From f095d5fd621343b11aaea5f13a307d485bad790f Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Thu, 18 Sep 2025 18:12:59 +0000
Subject: [PATCH 01/26] feat: optimize equality check with string literals

---
 mypyc/irbuild/ll_builder.py | 16 +++++++++++++++-
 mypyc/lib-rt/str_ops.c      | 29 +++++++++++++++++++++--------
 mypyc/primitives/str_ops.py |  8 ++++++++
 3 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 4b85c13892c1d..e290b7c91adb4 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -185,6 +185,7 @@
 from mypyc.primitives.str_ops import (
     str_check_if_true,
     str_eq,
+    str_eq_literal,
     str_ssize_t_size_op,
     unicode_compare,
 )
@@ -1551,9 +1552,22 @@ def check_tagged_short_int(self, val: Value, line: int, negated: bool = False) -
     def compare_strings(self, lhs: Value, rhs: Value, op: str, line: int) -> Value:
         """Compare two strings"""
         if op == "==":
+            if isinstance(lhs, LoadLiteral) and is_str_rprimitive(lhs.type):
+                literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)
+                return self.primitive_op(str_eq_literal, [rhs, lhs, literal_length], line)
+            elif isinstance(rhs, LoadLiteral) and is_str_rprimitive(rhs.type):
+                literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)
+                return self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
             return self.primitive_op(str_eq, [lhs, rhs], line)
         elif op == "!=":
-            eq = self.primitive_op(str_eq, [lhs, rhs], line)
+            if isinstance(lhs, LoadLiteral) and is_str_rprimitive(lhs.type):
+                literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)
+                eq = self.primitive_op(str_eq_literal, [rhs, lhs, literal_length])
+            elif isinstance(rhs, LoadLiteral) and is_str_rprimitive(rhs.type):
+                literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)
+                eq = self.primitive_op(str_eq_literal, [lhs, rhs, literal_length])
+            else:
+                eq = self.primitive_op(str_eq, [lhs, rhs], line)
             return self.add(ComparisonOp(eq, self.false(), ComparisonOp.EQ, line))
 
         # TODO: modify 'str' to use same interface as 'compare_bytes' as it would avoid
diff --git a/mypyc/lib-rt/str_ops.c b/mypyc/lib-rt/str_ops.c
index 337ef14fc955f..01e85002f9f7c 100644
--- a/mypyc/lib-rt/str_ops.c
+++ b/mypyc/lib-rt/str_ops.c
@@ -64,20 +64,33 @@ make_bloom_mask(int kind, const void* ptr, Py_ssize_t len)
 #undef BLOOM_UPDATE
 }
 
-// Adapted from CPython 3.13.1 (_PyUnicode_Equal)
-char CPyStr_Equal(PyObject *str1, PyObject *str2) {
-    if (str1 == str2) {
-        return 1;
-    }
-    Py_ssize_t len = PyUnicode_GET_LENGTH(str1);
-    if (PyUnicode_GET_LENGTH(str2) != len)
+static char _CPyStr_Equal_NoIdentCheck(PyObject *str1, PyObject *str2, Py_ssize_t str2_length) {
+    // This helper function only exists to deduplicate code
+    Py_ssize_t str1_length = PyUnicode_GET_LENGTH(str1);
+    if (str1_length != str2_length)
         return 0;
     int kind = PyUnicode_KIND(str1);
     if (PyUnicode_KIND(str2) != kind)
         return 0;
     const void *data1 = PyUnicode_DATA(str1);
     const void *data2 = PyUnicode_DATA(str2);
-    return memcmp(data1, data2, len * kind) == 0;
+    return memcmp(data1, data2, str1_length * kind) == 0;
+}
+
+// Adapted from CPython 3.13.1 (_PyUnicode_Equal)
+char CPyStr_Equal(PyObject *str1, PyObject *str2) {
+    if (str1 == str2) {
+        return 1;
+    }
+    Py_ssize_t str2_length = PyUnicode_GET_LENGTH(str2);
+    return _CPyStr_Equal_NoIdentCheck(str1, str2, str2_length);
+}
+
+char CPyStr_EqualLiteral(PyObject *str1, PyObject *str2, Py_ssize_t literal_length) {
+    if (str1 == str2) {
+        return 1;
+    }
+    return _CPyStr_Equal_NoIdentCheck(str1, str2, literal_length)    
 }
 
