simply Union inside UnionAll inside Union during construction (JuliaL…

…ang#49279)

Allows more opporutunities to discover (and eliminate) repeated
components, as well as helping to separate the UnionAll variables into
separate domains for subtyping's separability analysis.

src/jltypes.c

@@ -341,21 +341,6 @@ JL_DLLEXPORT int jl_get_size(jl_value_t *val, size_t *pnt)
 
 // --- type union ---
 
-static int count_union_components(jl_value_t **types, size_t n)
-{
- size_t i, c = 0;
- for (i = 0; i < n; i++) {
- jl_value_t *e = types[i];
- while (jl_is_uniontype(e)) {
- jl_uniontype_t *u = (jl_uniontype_t*)e;
- c += count_union_components(&u->a, 1);
- e = u->b;
- }
- c++;
- }
- return c;
-}
-
 int jl_count_union_components(jl_value_t *v)
 {
  size_t c = 0;
@@ -404,21 +389,6 @@ int jl_find_union_component(jl_value_t *haystack, jl_value_t *needle, unsigned *
  return 0;
 }
 
-static void flatten_type_union(jl_value_t **types, size_t n, jl_value_t **out, size_t *idx) JL_NOTSAFEPOINT
-{
- size_t i;
- for (i = 0; i < n; i++) {
- jl_value_t *e = types[i];
- while (jl_is_uniontype(e)) {
- jl_uniontype_t *u = (jl_uniontype_t*)e;
- flatten_type_union(&u->a, 1, out, idx);
- e = u->b;
- }
- out[*idx] = e;
- (*idx)++;
- }
-}
-
 STATIC_INLINE const char *datatype_module_name(jl_value_t *t) JL_NOTSAFEPOINT
 {
  if (((jl_datatype_t*)t)->name->module == NULL)
@@ -515,6 +485,53 @@ static int union_sort_cmp(jl_value_t *a, jl_value_t *b) JL_NOTSAFEPOINT
  }
 }
 
+static int count_union_components(jl_value_t **types, size_t n)
+{
+ size_t i, c = 0;
+ for (i = 0; i < n; i++) {
+ jl_value_t *e = types[i];
+ while (jl_is_uniontype(e)) {
+ jl_uniontype_t *u = (jl_uniontype_t*)e;
+ c += count_union_components(&u->a, 1);
+ e = u->b;
+ }
+ if (jl_is_unionall(e) && jl_is_uniontype(jl_unwrap_unionall(e))) {
+ jl_uniontype_t *u = (jl_uniontype_t*)jl_unwrap_unionall(e);
+ c += count_union_components(&u->a, 2);
+ }
+ else {
+ c++;
+ }
+ }
+ return c;
+}
+
+static void flatten_type_union(jl_value_t **types, size_t n, jl_value_t **out, size_t *idx)
+{
+ size_t i;
+ for (i = 0; i < n; i++) {
+ jl_value_t *e = types[i];
+ while (jl_is_uniontype(e)) {
+ jl_uniontype_t *u = (jl_uniontype_t*)e;
+ flatten_type_union(&u->a, 1, out, idx);
+ e = u->b;
+ }
+ if (jl_is_unionall(e) && jl_is_uniontype(jl_unwrap_unionall(e))) {
+ // flatten this UnionAll into place by switching the union and unionall
+ jl_uniontype_t *u = (jl_uniontype_t*)jl_unwrap_unionall(e);
+ size_t old_idx = 0;
+ flatten_type_union(&u->a, 2, out, idx);
+ for (; old_idx < *idx; old_idx++)
+ out[old_idx] = jl_rewrap_unionall(out[old_idx], e);
+ }
+ else {
+ out[*idx] = e;
+ (*idx)++;
+ }
+ }
+}
+
+
 static void isort_union(jl_value_t **a, size_t len) JL_NOTSAFEPOINT
 {
  size_t i, j;
@@ -601,28 +618,27 @@ jl_value_t *simple_union(jl_value_t *a, jl_value_t *b)
  temp[j] == (jl_value_t*)jl_any_type ||
  jl_egal(temp[i], temp[j]) ||
  (!has_free && !jl_has_free_typevars(temp[j]) &&
-  // issue #24521: don't merge Type{T} where typeof(T) varies
-  !(jl_is_type_type(temp[i]) && jl_is_type_type(temp[j]) && jl_typeof(jl_tparam0(temp[i])) != jl_typeof(jl_tparam0(temp[j]))) &&
-  jl_subtype(temp[i], temp[j]))) {
+ // issue #24521: don't merge Type{T} where typeof(T) varies
+ !(jl_is_type_type(temp[i]) && jl_is_type_type(temp[j]) && jl_typeof(jl_tparam0(temp[i])) != jl_typeof(jl_tparam0(temp[j]))) &&
+ jl_subtype(temp[i], temp[j]))) {
  temp[i] = NULL;
  }
  }
  }
  }
  isort_union(temp, nt);
- jl_value_t **ptu = &temp[nt];
- *ptu = jl_bottom_type;
- int k;
- for (k = (int)nt-1; k >= 0; --k) {
+ temp[nt] = jl_bottom_type;
+ size_t k;
+ for (k = nt; k-- > 0; ) {
  if (temp[k] != NULL) {
- if (*ptu == jl_bottom_type)
- *ptu = temp[k];
+ if (temp[nt] == jl_bottom_type)
+ temp[nt] = temp[k];
  else
- *ptu = jl_new_struct(jl_uniontype_type, temp[k], *ptu);
+ temp[nt] = jl_new_struct(jl_uniontype_type, temp[k], temp[nt]);
  }
  }
- assert(*ptu != NULL);
- jl_value_t *tu = *ptu;
+ assert(temp[nt] != NULL);
+ jl_value_t *tu = temp[nt];
  JL_GC_POP();
  return tu;
 }