Document enabling AST type definition events during build

INSTRUMENTATION.md

@@ -94,3 +94,14 @@ printf "\nAllocation lifecycle (MALLOC/DEALLOC):\n" && \
 ```
 
 Each line in `/tmp/firm2_events.ndjson` is NDJSON with the common envelope (`event_id`, `pid`, `tid`, `ts_ns`) and the emitter-specific payload fields, letting you inspect or post-process the full stream.
+
+### AST type definition events during the CPython build
+
+The AST type-definition emitter (`emit_ast_type_def_event_json`) runs when the interpreter creates the `ast.*` types during initialization, which happens while the freshly built interpreter is used to compile the standard library. If you want those `"type":"ast_type_def"` lines to appear during `make`/`make install`, export the gate before invoking the build so `_firm2_enabled()` evaluates to true for the bootstrap interpreter:
+
+```bash
+FIRMAMENT2_ENABLE=1 make -j"$(nproc)"
+FIRMAMENT2_ENABLE=1 make install
+```
+
+Without the environment variable set, the generated code is still present but the emitter is a no-op.

Modules/_opcode.c

@@ -3,6 +3,8 @@
 #endif
 
 #include "Python.h"
+#include "pycore_asdl.h"
+#include "Python-ast.h"
 #include "compile.h"
 #include "opcode.h"
 #include "pycore_ceval.h"           // SPECIAL_MAX

Modules/_testinternalcapi.c

@@ -10,6 +10,8 @@
 #undef NDEBUG
 
 #include "Python.h"
+#include "pycore_asdl.h"
+#include "Python-ast.h"
 #include "pycore_backoff.h"       // JUMP_BACKWARD_INITIAL_VALUE
 #include "pycore_bitutils.h"      // _Py_bswap32()
 #include "pycore_bytesobject.h"   // _PyBytes_Find()

Objects/codeobject.c

@@ -26,6 +26,10 @@
 #include <string.h>
 #include <stdlib.h>
 
+#ifdef Py_GIL_DISABLED
+#define INITIAL_SPECIALIZED_CODE_SIZE 1
+#endif
+
 /* ------------------------------------------------------------------------
  * Firmament2: per-code provenance tag via a lightweight pointer map.
  * We keep a singly-linked list mapping code-object pointers to tags.
@@ -3155,6 +3159,43 @@ code__varname_from_oparg_impl(PyCodeObject *self, int oparg)
     return Py_NewRef(name);
 }
 
+#ifdef Py_GIL_DISABLED
+static int
+code_traverse(PyObject *self, visitproc visit, void *arg)
+{
+    PyCodeObject *co = _PyCodeObject_CAST(self);
+
+    Py_VISIT(co->co_consts);
+    Py_VISIT(co->co_names);
+    Py_VISIT(co->co_localsplusnames);
+    Py_VISIT(co->co_localspluskinds);
+    Py_VISIT(co->co_filename);
+    Py_VISIT(co->co_name);
+    Py_VISIT(co->co_qualname);
+    Py_VISIT(co->co_linetable);
+    Py_VISIT(co->co_exceptiontable);
+
+    if (co->_co_cached != NULL) {
+        Py_VISIT(co->_co_cached->_co_code);
+        Py_VISIT(co->_co_cached->_co_cellvars);
+        Py_VISIT(co->_co_cached->_co_freevars);
+        Py_VISIT(co->_co_cached->_co_varnames);
+    }
+
+    Py_VISIT(co->_co_monitoring);
+
+#ifdef _Py_TIER2
+    if (co->co_executors != NULL) {
+        for (int i = 0; i < co->co_executors->size; i++) {
+            Py_VISIT(co->co_executors->executors[i]);
+        }
+    }
+#endif
+
+    return 0;
+}
+#endif
+
 /* XXX code objects need to participate in GC? */
 
 static struct PyMethodDef code_methods[] = {