {10, offsetof(google_protobuf_FileOptions, java_multiple_files), 1, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {11, offsetof(google_protobuf_FileOptions, go_package), 12, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {16, offsetof(google_protobuf_FileOptions, cc_generic_services), 2, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {17, offsetof(google_protobuf_FileOptions, java_generic_services), 3, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {18, offsetof(google_protobuf_FileOptions, py_generic_services), 4, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {20, offsetof(google_protobuf_FileOptions, java_generate_equals_and_hash), 5, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {23, offsetof(google_protobuf_FileOptions, deprecated), 6, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {27, offsetof(google_protobuf_FileOptions, java_string_check_utf8), 7, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {31, offsetof(google_protobuf_FileOptions, cc_enable_arenas), 8, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {36, offsetof(google_protobuf_FileOptions, objc_class_prefix), 13, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {37, offsetof(google_protobuf_FileOptions, csharp_namespace), 14, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {38, offsetof(google_protobuf_FileOptions, javanano_use_deprecated_package), 9, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {40, offsetof(google_protobuf_FileOptions, php_class_prefix), 15, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {41, offsetof(google_protobuf_FileOptions, php_namespace), 16, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {999, offsetof(google_protobuf_FileOptions, uninterpreted_option), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {1, offsetof(google_protobuf_FileOptions, java_package), 10, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {8, offsetof(google_protobuf_FileOptions, java_outer_classname), 11, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {9, offsetof(google_protobuf_FileOptions, optimize_for), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 14, 1},
+  {10, offsetof(google_protobuf_FileOptions, java_multiple_files), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {11, offsetof(google_protobuf_FileOptions, go_package), 12, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {16, offsetof(google_protobuf_FileOptions, cc_generic_services), 2, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {17, offsetof(google_protobuf_FileOptions, java_generic_services), 3, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {18, offsetof(google_protobuf_FileOptions, py_generic_services), 4, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {20, offsetof(google_protobuf_FileOptions, java_generate_equals_and_hash), 5, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {23, offsetof(google_protobuf_FileOptions, deprecated), 6, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {27, offsetof(google_protobuf_FileOptions, java_string_check_utf8), 7, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {31, offsetof(google_protobuf_FileOptions, cc_enable_arenas), 8, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {36, offsetof(google_protobuf_FileOptions, objc_class_prefix), 13, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {37, offsetof(google_protobuf_FileOptions, csharp_namespace), 14, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {38, offsetof(google_protobuf_FileOptions, javanano_use_deprecated_package), 9, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {40, offsetof(google_protobuf_FileOptions, php_class_prefix), 15, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {41, offsetof(google_protobuf_FileOptions, php_namespace), 16, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {999, offsetof(google_protobuf_FileOptions, uninterpreted_option), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_FileOptions_msginit = {
   &google_protobuf_FileOptions_submsgs[0],
   &google_protobuf_FileOptions__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_FileOptions), 18, 0, false, true
 };
@@ -871,15 +873,15 @@ google_protobuf_FileOptions *google_protobuf_FileOptions_new(upb_env *env) {
   return msg;
 }
 google_protobuf_FileOptions *google_protobuf_FileOptions_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_FileOptions *msg = google_protobuf_FileOptions_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_FileOptions_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_FileOptions_serialize(google_protobuf_FileOptions *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_FileOptions_msginit, env, size);
 }
 upb_stringview google_protobuf_FileOptions_java_package(const google_protobuf_FileOptions *msg) {
   return msg->java_package;
@@ -1002,17 +1004,17 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_MessageOptions_subm
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_MessageOptions__fields[5] = {
-  {1, offsetof(google_protobuf_MessageOptions, message_set_wire_format), 0, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {2, offsetof(google_protobuf_MessageOptions, no_standard_descriptor_accessor), 1, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {3, offsetof(google_protobuf_MessageOptions, deprecated), 2, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {7, offsetof(google_protobuf_MessageOptions, map_entry), 3, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {999, offsetof(google_protobuf_MessageOptions, uninterpreted_option), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {1, offsetof(google_protobuf_MessageOptions, message_set_wire_format), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {2, offsetof(google_protobuf_MessageOptions, no_standard_descriptor_accessor), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {3, offsetof(google_protobuf_MessageOptions, deprecated), 2, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {7, offsetof(google_protobuf_MessageOptions, map_entry), 3, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {999, offsetof(google_protobuf_MessageOptions, uninterpreted_option), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_MessageOptions_msginit = {
   &google_protobuf_MessageOptions_submsgs[0],
   &google_protobuf_MessageOptions__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_MessageOptions), 5, 0, false, true
 };
@@ -1023,15 +1025,15 @@ google_protobuf_MessageOptions *google_protobuf_MessageOptions_new(upb_env *env)
   return msg;
 }
 google_protobuf_MessageOptions *google_protobuf_MessageOptions_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_MessageOptions *msg = google_protobuf_MessageOptions_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_MessageOptions_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_MessageOptions_serialize(google_protobuf_MessageOptions *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_MessageOptions_msginit, env, size);
 }
 bool google_protobuf_MessageOptions_message_set_wire_format(const google_protobuf_MessageOptions *msg) {
   return msg->message_set_wire_format;
@@ -1078,19 +1080,19 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_FieldOptions_submsg
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_FieldOptions__fields[7] = {
