diff --git a/generated_for_cmake/google/protobuf/descriptor.upb.c b/generated_for_cmake/google/protobuf/descriptor.upb.c
index ac95b2ec9e..38acc66406 100644
--- a/generated_for_cmake/google/protobuf/descriptor.upb.c
+++ b/generated_for_cmake/google/protobuf/descriptor.upb.c
@@ -23,7 +23,7 @@ static const upb_msglayout_field google_protobuf_FileDescriptorSet__fields[1] =
 const upb_msglayout google_protobuf_FileDescriptorSet_msginit = {
   {
     &fastdecode_generic,
-    &fastdecode_generic,
+    &upb_prm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -57,7 +57,7 @@ const upb_msglayout google_protobuf_FileDescriptorSet_msginit = {
   },
   {
     UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(10, 10),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -124,12 +124,12 @@ const upb_msglayout google_protobuf_FileDescriptorProto_msginit = {
     &upb_pss_1bt,
     &upb_pss_1bt,
     &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
+    &upb_prm_1bt,
+    &upb_prm_1bt,
+    &upb_prm_1bt,
+    &upb_prm_1bt,
+    &upb_psm_1bt,
+    &upb_psm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &upb_pss_1bt,
@@ -158,12 +158,12 @@ const upb_msglayout google_protobuf_FileDescriptorProto_msginit = {
     UPB_SIZE(1125899906973706, 2251799813816330),
     UPB_SIZE(3377699720790034, 6755399441317906),
     UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(844424930132002, 844424930132002),
+    UPB_SIZE(1125899906842666, 1125899906842666),
+    UPB_SIZE(1407374883553330, 1407374883553330),
+    UPB_SIZE(1688849860263994, 1688849860263994),
+    UPB_SIZE(1970324838023234, 1970324838023234),
+    UPB_SIZE(2251799815782474, 2251799815782474),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(5629499534737506, 11258999068950626),
@@ -219,14 +219,14 @@ const upb_msglayout google_protobuf_DescriptorProto_msginit = {
   {
     &fastdecode_generic,
     &upb_pss_1bt,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
+    &upb_prm_1bt,
+    &upb_prm_1bt,
+    &upb_prm_1bt,
+    &upb_prm_1bt,
+    &upb_prm_1bt,
+    &upb_psm_1bt,
+    &upb_prm_1bt,
+    &upb_prm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -253,14 +253,14 @@ const upb_msglayout google_protobuf_DescriptorProto_msginit = {
   {
     UPB_SIZE(0, 0),
     UPB_SIZE(1125899906973706, 2251799813816330),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(281474976710674, 281474976710674),
+    UPB_SIZE(562949953421338, 562949953421338),
+    UPB_SIZE(844424930132002, 844424930132002),
+    UPB_SIZE(1125899906842666, 1125899906842666),
+    UPB_SIZE(1407374883553330, 1407374883553330),
+    UPB_SIZE(1688849860526138, 1688849860526138),
+    UPB_SIZE(1970324836974658, 1970324836974658),
+    UPB_SIZE(2251799813685322, 2251799813685322),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -304,7 +304,7 @@ const upb_msglayout google_protobuf_DescriptorProto_ExtensionRange_msginit = {
     &fastdecode_generic,
     &upb_psv4_1bt,
     &upb_psv4_1bt,
-    &fastdecode_generic,
+    &upb_psm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -338,7 +338,7 @@ const upb_msglayout google_protobuf_DescriptorProto_ExtensionRange_msginit = {
     UPB_SIZE(0, 0),
     UPB_SIZE(1125899906973704, 1125899906973704),
     UPB_SIZE(2251799813947408, 2251799813947408),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(562949953945626, 562949953945626),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -562,7 +562,7 @@ const upb_msglayout google_protobuf_FieldDescriptorProto_msginit = {
     &upb_psv4_1bt,
     &upb_pss_1bt,
     &upb_pss_1bt,
-    &fastdecode_generic,
+    &upb_psm_1bt,
     &upb_psv4_1bt,
     &upb_pss_1bt,
     &fastdecode_generic,
@@ -596,7 +596,7 @@ const upb_msglayout google_protobuf_FieldDescriptorProto_msginit = {
     UPB_SIZE(4503599627632680, 4503599627632680),
     UPB_SIZE(14636698805731378, 20266198339944498),
     UPB_SIZE(16888498636193850, 24769797984092218),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(1970324971192386, 1970324971192386),
     UPB_SIZE(7881299348947016, 7881299348947016),
     UPB_SIZE(19140298483433554, 29273397645017170),
     UPB_SIZE(0, 0),
@@ -605,7 +605,7 @@ const upb_msglayout google_protobuf_FieldDescriptorProto_msginit = {
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
-    UPB_SIZE(9007199256838280, 9007199256838280),
+    UPB_SIZE(9007199256838536, 9007199256838536),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -639,7 +639,7 @@ const upb_msglayout google_protobuf_OneofDescriptorProto_msginit = {
   {
     &fastdecode_generic,
     &upb_pss_1bt,
-    &fastdecode_generic,
+    &upb_psm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -673,7 +673,7 @@ const upb_msglayout google_protobuf_OneofDescriptorProto_msginit = {
   {
     UPB_SIZE(0, 0),
     UPB_SIZE(1125899906973706, 2251799813816330),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(281474976972818, 281474976972818),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -727,9 +727,9 @@ const upb_msglayout google_protobuf_EnumDescriptorProto_msginit = {
   {
     &fastdecode_generic,
     &upb_pss_1bt,
-    &fastdecode_generic,
-    &fastdecode_generic,
-    &fastdecode_generic,
+    &upb_prm_1bt,
+    &upb_psm_1bt,
+    &upb_prm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -761,9 +761,9 @@ const upb_msglayout google_protobuf_EnumDescriptorProto_msginit = {
   {
     UPB_SIZE(0, 0),
     UPB_SIZE(1125899906973706, 2251799813816330),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(281474976710674, 281474976710674),
+    UPB_SIZE(562949953683482, 562949953683482),
+    UPB_SIZE(844424930132002, 844424930132002),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -891,7 +891,7 @@ const upb_msglayout google_protobuf_EnumValueDescriptorProto_msginit = {
