[Python-checkins] GH-90997: Document CACHEs (GH-95694)
brandtbucher
webhook-mailer at python.org
Fri Aug 5 01:45:10 EDT 2022
https://github.com/python/cpython/commit/5f3c9fda1825737fa7b671b995f84a8ab9a4adb8
commit: 5f3c9fda1825737fa7b671b995f84a8ab9a4adb8
branch: main
author: Brandt Bucher <brandtbucher at gmail.com>
committer: brandtbucher <brandtbucher at gmail.com>
date: 2022-08-04T22:45:05-07:00
summary:
GH-90997: Document CACHEs (GH-95694)
files:
M Doc/library/dis.rst
M Doc/whatsnew/3.11.rst
diff --git a/Doc/library/dis.rst b/Doc/library/dis.rst
index 68c3d1c0a4b2..63b064e7b444 100644
--- a/Doc/library/dis.rst
+++ b/Doc/library/dis.rst
@@ -408,6 +408,24 @@ The Python compiler currently generates the following bytecode instructions.
.. versionadded:: 3.11
+.. opcode:: CACHE
+
+ Rather than being an actual instruction, this opcode is used to mark extra
+ space for the interpreter to cache useful data directly in the bytecode
+ itself. It is automatically hidden by all ``dis`` utilities, but can be
+ viewed with ``show_caches=True``.
+
+ Logically, this space is part of the preceding instruction. Many opcodes
+ expect to be followed by an exact number of caches, and will instruct the
+ interpreter to skip over them at runtime.
+
+ Populated caches can look like arbitrary instructions, so great care should
+ be taken when reading or modifying raw, adaptive bytecode containing
+ quickened data.
+
+ .. versionadded:: 3.11
+
+
**Unary operations**
Unary operations take the top of the stack, apply the operation, and push the
diff --git a/Doc/whatsnew/3.11.rst b/Doc/whatsnew/3.11.rst
index c976eddb08ba..f5d5d5f2be06 100644
--- a/Doc/whatsnew/3.11.rst
+++ b/Doc/whatsnew/3.11.rst
@@ -1165,6 +1165,13 @@ contributors are volunteers from the community.
CPython bytecode changes
========================
+* The bytecode now contains inline cache entries, which take the form of
+ :opcode:`CACHE` instructions. Many opcodes expect to be followed by an exact
+ number of caches, and instruct the interpreter to skip over them at runtime.
+ Populated caches can look like arbitrary instructions, so great care should be
+ taken when reading or modifying raw, adaptive bytecode containing quickened
+ data.
+
* Replaced all numeric ``BINARY_*`` and ``INPLACE_*`` instructions with a single
:opcode:`BINARY_OP` implementation.
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