-  {1, offsetof(google_protobuf_FieldOptions, ctype), 0, UPB_NOT_IN_ONEOF, -1, 14, 1},
-  {2, offsetof(google_protobuf_FieldOptions, packed), 2, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {3, offsetof(google_protobuf_FieldOptions, deprecated), 3, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {5, offsetof(google_protobuf_FieldOptions, lazy), 4, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {6, offsetof(google_protobuf_FieldOptions, jstype), 1, UPB_NOT_IN_ONEOF, -1, 14, 1},
-  {10, offsetof(google_protobuf_FieldOptions, weak), 5, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {999, offsetof(google_protobuf_FieldOptions, uninterpreted_option), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {1, offsetof(google_protobuf_FieldOptions, ctype), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 14, 1},
+  {2, offsetof(google_protobuf_FieldOptions, packed), 2, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {3, offsetof(google_protobuf_FieldOptions, deprecated), 3, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {5, offsetof(google_protobuf_FieldOptions, lazy), 4, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {6, offsetof(google_protobuf_FieldOptions, jstype), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 14, 1},
+  {10, offsetof(google_protobuf_FieldOptions, weak), 5, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {999, offsetof(google_protobuf_FieldOptions, uninterpreted_option), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_FieldOptions_msginit = {
   &google_protobuf_FieldOptions_submsgs[0],
   &google_protobuf_FieldOptions__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_FieldOptions), 7, 0, false, true
 };
@@ -1101,15 +1103,15 @@ google_protobuf_FieldOptions *google_protobuf_FieldOptions_new(upb_env *env) {
   return msg;
 }
 google_protobuf_FieldOptions *google_protobuf_FieldOptions_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_FieldOptions *msg = google_protobuf_FieldOptions_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_FieldOptions_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_FieldOptions_serialize(google_protobuf_FieldOptions *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_FieldOptions_msginit, env, size);
 }
 google_protobuf_FieldOptions_CType google_protobuf_FieldOptions_ctype(const google_protobuf_FieldOptions *msg) {
   return msg->ctype;
@@ -1164,15 +1166,15 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_EnumOptions_submsgs
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_EnumOptions__fields[3] = {
-  {2, offsetof(google_protobuf_EnumOptions, allow_alias), 0, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {3, offsetof(google_protobuf_EnumOptions, deprecated), 1, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {999, offsetof(google_protobuf_EnumOptions, uninterpreted_option), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {2, offsetof(google_protobuf_EnumOptions, allow_alias), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {3, offsetof(google_protobuf_EnumOptions, deprecated), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {999, offsetof(google_protobuf_EnumOptions, uninterpreted_option), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_EnumOptions_msginit = {
   &google_protobuf_EnumOptions_submsgs[0],
   &google_protobuf_EnumOptions__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_EnumOptions), 3, 0, false, true
 };
@@ -1183,15 +1185,15 @@ google_protobuf_EnumOptions *google_protobuf_EnumOptions_new(upb_env *env) {
   return msg;
 }
 google_protobuf_EnumOptions *google_protobuf_EnumOptions_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_EnumOptions *msg = google_protobuf_EnumOptions_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_EnumOptions_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_EnumOptions_serialize(google_protobuf_EnumOptions *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_EnumOptions_msginit, env, size);
 }
 bool google_protobuf_EnumOptions_allow_alias(const google_protobuf_EnumOptions *msg) {
   return msg->allow_alias;
@@ -1221,14 +1223,14 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_EnumValueOptions_su
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_EnumValueOptions__fields[2] = {
-  {1, offsetof(google_protobuf_EnumValueOptions, deprecated), 0, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {999, offsetof(google_protobuf_EnumValueOptions, uninterpreted_option), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {1, offsetof(google_protobuf_EnumValueOptions, deprecated), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {999, offsetof(google_protobuf_EnumValueOptions, uninterpreted_option), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_EnumValueOptions_msginit = {
   &google_protobuf_EnumValueOptions_submsgs[0],
   &google_protobuf_EnumValueOptions__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_EnumValueOptions), 2, 0, false, true
 };
@@ -1239,15 +1241,15 @@ google_protobuf_EnumValueOptions *google_protobuf_EnumValueOptions_new(upb_env *
   return msg;
 }
 google_protobuf_EnumValueOptions *google_protobuf_EnumValueOptions_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_EnumValueOptions *msg = google_protobuf_EnumValueOptions_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_EnumValueOptions_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_EnumValueOptions_serialize(google_protobuf_EnumValueOptions *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_EnumValueOptions_msginit, env, size);
 }
 bool google_protobuf_EnumValueOptions_deprecated(const google_protobuf_EnumValueOptions *msg) {
   return msg->deprecated;
@@ -1271,14 +1273,14 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_ServiceOptions_subm
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_ServiceOptions__fields[2] = {
-  {33, offsetof(google_protobuf_ServiceOptions, deprecated), 0, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {999, offsetof(google_protobuf_ServiceOptions, uninterpreted_option), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {33, offsetof(google_protobuf_ServiceOptions, deprecated), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {999, offsetof(google_protobuf_ServiceOptions, uninterpreted_option), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_ServiceOptions_msginit = {
   &google_protobuf_ServiceOptions_submsgs[0],
   &google_protobuf_ServiceOptions__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_ServiceOptions), 2, 0, false, true
 };
@@ -1289,15 +1291,15 @@ google_protobuf_ServiceOptions *google_protobuf_ServiceOptions_new(upb_env *env)
   return msg;
 }
 google_protobuf_ServiceOptions *google_protobuf_ServiceOptions_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_ServiceOptions *msg = google_protobuf_ServiceOptions_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_ServiceOptions_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_ServiceOptions_serialize(google_protobuf_ServiceOptions *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_ServiceOptions_msginit, env, size);
 }
 bool google_protobuf_ServiceOptions_deprecated(const google_protobuf_ServiceOptions *msg) {
   return msg->deprecated;
@@ -1321,14 +1323,14 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_MethodOptions_subms
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_MethodOptions__fields[2] = {
