[codegen] add new recipe "rout" (#1014)

* [codegen] add new recipe "rout"

Add a new recipe "rout" intended to be used by arithematic operations
that output flags, currently being used for `iadd_cout` and `isub_bout`.

Fixes: https://github.com/CraneStation/cranelift/issues/1009

cranelift/codegen/meta/src/isa/x86/recipes.rs

@@ -2548,7 +2548,24 @@ pub(crate) fn define<'shared>(
             ),
     );
 
-    // Adding with carry
+    // Arithematic with flag I/O.
+
+    // XX /r, MR form. Add two GPR registers and set carry flag.
+    recipes.add_template_recipe(
+        EncodingRecipeBuilder::new("rout", f_binary, 1)
+            .operands_in(vec![gpr, gpr])
+            .operands_out(vec![
+                OperandConstraint::TiedInput(0),
+                OperandConstraint::FixedReg(reg_rflags),
+            ])
+            .clobbers_flags(true)
+            .emit(
+                r#"
+                    {{PUT_OP}}(bits, rex2(in_reg0, in_reg1), sink);
+                    modrm_rr(in_reg0, in_reg1, sink);
+                "#,
+            ),
+    );
 
     // XX /r, MR form. Add two GPR registers and get carry flag.
     recipes.add_template_recipe(