dump: ensure Array eltype layout is initialized early (#37594)

Deserializing an array needs to examine the element type (tparam0)
layout. Usually we know the layout of a DataType is initialized early
(when present). This also ensures that the path to it is initialized
(for our case where it may be inline allocated with interior pointers).

src/datatype.c

@@ -97,6 +97,9 @@ jl_datatype_t *jl_new_uninitialized_datatype(void)
  t->isinlinealloc = 0;
  t->has_concrete_subtype = 1;
  t->cached_by_hash = 0;
+ t->name = NULL;
+ t->super = NULL;
+ t->parameters = NULL;
  t->layout = NULL;
  t->names = NULL;
  t->types = NULL;

src/dump.c

@@ -1139,6 +1139,7 @@ static jl_value_t *jl_deserialize_value(jl_serializer_state *s, jl_value_t **loc
 
 static jl_value_t *jl_deserialize_datatype(jl_serializer_state *s, int pos, jl_value_t **loc) JL_GC_DISABLED
 {
+ assert(pos == backref_list.len - 1 && "nothing should have been deserialized since assigning pos");
  int tag = read_uint8(s->s);
  if (tag == 6 || tag == 7) {
  jl_typename_t *name = (jl_typename_t*)jl_deserialize_value(s, NULL);
@@ -1154,18 +1155,17 @@ static jl_value_t *jl_deserialize_datatype(jl_serializer_state *s, int pos, jl_v
  backref_list.items[pos] = dtv;
  return dtv;
  }
- size_t size = read_int32(s->s);
- uint8_t flags = read_uint8(s->s);
- uint8_t memflags = read_uint8(s->s);
- jl_datatype_t *dt = NULL;
- if (tag == 0 || tag == 5 || tag == 10 || tag == 11 || tag == 12)
- dt = jl_new_uninitialized_datatype();
- else {
+ if (!(tag == 0 || tag == 5 || tag == 10 || tag == 11 || tag == 12)) {
  assert(0 && "corrupt deserialization state");
  abort();
  }
- assert(pos == backref_list.len - 1 && "nothing should have been deserialized since assigning pos");
+ jl_datatype_t *dt = jl_new_uninitialized_datatype();
  backref_list.items[pos] = dt;
+ if (loc != NULL && loc != HT_NOTFOUND)
+ *loc = (jl_value_t*)dt;
+ size_t size = read_int32(s->s);
+ uint8_t flags = read_uint8(s->s);
+ uint8_t memflags = read_uint8(s->s);
  dt->size = size;
  dt->abstract = flags & 1;
  dt->mutabl = (flags >> 1) & 1;
@@ -1179,11 +1179,6 @@ static jl_value_t *jl_deserialize_datatype(jl_serializer_state *s, int pos, jl_v
  dt->isinlinealloc = (memflags >> 5) & 1;
  dt->has_concrete_subtype = (memflags >> 6) & 1;
  dt->cached_by_hash = (memflags >> 7) & 1;
- dt->types = NULL;
- dt->parameters = NULL;
- dt->name = NULL;
- dt->super = NULL;
- dt->layout = NULL;
  if (!dt->abstract)
  dt->ninitialized = read_uint16(s->s);
  else
@@ -1247,14 +1242,16 @@ static jl_value_t *jl_deserialize_datatype(jl_serializer_state *s, int pos, jl_v
  return (jl_value_t*)dt;
 }
 
-static jl_value_t *jl_deserialize_value_svec(jl_serializer_state *s, uint8_t tag) JL_GC_DISABLED
+static jl_value_t *jl_deserialize_value_svec(jl_serializer_state *s, uint8_t tag, jl_value_t **loc) JL_GC_DISABLED
 {
  size_t i, len;
  if (tag == TAG_SVEC)
  len = read_uint8(s->s);
  else
  len = read_int32(s->s);
- jl_svec_t *sv = jl_alloc_svec_uninit(len);
+ jl_svec_t *sv = jl_alloc_svec(len);
+ if (loc != NULL)
+ *loc = (jl_value_t*)sv;
  arraylist_push(&backref_list, (jl_value_t*)sv);
  jl_value_t **data = jl_svec_data(sv);
  for (i = 0; i < len; i++) {
@@ -1689,7 +1686,7 @@ static jl_value_t *jl_deserialize_value(jl_serializer_state *s, jl_value_t **loc
  }
  return (jl_value_t*)bp;
  case TAG_SVEC: JL_FALLTHROUGH; case TAG_LONG_SVEC:
- return jl_deserialize_value_svec(s, tag);
+ return jl_deserialize_value_svec(s, tag, loc);
  case TAG_COMMONSYM:
  return deser_symbols[read_uint8(s->s)];
  case TAG_SYMBOL: JL_FALLTHROUGH; case TAG_LONG_SYMBOL: