Sync from internal Google development.

Many improvements, too many to mention.  One significant
perf regression warrants investigation:

omitfp.parsetoproto2_googlemessage1.upb_jit: 343 -> 252 (-26.53)
plain.parsetoproto2_googlemessage1.upb_jit: 334 -> 251 (-24.85)

25% regression for this benchmark is bad, but since I don't think
there's any fundamental design issue that caused it I'm going to
go ahead with the commit anyway.  Can investigate and fix later.

Other benchmarks were neutral or showed slight improvement.

4 files changed, 34 insertions, 372 deletions

diff --git a/benchmarks/google_messages.proto b/benchmarks/google_messages.proto
index b43e94b..b367954 100644
--- a/benchmarks/google_messages.proto
+++ b/benchmarks/google_messages.proto
@@ -3,6 +3,11 @@ package benchmarks;
 
 option optimize_for = SPEED;
 
+enum Foo {
+  FOO_VALUE = 1;
+  FOO_VALUE2 = 2;
+}
+
 message SpeedMessage1 {
   required string field1 = 1;
   optional string field9 = 9;
@@ -45,6 +50,7 @@ message SpeedMessage1 {
   optional int32 field128 = 128 [default=0];
   optional string field129 = 129 [default="xxxxxxxxxxxxxxxxxxxxx"];
   optional int32 field131 = 131 [default=0];
+  optional Foo field132 = 132 [default=FOO_VALUE];
 }
 
 message SpeedMessage1SubMessage {
diff --git a/benchmarks/parsestream.upb.c b/benchmarks/parsestream.upb.c
index 0316a86..e9164d0 100644
--- a/benchmarks/parsestream.upb.c
+++ b/benchmarks/parsestream.upb.c
@@ -39,7 +39,7 @@ static bool initialize()
     return false;
   }
 
-  def = upb_dyncast_msgdef_const(upb_symtab_lookup(s, MESSAGE_NAME));
+  def = upb_dyncast_msgdef_const(upb_symtab_lookup(s, MESSAGE_NAME, &def));
   if(!def) {
     fprintf(stderr, "Error finding symbol '%s'.\n", MESSAGE_NAME);
     return false;
@@ -68,7 +68,7 @@ static bool initialize()
 static void cleanup()
 {
   free(input_str);
-  upb_def_unref(UPB_UPCAST(def));
+  upb_def_unref(UPB_UPCAST(def), &def);
   upb_decoder_uninit(&decoder);
   upb_decoderplan_unref(plan);
   upb_stringsrc_uninit(&stringsrc);
diff --git a/benchmarks/parsetoproto2.upb.cc b/benchmarks/parsetoproto2.upb.cc
index 988faad..5023b0e 100644
--- a/benchmarks/parsetoproto2.upb.cc
+++ b/benchmarks/parsetoproto2.upb.cc
@@ -1,320 +1,61 @@
-// This file is a crime against software engineering.  It breaks the
-// encapsulation of proto2 in numerous ways, violates the C++ standard
-// in others, and generally deserves to have comtempt and scorn heaped
-// upon it.
-//
-// Its purpose is to get an accurate benchmark for how fast upb can
-// parse into proto2 data structures.  To add proper support for this
-// functionality, proto2 would need to expose actual support for the
-// operations we are trying to perform here.
+// Tests speed of upb parsing into proto2 generated classes.
 
 #define __STDC_LIMIT_MACROS 1
 #include "main.c"
 
 #include <stdint.h>
-#include "upb/bytestream.h"
-#include "upb/def.h"
-#include "upb/msg.h"
-#include "upb/pb/decoder.h"
+#include "upb/bytestream.hpp"
+#include "upb/def.hpp"
+#include "upb/msg.hpp"
+#include "upb/pb/decoder.hpp"
 #include "upb/pb/glue.h"
-
-// Need to violate the encapsulation of GeneratedMessageReflection -- see below.
-#define private public
+#include "upb/proto2_bridge.hpp"
 #include MESSAGE_HFILE
-#include <google/protobuf/descriptor.h>
-#undef private
 
