Add a couple more comments.

markshannon · markshannon · commit f9cf3db6b9b8 · 2023-05-11T06:41:35.000+01:00
diff --git a/Python/ceval.c b/Python/ceval.c
@@ -801,6 +801,8 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
         }
         if (_PyOpcode_Caches[original_opcode]) {
             _PyBinaryOpCache *cache = (_PyBinaryOpCache *)(next_instr+1);
+            /* Prevent the underlying instruction from specializing
+             * and overwriting the instrumentation. */
             INCREMENT_ADAPTIVE_COUNTER(cache->counter);
         }
         opcode = original_opcode;
diff --git a/Python/instrumentation.c b/Python/instrumentation.c
@@ -1108,6 +1108,9 @@ _Py_call_instrumentation_line(PyThreadState *tstate, _PyInterpreterFrame* frame,
     int prev_line = _Py_Instrumentation_GetLine(code, prev_index);
     if (prev_line == line) {
         int prev_opcode = _PyCode_CODE(code)[prev_index].op.code;
+        /* RESUME and INSTRUMENTED_RESUME are needed for the operation of
+         * instrumentation, so must never be hidden by an INSTRUMENTED_LINE.
+         */
         if (prev_opcode != RESUME && prev_opcode != INSTRUMENTED_RESUME) {
             goto done;
         }

Original file line number	Diff line number	Diff line change
`@@ -801,6 +801,8 @@ _PyEval_EvalFrameDefault(PyThreadState tstate, _PyInterpreterFrame frame, int`
`801`	`801`	`}`
`802`	`802`	`if (_PyOpcode_Caches[original_opcode]) {`
`803`	`803`	`_PyBinaryOpCache cache = (_PyBinaryOpCache )(next_instr+1);`
	`804`	`+ /* Prevent the underlying instruction from specializing`
	`805`	`+ * and overwriting the instrumentation. */`
`804`	`806`	`INCREMENT_ADAPTIVE_COUNTER(cache->counter);`
`805`	`807`	`}`
`806`	`808`	`opcode = original_opcode;`