Make Integer#zero? a separated method and builtin (#3226)

A prerequisite to fix https://bugs.ruby-lang.org/issues/15589 with JIT.
This commit alone doesn't make a significant difference yet, but I thought
this commit should be committed independently.

This method override was discussed in [Misc #16961].

8 files changed, 44 insertions, 8 deletions

diff --git a/.document b/.document
index b18ca80971..0e0969a6d3 100644
--- a/.document
+++ b/.document
@@ -14,6 +14,7 @@ array.rb
 ast.rb
 dir.rb
 gc.rb
+integer.rb
 io.rb
 kernel.rb
 pack.rb
diff --git a/NEWS.md b/NEWS.md
index c69321d507..ac6c6de58b 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -214,6 +214,8 @@ Excluding feature bug fixes.
 
     * The issues of sdbm will handle at https://github.com/ruby/sdbm
 
+* `Integer#zero?` overrides `Numeric#zero?` for optimization.
+
 ## Stdlib compatibility issues
 
 Excluding feature bug fixes.
diff --git a/benchmark/num_zero_p.yml b/benchmark/num_zero_p.yml
new file mode 100644
index 0000000000..2195963433
--- /dev/null
+++ b/benchmark/num_zero_p.yml
@@ -0,0 +1,8 @@
+benchmark:
+  - 0.zero?
+  - 1.zero?
+  - 0r.zero?
+  - 1r.zero?
+  - 0i.zero?
+  - 1i.zero?
+loop_count: 50000000
diff --git a/common.mk b/common.mk
index 3a54b0e9e9..7f4e026b3f 100644
--- a/common.mk
+++ b/common.mk
@@ -1008,6 +1008,7 @@ $(srcs_vpath)mjit_compile.inc: $(tooldir)/ruby_vm/views/mjit_compile.inc.erb $(i
 BUILTIN_RB_SRCS = \
 		$(srcdir)/ast.rb \
 		$(srcdir)/gc.rb \
+		$(srcdir)/integer.rb \
 		$(srcdir)/io.rb \
 		$(srcdir)/dir.rb \
 		$(srcdir)/pack.rb \
@@ -8087,6 +8088,7 @@ miniinit.$(OBJEXT): {$(VPATH)}encoding.h
 miniinit.$(OBJEXT): {$(VPATH)}gc.rb
 miniinit.$(OBJEXT): {$(VPATH)}gem_prelude.rb
 miniinit.$(OBJEXT): {$(VPATH)}id.h
+miniinit.$(OBJEXT): {$(VPATH)}integer.rb
 miniinit.$(OBJEXT): {$(VPATH)}intern.h
 miniinit.$(OBJEXT): {$(VPATH)}internal.h
 miniinit.$(OBJEXT): {$(VPATH)}internal/anyargs.h
@@ -8921,12 +8923,15 @@ numeric.$(OBJEXT): {$(VPATH)}backward/2/r_cast.h
 numeric.$(OBJEXT): {$(VPATH)}backward/2/rmodule.h
 numeric.$(OBJEXT): {$(VPATH)}backward/2/stdalign.h
 numeric.$(OBJEXT): {$(VPATH)}backward/2/stdarg.h
+numeric.$(OBJEXT): {$(VPATH)}builtin.h
 numeric.$(OBJEXT): {$(VPATH)}config.h
 numeric.$(OBJEXT): {$(VPATH)}constant.h
 numeric.$(OBJEXT): {$(VPATH)}defines.h
 numeric.$(OBJEXT): {$(VPATH)}encoding.h
 numeric.$(OBJEXT): {$(VPATH)}id.h
 numeric.$(OBJEXT): {$(VPATH)}id_table.h
+numeric.$(OBJEXT): {$(VPATH)}integer.rb
+numeric.$(OBJEXT): {$(VPATH)}integer.rbinc
 numeric.$(OBJEXT): {$(VPATH)}intern.h
 numeric.$(OBJEXT): {$(VPATH)}internal.h
 numeric.$(OBJEXT): {$(VPATH)}internal/anyargs.h
diff --git a/inits.c b/inits.c
index 4e5d65ab85..ad57b754a4 100644
--- a/inits.c
+++ b/inits.c
@@ -82,6 +82,7 @@ rb_call_builtin_inits(void)
 {
 #define BUILTIN(n) CALL(builtin_##n)
     BUILTIN(gc);
+    BUILTIN(integer);
     BUILTIN(io);
     BUILTIN(dir);
     BUILTIN(ast);
diff --git a/integer.rb b/integer.rb
new file mode 100644
index 0000000000..2fd32ea463
--- /dev/null
+++ b/integer.rb
@@ -0,0 +1,9 @@
+class Integer
+  # call-seq:
+  #    int.zero? -> true or false
+  #
+  # Returns +true+ if +num+ has a zero value.
+  def zero?
+    Primitive.cexpr! 'int_zero_p(self);'
+  end
+end
diff --git a/numeric.c b/numeric.c
index 990d792245..76567f835b 100644
--- a/numeric.c
+++ b/numeric.c
@@ -39,6 +39,7 @@
 #include "internal/variable.h"
 #include "ruby/encoding.h"
 #include "ruby/util.h"
+#include "builtin.h"
 