-  {33, offsetof(google_protobuf_MethodOptions, deprecated), 0, UPB_NOT_IN_ONEOF, -1, 8, 1},
-  {999, offsetof(google_protobuf_MethodOptions, uninterpreted_option), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {33, offsetof(google_protobuf_MethodOptions, deprecated), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 1},
+  {999, offsetof(google_protobuf_MethodOptions, uninterpreted_option), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_MethodOptions_msginit = {
   &google_protobuf_MethodOptions_submsgs[0],
   &google_protobuf_MethodOptions__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_MethodOptions), 2, 0, false, true
 };
@@ -1339,15 +1341,15 @@ google_protobuf_MethodOptions *google_protobuf_MethodOptions_new(upb_env *env) {
   return msg;
 }
 google_protobuf_MethodOptions *google_protobuf_MethodOptions_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_MethodOptions *msg = google_protobuf_MethodOptions_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_MethodOptions_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_MethodOptions_serialize(google_protobuf_MethodOptions *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_MethodOptions_msginit, env, size);
 }
 bool google_protobuf_MethodOptions_deprecated(const google_protobuf_MethodOptions *msg) {
   return msg->deprecated;
@@ -1376,19 +1378,19 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_UninterpretedOption
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_UninterpretedOption__fields[7] = {
-  {2, offsetof(google_protobuf_UninterpretedOption, name), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
-  {3, offsetof(google_protobuf_UninterpretedOption, identifier_value), 3, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {4, offsetof(google_protobuf_UninterpretedOption, positive_int_value), 0, UPB_NOT_IN_ONEOF, -1, 4, 1},
-  {5, offsetof(google_protobuf_UninterpretedOption, negative_int_value), 1, UPB_NOT_IN_ONEOF, -1, 3, 1},
-  {6, offsetof(google_protobuf_UninterpretedOption, double_value), 2, UPB_NOT_IN_ONEOF, -1, 1, 1},
-  {7, offsetof(google_protobuf_UninterpretedOption, string_value), 4, UPB_NOT_IN_ONEOF, -1, 12, 1},
-  {8, offsetof(google_protobuf_UninterpretedOption, aggregate_value), 5, UPB_NOT_IN_ONEOF, -1, 9, 1},
+  {2, offsetof(google_protobuf_UninterpretedOption, name), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {3, offsetof(google_protobuf_UninterpretedOption, identifier_value), 3, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {4, offsetof(google_protobuf_UninterpretedOption, positive_int_value), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 4, 1},
+  {5, offsetof(google_protobuf_UninterpretedOption, negative_int_value), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 3, 1},
+  {6, offsetof(google_protobuf_UninterpretedOption, double_value), 2, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 1, 1},
+  {7, offsetof(google_protobuf_UninterpretedOption, string_value), 4, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 12, 1},
+  {8, offsetof(google_protobuf_UninterpretedOption, aggregate_value), 5, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_UninterpretedOption_msginit = {
   &google_protobuf_UninterpretedOption_submsgs[0],
   &google_protobuf_UninterpretedOption__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_UninterpretedOption), 7, 0, false, true
 };
@@ -1399,15 +1401,15 @@ google_protobuf_UninterpretedOption *google_protobuf_UninterpretedOption_new(upb
   return msg;
 }
 google_protobuf_UninterpretedOption *google_protobuf_UninterpretedOption_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_UninterpretedOption *msg = google_protobuf_UninterpretedOption_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_UninterpretedOption_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_UninterpretedOption_serialize(google_protobuf_UninterpretedOption *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_UninterpretedOption_msginit, env, size);
 }
 upb_array* google_protobuf_UninterpretedOption_name(const google_protobuf_UninterpretedOption *msg) {
   return msg->name;
@@ -1457,14 +1459,14 @@ struct google_protobuf_UninterpretedOption_NamePart {
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_UninterpretedOption_NamePart__fields[2] = {
-  {1, offsetof(google_protobuf_UninterpretedOption_NamePart, name_part), 1, UPB_NOT_IN_ONEOF, -1, 9, 2},
-  {2, offsetof(google_protobuf_UninterpretedOption_NamePart, is_extension), 0, UPB_NOT_IN_ONEOF, -1, 8, 2},
+  {1, offsetof(google_protobuf_UninterpretedOption_NamePart, name_part), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 2},
+  {2, offsetof(google_protobuf_UninterpretedOption_NamePart, is_extension), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 8, 2},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_UninterpretedOption_NamePart_msginit = {
   NULL,
   &google_protobuf_UninterpretedOption_NamePart__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_UninterpretedOption_NamePart), 2, 0, false, true
 };
@@ -1475,15 +1477,15 @@ google_protobuf_UninterpretedOption_NamePart *google_protobuf_UninterpretedOptio
   return msg;
 }
 google_protobuf_UninterpretedOption_NamePart *google_protobuf_UninterpretedOption_NamePart_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_UninterpretedOption_NamePart *msg = google_protobuf_UninterpretedOption_NamePart_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_UninterpretedOption_NamePart_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_UninterpretedOption_NamePart_serialize(google_protobuf_UninterpretedOption_NamePart *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_UninterpretedOption_NamePart_msginit, env, size);
 }
 upb_stringview google_protobuf_UninterpretedOption_NamePart_name_part(const google_protobuf_UninterpretedOption_NamePart *msg) {
   return msg->name_part;
@@ -1506,13 +1508,13 @@ static const upb_msglayout_msginit_v1 *const google_protobuf_SourceCodeInfo_subm
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_SourceCodeInfo__fields[1] = {
-  {1, offsetof(google_protobuf_SourceCodeInfo, location), -1, UPB_NOT_IN_ONEOF, 0, 11, 3},
+  {1, offsetof(google_protobuf_SourceCodeInfo, location), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, 0, 11, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_SourceCodeInfo_msginit = {
   &google_protobuf_SourceCodeInfo_submsgs[0],
   &google_protobuf_SourceCodeInfo__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_SourceCodeInfo), 1, 0, false, true
 };
@@ -1523,15 +1525,15 @@ google_protobuf_SourceCodeInfo *google_protobuf_SourceCodeInfo_new(upb_env *env)
   return msg;
 }
 google_protobuf_SourceCodeInfo *google_protobuf_SourceCodeInfo_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_SourceCodeInfo *msg = google_protobuf_SourceCodeInfo_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_SourceCodeInfo_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_SourceCodeInfo_serialize(google_protobuf_SourceCodeInfo *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_SourceCodeInfo_msginit, env, size);
 }
 upb_array* google_protobuf_SourceCodeInfo_location(const google_protobuf_SourceCodeInfo *msg) {
   return msg->location;
@@ -1548,17 +1550,17 @@ struct google_protobuf_SourceCodeInfo_Location {
 };
 