     &fastdecode_generic,
     &upb_pss_1bt,
     &upb_psv4_1bt,
-    &fastdecode_generic,
+    &upb_psm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -925,7 +925,7 @@ const upb_msglayout google_protobuf_EnumValueDescriptorProto_msginit = {
     UPB_SIZE(0, 0),
     UPB_SIZE(2251799813947402, 2251799813947402),
     UPB_SIZE(1125899906973712, 1125899906973712),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(562949953945626, 562949953945626),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -975,8 +975,8 @@ const upb_msglayout google_protobuf_ServiceDescriptorProto_msginit = {
   {
     &fastdecode_generic,
     &upb_pss_1bt,
-    &fastdecode_generic,
-    &fastdecode_generic,
+    &upb_prm_1bt,
+    &upb_psm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -1009,8 +1009,8 @@ const upb_msglayout google_protobuf_ServiceDescriptorProto_msginit = {
   {
     UPB_SIZE(0, 0),
     UPB_SIZE(1125899906973706, 2251799813816330),
-    UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(281474976710674, 281474976710674),
+    UPB_SIZE(562949953683482, 562949953683482),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -1064,7 +1064,7 @@ const upb_msglayout google_protobuf_MethodDescriptorProto_msginit = {
     &upb_pss_1bt,
     &upb_pss_1bt,
     &upb_pss_1bt,
-    &fastdecode_generic,
+    &upb_psm_1bt,
     &upb_psb1_1bt,
     &upb_psb1_1bt,
     &fastdecode_generic,
@@ -1098,7 +1098,7 @@ const upb_msglayout google_protobuf_MethodDescriptorProto_msginit = {
     UPB_SIZE(1125899907366922, 2251799814209546),
     UPB_SIZE(3377699721576466, 6755399442104338),
     UPB_SIZE(5629499536310298, 11258999070523418),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(844424934326306, 844424934326306),
     UPB_SIZE(281474976841768, 281474976841768),
     UPB_SIZE(562949953683504, 562949953683504),
     UPB_SIZE(0, 0),
@@ -1212,22 +1212,22 @@ const upb_msglayout google_protobuf_FileOptions_msginit = {
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
-    UPB_SIZE(4785074604605568, 4785074604605568),
-    UPB_SIZE(5066549581840520, 5066549581840520),
-    UPB_SIZE(5348024559599760, 5348024559599760),
+    UPB_SIZE(4785074604605824, 4785074604605824),
+    UPB_SIZE(5066549581840776, 5066549581840776),
+    UPB_SIZE(5348024559600016, 5348024559600016),
     UPB_SIZE(0, 0),
-    UPB_SIZE(5629499538407584, 5629499538407584),
+    UPB_SIZE(5629499538407840, 5629499538407840),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
-    UPB_SIZE(5910974519312568, 5910974519312568),
+    UPB_SIZE(5910974519312824, 5910974519312824),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
-    UPB_SIZE(6192449504411864, 6192449504411864),
+    UPB_SIZE(6192449504412120, 6192449504412120),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
-    UPB_SIZE(6473924497899768, 6473924497899768),
+    UPB_SIZE(6473924497900024, 6473924497900024),
   },
   &google_protobuf_FileOptions_submsgs[0],
   &google_protobuf_FileOptions__fields[0],
@@ -1842,12 +1842,12 @@ const upb_msglayout google_protobuf_UninterpretedOption_msginit = {
   {
     &fastdecode_generic,
     &fastdecode_generic,
-    &fastdecode_generic,
+    &upb_prm_1bt,
     &upb_pss_1bt,
     &upb_psv8_1bt,
     &upb_psv8_1bt,
     &fastdecode_generic,
-    &upb_pss_1bt,
+    &fastdecode_generic,
     &upb_pss_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -1876,12 +1876,12 @@ const upb_msglayout google_protobuf_UninterpretedOption_msginit = {
   {
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(18, 18),
     UPB_SIZE(9007199255789594, 9007199255789594),
     UPB_SIZE(2251799813816352, 2251799813816352),
     UPB_SIZE(4503599627632680, 4503599627632680),
     UPB_SIZE(0, 0),
-    UPB_SIZE(11258999070523450, 13510798884208698),
+    UPB_SIZE(0, 0),
     UPB_SIZE(13510798886305858, 18014398513676354),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -2002,7 +2002,7 @@ static const upb_msglayout_field google_protobuf_SourceCodeInfo__fields[1] = {
 const upb_msglayout google_protobuf_SourceCodeInfo_msginit = {
   {
     &fastdecode_generic,
-    &fastdecode_generic,
+    &upb_prm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -2036,7 +2036,7 @@ const upb_msglayout google_protobuf_SourceCodeInfo_msginit = {
   },
   {
     UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(10, 10),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
@@ -2166,7 +2166,7 @@ static const upb_msglayout_field google_protobuf_GeneratedCodeInfo__fields[1] =
 const upb_msglayout google_protobuf_GeneratedCodeInfo_msginit = {
   {
     &fastdecode_generic,
-    &fastdecode_generic,
+    &upb_prm_1bt,
     &fastdecode_generic,
     &fastdecode_generic,
     &fastdecode_generic,
@@ -2200,7 +2200,7 @@ const upb_msglayout google_protobuf_GeneratedCodeInfo_msginit = {
   },
   {
     UPB_SIZE(0, 0),
-    UPB_SIZE(0, 0),
+    UPB_SIZE(10, 10),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
     UPB_SIZE(0, 0),
diff --git a/tests/benchmark.cc b/tests/benchmark.cc
index b0cbba7b78..c4b1abfeaa 100644
--- a/tests/benchmark.cc
+++ b/tests/benchmark.cc
@@ -41,7 +41,7 @@ static void BM_ParseDescriptorNoHeap(benchmark::State& state) {
     }
     bytes += descriptor.size;
     upb_arena_free(arena);
-    fprintf(stderr, "+++ finished parse\n");
+    //fprintf(stderr, "+++ finished parse: %zu\n", descriptor.size);
   }
   state.SetBytesProcessed(state.iterations() * descriptor.size);
 }
diff --git a/upb/decode.c b/upb/decode.c
index 2bc4d9c818..8383cef946 100644
--- a/upb/decode.c
+++ b/upb/decode.c
@@ -565,9 +565,14 @@ static const char *decode_tomsg(upb_decstate *d, const char *ptr, upb_msg *msg,
   return ptr;
 }
 
