[mono][jit] Optimize constrained calls to object.GetHashCode () where the receiver...

diff --git a/src/mono/mono/mini/method-to-ir.c b/src/mono/mono/mini/method-to-ir.c
index 9e5d8e4..8ea45f6 100644 (file)
--- a/src/mono/mono/mini/method-to-ir.c
+++ b/src/mono/mono/mini/method-to-ir.c
@@ -5680,12 +5680,17 @@ handle_constrained_call (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSignat
        gboolean constrained_is_generic_param =
                m_class_get_byval_arg (constrained_class)->type == MONO_TYPE_VAR ||
                m_class_get_byval_arg (constrained_class)->type == MONO_TYPE_MVAR;
+       MonoType *gshared_constraint = NULL;
 
        if (constrained_is_generic_param && cfg->gshared) {
                if (!mini_is_gsharedvt_klass (constrained_class)) {
                        g_assert (!m_class_is_valuetype (cmethod->klass));
                        if (!mini_type_is_reference (m_class_get_byval_arg (constrained_class)))
                                constrained_partial_call = TRUE;
+
+                       MonoType *t = m_class_get_byval_arg (constrained_class);
+                       MonoGenericParam *gparam = t->data.generic_param;
+                       gshared_constraint = gparam->gshared_constraint;
                }
        }
 
@@ -5727,6 +5732,24 @@ handle_constrained_call (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSignat
                        need_box = FALSE;
                }
 
+               if (gshared_constraint && MONO_TYPE_IS_PRIMITIVE (gshared_constraint) && cmethod->klass == mono_defaults.object_class &&
+                       !strcmp (cmethod->name, "GetHashCode")) {
+                       /*
+                        * The receiver is constrained to a primitive type or an enum with the same basetype.
+                        * Enum.GetHashCode () returns the hash code of the underlying type (see comments in Enum.cs),
+                        * so the constrained call can be replaced with a normal call to the basetype GetHashCode ()
+                        * method.
+                        */
+                       MonoClass *gshared_constraint_class = mono_class_from_mono_type_internal (gshared_constraint);
+                       cmethod = get_method_nofail (gshared_constraint_class, cmethod->name, 0, 0);
+                       g_assert (cmethod);
+                       *ref_cmethod = cmethod;
+                       *ref_virtual = FALSE;
+                       if (cfg->verbose_level)
+                               printf (" -> %s\n", mono_method_get_full_name (cmethod));
+                       return NULL;
+               }
+
                if (!(cmethod->flags & METHOD_ATTRIBUTE_VIRTUAL) && (cmethod->klass == mono_defaults.object_class || cmethod->klass == m_class_get_parent (mono_defaults.enum_class) || cmethod->klass == mono_defaults.enum_class)) {
                        /* The called method is not virtual, i.e. Object:GetType (), the receiver is a vtype, has to box */
                        EMIT_NEW_LOAD_MEMBASE_TYPE (cfg, ins, m_class_get_byval_arg (constrained_class), sp [0]->dreg, 0);