 static const upb_msglayout_fieldinit_v1 google_protobuf_SourceCodeInfo_Location__fields[5] = {
-  {1, offsetof(google_protobuf_SourceCodeInfo_Location, path), -1, UPB_NOT_IN_ONEOF, -1, 5, 3},
-  {2, offsetof(google_protobuf_SourceCodeInfo_Location, span), -1, UPB_NOT_IN_ONEOF, -1, 5, 3},
-  {3, offsetof(google_protobuf_SourceCodeInfo_Location, leading_comments), 0, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {4, offsetof(google_protobuf_SourceCodeInfo_Location, trailing_comments), 1, UPB_NOT_IN_ONEOF, -1, 9, 1},
-  {6, offsetof(google_protobuf_SourceCodeInfo_Location, leading_detached_comments), -1, UPB_NOT_IN_ONEOF, -1, 9, 3},
+  {1, offsetof(google_protobuf_SourceCodeInfo_Location, path), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 3},
+  {2, offsetof(google_protobuf_SourceCodeInfo_Location, span), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 5, 3},
+  {3, offsetof(google_protobuf_SourceCodeInfo_Location, leading_comments), 0, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {4, offsetof(google_protobuf_SourceCodeInfo_Location, trailing_comments), 1, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 1},
+  {6, offsetof(google_protobuf_SourceCodeInfo_Location, leading_detached_comments), UPB_NO_HASBIT, UPB_NOT_IN_ONEOF, UPB_NO_SUBMSG, 9, 3},
 };
 
