From 42abad2464a78e3ec8a42f85c7bc878233f3ce16 Mon Sep 17 00:00:00 2001
From: Yusuke Endoh <mame@ruby-lang.org>
Date: Tue, 12 May 2020 02:12:06 +0900
Subject: [PATCH] numeric.c: optimize `float ** 2` case by fastpath

It would be a relatively frequent case.  It is still slower than
`float * float` because `*` has a dedicated VM instruction (opt_mult),
though.
---
 numeric.c               | 6 +++++-
 test/ruby/test_float.rb | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/numeric.c b/numeric.c
index 03d8b86a1d..04fd3a24af 100644
--- a/numeric.c
+++ b/numeric.c
@@ -1309,7 +1309,11 @@ VALUE
 rb_float_pow(VALUE x, VALUE y)
 {
     double dx, dy;
-    if (RB_TYPE_P(y, T_FIXNUM)) {
+    if (y == INT2FIX(2)) {
+	dx = RFLOAT_VALUE(x);
+        return DBL2NUM(dx * dx);
+    }
+    else if (RB_TYPE_P(y, T_FIXNUM)) {
 	dx = RFLOAT_VALUE(x);
 	dy = (double)FIX2LONG(y);
     }
diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb
index 0daa3cca57..fbf0d87f8e 100644
--- a/test/ruby/test_float.rb
+++ b/test/ruby/test_float.rb
@@ -305,6 +305,7 @@ class TestFloat < Test::Unit::TestCase
     assert_equal(1.0, 1.0 ** (2**32))
     assert_equal(1.0, 1.0 ** 1.0)
     assert_raise(TypeError) { 1.0 ** nil }
+    assert_equal(9.0, 3.0 ** 2)
   end
 
   def test_eql