2 files changed, 21 insertions, 4 deletions
diff --git a/test/ruby/test_zjit.rb b/test/ruby/test_zjit.rb
index c937156fa0..6479d7380e 100644
--- a/test/ruby/test_zjit.rb
+++ b/test/ruby/test_zjit.rb
@@ -73,13 +73,19 @@ class TestZJIT < Test::Unit::TestCase
     }, call_threshold: 2
   end
 
-  # FIXME: need to call twice because of call threshold 2, but
-  # then this fails because of missing FixnumLt
-  def test_less_than
+  def test_less_than_true
     assert_compiles 'true', %q{
       def test(a, b) = a < b
       test(2, 5)
-      #test(2, 5)
+      test(2, 5)
+    }, call_threshold: 2
+  end
+
+  def test_less_than_false
+    assert_compiles '[false, false]', %q{
+      def test(a, b) = a < b
+      test(5, 2)
+      [test(5, 2), test(2, 2)]
     }, call_threshold: 2
   end
 
diff --git a/zjit/src/codegen.rs b/zjit/src/codegen.rs
index 28e71fc4c5..9117b6d389 100644
--- a/zjit/src/codegen.rs
+++ b/zjit/src/codegen.rs
@@ -117,6 +117,8 @@ fn gen_insn(jit: &mut JITState, asm: &mut Assembler, function: &Function, insn_i
         Insn::Return { val } => return Some(gen_return(&jit, asm, *val)?),
         Insn::FixnumAdd { left, right, state } => gen_fixnum_add(jit, asm, *left, *right, function.frame_state(*state))?,
         Insn::FixnumSub { left, right, state } => gen_fixnum_sub(jit, asm, *left, *right, function.frame_state(*state))?,
+        // TODO(max): Remove FrameState from FixnumLt
+        Insn::FixnumLt { left, right, .. } => gen_fixnum_lt(jit, asm, *left, *right)?,
         Insn::GuardType { val, guard_type, state } => gen_guard_type(jit, asm, *val, *guard_type, function.frame_state(*state))?,
         Insn::PatchPoint(_) => return Some(()), // For now, rb_zjit_bop_redefined() panics. TODO: leave a patch point and fix rb_zjit_bop_redefined()
         _ => {
@@ -216,6 +218,15 @@ fn gen_fixnum_add(jit: &mut JITState, asm: &mut Assembler, left: InsnId, right:
     Some(out_val)
 }
 
+/// Compile Fixnum < Fixnum
+fn gen_fixnum_lt(jit: &mut JITState, asm: &mut Assembler, left: InsnId, right: InsnId) -> Option<lir::Opnd> {
+    let left_opnd = jit.get_opnd(left)?;
+    let right_opnd = jit.get_opnd(right)?;
+    asm.cmp(left_opnd, right_opnd);
+    let out_val = asm.csel_l(Qtrue.into(), Qfalse.into());
+    Some(out_val)
+}
+
 /// Compile Fixnum - Fixnum
 fn gen_fixnum_sub(jit: &mut JITState, asm: &mut Assembler, left: InsnId, right: InsnId, state: &FrameState) -> Option<lir::Opnd> {
     let left_opnd = jit.get_opnd(left)?;