ZJIT: Add CallableMethodEntry to type lattice (rubyGH-13459)

This will be useful when we split Send into Lookup+Call.
For reasoning about various method types during optimization.

Author: tekknolagi

zjit/src/cruby.rs

@@ -573,6 +573,11 @@ impl VALUE {
         ptr
     }
 
+    pub fn cme_p(self) -> bool {
+        if self == VALUE(0) { return false; }
+        unsafe { rb_IMEMO_TYPE_P(self, imemo_ment) == 1 }
+    }
+
     /// Assert that `self` is a method entry in debug builds
     pub fn as_cme(self) -> *const rb_callable_method_entry_t {
         let ptr: *const rb_callable_method_entry_t = self.as_ptr();

zjit/src/hir_type/gen_hir_type.rb

@@ -48,6 +48,7 @@ def to_graphviz type
 # Build the Ruby object universe.
 value = any.subtype "RubyValue"
 undef_ = value.subtype "Undef"
+value.subtype "CallableMethodEntry"  # rb_callable_method_entry_t*
 basic_object = value.subtype "BasicObject"
 basic_object_exact = basic_object.subtype "BasicObjectExact"
 basic_object_subclass = basic_object.subtype "BasicObjectSubclass"

zjit/src/hir_type/hir_type.inc.rs

@@ -163,6 +163,11 @@ impl Type {
         else if val == Qnil { types::NilClassExact }
         else if val == Qtrue { types::TrueClassExact }
         else if val == Qfalse { types::FalseClassExact }
+        else if val.cme_p() {
+            // NB: Checking for CME has to happen before looking at class_of because that's not
+            // valid on imemo.
+            Type { bits: bits::CallableMethodEntry, spec: Specialization::Object(val) }
+        }
         else if val.class_of() == unsafe { rb_cInteger } {
             Type { bits: bits::Bignum, spec: Specialization::Object(val) }
         }
@@ -682,6 +687,19 @@ mod tests {
         });
     }
 
+    #[test]
+    fn cme() {
+        use crate::cruby::{rb_callable_method_entry, ID};
+        crate::cruby::with_rubyvm(|| {
+            let cme = unsafe { rb_callable_method_entry(rb_cInteger, ID!(to_s)) };
+            assert!(!cme.is_null());
+            let cme_value: VALUE = cme.into();
+            let ty = Type::from_value(cme_value);
+            assert_subtype(ty, types::CallableMethodEntry);
+            assert!(ty.ruby_object_known());
+        });
+    }
+
     #[test]
     fn union_specialized_with_no_relation_returns_unspecialized() {
         crate::cruby::with_rubyvm(|| {