-static size_t len;
+const char *str;
+size_t len;
 MESSAGE_CIDENT msg[NUM_MESSAGES];
 MESSAGE_CIDENT msg2;
-static upb_stringsrc strsrc;
-static upb_decoder d;
-static const upb_msgdef *def;
-static upb_decoderplan *p;
-char *str;
-
-#define PROTO2_APPEND(type, ctype) \
-  upb_flow_t proto2_append_ ## type(void *_r, upb_value fval, upb_value val) { \
-    (void)fval; \
-    typedef google::protobuf::RepeatedField<ctype> R; \
-    R *r = (R*)_r; \
-    r->Add(upb_value_get ## type(val)); \
-    return UPB_CONTINUE; \
-  }
-
-PROTO2_APPEND(double, double)
-PROTO2_APPEND(float, float)
-PROTO2_APPEND(uint64, uint64_t)
-PROTO2_APPEND(int64, int64_t)
-PROTO2_APPEND(int32, int32_t)
-PROTO2_APPEND(uint32, uint32_t)
-PROTO2_APPEND(bool, bool)
-
-upb_flow_t proto2_setstr(void *m, upb_value fval, upb_value val) {
-  assert(m != NULL);
-  const upb_fielddef *f = upb_value_getfielddef(fval);
-  std::string **str = (std::string**)UPB_INDEX(m, f->offset, 1);
-  if (*str == f->default_ptr) *str = new std::string;
-  const upb_byteregion *reg = upb_value_getbyteregion(val);
-  size_t len;
-  (*str)->assign(
-      upb_byteregion_getptr(reg, upb_byteregion_startofs(reg), &len),
-      upb_byteregion_len(reg));
-  // XXX: only supports contiguous strings atm.
-  assert(len == upb_byteregion_len(reg));
-  return UPB_CONTINUE;
-}
-
-upb_flow_t proto2_append_str(void *_r, upb_value fval, upb_value val) {
-  assert(_r != NULL);
-  typedef google::protobuf::RepeatedPtrField<std::string> R;
-  (void)fval;
-  R *r = (R*)_r;
-  const upb_byteregion *reg = upb_value_getbyteregion(val);
-  size_t len;
-  r->Add()->assign(
-      upb_byteregion_getptr(reg, upb_byteregion_startofs(reg), &len),
-      upb_byteregion_len(reg));
-  // XXX: only supports contiguous strings atm.
-  assert(len == upb_byteregion_len(reg));
-  return UPB_CONTINUE;
-}
-
-upb_sflow_t proto2_startseq(void *m, upb_value fval) {
-  assert(m != NULL);
-  const upb_fielddef *f = upb_value_getfielddef(fval);
-  return UPB_CONTINUE_WITH(UPB_INDEX(m, f->offset, 1));
-}
-
-upb_sflow_t proto2_startsubmsg(void *m, upb_value fval) {
-  assert(m != NULL);
-  const upb_fielddef *f = upb_value_getfielddef(fval);
-  google::protobuf::Message *prototype = (google::protobuf::Message*)f->prototype;
-  void **subm = (void**)UPB_INDEX(m, f->offset, 1);
-  if (*subm == NULL || *subm == f->default_ptr)
-    *subm = prototype->New();
-  assert(*subm != NULL);
-  return UPB_CONTINUE_WITH(*subm);
-}
-
-class UpbRepeatedPtrField : public google::protobuf::internal::RepeatedPtrFieldBase {
- public:
-  class TypeHandler {
-   public:
-    typedef void Type;
-    // AddAllocated() calls this, but only if other objects are sitting
-    // around waiting for reuse, which we will not do.
-    static void Delete(Type*) { assert(false); }
-  };
-  void *Add(google::protobuf::Message *m) {
-    void *submsg = RepeatedPtrFieldBase::AddFromCleared<TypeHandler>();
-    if (!submsg) {
-      submsg = m->New();
-      RepeatedPtrFieldBase::AddAllocated<TypeHandler>(submsg);
-    }
-    return submsg;
-  }
-};
-
-upb_sflow_t proto2_startsubmsg_r(void *_r, upb_value fval) {
-  assert(_r != NULL);
-  // Compared to the other writers, this implementation is particularly sketchy.
-  // The object we are modifying is a RepeatedPtrField<SubType>*, but we can't
-  // properly declare that templated pointer because we don't have access to
-  // that type at compile-time (and wouldn't want to create a separate callback
-  // for each type anyway).  Instead we access the pointer as a
-  // RepeatedPtrFieldBase, which is indeed a superclass of RepeatedPtrField.
-  // But we can't properly declare a TypeHandler for the submessage's type,
-  // for the same reason that we can't create a RepeatedPtrField<SubType>*.