 PyObject *CPyStr_GetItem(PyObject *str, CPyTagged index) {
diff --git a/mypyc/primitives/str_ops.py b/mypyc/primitives/str_ops.py
index a8f4e4df74c2d..d39f1f872763e 100644
--- a/mypyc/primitives/str_ops.py
+++ b/mypyc/primitives/str_ops.py
@@ -88,6 +88,14 @@
     error_kind=ERR_NEVER,
 )
 
+str_eq_literal = custom_primitive_op(
+    name="str_eq_literal",
+    c_function_name="CPyStr_EqualLiteral",
+    arg_types=[str_rprimitive, str_rprimitive, c_pyssize_t_rprimitive],
+    return_type=bool_rprimitive,
+    error_kind=ERR_NEVER,
+)
+
 unicode_compare = custom_op(
     arg_types=[str_rprimitive, str_rprimitive],
     return_type=c_int_rprimitive,

From c3c04a57b61780e97c3b881919aaf7fec14f122f Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 18 Sep 2025 18:20:41 +0000
Subject: [PATCH 02/26] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/lib-rt/str_ops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/lib-rt/str_ops.c b/mypyc/lib-rt/str_ops.c
index 01e85002f9f7c..fb4e956ad4cf9 100644
--- a/mypyc/lib-rt/str_ops.c
+++ b/mypyc/lib-rt/str_ops.c
@@ -90,7 +90,7 @@ char CPyStr_EqualLiteral(PyObject *str1, PyObject *str2, Py_ssize_t literal_leng
     if (str1 == str2) {
         return 1;
     }
-    return _CPyStr_Equal_NoIdentCheck(str1, str2, literal_length)    
+    return _CPyStr_Equal_NoIdentCheck(str1, str2, literal_length)
 }
 
 PyObject *CPyStr_GetItem(PyObject *str, CPyTagged index) {

From 6528245920f0f9fa3a36ee4295432f95d7f54491 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 18 Sep 2025 14:36:13 -0400
Subject: [PATCH 03/26] refactor

---
 mypyc/irbuild/ll_builder.py | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index e290b7c91adb4..868f8eac86189 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1551,21 +1551,31 @@ def check_tagged_short_int(self, val: Value, line: int, negated: bool = False) -
 
     def compare_strings(self, lhs: Value, rhs: Value, op: str, line: int) -> Value:
         """Compare two strings"""
+        
+        def is_string_literal(value: Value) -> bool:
+            return isinstance(value, LoadLiteral) and is_str_rprimitive(value.type)
+        
         if op == "==":
-            if isinstance(lhs, LoadLiteral) and is_str_rprimitive(lhs.type):
-                literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)
+            if is_string_literal(lhs):
+                if is_string_literal(rhs):
+                    # we can optimize out the check entirely in some Final cases
+                    return self.true() if lhs.value == rhs.value else self.false()
+                literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
                 return self.primitive_op(str_eq_literal, [rhs, lhs, literal_length], line)
-            elif isinstance(rhs, LoadLiteral) and is_str_rprimitive(rhs.type):
-                literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)
+            elif is_string_literal(rhs):
+                literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
                 return self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
             return self.primitive_op(str_eq, [lhs, rhs], line)
         elif op == "!=":
-            if isinstance(lhs, LoadLiteral) and is_str_rprimitive(lhs.type):
-                literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)
-                eq = self.primitive_op(str_eq_literal, [rhs, lhs, literal_length])
-            elif isinstance(rhs, LoadLiteral) and is_str_rprimitive(rhs.type):
-                literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)
-                eq = self.primitive_op(str_eq_literal, [lhs, rhs, literal_length])
+            if is_string_literal(lhs):
+                if is_string_literal(rhs):
+                    # we can optimize out the check entirely in some Final cases
+                    return self.true() if lhs.value != rhs.value else self.false()
+                literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
+                eq = self.primitive_op(str_eq_literal, [rhs, lhs, literal_length], line)
+            elif is_string_literal(rhs):
+                literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
+                eq = self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
             else:
                 eq = self.primitive_op(str_eq, [lhs, rhs], line)
             return self.add(ComparisonOp(eq, self.false(), ComparisonOp.EQ, line))