 const upb_msglayout_msginit_v1 google_protobuf_SourceCodeInfo_Location_msginit = {
   NULL,
   &google_protobuf_SourceCodeInfo_Location__fields[0],
-  NULL, /* TODO. oneofs */
+  NULL,
   NULL, /* TODO. default_msg */
   UPB_ALIGNED_SIZEOF(google_protobuf_SourceCodeInfo_Location), 5, 0, false, true
 };
@@ -1569,15 +1571,15 @@ google_protobuf_SourceCodeInfo_Location *google_protobuf_SourceCodeInfo_Location
   return msg;
 }
 google_protobuf_SourceCodeInfo_Location *google_protobuf_SourceCodeInfo_Location_parsenew(upb_stringview buf, upb_env *env) {
-  UPB_UNUSED(buf);
-  UPB_UNUSED(env);
-  return NULL;
+  google_protobuf_SourceCodeInfo_Location *msg = google_protobuf_SourceCodeInfo_Location_new(env);
+  if (upb_decode(buf, msg, &google_protobuf_SourceCodeInfo_Location_msginit, env)) {
+    return msg;
+  } else {
+    return NULL;
+  }
 }
 char *google_protobuf_SourceCodeInfo_Location_serialize(google_protobuf_SourceCodeInfo_Location *msg, upb_env *env, size_t *size) {
-  UPB_UNUSED(msg);
-  UPB_UNUSED(env);
-  UPB_UNUSED(size);
-  return NULL; /* TODO. */
+  return upb_encode(msg, &google_protobuf_SourceCodeInfo_Location_msginit, env, size);
 }
 upb_array* google_protobuf_SourceCodeInfo_Location_path(const google_protobuf_SourceCodeInfo_Location *msg) {
   return msg->path;
diff --git a/upb/encode.c b/upb/encode.c
new file mode 100644
index 0000000..5acb492
--- /dev/null
+++ b/upb/encode.c
@@ -0,0 +1,394 @@
+/* We encode backwards, to avoid pre-computing lengths (one-pass encode). */
+
+#include "upb/upb.h"
+#include "upb/encode.h"
+#include "upb/structs.int.h"
+
+#define UPB_PB_VARINT_MAX_LEN 10
+#define CHK(x) do { if (!(x)) { return false; } } while(0)
+
+/* Maps descriptor type -> upb field type.  */
+static const uint8_t upb_desctype_to_fieldtype2[] = {
+  UPB_WIRE_TYPE_END_GROUP,  /* ENDGROUP */
+  UPB_TYPE_DOUBLE,          /* DOUBLE */
+  UPB_TYPE_FLOAT,           /* FLOAT */
+  UPB_TYPE_INT64,           /* INT64 */
+  UPB_TYPE_UINT64,          /* UINT64 */
+  UPB_TYPE_INT32,           /* INT32 */
+  UPB_TYPE_UINT64,          /* FIXED64 */
+  UPB_TYPE_UINT32,          /* FIXED32 */
+  UPB_TYPE_BOOL,            /* BOOL */
+  UPB_TYPE_STRING,          /* STRING */
+  UPB_TYPE_MESSAGE,         /* GROUP */
+  UPB_TYPE_MESSAGE,         /* MESSAGE */
+  UPB_TYPE_BYTES,           /* BYTES */
+  UPB_TYPE_UINT32,          /* UINT32 */
+  UPB_TYPE_ENUM,            /* ENUM */
+  UPB_TYPE_INT32,           /* SFIXED32 */
+  UPB_TYPE_INT64,           /* SFIXED64 */
+  UPB_TYPE_INT32,           /* SINT32 */
+  UPB_TYPE_INT64,           /* SINT64 */
+};
+
+static size_t upb_encode_varint(uint64_t val, char *buf) {
+  size_t i;
+  if (val < 128) { buf[0] = val; return 1; }
+  i = 0;
+  while (val) {
+    uint8_t byte = val & 0x7fU;
+    val >>= 7;
+    if (val) byte |= 0x80U;
+    buf[i++] = byte;
+  }
+  return i;
+}
+
+static uint32_t upb_zzencode_32(int32_t n) { return (n << 1) ^ (n >> 31); }
+static uint64_t upb_zzencode_64(int64_t n) { return (n << 1) ^ (n >> 63); }
+
+typedef struct {
+  upb_env *env;
+  char *buf, *ptr, *limit;
+} upb_encstate;
+
+static size_t upb_roundup_pow2(size_t bytes) {
+  size_t ret = 128;
+  while (ret < bytes) {
+    ret *= 2;
+  }
+  return ret;
+}
+
+static bool upb_encode_growbuffer(upb_encstate *e, size_t bytes) {
+  size_t old_size = e->limit - e->buf;
+  size_t new_size = upb_roundup_pow2(bytes + (e->limit - e->ptr));
+  char *new_buf = upb_env_realloc(e->env, e->buf, old_size, new_size);
+  CHK(new_buf);
+
+  /* We want previous data at the end, realloc() put it at the beginning. */
+  memmove(e->limit - old_size, e->buf, old_size);
+
+  e->ptr = new_buf + new_size - (e->limit - e->ptr);
+  e->limit = new_buf + new_size;
+  e->buf = new_buf;
+  return true;
+}
+
+/* Call to ensure that at least "bytes" bytes are available for writing at
+ * e->ptr.  Returns false if the bytes could not be allocated. */
+static bool upb_encode_reserve(upb_encstate *e, size_t bytes) {
+  CHK(UPB_LIKELY((size_t)(e->ptr - e->buf) >= bytes) ||
+      upb_encode_growbuffer(e, bytes));
+
+  e->ptr -= bytes;
+  return true;
+}
+
+/* Writes the given bytes to the buffer, handling reserve/advance. */
+static bool upb_put_bytes(upb_encstate *e, const void *data, size_t len) {
+  CHK(upb_encode_reserve(e, len));
+  memcpy(e->ptr, data, len);
+  return true;
+}
+
+static bool upb_put_fixed64(upb_encstate *e, uint64_t val) {
+  /* TODO(haberman): byte-swap for big endian. */
+  return upb_put_bytes(e, &val, sizeof(uint64_t));
+}
+
+static bool upb_put_fixed32(upb_encstate *e, uint32_t val) {
+  /* TODO(haberman): byte-swap for big endian. */
+  return upb_put_bytes(e, &val, sizeof(uint32_t));
+}
+
+static bool upb_put_varint(upb_encstate *e, uint64_t val) {
+  size_t len;
+  char *start;
+  CHK(upb_encode_reserve(e, UPB_PB_VARINT_MAX_LEN));
+  len = upb_encode_varint(val, e->ptr);
+  start = e->ptr + UPB_PB_VARINT_MAX_LEN - len;
+  memmove(start, e->ptr, len);
+  e->ptr = start;
+  return true;
+}
+
