simplify: port LoadTupleItem constant-fold to C

simplify_load_tuple_item_c: if src is a known tuple object, fold
item access to LoadConst. Uses hir_c_load_tuple_item_idx for index,
hir_func_add_reference to register the item, hir_type_from_object
for the result type.

Author: SonicField

Python/jit/hir/simplify.cpp

@@ -2798,9 +2798,12 @@ Register* simplifyInstr(Env& env, const Instr* instr) {
       sync_c_env(cenv);
       return r;
     }
-    case Opcode::kLoadTupleItem:
-      return simplifyLoadTupleItem(
-          env, static_cast<const LoadTupleItem*>(instr));
+    case Opcode::kLoadTupleItem: {
+      SimplifyEnv cenv = make_c_env();
+      auto *r = static_cast<Register*>(simplify_load_tuple_item_c(&cenv, instr));
+      sync_c_env(cenv);
+      return r;
+    }
     case Opcode::kLoadArrayItem:
       return simplifyLoadArrayItem(
           env, static_cast<const LoadArrayItem*>(instr));

Python/jit/hir/simplify_c.c

@@ -212,6 +212,24 @@ void *simplify_primitive_compare_box_true_c(const void *instr) {
     return hir_c_get_operand(left_def, 0);
 }
 
+/* ---- simplifyLoadTupleItem ----
+ * If src is a known tuple object, fold to the constant item. */
+void *simplify_load_tuple_item_c(SimplifyEnv *env, const void *instr) {
+    void *src = hir_c_get_operand(instr, 0);
+    HirType src_type = hir_register_type(src);
+    HirType t_tuple = HIR_TYPE_TUPLE;
+    if (!hir_type_has_value_spec(&src_type, t_tuple)) return NULL;
+
+    simplify_env_emit_use_type(env, src, src_type);
+    PyObject *tuple_obj = hir_type_object_spec(&src_type);
+    size_t idx = hir_c_load_tuple_item_idx(instr);
+    PyObject *item = PyTuple_GET_ITEM(tuple_obj, idx);
+    extern PyObject *hir_func_add_reference(void *func, PyObject *obj);
+    PyObject *ref = hir_func_add_reference(env->func, item);
+    HirType item_type = hir_type_from_object(ref);
+    return simplify_env_emit_load_const(env, item_type);
+}
+
 /* ---- simplifyLoadField (partial — known float object) ----
  * If loadee is a known float and we're loading ob_fval, fold to constant. */
 void *simplify_load_field_float_c(SimplifyEnv *env, const void *instr) {

Python/jit/hir/simplify_c.h

@@ -32,6 +32,7 @@ void *simplify_guard_type_identity_c(const void *instr);
 void *simplify_primitive_compare_box_true_c(const void *instr);
 void *simplify_unbox_box_c(const void *instr);
 void *simplify_cond_branch_check_type_c(SimplifyEnv *env, const void *instr);
+void *simplify_load_tuple_item_c(SimplifyEnv *env, const void *instr);
 void *simplify_load_field_float_c(SimplifyEnv *env, const void *instr);
 void *simplify_int_convert_c(SimplifyEnv *env, const void *instr);