From d781dde9471dea619b9e905429f448ea43b76adb Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 18 Sep 2025 18:37:40 +0000
Subject: [PATCH 04/26] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/ll_builder.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 868f8eac86189..891ca93eb6e3c 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1551,10 +1551,10 @@ def check_tagged_short_int(self, val: Value, line: int, negated: bool = False) -
 
     def compare_strings(self, lhs: Value, rhs: Value, op: str, line: int) -> Value:
         """Compare two strings"""
-        
+
         def is_string_literal(value: Value) -> bool:
             return isinstance(value, LoadLiteral) and is_str_rprimitive(value.type)
-        
+
         if op == "==":
             if is_string_literal(lhs):
                 if is_string_literal(rhs):

From 2580b10f83d735f508c8ee0c9eeb88342ea8e0d5 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 18 Sep 2025 14:41:02 -0400
Subject: [PATCH 05/26] Update ll_builder.py

---
 mypyc/irbuild/ll_builder.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 891ca93eb6e3c..d71c480b961f3 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -8,7 +8,7 @@
 
 import sys
 from collections.abc import Sequence
-from typing import Callable, Final, Optional
+from typing import Callable, Final, Optional, TypeGuard
 
 from mypy.argmap import map_actuals_to_formals
 from mypy.nodes import ARG_POS, ARG_STAR, ARG_STAR2, ArgKind
@@ -1552,7 +1552,7 @@ def check_tagged_short_int(self, val: Value, line: int, negated: bool = False) -
     def compare_strings(self, lhs: Value, rhs: Value, op: str, line: int) -> Value:
         """Compare two strings"""
 
-        def is_string_literal(value: Value) -> bool:
+        def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
             return isinstance(value, LoadLiteral) and is_str_rprimitive(value.type)
 
         if op == "==":

From fea651dc8b9df12cb2d965d5ee6575ee299fb458 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 18 Sep 2025 14:41:44 -0400
Subject: [PATCH 06/26] Update ll_builder.py

---
 mypyc/irbuild/ll_builder.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index d71c480b961f3..bdd2eeeda5150 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -8,7 +8,9 @@
 
 import sys
 from collections.abc import Sequence
-from typing import Callable, Final, Optional, TypeGuard
+from typing import Callable, Final, Optional
+
+from typing_extensions import TypeGuard
 
 from mypy.argmap import map_actuals_to_formals
 from mypy.nodes import ARG_POS, ARG_STAR, ARG_STAR2, ArgKind

From 9ed369cefa50af65ccab22b6a41482bf337b321a Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 18 Sep 2025 18:45:47 +0000
Subject: [PATCH 07/26] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/ll_builder.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index bdd2eeeda5150..0a58369d10b2e 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -9,7 +9,6 @@
 import sys
 from collections.abc import Sequence
 from typing import Callable, Final, Optional
-
 from typing_extensions import TypeGuard
 
 from mypy.argmap import map_actuals_to_formals

From fb2118795dc0eb019b26cb3162f572024f87f6f1 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 18 Sep 2025 14:54:57 -0400
Subject: [PATCH 08/26] fix: missing ;

---
 mypyc/lib-rt/str_ops.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mypyc/lib-rt/str_ops.c b/mypyc/lib-rt/str_ops.c
index fb4e956ad4cf9..d61e14f96e141 100644
--- a/mypyc/lib-rt/str_ops.c
+++ b/mypyc/lib-rt/str_ops.c
@@ -65,7 +65,7 @@ make_bloom_mask(int kind, const void* ptr, Py_ssize_t len)
 }
 
 static char _CPyStr_Equal_NoIdentCheck(PyObject *str1, PyObject *str2, Py_ssize_t str2_length) {
-    // This helper function only exists to deduplicate code
+    // This helper function only exists to deduplicate code in CPyStr_Equal and CPyStr_EqualLiteral
     Py_ssize_t str1_length = PyUnicode_GET_LENGTH(str1);
     if (str1_length != str2_length)
         return 0;
@@ -86,11 +86,11 @@ char CPyStr_Equal(PyObject *str1, PyObject *str2) {
     return _CPyStr_Equal_NoIdentCheck(str1, str2, str2_length);
 }
 