+typedef struct {
+  const char *ptr;
+  bool group_end;
+} decode_parseret;
+
 UPB_FORCEINLINE
-static const char *decode_field(upb_decstate *d, const char *ptr, upb_msg *msg,
-                                const upb_msglayout *layout) {
+static decode_parseret decode_field(upb_decstate *d, const char *ptr,
+                                    upb_msg *msg, const upb_msglayout *layout) {
   uint32_t tag;
   const upb_msglayout_field *field;
   int field_number;
@@ -575,6 +580,7 @@ static const char *decode_field(upb_decstate *d, const char *ptr, upb_msg *msg,
   const char *field_start = ptr;
   wireval val;
   int op;
+  decode_parseret ret;
 
   ptr = decode_varint32(d, ptr, d->limit, &tag);
   field_number = tag >> 3;
@@ -625,7 +631,9 @@ static const char *decode_field(upb_decstate *d, const char *ptr, upb_msg *msg,
       break;
     case UPB_WIRE_TYPE_END_GROUP:
       d->end_group = field_number;
-      return ptr;
+      ret.ptr = ptr;
+      ret.group_end = true;
+      return ret;
     default:
       decode_err(d);
   }
@@ -656,24 +664,36 @@ static const char *decode_field(upb_decstate *d, const char *ptr, upb_msg *msg,
     }
   }
 
