ZJIT: Add codegen for FixnumDiv (#15452)

Fixes https://github.com/Shopify/ruby/issues/902

This pull request adds code generation for dividing fixnums.
Testing confirms the normal case, flooring, and side-exiting on division by zero.

1 files changed, 31 insertions, 0 deletions

diff --git a/test/ruby/test_zjit.rb b/test/ruby/test_zjit.rb
index 03d2461fa0..cc5143aee5 100644
--- a/test/ruby/test_zjit.rb
+++ b/test/ruby/test_zjit.rb
@@ -960,6 +960,37 @@ class TestZJIT < Test::Unit::TestCase
     }, call_threshold: 2, insns: [:opt_mult]
   end
 
+  def test_fixnum_div
+    assert_compiles '12', %q{
+      C = 48
+      def test(n) = C / n
+      test(4)
+      test(4)
+    }, call_threshold: 2, insns: [:opt_div]
+  end
+
+  def test_fixnum_floor
+    assert_compiles '0', %q{
+      C = 3
+      def test(n) = C / n
+      test(4)
+      test(4)
+    }, call_threshold: 2, insns: [:opt_div]
+  end
+
+  def test_fixnum_div_zero
+    assert_runs '"divided by 0"', %q{
+      def test(n)
+        n / 0
+      rescue ZeroDivisionError => e
+        e.message
+      end
+
+      test(0)
+      test(0)
+    }, call_threshold: 2, insns: [:opt_div]
+  end
+
   def test_opt_not
     assert_compiles('[true, true, false]', <<~RUBY, insns: [:opt_not])
       def test(obj) = !obj