-char CPyStr_EqualLiteral(PyObject *str1, PyObject *str2, Py_ssize_t literal_length) {
-    if (str1 == str2) {
+char CPyStr_EqualLiteral(PyObject *str, PyObject *literal_str, Py_ssize_t literal_length) {
+    if (str == literal_str) {
         return 1;
     }
-    return _CPyStr_Equal_NoIdentCheck(str1, str2, literal_length)
+    return _CPyStr_Equal_NoIdentCheck(str1, str2, literal_length);
 }
 
 PyObject *CPyStr_GetItem(PyObject *str, CPyTagged index) {

From a0d36ec5597bd2f6b7694d4bfccc73ff3ce8083b Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 18 Sep 2025 15:03:19 -0400
Subject: [PATCH 09/26] fix name err

---
 mypyc/lib-rt/str_ops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/lib-rt/str_ops.c b/mypyc/lib-rt/str_ops.c
index d61e14f96e141..abc0de5db2d85 100644
--- a/mypyc/lib-rt/str_ops.c
+++ b/mypyc/lib-rt/str_ops.c
@@ -90,7 +90,7 @@ char CPyStr_EqualLiteral(PyObject *str, PyObject *literal_str, Py_ssize_t litera
     if (str == literal_str) {
         return 1;
     }
-    return _CPyStr_Equal_NoIdentCheck(str1, str2, literal_length);
+    return _CPyStr_Equal_NoIdentCheck(str, literal_str, literal_length);
 }
 
 PyObject *CPyStr_GetItem(PyObject *str, CPyTagged index) {

From 577cd74ebb7ca9a189f7897251c498c3e55f1b42 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 18 Sep 2025 15:21:23 -0400
Subject: [PATCH 10/26] Update CPy.h

---
 mypyc/lib-rt/CPy.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mypyc/lib-rt/CPy.h b/mypyc/lib-rt/CPy.h
index 5dec7509ac7b9..d75ae31b66627 100644
--- a/mypyc/lib-rt/CPy.h
+++ b/mypyc/lib-rt/CPy.h
@@ -734,6 +734,7 @@ static inline char CPyDict_CheckSize(PyObject *dict, Py_ssize_t size) {
 #define BOTHSTRIP  2
 
 char CPyStr_Equal(PyObject *str1, PyObject *str2);
+char CPyStr_EqualLiteral(PyObject *str, PyObject *literal_str, Py_ssize_t literal_length);
 PyObject *CPyStr_Build(Py_ssize_t len, ...);
 PyObject *CPyStr_GetItem(PyObject *str, CPyTagged index);
 PyObject *CPyStr_GetItemUnsafe(PyObject *str, Py_ssize_t index);

From 9bec5811fa255d36896f03e37dcc03e1b1a79956 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 18 Sep 2025 15:24:29 -0400
Subject: [PATCH 11/26] Update irbuild-dict.test

---
 mypyc/test-data/irbuild-dict.test | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/test-data/irbuild-dict.test b/mypyc/test-data/irbuild-dict.test
index e0c014f078138..e7a330951ab0d 100644
--- a/mypyc/test-data/irbuild-dict.test
+++ b/mypyc/test-data/irbuild-dict.test
@@ -410,7 +410,7 @@ L2:
     k = r8
     v = r7
     r9 = 'name'
-    r10 = CPyStr_Equal(k, r9)
+    r10 = CPyStr_EqualLiteral(k, r9, 4)
     if r10 goto L3 else goto L4 :: bool
 L3:
     name = v

From bdee878ae78dc78d7be60e18a84665b0e6d36f94 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 18 Sep 2025 15:25:09 -0400
Subject: [PATCH 12/26] Update irbuild-unreachable.test