+static bool upb_put_double(upb_encstate *e, double d) {
+  uint64_t u64;
+  UPB_ASSERT(sizeof(double) == sizeof(uint64_t));
+  memcpy(&u64, &d, sizeof(uint64_t));
+  return upb_put_fixed64(e, u64);
+}
+
+static bool upb_put_float(upb_encstate *e, float d) {
+  uint32_t u32;
+  UPB_ASSERT(sizeof(float) == sizeof(uint32_t));
+  memcpy(&u32, &d, sizeof(uint32_t));
+  return upb_put_fixed32(e, u32);
+}
+
+static uint32_t upb_readcase(const char *msg, const upb_msglayout_msginit_v1 *m,
+                             int oneof_index) {
+  uint32_t ret;
+  memcpy(&ret, msg + m->oneofs[oneof_index].case_offset, sizeof(ret));
+  return ret;
+}
+
+static bool upb_readhasbit(const char *msg,
+                           const upb_msglayout_fieldinit_v1 *f) {
+  UPB_ASSERT(f->hasbit != UPB_NO_HASBIT);
+  return msg[f->hasbit / 8] & (1 << (f->hasbit % 8));
+}
+
+static bool upb_put_tag(upb_encstate *e, int field_number, int wire_type) {
+  return upb_put_varint(e, (field_number << 3) | wire_type);
+}
+
+static bool upb_put_fixedarray(upb_encstate *e, const upb_array *arr,
+                               size_t size) {
+  size_t bytes = arr->len * size;
+  return upb_put_bytes(e, arr->data, bytes) && upb_put_varint(e, bytes);
+}
+
+bool upb_encode_message(upb_encstate *e, const char *msg,
+                        const upb_msglayout_msginit_v1 *m,
+                        size_t *size);
+
+static bool upb_encode_array(upb_encstate *e, const char *field_mem,
+                             const upb_msglayout_msginit_v1 *m,
+                             const upb_msglayout_fieldinit_v1 *f) {
+  const upb_array *arr = *(const upb_array**)field_mem;
+
+  if (arr == NULL || arr->len == 0) {
+    return true;
+  }
+
+  UPB_ASSERT(arr->type == upb_desctype_to_fieldtype2[f->type]);
+
+#define VARINT_CASE(ctype, encode) { \
+  ctype *start = arr->data; \
+  ctype *ptr = start + arr->len; \
+  size_t pre_len = e->limit - e->ptr; \
+  do { \
+    ptr--; \
+    CHK(upb_put_varint(e, encode)); \
+  } while (ptr != start); \
+  CHK(upb_put_varint(e, e->limit - e->ptr - pre_len)); \
+} \
+break; \
+do { ; } while(0)
+
+  switch (f->type) {
+    case UPB_DESCRIPTOR_TYPE_DOUBLE:
+      CHK(upb_put_fixedarray(e, arr, sizeof(double)));
+      break;
+    case UPB_DESCRIPTOR_TYPE_FLOAT:
+      CHK(upb_put_fixedarray(e, arr, sizeof(float)));
+      break;
+    case UPB_DESCRIPTOR_TYPE_SFIXED64:
+    case UPB_DESCRIPTOR_TYPE_FIXED64:
+      CHK(upb_put_fixedarray(e, arr, sizeof(uint64_t)));
+      break;
+    case UPB_DESCRIPTOR_TYPE_FIXED32:
+    case UPB_DESCRIPTOR_TYPE_SFIXED32:
+      CHK(upb_put_fixedarray(e, arr, sizeof(uint32_t)));
+      break;
+    case UPB_DESCRIPTOR_TYPE_INT64:
+    case UPB_DESCRIPTOR_TYPE_UINT64:
+      VARINT_CASE(uint64_t, *ptr);
+    case UPB_DESCRIPTOR_TYPE_UINT32:
+    case UPB_DESCRIPTOR_TYPE_INT32:
+    case UPB_DESCRIPTOR_TYPE_ENUM:
+      VARINT_CASE(uint32_t, *ptr);
+    case UPB_DESCRIPTOR_TYPE_BOOL:
+      VARINT_CASE(bool, *ptr);
+    case UPB_DESCRIPTOR_TYPE_SINT32:
+      VARINT_CASE(int32_t, upb_zzencode_32(*ptr));
+    case UPB_DESCRIPTOR_TYPE_SINT64:
+      VARINT_CASE(int64_t, upb_zzencode_64(*ptr));
+    case UPB_DESCRIPTOR_TYPE_STRING:
+    case UPB_DESCRIPTOR_TYPE_BYTES: {
+      upb_stringview *start = arr->data;
+      upb_stringview *ptr = start + arr->len;
+      do {
+        ptr--;
+        CHK(upb_put_bytes(e, ptr->data, ptr->size) &&
+            upb_put_varint(e, ptr->size) &&
+            upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED));
+      } while (ptr != start);
+      return true;
+    }
+    case UPB_DESCRIPTOR_TYPE_GROUP: {
+      void **start = arr->data;
+      void **ptr = start + arr->len;
+      const upb_msglayout_msginit_v1 *subm = m->submsgs[f->submsg_index];
+      do {
+        size_t size;
+        ptr--;
+        CHK(upb_put_tag(e, f->number, UPB_WIRE_TYPE_END_GROUP) &&
+            upb_encode_message(e, *ptr, subm, &size) &&
+            upb_put_tag(e, f->number, UPB_WIRE_TYPE_START_GROUP));
+      } while (ptr != start);
+      return true;
+    }
+    case UPB_DESCRIPTOR_TYPE_MESSAGE: {
+      void **start = arr->data;
+      void **ptr = start + arr->len;
+      const upb_msglayout_msginit_v1 *subm = m->submsgs[f->submsg_index];
+      do {
+        size_t size;
+        ptr--;
+        CHK(upb_encode_message(e, *ptr, subm, &size) &&
+            upb_put_varint(e, size) &&
+            upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED));
+      } while (ptr != start);
+      return true;
+    }
+  }
+#undef VARINT_CASE
+
+  /* We encode all primitive arrays as packed, regardless of what was specified
+   * in the .proto file.  Could special case 1-sized arrays. */
+  CHK(upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED));
+  return true;
+}
+
+static bool upb_encode_scalarfield(upb_encstate *e, const char *field_mem,
+                                   const upb_msglayout_msginit_v1 *m,
+                                   const upb_msglayout_fieldinit_v1 *f,
