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[mono] Disable partial generic sharing for gparams with non-enum cons…
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…traints. (#59437)

If a generic argument is a primitive type, and it has an interface constraint
that enums don't implement, then partial sharing for that instance is not
useful, since only the specific primitive type instance will be able
to use the shared version.

Fixes #54910.
vargaz authored Nov 14, 2021

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1 parent aa06797 commit edd6467
Showing 1 changed file with 65 additions and 10 deletions.
75 changes: 65 additions & 10 deletions src/mono/mono/mini/mini-generic-sharing.c
Original file line number Diff line number Diff line change
@@ -3324,6 +3324,16 @@ mono_generic_context_is_sharable (MonoGenericContext *context, gboolean allow_ty
return mono_generic_context_is_sharable_full (context, allow_type_vars, partial_sharing_supported ());
}

static gboolean
is_primitive_inst (MonoGenericInst *inst)
{
for (int i = 0; i < inst->type_argc; ++i) {
if (!MONO_TYPE_IS_PRIMITIVE (inst->type_argv [i]))
return FALSE;
}
return TRUE;
}

/*
* mono_method_is_generic_impl:
* @method: a method
@@ -3350,18 +3360,45 @@ mono_method_is_generic_impl (MonoMethod *method)
static gboolean
has_constraints (MonoGenericContainer *container)
{
//int i;
int i;

return FALSE;
/*
g_assert (container->type_argc > 0);
g_assert (container->type_params);

for (i = 0; i < container->type_argc; ++i)
if (container->type_params [i].constraints)
if (container->type_params [i].info.constraints)
return TRUE;
return FALSE;
*/
}

/*
* Return whenever GPARAM can be instantiated with an enum.
*/
static gboolean
gparam_can_be_enum (MonoGenericParam *gparam)
{
if (!gparam->info.constraints)
return TRUE;
/*
* If a constraint is an interface which is not implemented by Enum, then the gparam can't be
* instantiated with an enum.
*/
for (int cindex = 0; gparam->info.constraints [cindex]; cindex ++) {
MonoClass *k = gparam->info.constraints [cindex];
if (MONO_CLASS_IS_INTERFACE_INTERNAL (k)) {
MonoClass **enum_ifaces = m_class_get_interfaces (mono_defaults.enum_class);
gboolean is_enum_iface = FALSE;
for (int i = 0; i < m_class_get_interface_count (mono_defaults.enum_class); i++) {
if (k == enum_ifaces [i]) {
is_enum_iface = TRUE;
break;
}
}
if (!is_enum_iface)
return FALSE;
}
}
return TRUE;
}

static gboolean
@@ -3488,21 +3525,39 @@ mono_method_is_generic_sharable_full (MonoMethod *method, gboolean allow_type_va

g_assert (inflated->declaring);

#if FALSE
if (inflated->declaring->is_generic) {
if (has_constraints (mono_method_get_generic_container (inflated->declaring)))
return FALSE;
if (has_constraints (mono_method_get_generic_container (inflated->declaring))) {
}
}
#endif
}

if (mono_class_is_ginst (method->klass)) {
if (!mono_generic_context_is_sharable_full (&mono_class_get_generic_class (method->klass)->context, allow_type_vars, allow_partial))
MonoGenericContext *ctx = &mono_class_get_generic_class (method->klass)->context;
if (!mono_generic_context_is_sharable_full (ctx, allow_type_vars, allow_partial))
return FALSE;

g_assert (mono_class_get_generic_class (method->klass)->container_class &&
mono_class_is_gtd (mono_class_get_generic_class (method->klass)->container_class));

if (has_constraints (mono_class_get_generic_container (mono_class_get_generic_class (method->klass)->container_class)))
return FALSE;
/*
* If all the parameters are primitive types and constraints prevent
* them from being instantiated with enums, then only the primitive
* type instantiation is possible, thus sharing is not useful.
* Happens with generic math interfaces.
*/
if ((!ctx->class_inst || is_primitive_inst (ctx->class_inst)) &&
(!ctx->method_inst || is_primitive_inst (ctx->method_inst))) {
MonoGenericContainer *container = mono_class_get_generic_container (mono_class_get_generic_class (method->klass)->container_class);
if (has_constraints (container)) {
g_assert (ctx->class_inst->type_argc == container->type_argc);
for (int i = 0; i < container->type_argc; ++i) {
if (!gparam_can_be_enum (&container->type_params [i]))
return FALSE;
}
}
}
}

if (mono_class_is_gtd (method->klass) && !allow_type_vars)

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