Make has_concrete_subtype a memoized property

Fixes #31062

Author: Keno

src/datatype.c

@@ -85,6 +85,7 @@ jl_datatype_t *jl_new_uninitialized_datatype(void)
     t->isbitstype = 0;
     t->zeroinit = 0;
     t->isinlinealloc = 0;
+    t->has_concrete_subtype = 1;
     t->layout = NULL;
     t->names = NULL;
     return t;
@@ -309,6 +310,12 @@ void jl_compute_field_offsets(jl_datatype_t *st)
                     st->isbitstype = jl_is_datatype(fld) && ((jl_datatype_t*)fld)->isbitstype;
                 if (!st->zeroinit)
                     st->zeroinit = (jl_is_datatype(fld) && ((jl_datatype_t*)fld)->isinlinealloc) ? ((jl_datatype_t*)fld)->zeroinit : 1;
+                if (i < st->ninitialized) {
+                    if (fld == jl_bottom_type)
+                        st->has_concrete_subtype = 0;
+                    else
+                        st->has_concrete_subtype &= !jl_is_datatype(fld) || ((jl_datatype_t *)fld)->has_concrete_subtype;
+                }
             }
             if (st->isbitstype) {
                 st->isinlinealloc = 1;

src/dump.c

@@ -369,7 +369,8 @@ static void jl_serialize_datatype(jl_serializer_state *s, jl_datatype_t *dt) JL_
             | (dt->isdispatchtuple << 2)
             | (dt->isbitstype << 3)
             | (dt->zeroinit << 4)
-            | (dt->isinlinealloc << 5));
+            | (dt->isinlinealloc << 5)
+            | (dt->has_concrete_subtype << 6));
     if (!dt->abstract) {
         write_uint16(s->s, dt->ninitialized);
     }
@@ -1403,6 +1404,7 @@ static jl_value_t *jl_deserialize_datatype(jl_serializer_state *s, int pos, jl_v
     dt->isbitstype = (memflags >> 3) & 1;
     dt->zeroinit = (memflags >> 4) & 1;
     dt->isinlinealloc = (memflags >> 5) & 1;
+    dt->has_concrete_subtype = (memflags >> 6) & 1;
     dt->types = NULL;
     dt->parameters = NULL;
     dt->name = NULL;

src/gf.c

@@ -2582,19 +2582,7 @@ int jl_has_concrete_subtype(jl_value_t *typ)
         typ = jl_unwrap_vararg(typ);
     if (!jl_is_datatype(typ))
         return 1;
-    if (((jl_datatype_t*)typ)->name == jl_namedtuple_typename)
-        return jl_has_concrete_subtype(jl_tparam1(typ));
-    jl_svec_t *fields = jl_get_fieldtypes((jl_datatype_t*)typ);
-    size_t i, l = jl_svec_len(fields);
-    if (l != ((jl_datatype_t*)typ)->ninitialized)
-        if (((jl_datatype_t*)typ)->name != jl_tuple_typename)
-            return 1;
-    for (i = 0; i < l; i++) {
-        jl_value_t *ft = jl_svecref(fields, i);
-        if (!jl_has_concrete_subtype(ft))
-            return 0;
-    }
-    return 1;
+    return ((jl_datatype_t*)typ)->has_concrete_subtype;
 }
 
 // TODO: separate the codegen and typeinf locks

src/jltypes.c

@@ -1707,7 +1707,7 @@ void jl_init_types(void) JL_GC_DISABLED
     jl_datatype_type->name->wrapper = (jl_value_t*)jl_datatype_type;
     jl_datatype_type->super = (jl_datatype_t*)jl_type_type;
     jl_datatype_type->parameters = jl_emptysvec;
-    jl_datatype_type->name->names = jl_perm_symsvec(20,
+    jl_datatype_type->name->names = jl_perm_symsvec(21,
                                                     "name",
                                                     "super",
                                                     "parameters",
@@ -1726,9 +1726,10 @@ void jl_init_types(void) JL_GC_DISABLED
                                                     "isbitstype",
                                                     "zeroinit",
                                                     "isinlinealloc",
+                                                    "has_concrete_subtype",
                                                     "llvm::StructType",
                                                     "llvm::DIType");
-    jl_datatype_type->types = jl_svec(20,
+    jl_datatype_type->types = jl_svec(21,
                                       jl_typename_type,
                                       jl_datatype_type,
                                       jl_simplevector_type,
@@ -1737,7 +1738,7 @@ void jl_init_types(void) JL_GC_DISABLED
                                       jl_any_type, jl_any_type, jl_any_type, jl_any_type,
                                       jl_any_type, jl_any_type, jl_any_type, jl_any_type,
                                       jl_any_type, jl_any_type, jl_any_type, jl_any_type,
-                                      jl_any_type, jl_any_type);
+                                      jl_any_type, jl_any_type, jl_any_type);
     jl_datatype_type->instance = NULL;
     jl_datatype_type->uid = jl_assign_type_uid();
     jl_datatype_type->struct_decl = NULL;
@@ -2293,8 +2294,9 @@ void jl_init_types(void) JL_GC_DISABLED
     jl_svecset(jl_datatype_type->types, 15, jl_bool_type);
     jl_svecset(jl_datatype_type->types, 16, jl_bool_type);
     jl_svecset(jl_datatype_type->types, 17, jl_bool_type);
-    jl_svecset(jl_datatype_type->types, 18, jl_voidpointer_type);
+    jl_svecset(jl_datatype_type->types, 18, jl_bool_type);
     jl_svecset(jl_datatype_type->types, 19, jl_voidpointer_type);
+    jl_svecset(jl_datatype_type->types, 20, jl_voidpointer_type);
     jl_svecset(jl_typename_type->types, 1, jl_module_type);
     jl_svecset(jl_typename_type->types, 6, jl_long_type);
     jl_svecset(jl_typename_type->types, 3, jl_type_type);

src/julia.h

@@ -442,6 +442,7 @@ typedef struct _jl_datatype_t {
     uint8_t isbitstype; // relevant query for C-api and type-parameters
     uint8_t zeroinit; // if one or more fields requires zero-initialization
     uint8_t isinlinealloc; // if this is allocated inline
+    uint8_t has_concrete_subtype; // If clear, no value will have this datatype
     void *struct_decl;  //llvm::Type*
     void *ditype; // llvm::MDNode* to be used as llvm::DIType(ditype)
 } jl_datatype_t;

test/core.jl

@@ -6976,3 +6976,15 @@ let spvec = sparse_t31649(zeros(Float64,5), Vector{Int64}())
     @test convert(Any, nothing) === nothing
     @test_throws MethodError repr(spvec)
 end
+
+# Issue #31062 - Accidental recursion in jl_has_concrete_subtype
+struct Bar31062
+    x::NTuple{N, Bar31062} where N
+end
+struct Foo31062
+    x::Foo31062
+end
+# Use eval to make sure that this actually gets executed and not
+# just constant folded by (future) over-eager compiler optimizations
+@test isa(Core.eval(@__MODULE__, :(Bar31062(()))), Bar31062)
+@test precompile(identity, (Foo31062,))