Properly cache decoder methods, instead of regenerating every time.

This doesn't fully share bytecode.  If you generate for message A
which has B as a sub-message, then generate B, B's code will be
generated twice.  This could be optimized later if desired.  But
this addresses the leak in PHP.

Also removed some obsolete JIT-only code.

upb/pb/compile_decoder.c

@@ -822,12 +822,10 @@ static void set_bytecode_handlers(mgroup *g) {
 
 /* TODO(haberman): allow this to be constructed for an arbitrary set of dest
  * handlers and other mgroups (but verify we have a transitive closure). */
-const mgroup *mgroup_new(const upb_handlers *dest, bool allowjit, bool lazy) {
+const mgroup *mgroup_new(const upb_handlers *dest, bool lazy) {
   mgroup *g;
   compiler *c;
 
-  UPB_UNUSED(allowjit);
-
   g = newgroup();
   c = newcompiler(g, lazy);
   find_methods(c, dest);
@@ -872,7 +870,6 @@ upb_pbcodecache *upb_pbcodecache_new(upb_handlercache *dest) {
   if (!c) return NULL;
 
   c->dest = dest;
-  c->allow_jit = true;
   c->lazy = false;
 
   c->arena = upb_arena_new();
@@ -882,13 +879,12 @@ upb_pbcodecache *upb_pbcodecache_new(upb_handlercache *dest) {
 }
 
 void upb_pbcodecache_free(upb_pbcodecache *c) {
-  size_t i;
+  upb_inttable_iter i;
 
-  for (i = 0; i < upb_inttable_count(&c->groups); i++) {
-    upb_value v;
-    bool ok = upb_inttable_lookup(&c->groups, i, &v);
-    UPB_ASSERT(ok);
-    freegroup((void*)upb_value_getconstptr(v));
+  upb_inttable_begin(&i, &c->groups);
+  for(; !upb_inttable_done(&i); upb_inttable_next(&i)) {
+    upb_value val = upb_inttable_iter_value(&i);
+    freegroup((void*)upb_value_getconstptr(val));
   }
 
   upb_inttable_uninit(&c->groups);
@@ -896,15 +892,6 @@ void upb_pbcodecache_free(upb_pbcodecache *c) {
   upb_gfree(c);
 }
 
-bool upb_pbcodecache_allowjit(const upb_pbcodecache *c) {
-  return c->allow_jit;
-}
-
-void upb_pbcodecache_setallowjit(upb_pbcodecache *c, bool allow) {
-  UPB_ASSERT(upb_inttable_count(&c->groups) == 0);
-  c->allow_jit = allow;
-}
-
 void upb_pbdecodermethodopts_setlazy(upb_pbcodecache *c, bool lazy) {
   UPB_ASSERT(upb_inttable_count(&c->groups) == 0);
   c->lazy = lazy;
@@ -917,11 +904,13 @@ const upb_pbdecodermethod *upb_pbcodecache_get(upb_pbcodecache *c,
   const upb_handlers *h;
   const mgroup *g;
 
-  /* Right now we build a new DecoderMethod every time.
-   * TODO(haberman): properly cache methods by their true key. */
   h = upb_handlercache_get(c->dest, md);
-  g = mgroup_new(h, c->allow_jit, c->lazy);
+  if (upb_inttable_lookupptr(&c->groups, md, &v)) {
+    g = upb_value_getconstptr(v);
+  } else {
+    g = mgroup_new(h, c->lazy);
     upb_inttable_push(&c->groups, upb_value_constptr(g));
+  }
 
   ok = upb_inttable_lookupptr(&g->methods, h, &v);
   UPB_ASSERT(ok);

upb/pb/decoder.c

@@ -77,16 +77,6 @@ static size_t stacksize(upb_pbdecoder *d, size_t entries) {
 static size_t callstacksize(upb_pbdecoder *d, size_t entries) {
   UPB_UNUSED(d);
 