---
 mypyc/test-data/irbuild-unreachable.test | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mypyc/test-data/irbuild-unreachable.test b/mypyc/test-data/irbuild-unreachable.test
index a4f1ef8c7dba4..8eafede66b56e 100644
--- a/mypyc/test-data/irbuild-unreachable.test
+++ b/mypyc/test-data/irbuild-unreachable.test
@@ -20,7 +20,7 @@ L0:
     r2 = CPyObject_GetAttr(r0, r1)
     r3 = cast(str, r2)
     r4 = 'x'
-    r5 = CPyStr_Equal(r3, r4)
+    r5 = CPyStr_EqualLiteral(r3, r4, 1)
     if r5 goto L2 else goto L1 :: bool
 L1:
     r6 = r5
@@ -54,7 +54,7 @@ L0:
     r2 = CPyObject_GetAttr(r0, r1)
     r3 = cast(str, r2)
     r4 = 'x'
-    r5 = CPyStr_Equal(r3, r4)
+    r5 = CPyStr_EqualLiteral(r3, r4, 1)
     if r5 goto L2 else goto L1 :: bool
 L1:
     r6 = r5

From 613f644e2f6abfeb3eb693053e9c84e66ebf5b74 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Tue, 30 Sep 2025 10:35:53 -0400
Subject: [PATCH 13/26] Update irbuild-classes.test

---
 mypyc/test-data/irbuild-classes.test | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mypyc/test-data/irbuild-classes.test b/mypyc/test-data/irbuild-classes.test
index a98b3a7d3dcf9..b2313ccba911e 100644
--- a/mypyc/test-data/irbuild-classes.test
+++ b/mypyc/test-data/irbuild-classes.test
@@ -2302,7 +2302,7 @@ def SetAttr.__setattr__(self, key, val):
     r12 :: bit
 L0:
     r0 = 'regular_attr'
-    r1 = CPyStr_Equal(key, r0)
+    r1 = CPyStr_EqualLiteral(key, r0, 12)
     if r1 goto L1 else goto L2 :: bool
 L1:
     r2 = unbox(int, val)
@@ -2310,7 +2310,7 @@ L1:
     goto L6
 L2:
     r4 = 'class_var'
-    r5 = CPyStr_Equal(key, r4)
+    r5 = CPyStr_EqualLiteral(key, r4, 9)
     if r5 goto L3 else goto L4 :: bool
 L3:
     r6 = builtins :: module

From e99864d767cf4ad40a513e8f0603f04bed088914 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Wed, 1 Oct 2025 05:25:38 -0400
Subject: [PATCH 14/26] Update ll_builder.py

---
 mypyc/irbuild/ll_builder.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index fba3b925d03c4..4bd6873645807 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1559,7 +1559,7 @@ def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
         if op == "==":
             if is_string_literal(lhs):
                 if is_string_literal(rhs):
-                    # we can optimize out the check entirely in some Final cases
+                    # we can optimize out the check entirely in some constant-folded cases
                     return self.true() if lhs.value == rhs.value else self.false()
                 literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
                 return self.primitive_op(str_eq_literal, [rhs, lhs, literal_length], line)
@@ -1570,7 +1570,7 @@ def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
         elif op == "!=":
             if is_string_literal(lhs):
                 if is_string_literal(rhs):
-                    # we can optimize out the check entirely in some Final cases
+                    # we can optimize out the check entirely in some constant-folded cases
                     return self.true() if lhs.value != rhs.value else self.false()
                 literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
                 eq = self.primitive_op(str_eq_literal, [rhs, lhs, literal_length], line)

From 001421222348b0d223c3bc688c193319fa170952 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Wed, 1 Oct 2025 09:54:37 -0400
Subject: [PATCH 15/26] refactor

---
 mypyc/irbuild/ll_builder.py | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 4bd6873645807..27042c31df115 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1568,17 +1568,8 @@ def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
                 return self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
             return self.primitive_op(str_eq, [lhs, rhs], line)
         elif op == "!=":
-            if is_string_literal(lhs):
-                if is_string_literal(rhs):
-                    # we can optimize out the check entirely in some constant-folded cases
-                    return self.true() if lhs.value != rhs.value else self.false()
-                literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
-                eq = self.primitive_op(str_eq_literal, [rhs, lhs, literal_length], line)
-            elif is_string_literal(rhs):
-                literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
-                eq = self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
-            else:
-                eq = self.primitive_op(str_eq, [lhs, rhs], line)
+            # perform a standard equality check, then negate
+            eq = compare_strings(lhs, rhs, "==", line)
             return self.add(ComparisonOp(eq, self.false(), ComparisonOp.EQ, line))
 