+                                   bool is_proto3) {
+  bool skip_zero_value = is_proto3 && f->oneof_index == UPB_NOT_IN_ONEOF;
+
+#define CASE(ctype, type, wire_type, encodeval) do { \
+  ctype val = *(ctype*)field_mem; \
+  if (skip_zero_value && val == 0) { \
+    return true; \
+  } \
+  return upb_put_ ## type(e, encodeval) && \
+      upb_put_tag(e, f->number, wire_type); \
+} while(0)
+
+  switch (f->type) {
+    case UPB_DESCRIPTOR_TYPE_DOUBLE:
+      CASE(double, double, UPB_WIRE_TYPE_64BIT, val);
+    case UPB_DESCRIPTOR_TYPE_FLOAT:
+      CASE(float, float, UPB_WIRE_TYPE_32BIT, val);
+    case UPB_DESCRIPTOR_TYPE_INT64:
+    case UPB_DESCRIPTOR_TYPE_UINT64:
+      CASE(uint64_t, varint, UPB_WIRE_TYPE_VARINT, val);
+    case UPB_DESCRIPTOR_TYPE_UINT32:
+    case UPB_DESCRIPTOR_TYPE_INT32:
+    case UPB_DESCRIPTOR_TYPE_ENUM:
+      CASE(uint32_t, varint, UPB_WIRE_TYPE_VARINT, val);
+    case UPB_DESCRIPTOR_TYPE_SFIXED64:
+    case UPB_DESCRIPTOR_TYPE_FIXED64:
+      CASE(uint64_t, fixed64, UPB_WIRE_TYPE_64BIT, val);
+    case UPB_DESCRIPTOR_TYPE_FIXED32:
+    case UPB_DESCRIPTOR_TYPE_SFIXED32:
+      CASE(uint32_t, fixed32, UPB_WIRE_TYPE_32BIT, val);
+    case UPB_DESCRIPTOR_TYPE_BOOL:
+      CASE(bool, varint, UPB_WIRE_TYPE_VARINT, val);
+    case UPB_DESCRIPTOR_TYPE_SINT32:
+      CASE(int32_t, varint, UPB_WIRE_TYPE_VARINT, upb_zzencode_32(val));
+    case UPB_DESCRIPTOR_TYPE_SINT64:
+      CASE(int64_t, varint, UPB_WIRE_TYPE_VARINT, upb_zzencode_64(val));
+    case UPB_DESCRIPTOR_TYPE_STRING:
+    case UPB_DESCRIPTOR_TYPE_BYTES: {
+      upb_stringview view = *(upb_stringview*)field_mem;
+      if (skip_zero_value && view.size == 0) {
+        return true;
+      }
+      return upb_put_bytes(e, view.data, view.size) &&
+          upb_put_varint(e, view.size) &&
+          upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED);
+    }
+    case UPB_DESCRIPTOR_TYPE_GROUP: {
+      size_t size;
+      void *submsg = *(void**)field_mem;
+      const upb_msglayout_msginit_v1 *subm = m->submsgs[f->submsg_index];
+      if (skip_zero_value && submsg == NULL) {
+        return true;
+      }
+      return upb_put_tag(e, f->number, UPB_WIRE_TYPE_END_GROUP) &&
+          upb_encode_message(e, submsg, subm, &size) &&
+          upb_put_tag(e, f->number, UPB_WIRE_TYPE_START_GROUP);
+    }
+    case UPB_DESCRIPTOR_TYPE_MESSAGE: {
+      size_t size;
+      void *submsg = *(void**)field_mem;
+      const upb_msglayout_msginit_v1 *subm = m->submsgs[f->submsg_index];
+      if (skip_zero_value && submsg == NULL) {
+        return true;
+      }
+      return upb_encode_message(e, submsg, subm, &size) &&
+          upb_put_varint(e, size) &&
+          upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED);
+    }
+  }
+#undef CASE
+  UPB_UNREACHABLE();
+}
+
+bool upb_encode_hasscalarfield(const char *msg,
+                               const upb_msglayout_msginit_v1 *m,
+                               const upb_msglayout_fieldinit_v1 *f) {
+  if (f->oneof_index != UPB_NOT_IN_ONEOF) {
+    return upb_readcase(msg, m, f->oneof_index) == f->number;
+  } else if (m->is_proto2) {
+    return upb_readhasbit(msg, f);
+  } else {
+    /* For proto3, we'll test for the field being empty later. */
+    return true;
+  }
+}
+
+bool upb_encode_message(upb_encstate* e, const char *msg,
+                        const upb_msglayout_msginit_v1 *m,
+                        size_t *size) {
+  int i;
+  char *buf_end = e->ptr;
+
+  if (msg == NULL) {
+    return true;
+  }
+
+  for (i = m->field_count - 1; i >= 0; i--) {
+    const upb_msglayout_fieldinit_v1 *f = &m->fields[i];
+
+    if (f->label == UPB_LABEL_REPEATED) {
+      CHK(upb_encode_array(e, msg + f->offset, m, f));
+    } else {
+      if (upb_encode_hasscalarfield(msg, m, f)) {
+        CHK(upb_encode_scalarfield(e, msg + f->offset, m, f, !m->is_proto2));
+      }
+    }
+  }
+
+  *size = buf_end - e->ptr;
+  return true;
+}
+
+char *upb_encode(const void *msg, const upb_msglayout_msginit_v1 *m,
+                 upb_env *env, size_t *size) {
+  upb_encstate e;
+  e.env = env;
+  e.buf = NULL;
+  e.limit = NULL;
+  e.ptr = NULL;
+
+  if (!upb_encode_message(&e, msg, m, size)) {
+    *size = 0;
+    return NULL;
+  }
+
+  *size = e.limit - e.ptr;
+
+  if (*size == 0) {
+    static char ch;
+    return &ch;
+  } else {
+    UPB_ASSERT(e.ptr);
+    return e.ptr;
+  }
+}
+
+#undef CHK
diff --git a/upb/encode.h b/upb/encode.h
new file mode 100644
index 0000000..83908d4
--- /dev/null
+++ b/upb/encode.h
@@ -0,0 +1,17 @@
+/*
+** upb_encode: parsing into a upb_msg using a upb_msglayout.
+*/
+
+#ifndef UPB_ENCODE_H_
+#define UPB_ENCODE_H_
+
+#include "upb/msg.h"
+
+UPB_BEGIN_EXTERN_C
+
+char *upb_encode(const void *msg, const upb_msglayout_msginit_v1 *l,
+                 upb_env *env, size_t *size);
+
+UPB_END_EXTERN_C
+
+#endif  /* UPB_ENCODE_H_ */
diff --git a/upb/msg.c b/upb/msg.c
index f1070d7..b3b0420 100644
--- a/upb/msg.c
+++ b/upb/msg.c
@@ -1,5 +1,6 @@
 