-  // Instead we treat it as a void*, and create the submessage using
-  // google::protobuf::Message::New() if we need to.
-  class TypeHandler {
-   public:
-    typedef void Type;
-  };
-  const upb_fielddef *f = upb_value_getfielddef(fval);
-  UpbRepeatedPtrField *r = (UpbRepeatedPtrField*)_r;
-  void *submsg = r->Add((google::protobuf::Message*)f->prototype);
-  assert(submsg != NULL);
-  return UPB_CONTINUE_WITH(submsg);
-}
-
-#define PROTO2MSG(type, size) { static upb_accessor_vtbl vtbl = { \
-    &proto2_startsubmsg, \
-    &upb_stdmsg_set ## type, \
-    &proto2_startseq, \
-    &proto2_startsubmsg_r, \
-    &proto2_append_ ## type, \
-    NULL, NULL, NULL, NULL, NULL, NULL}; \
-  return &vtbl; }
-
-static upb_accessor_vtbl *proto2_accessor(upb_fielddef *f) {
-  switch (f->type) {
-    case UPB_TYPE(DOUBLE): PROTO2MSG(double, 8)
-    case UPB_TYPE(FLOAT): PROTO2MSG(float, 4)
-    case UPB_TYPE(UINT64):
-    case UPB_TYPE(FIXED64): PROTO2MSG(uint64, 8)
-    case UPB_TYPE(INT64):
-    case UPB_TYPE(SFIXED64):
-    case UPB_TYPE(SINT64): PROTO2MSG(int64, 8)
-    case UPB_TYPE(INT32):
-    case UPB_TYPE(SINT32):
-    case UPB_TYPE(ENUM):
-    case UPB_TYPE(SFIXED32): PROTO2MSG(int32, 4)
-    case UPB_TYPE(UINT32):
-    case UPB_TYPE(FIXED32): PROTO2MSG(uint32, 4)
-    case UPB_TYPE(BOOL): PROTO2MSG(bool, 1)
-    case UPB_TYPE(STRING):
-    case UPB_TYPE(BYTES):
-    case UPB_TYPE(GROUP):
-    case UPB_TYPE(MESSAGE): {
-        static upb_accessor_vtbl vtbl = {
-        &proto2_startsubmsg,
-        &proto2_setstr,
-        &proto2_startseq,
-        &proto2_startsubmsg_r,
-        &proto2_append_str,
-        NULL, NULL, NULL, NULL, NULL, NULL};
-        return &vtbl;
-    }
-  }
-  return NULL;
-}
-
-static void layout_msgdef_from_proto2(upb_msgdef *upb_md,
-                                      const google::protobuf::Message *m,
-                                      const google::protobuf::Descriptor *proto2_d) {
-  // Hack: we break the encapsulation of GeneratedMessageReflection to get at
-  // the offsets we need.  If/when we do this for real, we will need
-  // GeneratedMessageReflection to expose those offsets publicly.
-  const google::protobuf::internal::GeneratedMessageReflection *r =
-      (google::protobuf::internal::GeneratedMessageReflection*)m->GetReflection();
-  for (int i = 0; i < proto2_d->field_count(); i++) {
-    const google::protobuf::FieldDescriptor *proto2_f = proto2_d->field(i);
-    upb_fielddef *upb_f = upb_msgdef_itof(upb_md, proto2_f->number());
-    assert(upb_f);
-
-    // Encapsulation violation BEGIN
-    uint32_t data_offset = r->offsets_[proto2_f->index()];
-    uint32_t hasbit = (r->has_bits_offset_ * 8) + proto2_f->index();
-    // Encapsulation violation END
-
-    if (upb_isseq(upb_f)) {
-      // proto2 does not store hasbits for repeated fields.
-      upb_f->hasbit = -1;
-    } else {
-      upb_f->hasbit = hasbit;
-    }
-    upb_f->offset = data_offset;
-    upb_fielddef_setaccessor(upb_f, proto2_accessor(upb_f));
-
-    if (upb_isstring(upb_f) && !upb_isseq(upb_f)) {
-      upb_f->default_ptr = &r->GetStringReference(*m, proto2_f, NULL);
-    } else if (upb_issubmsg(upb_f)) {
-      // XXX: skip leading "."
-      const google::protobuf::Descriptor *subm_descriptor =
-          google::protobuf::DescriptorPool::generated_pool()->
-              FindMessageTypeByName(upb_fielddef_typename(upb_f) + 1);
-      assert(subm_descriptor);
-      upb_f->prototype = google::protobuf::MessageFactory::generated_factory()->GetPrototype(subm_descriptor);
-      if (!upb_isseq(upb_f))
-        upb_f->default_ptr = &r->GetMessage(*m, proto2_f);
-    }
-  }
-}
+upb::StringSource strsrc;
+upb::Decoder d;
+const upb::MessageDef *def;
+upb::DecoderPlan* plan;
 