-  return ptr;
+  ret.ptr = ptr;
+  ret.group_end = false;
+  return ret;
 }
 
 UPB_NOINLINE
 const char *fastdecode_generic(upb_decstate *d, const char *ptr, upb_msg *msg,
                                const upb_msglayout *table, uint64_t hasbits,
                                uint64_t data) {
+  decode_parseret ret;
   *(uint32_t*)msg |= hasbits >> 16;  /* Sync hasbits. */
   (void)data;
   if (ptr == d->limit) return ptr;
-  ptr = decode_field(d, ptr, msg, table);
-  return fastdecode_dispatch(d, ptr, msg, table, hasbits);
+  ret = decode_field(d, ptr, msg, table);
+  if (ret.group_end) return ptr;
+  return fastdecode_dispatch(d, ret.ptr, msg, table, hasbits);
 }
 
 UPB_NOINLINE
 static const char *decode_msg(upb_decstate *d, const char *ptr, upb_msg *msg,
                               const upb_msglayout *layout) {
-  ptr = fastdecode_dispatch(d, ptr, msg, layout, 0);
+  if (msg) {
+    ptr = fastdecode_dispatch(d, ptr, msg, layout, 0);
+  } else {
+    while (ptr < d->limit) {
+      decode_parseret ret = decode_field(d, ptr, msg, layout);
+      ptr = ret.ptr;
+      if (ret.group_end) return ptr;
+    }
+  }
   if (ptr != d->limit) decode_err(d);
   return ptr;
 }
diff --git a/upb/decode.h b/upb/decode.h
index eeeb61aa1f..ceee70c539 100644
--- a/upb/decode.h
+++ b/upb/decode.h
@@ -54,9 +54,17 @@ static void *decode_malloc(upb_decstate *d, size_t size) {
 
 UPB_INLINE
 upb_msg *decode_newmsg(upb_decstate *d, const upb_msglayout *l) {
+  const size_t cutoff = 192;
   size_t size = l->size + sizeof(upb_msg_internal);
-  char *msg_data = (char*)decode_malloc(d, size);
-  memset(msg_data, 0, size);
+  char *msg_data;
+  if (size <= cutoff && (size_t)(d->arena_end - d->arena_ptr) >= cutoff) {
+    msg_data = d->arena_ptr;
+    memset(msg_data, 0, cutoff);
+    d->arena_ptr += size;
+  } else {
+    msg_data = (char*)decode_malloc(d, size);
+    memset(msg_data, 0, size);
+  }
   return msg_data + sizeof(upb_msg_internal);
 }
 
diff --git a/upb/decode_fast.c b/upb/decode_fast.c
index 7156b75fb8..2a7e73ba98 100644
--- a/upb/decode_fast.c
+++ b/upb/decode_fast.c
@@ -9,6 +9,10 @@
 
