From e6a0f2a3ab2e8b6e59cbfecd879c64db5a20c806 Mon Sep 17 00:00:00 2001
From: Sacul0457Deve <183588943+Sacul0457@users.noreply.github.com.>
Date: Wed, 4 Feb 2026 19:35:06 +0800
Subject: [PATCH 1/6] add _GUARD_TOS_SLICE to optimizer_bytecodes

---
 Lib/test/test_capi/test_opt.py | 17 +++++++++++++++++
 Python/optimizer_bytecodes.c   |  7 +++++++
 Python/optimizer_cases.c.h     |  6 ++++++
 3 files changed, 30 insertions(+)

diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
index 437cc340fc90e3..02866b5341586f 100644
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -2045,6 +2045,23 @@ def f(n):
         self.assertNotIn("_GUARD_BINARY_OP_SUBSCR_TUPLE_INT_BOUNDS", uops)
         self.assertIn("_BINARY_OP_SUBSCR_TUPLE_INT", uops)
 
+    def test_remove_guard_for_known_type_slice(self):
+        def f(n):
+            x = 0
+            for _ in range(n):
+                l = [1, 2, 3]
+                slice_obj = slice(0, 1)
+                x += l[slice_obj][0] # guarded
+                x += l[slice_obj][0] # unguarded
+            return x
+        res, ex = self._run_with_optimizer(f, TIER2_THRESHOLD)
+        self.assertEqual(res, TIER2_THRESHOLD * 2)
+        uops = get_opnames(ex)
+
+        count = count_ops(ex, "_GUARD_TOS_SLICE")
+        self.assertEqual(count, 1)
+        self.assertIn("_BINARY_OP_SUBSCR_LIST_INT", uops)
+
     def test_binary_subcsr_str_int_narrows_to_str(self):
         def testfunc(n):
             x = []
diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index 89c6707160326c..93ae5555a8e8cf 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -1416,6 +1416,13 @@ dummy_func(void) {
             ADD_OP(_NOP, 0, 0);
         }
     }
+    op(_GUARD_TOS_SLICE, (tos -- tos)){
+        if (sym_matches_type(tos, &PySlice_Type)){
+            ADD_OP(_NOP, 0, 0);
+        }
+        sym_set_type(tos, &PySlice_Type);
+    }
+
 
     op(_GUARD_NOS_NULL, (null, unused -- null, unused)) {
         if (sym_is_null(null)) {
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index 61a30314c21789..259cf2a1c32dc7 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -370,6 +370,12 @@
         }
 
         case _GUARD_TOS_SLICE: {
+            JitOptRef tos;
+            tos = stack_pointer[-1];
+            if (sym_matches_type(tos, &PySlice_Type)){
+                ADD_OP(_NOP, 0, 0);
+            }
+            sym_set_type(tos, &PySlice_Type);
             break;
         }
 

From d2e98d715121e102d8b3a9ee6dc4c361a8be32ed Mon Sep 17 00:00:00 2001
From: Sacul0457Deve <183588943+Sacul0457@users.noreply.github.com.>
Date: Wed, 4 Feb 2026 19:37:45 +0800
Subject: [PATCH 2/6] shift test function up

---
 Lib/test/test_capi/test_opt.py | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
index 02866b5341586f..9463e5d5594d47 100644
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -2030,21 +2030,6 @@ def f(n):
         self.assertNotIn("_GUARD_NOS_TUPLE", uops)
         self.assertIn("_BINARY_OP_SUBSCR_TUPLE_INT", uops)
 
-    def test_remove_guard_for_tuple_bounds_check(self):
-        def f(n):
-            x = 0
-            for _ in range(n):
-                t = (1, 2, 3)
-                x += t[0]
-            return x
-
-        res, ex = self._run_with_optimizer(f, TIER2_THRESHOLD)
-        self.assertEqual(res, TIER2_THRESHOLD)
-        self.assertIsNotNone(ex)
-        uops = get_opnames(ex)
-        self.assertNotIn("_GUARD_BINARY_OP_SUBSCR_TUPLE_INT_BOUNDS", uops)
-        self.assertIn("_BINARY_OP_SUBSCR_TUPLE_INT", uops)
-
     def test_remove_guard_for_known_type_slice(self):
         def f(n):
             x = 0
@@ -2062,6 +2047,21 @@ def f(n):
         self.assertEqual(count, 1)
         self.assertIn("_BINARY_OP_SUBSCR_LIST_INT", uops)
 