 /* use IEEE 64bit values if not defined */
 #ifndef FLT_RADIX
@@ -769,20 +770,27 @@ num_abs(VALUE num)
 static VALUE
 num_zero_p(VALUE num)
 {
+    if (rb_equal(num, INT2FIX(0))) {
+        return Qtrue;
+    }
+    return Qfalse;
+}
+
+static VALUE
+int_zero_p(VALUE num)
+{
     if (FIXNUM_P(num)) {
 	if (FIXNUM_ZERO_P(num)) {
 	    return Qtrue;
 	}
     }
-    else if (RB_TYPE_P(num, T_BIGNUM)) {
+    else {
+        assert(RB_TYPE_P(num, T_BIGNUM));
 	if (rb_bigzero_p(num)) {
 	    /* this should not happen usually */
 	    return Qtrue;
 	}
     }
-    else if (rb_equal(num, INT2FIX(0))) {
-	return Qtrue;
-    }
     return Qfalse;
 }
 
@@ -3307,7 +3315,7 @@ static VALUE
 int_anybits_p(VALUE num, VALUE mask)
 {
     mask = rb_to_int(mask);
-    return num_zero_p(rb_int_and(num, mask)) ? Qfalse : Qtrue;
+    return int_zero_p(rb_int_and(num, mask)) ? Qfalse : Qtrue;
 }
 
 /*
@@ -3321,7 +3329,7 @@ static VALUE
 int_nobits_p(VALUE num, VALUE mask)
 {
     mask = rb_to_int(mask);
-    return num_zero_p(rb_int_and(num, mask));
+    return int_zero_p(rb_int_and(num, mask));
 }
 
 /*
@@ -4722,7 +4730,7 @@ int_aref1(VALUE num, VALUE arg)
             if (!RTEST(num_negative_p(end))) {
                 if (!excl) end = rb_int_plus(end, INT2FIX(1));
                 VALUE mask = generate_mask(end);
-                if (RTEST(num_zero_p(rb_int_and(num, mask)))) {
+                if (RTEST(int_zero_p(rb_int_and(num, mask)))) {
                     return INT2FIX(0);
                 }
                 else {
@@ -5844,3 +5852,5 @@ rb_float_new(double d)
 {
     return rb_float_new_inline(d);
 }
+
+#include "integer.rbinc"
diff --git a/test/ruby/test_jit.rb b/test/ruby/test_jit.rb
index 97c287f692..0a7089375d 100644
--- a/test/ruby/test_jit.rb
+++ b/test/ruby/test_jit.rb
@@ -980,7 +980,7 @@ class TestJIT < Test::Unit::TestCase
   def test_frame_omitted_inlining
     assert_eval_with_jit("#{<<~"begin;"}\n#{<<~"end;"}", stdout: "true\ntrue\ntrue\n", success_count: 1, min_calls: 2)
     begin;
-      class Numeric
+      class Integer
         remove_method :zero?
         def zero?
           self == 0