 #define UPB_PARSE_ARGS d, ptr, msg, table, hasbits, data
 
+#define RETURN_GENERIC(msg)  \
+  /* fprintf(stderr, msg); */ \
+  return fastdecode_generic(UPB_PARSE_ARGS);
+
 typedef enum {
   CARD_s = 0,
   CARD_o = 1,
@@ -24,10 +28,10 @@ const char *fastdecode_dispatch(upb_decstate *d, const char *ptr, upb_msg *msg,
   size_t idx;
   if (UPB_UNLIKELY(ptr >= d->fastlimit)) {
     if (UPB_LIKELY(ptr == d->limit)) {
+      *(uint32_t*)msg |= hasbits >> 16;  /* Sync hasbits. */
       return ptr;
     }
-    //fprintf(stderr, "dispatch hit end\n");
-    return fastdecode_generic(UPB_PARSE_ARGS);
+    RETURN_GENERIC("dispatch hit end\n");
   }
   memcpy(&tag, ptr, 2);
   idx = (tag & 0xf8) >> 3;
@@ -166,8 +170,7 @@ static const char *fastdecode_varint(UPB_PARSE_PARAMS, int tagbytes,
   uint64_t val = 0;
   void *dst;
   if (UPB_UNLIKELY(!fastdecode_checktag(data, tagbytes))) {
-    //fprintf(stderr, "varint field tag mismatch\n");
-    return fastdecode_generic(UPB_PARSE_ARGS);;
+    RETURN_GENERIC("varint field tag mismatch\n");
   }
   dst = fastdecode_getfield(d, ptr, msg, &data, &hasbits, tagbytes, valbytes,
                             card);
@@ -176,8 +179,7 @@ static const char *fastdecode_varint(UPB_PARSE_PARAMS, int tagbytes,
     uint32_t byte = (uint8_t)ptr[tagbytes + 1];
     val += (byte - 1) << 7;
     if (UPB_UNLIKELY(byte & 0x80)) {
-      //fprintf(stderr, "varint field >2 bytes\n");
-      return fastdecode_generic(UPB_PARSE_ARGS);
+      RETURN_GENERIC("varint field >2 bytes\n");
     }
     ptr++;
   }
@@ -241,16 +243,14 @@ static const char *fastdecode_string(UPB_PARSE_PARAMS, int tagbytes,
   upb_strview *dst;
   int64_t len;
   if (UPB_UNLIKELY(!fastdecode_checktag(data, tagbytes))) {
-    //fprintf(stderr, "string field tag mismatch\n");
-    return fastdecode_generic(UPB_PARSE_ARGS);
+    RETURN_GENERIC("string field tag mismatch\n");
   }
 
   dst = fastdecode_getfield(d, ptr, msg, &data, &hasbits, tagbytes,
                             sizeof(upb_strview), card);
   len = ptr[tagbytes];
   if (UPB_UNLIKELY(len < 0)) {
-    //fprintf(stderr, "string field len >1 byte\n");
-    return fastdecode_generic(UPB_PARSE_ARGS);
+    RETURN_GENERIC("string field len >1 byte\n");
   }
   ptr += tagbytes + 1;
   dst->data = ptr;
@@ -292,8 +292,7 @@ static const char *fastdecode_submsg(UPB_PARSE_PARAMS, int tagbytes,
   void *end;
 
   if (UPB_UNLIKELY(!fastdecode_checktag(data, tagbytes))) {
-    //fprintf(stderr, "submessage field tag mismatch\n");
-    return fastdecode_generic(UPB_PARSE_ARGS);
+    RETURN_GENERIC("submessage field tag mismatch\n");
   }
 
   submsg = fastdecode_getfield_ofs(d, ptr, msg, ofs, &data, &hasbits, &arr,
@@ -302,8 +301,7 @@ static const char *fastdecode_submsg(UPB_PARSE_PARAMS, int tagbytes,
 again:
   if (card == CARD_r) {
     if (UPB_UNLIKELY(submsg == end)) {
-      //fprintf(stderr, "need array realloc\n");
-      return fastdecode_generic(UPB_PARSE_ARGS);
+      RETURN_GENERIC("need array realloc\n");
     }
   }
 
@@ -313,8 +311,7 @@ again:
       uint32_t byte = (uint8_t)ptr[tagbytes + 1];
       len += (byte - 1) << 7;
       if (UPB_UNLIKELY(byte & 0x80)) {
-        //fprintf(stderr, "submessage field len >2 bytes\n");
-        return fastdecode_generic(UPB_PARSE_ARGS);
+        RETURN_GENERIC("submessage field len >2 bytes\n");
       }
       ptr++;
     }
diff --git a/upbc/generator.cc b/upbc/generator.cc
index d5a02f7f0e..0ea76163be 100644
--- a/upbc/generator.cc
+++ b/upbc/generator.cc
@@ -733,7 +733,7 @@ void TryFillTableEntry(const protobuf::Descriptor* message,
       type = "z8";
       break;
     case protobuf::FieldDescriptor::TYPE_STRING:
-    case protobuf::FieldDescriptor::TYPE_BYTES:
+    //case protobuf::FieldDescriptor::TYPE_BYTES:
       type = "s";
       wire_type = 2;
       break;