bpo-31344: Per-frame control of trace events (GH-3417)

f_trace_lines: enable/disable line trace events
f_trace_opcodes: enable/disable opcode trace events

These are intended primarily for testing of the interpreter
itself, as they make it much easier to emulate signals
arriving at unfortunate times.

2 files changed, 17 insertions, 9 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index 8fc65cd..a072a5f 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4458,12 +4458,19 @@ maybe_call_line_trace(Py_tracefunc func, PyObject *obj,
         *instr_lb = bounds.ap_lower;
         *instr_ub = bounds.ap_upper;
     }
-    /* If the last instruction falls at the start of a line or if
-       it represents a jump backwards, update the frame's line
-       number and call the trace function. */
-    if (frame->f_lasti == *instr_lb || frame->f_lasti < *instr_prev) {
+    /* Always emit an opcode event if we're tracing all opcodes. */
+    if (frame->f_trace_opcodes) {
+        result = call_trace(func, obj, tstate, frame, PyTrace_OPCODE, Py_None);
+    }
+    /* If the last instruction falls at the start of a line or if it
+       represents a jump backwards, update the frame's line number and
+       then call the trace function if we're tracing source lines.
+    */
+    if ((frame->f_lasti == *instr_lb || frame->f_lasti < *instr_prev)) {
         frame->f_lineno = line;
-        result = call_trace(func, obj, tstate, frame, PyTrace_LINE, Py_None);
+        if (frame->f_trace_lines) {
+            result = call_trace(func, obj, tstate, frame, PyTrace_LINE, Py_None);
+        }
     }
     *instr_prev = frame->f_lasti;
     return result;
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index fba7220..021b95d 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -349,18 +349,19 @@ same value.");
  * Cached interned string objects used for calling the profile and
  * trace functions.  Initialized by trace_init().
  */
-static PyObject *whatstrings[7] = {NULL, NULL, NULL, NULL, NULL, NULL, NULL};
+static PyObject *whatstrings[8] = {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL};
 
 static int
 trace_init(void)
 {
-    static const char * const whatnames[7] = {
+    static const char * const whatnames[8] = {
         "call", "exception", "line", "return",
-        "c_call", "c_exception", "c_return"
+        "c_call", "c_exception", "c_return",
+        "opcode"
     };
     PyObject *name;
     int i;
-    for (i = 0; i < 7; ++i) {
+    for (i = 0; i < 8; ++i) {
         if (whatstrings[i] == NULL) {
             name = PyUnicode_InternFromString(whatnames[i]);
             if (name == NULL)