gh-111354: simplify detection of RESUME after YIELD_VALUE at except-depth 1 (#111459)

Author: iritkatriel

Doc/library/dis.rst

@@ -823,6 +823,8 @@ iterations of the loop.
  .. versionchanged:: 3.12
  oparg set to be the exception block depth, for efficient closing of generators.
 
+ .. versionchanged:: 3.13
+ this opcode no longer has an oparg
 
 .. opcode:: SETUP_ANNOTATIONS
 
@@ -1625,20 +1627,27 @@ iterations of the loop.
  success (``True``) or failure (``False``).
 
 
-.. opcode:: RESUME (where)
+.. opcode:: RESUME (context)
 
  A no-op. Performs internal tracing, debugging and optimization checks.
 
- The ``where`` operand marks where the ``RESUME`` occurs:
+ The ``context`` oparand consists of two parts. The lowest two bits
+ indicate where the ``RESUME`` occurs:
 
  * ``0`` The start of a function, which is neither a generator, coroutine
  nor an async generator
  * ``1`` After a ``yield`` expression
  * ``2`` After a ``yield from`` expression
  * ``3`` After an ``await`` expression
 
+ The next bit is ``1`` if the RESUME is at except-depth ``1``, and ``0``
+ otherwise.
+
  .. versionadded:: 3.11
 
+ .. versionchanged:: 3.13
+ The oparg value changed to include information about except-depth
+
 
 .. opcode:: RETURN_GENERATOR
 

Doc/whatsnew/3.13.rst

@@ -945,6 +945,14 @@ Others
 
 * None yet
 
+CPython bytecode changes
+========================
+
+* ``YIELD_VALUE`` no longer has an oparg. The oparg of ``RESUME`` was
+ changed to add a bit indicating whether the except-depth is 1, which
+ is needed to optimize closing of generators.
+ (Contributed by Irit Katriel in :gh:`111354`.)
+
 Porting to Python 3.13
 ======================
 

Include/internal/pycore_opcode_metadata.h

@@ -64,6 +64,8 @@ extern "C" {
 #define RESUME_AFTER_YIELD_FROM 2
 #define RESUME_AFTER_AWAIT 3
 
+#define RESUME_OPARG_LOCATION_MASK 0x3
+#define RESUME_OPARG_DEPTH1_MASK 0x4
 
 #ifdef __cplusplus
 }