         # TODO: modify 'str' to use same interface as 'compare_bytes' as it would avoid

From 4f8786fcd565e4f0f4e30e9fd7984fa2921cc0e1 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Wed, 1 Oct 2025 09:57:16 -0400
Subject: [PATCH 16/26] refactor

---
 mypyc/irbuild/ll_builder.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 27042c31df115..027ad84f56e05 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1552,11 +1552,12 @@ def check_tagged_short_int(self, val: Value, line: int, negated: bool = False) -
 
     def compare_strings(self, lhs: Value, rhs: Value, op: str, line: int) -> Value:
         """Compare two strings"""
-
-        def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
-            return isinstance(value, LoadLiteral) and is_str_rprimitive(value.type)
-
         if op == "==":
+            # We can specialize this case if one or both values are string literals
+            
+            def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
+                return isinstance(value, LoadLiteral) and is_str_rprimitive(value.type)
+                
             if is_string_literal(lhs):
                 if is_string_literal(rhs):
                     # we can optimize out the check entirely in some constant-folded cases
@@ -1567,6 +1568,7 @@ def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
                 literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
                 return self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
             return self.primitive_op(str_eq, [lhs, rhs], line)
+            
         elif op == "!=":
             # perform a standard equality check, then negate
             eq = compare_strings(lhs, rhs, "==", line)

From 996c4d6f6d2cabaf0e7a3c5280d4d36f7f563e20 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Wed, 1 Oct 2025 13:58:38 +0000
Subject: [PATCH 17/26] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/ll_builder.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 027ad84f56e05..4b1fa1516ced9 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1554,10 +1554,10 @@ def compare_strings(self, lhs: Value, rhs: Value, op: str, line: int) -> Value:
         """Compare two strings"""
         if op == "==":
             # We can specialize this case if one or both values are string literals
-            
+
             def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
                 return isinstance(value, LoadLiteral) and is_str_rprimitive(value.type)
-                
+
             if is_string_literal(lhs):
                 if is_string_literal(rhs):
                     # we can optimize out the check entirely in some constant-folded cases
@@ -1568,7 +1568,7 @@ def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
                 literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
                 return self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
             return self.primitive_op(str_eq, [lhs, rhs], line)
-            
+
         elif op == "!=":
             # perform a standard equality check, then negate
             eq = compare_strings(lhs, rhs, "==", line)

From 4054151ea8a69a9905783c4ef8d72ceac73d626a Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Wed, 1 Oct 2025 10:14:08 -0400
Subject: [PATCH 18/26] Update ll_builder.py

---
 mypyc/irbuild/ll_builder.py | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 4b1fa1516ced9..36a42d54fb272 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1554,6 +1554,7 @@ def compare_strings(self, lhs: Value, rhs: Value, op: str, line: int) -> Value:
         """Compare two strings"""
         if op == "==":
             # We can specialize this case if one or both values are string literals
+            literal_fastpath = False
 
             def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
                 return isinstance(value, LoadLiteral) and is_str_rprimitive(value.type)
@@ -1562,11 +1563,18 @@ def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
                 if is_string_literal(rhs):
                     # we can optimize out the check entirely in some constant-folded cases
                     return self.true() if lhs.value == rhs.value else self.false()
-                literal_length = Integer(len(lhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
-                return self.primitive_op(str_eq_literal, [rhs, lhs, literal_length], line)
+                
+                # if lhs argument is string literal, switch sides to match specializer C api
+                lhs, rhs = rhs, lhs
+                literal_fastpath = True
             elif is_string_literal(rhs):
-                literal_length = Integer(len(rhs.value), c_pyssize_t_rprimitive, line)  # type: ignore [arg-type]
+                literal_fastpath = True
+                
+            if literal_fastpath:
+                literal_string = cast(str, cast(LoadLiteral, rhs).value)
+                literal_length = Integer(len(literal_string), c_pyssize_t_rprimitive, line)
                 return self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
+            
             return self.primitive_op(str_eq, [lhs, rhs], line)
 
         elif op == "!=":