 static bool initialize()
 {
-  // Initialize upb state, decode descriptor.
-  upb_status status = UPB_STATUS_INIT;
-  upb_symtab *s = upb_symtab_new();
-
-  char *data = upb_readfile(MESSAGE_DESCRIPTOR_FILE, &len);
-  if (!data) {
-    fprintf(stderr, "Couldn't read file: " MESSAGE_DESCRIPTOR_FILE);
-    return false;
-  }
-  int n;
-  upb_def **defs = upb_load_defs_from_descriptor(data, len, &n, &status);
-  free(data);
-  if(!upb_ok(&status)) {
-    fprintf(stderr, "Error reading descriptor: %s\n",
-            upb_status_getstr(&status));
-    return false;
-  }
-
-  // Setup offsets and accessors to properly write into a proto2 generated
-  // class.
-  for (int i = 0; i < n; i++) {
-    upb_def *def = defs[i];
-    upb_msgdef *upb_md = upb_dyncast_msgdef(def);
-    if (!upb_md) continue;
-    const google::protobuf::Descriptor *proto2_md =
-        google::protobuf::DescriptorPool::generated_pool()->
-            FindMessageTypeByName(upb_def_fqname(def));
-    if (!proto2_md) abort();
-    const google::protobuf::Message *proto2_m =
-        google::protobuf::MessageFactory::generated_factory()->GetPrototype(proto2_md);
-    layout_msgdef_from_proto2(upb_md, proto2_m, proto2_md);
-  }
-
-  upb_symtab_add(s, defs, n, &status);
-  if(!upb_ok(&status)) {
-    fprintf(stderr, "Error reading adding to symtab: %s\n",
-            upb_status_getstr(&status));
-    return false;
-  }
-  for(int i = 0; i < n; i++) upb_def_unref(defs[i]);
-  free(defs);
-
-  def = upb_dyncast_msgdef_const(upb_symtab_lookup(s, MESSAGE_NAME));
-  if(!def) {
-    fprintf(stderr, "Error finding symbol '%s'.\n", MESSAGE_NAME);
-    return false;
-  }
-  upb_symtab_unref(s);
-
   // Read the message data itself.
   str = upb_readfile(MESSAGE_FILE, &len);
   if(str == NULL) {
     fprintf(stderr, "Error reading " MESSAGE_FILE "\n");
     return false;
   }
-  upb_status_uninit(&status);
+
+  def = upb::proto2_bridge::NewFinalMessageDef(msg2, &def);
 
