From bd19d798842155d5e4c73ba5b6aff25b5eff0c76 Mon Sep 17 00:00:00 2001
From: Guido van Rossum <guido@python.org>
Date: Wed, 8 Feb 2023 15:14:24 -0800
Subject: [PATCH] stack_effect() for specialized opcode is an error

---
 Python/compile.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Python/compile.c b/Python/compile.c
index f1f95b886762e8..061b6d3f6461c1 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -1075,6 +1075,10 @@ static int
 stack_effect(int opcode, int oparg, int jump)
 {
     if (0 <= opcode && opcode < 256) {
+        if (_PyOpcode_Deopt[opcode] != opcode) {
+            // Specialized instructions are not supported.
+            return PY_INVALID_STACK_EFFECT;
+        }
         int popped, pushed;
         if (jump > 0) {
             popped = _PyOpcode_num_popped(opcode, oparg, true);