ZJIT: Improve Ractor mode patch point comments

Co-authored-by: Takashi Kokubun <takashikkbn@gmail.com>

Author: st0012

zjit/src/hir.rs

@@ -1672,7 +1672,8 @@ impl Function {
                             }
                             let id = unsafe { get_cme_def_body_attr_id(cme) };
 
-                            // Check if we're accessing ivars of a Class or Module object as they require single-ractor mode
+                            // Check if we're accessing ivars of a Class or Module object as they require single-ractor mode.
+                            // We omit gen_prepare_non_leaf_call on gen_getivar, so it's unsafe to raise for multi-ractor mode.
                             if unsafe { rb_zjit_singleton_class_p(klass) } {
                                 let attached = unsafe { rb_class_attached_object(klass) };
                                 if unsafe { RB_TYPE_P(attached, RUBY_T_CLASS) || RB_TYPE_P(attached, RUBY_T_MODULE) } {
@@ -3333,6 +3334,7 @@ pub fn iseq_to_hir(iseq: *const rb_iseq_t) -> Result<Function, ParseError> {
                     let id = ID(get_arg(pc, 0).as_u64());
                     // ic is in arg 1
                     let exit_id = fun.push_insn(block, Insn::Snapshot { state: exit_state });
+                    // Assume single-Ractor mode to omit gen_prepare_non_leaf_call on gen_getivar
                     // TODO: We only really need this if self_val is a class/module
                     fun.push_insn(block, Insn::PatchPoint { invariant: Invariant::SingleRactorMode, state: exit_id });
                     let result = fun.push_insn(block, Insn::GetIvar { self_val: self_param, id, state: exit_id });
@@ -3342,6 +3344,7 @@ pub fn iseq_to_hir(iseq: *const rb_iseq_t) -> Result<Function, ParseError> {
                     let id = ID(get_arg(pc, 0).as_u64());
                     // ic is in arg 1
                     let exit_id = fun.push_insn(block, Insn::Snapshot { state: exit_state });
+                    // Assume single-Ractor mode to omit gen_prepare_non_leaf_call on gen_setivar
                     // TODO: We only really need this if self_val is a class/module
                     fun.push_insn(block, Insn::PatchPoint { invariant: Invariant::SingleRactorMode, state: exit_id });
                     let val = state.stack_pop()?;