   msg2.ParseFromArray(str, len);
 
-  upb_stringsrc_init(&strsrc);
-  upb_handlers *h = upb_handlers_new();
-  upb_accessors_reghandlers(h, def);
-  p = upb_decoderplan_new(h, JIT);
-  upb_decoder_init(&d);
-  upb_decoder_resetplan(&d, p, 0);
-  upb_handlers_unref(h);
+  upb::Handlers* h = upb::Handlers::New();
+  upb::RegisterWriteHandlers(h, def);
+  plan = upb::DecoderPlan::New(h, JIT);
+  d.ResetPlan(plan, 0);
+  h->Unref();
 
   return true;
 }
 
 static void cleanup() {
-  upb_stringsrc_uninit(&strsrc);
-  upb_decoder_uninit(&d);
-  upb_def_unref(UPB_UPCAST(def));
-  upb_decoderplan_unref(p);
-  free(str);
+  def->Unref(&def);
+  plan->Unref();
 }
 
-static size_t run(int i)
-{
-  (void)i;
-  upb_status status = UPB_STATUS_INIT;
+static size_t run(int i) {
   msg[i % NUM_MESSAGES].Clear();
-  upb_stringsrc_reset(&strsrc, str, len);
-  upb_decoder_resetinput(
-      &d, upb_stringsrc_allbytes(&strsrc), &msg[i % NUM_MESSAGES]);
-  if (upb_decoder_decode(&d) != UPB_OK) goto err;
+  strsrc.Reset(str, len);
+  d.ResetInput(strsrc.AllBytes(), &msg[i % NUM_MESSAGES]);
+  if (d.Decode() != UPB_OK) goto err;
   return len;
 
 err:
-  fprintf(stderr, "Decode error: %s", upb_status_getstr(&status));
+  fprintf(stderr, "Decode error: %s", d.status().GetString());
   return 0;
 }
diff --git a/benchmarks/parsetostruct.upb.c b/benchmarks/parsetostruct.upb.c
deleted file mode 100644
index 9487577..0000000
--- a/benchmarks/parsetostruct.upb.c
+++ /dev/null
@@ -1,85 +0,0 @@
-
-#include "main.c"
-
-#include "upb/bytestream.h"
-#include "upb/def.h"
-#include "upb/msg.h"
-#include "upb/pb/decoder.h"
-#include "upb/pb/glue.h"
-
-static const upb_msgdef *def;
-static size_t len;
-static void *msg[NUM_MESSAGES];
-static upb_stringsrc strsrc;
-static upb_decoder d;
-static upb_decoderplan *p;
-char *str;
-
-static bool initialize()
-{
-  // Initialize upb state, decode descriptor.
-  upb_status status = UPB_STATUS_INIT;
-  upb_symtab *s = upb_symtab_new();
-  upb_load_descriptor_file_into_symtab(s, MESSAGE_DESCRIPTOR_FILE, &status);
-  if(!upb_ok(&status)) {
-    fprintf(stderr, "Error reading descriptor: %s\n",
-            upb_status_getstr(&status));
-    return false;
-  }
-
-  def = upb_dyncast_msgdef_const(upb_symtab_lookup(s, MESSAGE_NAME));
-  if(!def) {
-    fprintf(stderr, "Error finding symbol '%s'.\n", MESSAGE_NAME);
-    return false;
-  }
-  upb_symtab_unref(s);
-
-  // Read the message data itself.
-  str = upb_readfile(MESSAGE_FILE, &len);
-  if(str == NULL) {
-    fprintf(stderr, "Error reading " MESSAGE_FILE "\n");
-    return false;
-  }
-  upb_status_uninit(&status);
-  for (int i = 0; i < NUM_MESSAGES; i++)
-    msg[i] = upb_stdmsg_new(def);
-
-  upb_stringsrc_init(&strsrc);
-  upb_handlers *h = upb_handlers_new();
-  upb_accessors_reghandlers(h, def);
-  p = upb_decoderplan_new(h, JIT);
-  upb_decoder_init(&d);
-  upb_handlers_unref(h);
-  upb_decoder_resetplan(&d, p, 0);
-
-  if (!BYREF) {
-    // TODO: use byref/byval accessors.
-  }
-  return true;
-}
-
-static void cleanup()
-{
-  for (int i = 0; i < NUM_MESSAGES; i++)
-    upb_stdmsg_free(msg[i], def);
-  upb_def_unref(UPB_UPCAST(def));
-  upb_stringsrc_uninit(&strsrc);
-  upb_decoder_uninit(&d);
-  upb_decoderplan_unref(p);
-  free(str);
-}
-
-static size_t run(int i)
-{
-  upb_status status = UPB_STATUS_INIT;
-  i %= NUM_MESSAGES;
-  upb_msg_clear(msg[i], def);
-  upb_stringsrc_reset(&strsrc, str, len);
-  upb_decoder_resetinput(&d, upb_stringsrc_allbytes(&strsrc), msg[i]);
-  if (upb_decoder_decode(&d) != UPB_OK) goto err;
-  return len;
-
-err:
-  fprintf(stderr, "Decode error: %s", upb_status_getstr(&status));
-  return 0;
-}