Annotate Kernel#nil?

Author: st0012

test/ruby/test_zjit.rb

@@ -844,7 +844,6 @@ def test_nil_nil
     assert_compiles 'true', %q{
       def test = nil.nil?
       test
-      test
     }
   end
 
@@ -855,6 +854,22 @@ def test
         1
       end
       test
+    }
+  end
+
+  def test_non_nil_nil
+    assert_compiles 'false', %q{
+      def test = 1.nil?
+      test
+    }
+  end
+
+  def test_obsolete_non_nil_nil
+    assert_compiles '2', %q{
+      def test
+        1.nil?
+        2
+      end
       test
     }
   end

zjit/src/cruby_methods.rs

@@ -81,6 +81,7 @@ pub fn init() -> Annotations {
     annotate!(rb_cArray, "length", types::Fixnum, no_gc, leaf, elidable);
     annotate!(rb_cArray, "size", types::Fixnum, no_gc, leaf, elidable);
     annotate!(rb_cNilClass, "nil?", types::TrueClassExact, no_gc, leaf, elidable);
+    annotate!(rb_mKernel, "nil?", types::FalseClassExact, no_gc, leaf, elidable);
 
     Annotations {
         cfuncs: std::mem::take(cfuncs)

zjit/src/hir.rs

@@ -6344,18 +6344,34 @@ mod opt_tests {
     }
 
     #[test]
-    fn test_object_nil_specialized_to_send() {
+    fn test_non_nil_nil_specialized_to_ccall() {
         eval("
-            def test = Object.new.nil?
+            def test = 1.nil?
         ");
         assert_optimized_method_hir("test", expect![[r#"
             fn test:
             bb0(v0:BasicObject):
-              v3:BasicObject = GetConstantPath 0x1000
-              v4:NilClassExact = Const Value(nil)
-              v11:BasicObject = SendWithoutBlock v3, :new
-              v18:BasicObject = SendWithoutBlock v11, :nil?
-              Return v18
+              v2:Fixnum[1] = Const Value(1)
+              PatchPoint MethodRedefined(Integer@0x1000, nil?@0x1008)
+              v7:FalseClassExact = CCall nil?@0x1010, v2
+              Return v7
+        "#]]);
+    }
+
+    #[test]
+    fn test_eliminate_non_nil_nil_specialized_to_ccall() {
+        eval("
+            def test
+              1.nil?
+              2
+            end
+        ");
+        assert_optimized_method_hir("test", expect![[r#"
+            fn test:
+            bb0(v0:BasicObject):
+              PatchPoint MethodRedefined(Integer@0x1000, nil?@0x1008)
+              v5:Fixnum[2] = Const Value(2)
+              Return v5
         "#]]);
     }
 }