 #include "upb/msg.h"
+#include "upb/structs.int.h"
 
 static bool is_power_of_two(size_t val) {
   return (val & (val - 1)) == 0;
@@ -67,7 +68,7 @@ static size_t upb_msgval_sizeof(upb_fieldtype_t type) {
     case UPB_TYPE_MESSAGE:
       return sizeof(void*);
     case UPB_TYPE_STRING:
-      return sizeof(char*) + sizeof(size_t);
+      return sizeof(upb_stringview);
   }
   UPB_UNREACHABLE();
 }
@@ -794,15 +795,6 @@ void upb_msg_set(upb_msg *msg, int field_index, upb_msgval val,
 
 /** upb_array *****************************************************************/
 
-struct upb_array {
-  upb_fieldtype_t type;
-  uint8_t element_size;
-  void *data;   /* Each element is element_size. */
-  size_t len;   /* Measured in elements. */
-  size_t size;  /* Measured in elements. */
-  upb_alloc *alloc;
-};
-
 #define DEREF_ARR(arr, i, type) ((type*)arr->data)[i]
 
 size_t upb_array_sizeof(upb_fieldtype_t type) {
diff --git a/upb/msg.h b/upb/msg.h
index dd25542..3579a3f 100644
--- a/upb/msg.h
+++ b/upb/msg.h
@@ -387,13 +387,15 @@ bool upb_msg_getscalarhandlerdata(const upb_handlers *h,
 /** Interfaces for generated code *********************************************/
 
 #define UPB_NOT_IN_ONEOF UINT16_MAX
+#define UPB_NO_HASBIT UINT16_MAX
+#define UPB_NO_SUBMSG UINT16_MAX
 
 typedef struct {
   uint32_t number;
   uint32_t offset;  /* If in a oneof, offset of default in default_msg below. */
-  uint16_t hasbit;
-  uint16_t oneof_index;  /* UPB_NOT_IN_ONEOF if not in a oneof. */
-  uint16_t submsg_index;
+  uint16_t hasbit;        /* UPB_NO_HASBIT if no hasbit. */
+  uint16_t oneof_index;   /* UPB_NOT_IN_ONEOF if not in a oneof. */
+  uint16_t submsg_index;  /* UPB_NO_SUBMSG if no submsg. */
   uint8_t type;
   uint8_t label;
 } upb_msglayout_fieldinit_v1;
diff --git a/upb/pb/varint.int.h b/upb/pb/varint.int.h
index 3ef84fb..9c54311 100644
--- a/upb/pb/varint.int.h
+++ b/upb/pb/varint.int.h
@@ -15,21 +15,9 @@
 extern "C" {
 #endif
 
-/* A list of types as they are encoded on-the-wire. */
-typedef enum {
-  UPB_WIRE_TYPE_VARINT      = 0,
-  UPB_WIRE_TYPE_64BIT       = 1,
-  UPB_WIRE_TYPE_DELIMITED   = 2,
-  UPB_WIRE_TYPE_START_GROUP = 3,
-  UPB_WIRE_TYPE_END_GROUP   = 4,
-  UPB_WIRE_TYPE_32BIT       = 5
-} upb_wiretype_t;
-
 #define UPB_MAX_WIRE_TYPE 5
 
-/* The maximum number of bytes that it takes to encode a 64-bit varint.
- * Note that with a better encoding this could be 9 (TODO: write up a
- * wiki document about this). */
+/* The maximum number of bytes that it takes to encode a 64-bit varint. */
 #define UPB_PB_VARINT_MAX_LEN 10
 
 /* Array of the "native" (ie. non-packed-repeated) wire type for the given a
diff --git a/upb/structs.int.h b/upb/structs.int.h
new file mode 100644
index 0000000..242155b
--- /dev/null
+++ b/upb/structs.int.h
@@ -0,0 +1,18 @@
+/*
+** structs.int.h: structures definitions that are internal to upb.
+*/
+
+#ifndef UPB_STRUCTS_H_
+#define UPB_STRUCTS_H_
+
+struct upb_array {
+  upb_fieldtype_t type;
+  uint8_t element_size;
+  void *data;   /* Each element is element_size. */
+  size_t len;   /* Measured in elements. */
+  size_t size;  /* Measured in elements. */
+  upb_alloc *alloc;
+};
+
+#endif  /* UPB_STRUCTS_H_ */
+
diff --git a/upb/upb.h b/upb/upb.h
index a2b79ca..2d6db8e 100644
--- a/upb/upb.h
+++ b/upb/upb.h
@@ -34,6 +34,9 @@ template <int N> class InlinedEnvironment;
 #define UPB_INLINE static
 #endif
 
+/* Hints to the compiler about likely/unlikely branches. */
+#define UPB_LIKELY(x) __builtin_expect((x),1)
+
 /* Define UPB_BIG_ENDIAN manually if you're on big endian and your compiler
  * doesn't provide these preprocessor symbols. */
 #if defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
@@ -295,6 +298,16 @@ class PointerBase2 : public PointerBase<T, Base> {
 
 #endif
 
+/* A list of types as they are encoded on-the-wire. */
+typedef enum {
+  UPB_WIRE_TYPE_VARINT      = 0,
+  UPB_WIRE_TYPE_64BIT       = 1,
+  UPB_WIRE_TYPE_DELIMITED   = 2,
+  UPB_WIRE_TYPE_START_GROUP = 3,
+  UPB_WIRE_TYPE_END_GROUP   = 4,
+  UPB_WIRE_TYPE_32BIT       = 5
+} upb_wiretype_t;
+
 
 /* upb::ErrorSpace ************************************************************/
 
@@ -623,7 +636,7 @@ void upb_env_uninit(upb_env *e);
 
 void upb_env_initonly(upb_env *e);
 
-upb_arena *upb_env_arena(upb_env *e);
+UPB_INLINE upb_arena *upb_env_arena(upb_env *e) { return (upb_arena*)e; }
 bool upb_env_ok(const upb_env *e);
 void upb_env_seterrorfunc(upb_env *e, upb_error_func *func, void *ud);