+    def test_remove_guard_for_tuple_bounds_check(self):
+        def f(n):
+            x = 0
+            for _ in range(n):
+                t = (1, 2, 3)
+                x += t[0]
+            return x
+
+        res, ex = self._run_with_optimizer(f, TIER2_THRESHOLD)
+        self.assertEqual(res, TIER2_THRESHOLD)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        self.assertNotIn("_GUARD_BINARY_OP_SUBSCR_TUPLE_INT_BOUNDS", uops)
+        self.assertIn("_BINARY_OP_SUBSCR_TUPLE_INT", uops)
+
     def test_binary_subcsr_str_int_narrows_to_str(self):
         def testfunc(n):
             x = []

From 41544e78122889f93241b1549ef81b1395fd6d2a Mon Sep 17 00:00:00 2001
From: Sacul0457Deve <183588943+Sacul0457@users.noreply.github.com.>
Date: Wed, 4 Feb 2026 20:11:49 +0800
Subject: [PATCH 3/6] add spacing between ops

---
 Python/optimizer_bytecodes.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index 93ae5555a8e8cf..f27fcb6d86f9ba 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -1416,6 +1416,8 @@ dummy_func(void) {
             ADD_OP(_NOP, 0, 0);
         }
     }
+
+
     op(_GUARD_TOS_SLICE, (tos -- tos)){
         if (sym_matches_type(tos, &PySlice_Type)){
             ADD_OP(_NOP, 0, 0);

From 8fe5b1213178361737e0eaee87d88bbb131b2edf Mon Sep 17 00:00:00 2001
From: Sacul0457Deve <183588943+Sacul0457@users.noreply.github.com.>
Date: Wed, 4 Feb 2026 20:13:13 +0800
Subject: [PATCH 4/6] resize spacing between ops again

---
 Python/optimizer_bytecodes.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index f27fcb6d86f9ba..3a2af7d9198175 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -1417,7 +1417,6 @@ dummy_func(void) {
         }
     }
 
-
     op(_GUARD_TOS_SLICE, (tos -- tos)){
         if (sym_matches_type(tos, &PySlice_Type)){
             ADD_OP(_NOP, 0, 0);
@@ -1425,7 +1424,6 @@ dummy_func(void) {
         sym_set_type(tos, &PySlice_Type);
     }
 
-
     op(_GUARD_NOS_NULL, (null, unused -- null, unused)) {
         if (sym_is_null(null)) {
             ADD_OP(_NOP, 0, 0);

From 1216b7cfaa9ac0219d91dc0e36c4404514b125ad Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Wed, 4 Feb 2026 12:19:50 +0000
Subject: [PATCH 5/6] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst               | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst
new file mode 100644
index 00000000000000..f14f870d582c30
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst
@@ -0,0 +1 @@
+Optimise `_GUARD_TOS_SLICE` in the JIT.

From 5887eb8fbab5f29c2bbf192b21287ac08110bc62 Mon Sep 17 00:00:00 2001
From: Sacul <183588943+Sacul0457@users.noreply.github.com>
Date: Wed, 4 Feb 2026 20:28:22 +0800
Subject: [PATCH 6/6] Fix formatting of _GUARD_TOS_SLICE in NEWS entry

---
 .../2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst              | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst
index f14f870d582c30..849889f81fc323 100644
--- a/Misc/NEWS.d/next/Core_and_Builtins/2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-02-04-12-19-48.gh-issue-131798.My5jLy.rst
@@ -1 +1 @@
-Optimise `_GUARD_TOS_SLICE` in the JIT.
+Optimise ``_GUARD_TOS_SLICE`` in the JIT.