From: Batuhan Taskaya <isidentical@gmail.com>
Date: Sun, 5 Dec 2021 21:03:48 +0000 (+0300)
Subject: perf: drop the initial stack copy (#2670)
X-Git-Url: https://git.madduck.net/etc/vim.git/commitdiff_plain/28ab82aab013978b7ed91bda816de3d41385f260?hp=d9eee31ec81c42d9953aee0d7f0adaf211519a10

perf: drop the initial stack copy (#2670)

Co-authored-by: Richard Si <63936253+ichard26@users.noreply.github.com>
---

diff --git a/CHANGES.md b/CHANGES.md
index 097725e..434f809 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -26,6 +26,8 @@
 - Fix styling of starred expressions inside `match` subject (#2667)
 - Fix parser error location on invalid syntax in a `match` statement (#2649)
 - Fix Python 3.10 support on platforms without ProcessPoolExecutor (#2631)
+- Improve parsing performance on code that uses `match` under `--target-version py310`
+  up to ~50% (#2670)
 
 ### Packaging
 
diff --git a/src/blib2to3/pgen2/parse.py b/src/blib2to3/pgen2/parse.py
index 792e8e6..e5dad3a 100644
--- a/src/blib2to3/pgen2/parse.py
+++ b/src/blib2to3/pgen2/parse.py
@@ -53,7 +53,7 @@ class Recorder:
         self.context = context  # not really matter
 
         self._dead_ilabels: Set[int] = set()
-        self._start_point = copy.deepcopy(self.parser.stack)
+        self._start_point = self.parser.stack
         self._points = {ilabel: copy.deepcopy(self._start_point) for ilabel in ilabels}
 
     @property