-#ifdef UPB_USE_JIT_X64
-  if (d->method_->is_native_) {
-    /* Each native stack frame needs two pointers, plus we need a few frames for
-     * the enter/exit trampolines. */
-    size_t ret = entries * sizeof(void*) * 2;
-    ret += sizeof(void*) * 10;
-    return ret;
-  }
-#endif
-
   return entries * sizeof(uint32_t*);
 }
 
@@ -902,17 +892,6 @@ void *upb_pbdecoder_startbc(void *closure, const void *pc, size_t size_hint) {
   return d;
 }
 
-void *upb_pbdecoder_startjit(void *closure, const void *hd, size_t size_hint) {
-  upb_pbdecoder *d = closure;
-  UPB_UNUSED(hd);
-  UPB_UNUSED(size_hint);
-  d->top->end_ofs = UINT64_MAX;
-  d->bufstart_ofs = 0;
-  d->call_len = 0;
-  d->skip = 0;
-  return d;
-}
-
 bool upb_pbdecoder_end(void *closure, const void *handler_data) {
   upb_pbdecoder *d = closure;
   const upb_pbdecodermethod *method = handler_data;
@@ -938,14 +917,6 @@ bool upb_pbdecoder_end(void *closure, const void *handler_data) {
   end = offset(d);
   d->top->end_ofs = end;
 
-#ifdef UPB_USE_JIT_X64
-  if (method->is_native_) {
-    const mgroup *group = (const mgroup*)method->group;
-    if (d->top != d->stack)
-      d->stack->end_ofs = 0;
-    group->jit_code(closure, method->code_base.ptr, &dummy, 0, NULL);
-  } else
-#endif
   {
     const uint32_t *p = d->pc;
     d->stack->end_ofs = end;

upb/pb/decoder.int.h

@@ -80,7 +80,7 @@ struct upb_pbcodecache {
   bool allow_jit;
   bool lazy;
 
-  /* Array of mgroups. */
+  /* Map of upb_msgdef -> mgroup. */
   upb_inttable groups;
 };
 
@@ -96,15 +96,6 @@ typedef struct {
   /* The bytecode for our methods, if any exists.  Owned by us. */
   uint32_t *bytecode;
   uint32_t *bytecode_end;
-
-#ifdef UPB_USE_JIT_X64
-  /* JIT-generated machine code, if any. */
-  upb_string_handlerfunc *jit_code;
-  /* The size of the jit_code (required to munmap()). */
-  size_t jit_size;
-  char *debug_info;
-  void *dl;
-#endif
 } mgroup;
 
 /* The maximum that any submessages can be nested.  Matches proto2's limit.
@@ -215,19 +206,10 @@ struct upb_pbdecoder {
   size_t stack_size;
 
   upb_status *status;
-
-#ifdef UPB_USE_JIT_X64
-  /* Used momentarily by the generated code to store a value while a user
-   * function is called. */
-  uint32_t tmp_len;
-
-  const void *saved_rsp;
-#endif
 };
 
 /* Decoder entry points; used as handlers. */
 void *upb_pbdecoder_startbc(void *closure, const void *pc, size_t size_hint);
-void *upb_pbdecoder_startjit(void *closure, const void *hd, size_t size_hint);
 size_t upb_pbdecoder_decode(void *closure, const void *hd, const char *buf,
                             size_t size, const upb_bufhandle *handle);
 bool upb_pbdecoder_end(void *closure, const void *handler_data);
@@ -251,10 +233,6 @@ extern const char *kPbDecoderSubmessageTooLong;
 /* Access to decoderplan members needed by the decoder. */
 const char *upb_pbdecoder_getopname(unsigned int op);
 
-/* JIT codegen entry point. */
-void upb_pbdecoder_jit(mgroup *group);
-void upb_pbdecoder_freejit(mgroup *group);
-
 /* A special label that means "do field dispatch for this message and branch to
  * wherever that takes you." */
 #define LABEL_DISPATCH 0