move _PyLong_IsNonNegativeCompact into specialize

and just assert in the bytecodes

Author: chris-eibl

Python/bytecodes.c

@@ -951,7 +951,7 @@ dummy_func(
 
             assert(PyLong_CheckExact(sub));
             assert(PyUnicode_CheckExact(str));
-            DEOPT_IF(!_PyLong_IsNonNegativeCompact((PyLongObject *)sub));
+            assert(_PyLong_IsNonNegativeCompact((PyLongObject *)sub));
             Py_ssize_t index = ((PyLongObject*)sub)->long_value.ob_digit[0];
             DEOPT_IF(PyUnicode_GET_LENGTH(str) <= index);
             uint8_t c = PyUnicode_1BYTE_DATA(str)[index];
@@ -973,7 +973,7 @@ dummy_func(
 
             assert(PyLong_CheckExact(sub));
             assert(PyUnicode_CheckExact(str));
-            DEOPT_IF(!_PyLong_IsNonNegativeCompact((PyLongObject *)sub));
+            assert(_PyLong_IsNonNegativeCompact((PyLongObject *)sub));
             Py_ssize_t index = ((PyLongObject*)sub)->long_value.ob_digit[0];
             DEOPT_IF(PyUnicode_GET_LENGTH(str) <= index);
             // Specialize for reading an ASCII character from any string:

Python/executor_cases.c.h

@@ -2242,7 +2242,7 @@ _Py_Specialize_BinaryOp(_PyStackRef lhs_st, _PyStackRef rhs_st, _Py_CODEUNIT *in
                     specialize(instr, BINARY_OP_SUBSCR_TUPLE_INT);
                     return;
                 }
-                if (PyUnicode_CheckExact(lhs)) {
+                if (PyUnicode_CheckExact(lhs) && _PyLong_IsNonNegativeCompact((PyLongObject*)rhs)) {
                     if (PyUnicode_IS_COMPACT_ASCII(lhs)) {
                         specialize(instr, BINARY_OP_SUBSCR_STR_INT);
                         return;