ZJIT: Drop a duplicated call into optimize (ruby#13196)

* ZJIT: Drop a duplicated call into optimize

* Update a comment

Co-authored-by: Max Bernstein <tekknolagi@gmail.com>

---------

Co-authored-by: Max Bernstein <tekknolagi@gmail.com>

Author: k0kubun

zjit/src/codegen.rs

@@ -169,12 +169,11 @@ fn gen_iseq(cb: &mut CodeBlock, iseq: IseqPtr) -> Option<(CodePtr, Vec<(Rc<Branc
         return Some((start_ptr, vec![]));
     }
 
-    // Convert ISEQ into High-level IR
-    let mut function = match compile_iseq(iseq) {
+    // Convert ISEQ into High-level IR and optimize HIR
+    let function = match compile_iseq(iseq) {
         Some(function) => function,
         None => return None,
     };
-    function.optimize();
 
     // Compile the High-level IR
     let result = gen_function(cb, iseq, &function);