From f22d8ac9612ea6bb41c68506b2081a385e7e24af Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Wed, 1 Oct 2025 14:15:29 +0000
Subject: [PATCH 19/26] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/ll_builder.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 36a42d54fb272..45cc7397c15f7 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1563,18 +1563,18 @@ def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
                 if is_string_literal(rhs):
                     # we can optimize out the check entirely in some constant-folded cases
                     return self.true() if lhs.value == rhs.value else self.false()
-                
+
                 # if lhs argument is string literal, switch sides to match specializer C api
                 lhs, rhs = rhs, lhs
                 literal_fastpath = True
             elif is_string_literal(rhs):
                 literal_fastpath = True
-                
+
             if literal_fastpath:
                 literal_string = cast(str, cast(LoadLiteral, rhs).value)
                 literal_length = Integer(len(literal_string), c_pyssize_t_rprimitive, line)
                 return self.primitive_op(str_eq_literal, [lhs, rhs, literal_length], line)
-            
+
             return self.primitive_op(str_eq, [lhs, rhs], line)
 
         elif op == "!=":

From b95facdf15a7496ece5bc38a861ae3ec6462f4b2 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Wed, 1 Oct 2025 10:39:18 -0400
Subject: [PATCH 20/26] missing import

---
 mypyc/irbuild/ll_builder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 45cc7397c15f7..96039379d0c8f 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -8,7 +8,7 @@
 
 import sys
 from collections.abc import Sequence
-from typing import Callable, Final, Optional
+from typing import Callable, Final, Optional, cast
 from typing_extensions import TypeGuard
 
 from mypy.argmap import map_actuals_to_formals

From e27c716cf09c8ed433f53a5c7f2b47822ad8a157 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Wed, 1 Oct 2025 10:49:08 -0400
Subject: [PATCH 21/26] Update ll_builder.py

---
 mypyc/irbuild/ll_builder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 96039379d0c8f..d33497d4987bd 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -1579,7 +1579,7 @@ def is_string_literal(value: Value) -> TypeGuard[LoadLiteral]:
 
         elif op == "!=":
             # perform a standard equality check, then negate
-            eq = compare_strings(lhs, rhs, "==", line)
+            eq = self.compare_strings(lhs, rhs, "==", line)
             return self.add(ComparisonOp(eq, self.false(), ComparisonOp.EQ, line))
 
         # TODO: modify 'str' to use same interface as 'compare_bytes' as it would avoid

From 28c651055a5b814c84c5153fbdc30550bdfc2e4c Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Fri, 10 Oct 2025 13:11:25 -0400
Subject: [PATCH 22/26] Update irbuild-classes.test

---
 mypyc/test-data/irbuild-classes.test | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mypyc/test-data/irbuild-classes.test b/mypyc/test-data/irbuild-classes.test
index 8f149def56d92..3280b21cf7e66 100644
--- a/mypyc/test-data/irbuild-classes.test
+++ b/mypyc/test-data/irbuild-classes.test
@@ -2468,7 +2468,7 @@ def SetAttr.__setattr__(self, key, val):
     r12 :: bit
 L0:
     r0 = 'regular_attr'
-    r1 = CPyStr_Equal(key, r0)
+    r1 = CPyStr_EqualLiteral(key, r0, 12)
     if r1 goto L1 else goto L2 :: bool
 L1:
     r2 = unbox(int, val)
@@ -2476,7 +2476,7 @@ L1:
     goto L6
 L2:
     r4 = 'class_var'
-    r5 = CPyStr_Equal(key, r4)
+    r5 = CPyStr_EqualLiteral(key, r4, 9)
     if r5 goto L3 else goto L4 :: bool
 L3:
     r6 = builtins :: module

From b957e1489994f56a755716f1bd4f4e74c1e5f4f0 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Mon, 13 Oct 2025 14:02:46 -0400
Subject: [PATCH 23/26] Update str_ops.c

---
 mypyc/lib-rt/str_ops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/lib-rt/str_ops.c b/mypyc/lib-rt/str_ops.c
index abc0de5db2d85..f16e99bb4159b 100644
--- a/mypyc/lib-rt/str_ops.c
+++ b/mypyc/lib-rt/str_ops.c
@@ -64,7 +64,7 @@ make_bloom_mask(int kind, const void* ptr, Py_ssize_t len)
 #undef BLOOM_UPDATE
 }
 
-static char _CPyStr_Equal_NoIdentCheck(PyObject *str1, PyObject *str2, Py_ssize_t str2_length) {
+static inline char _CPyStr_Equal_NoIdentCheck(PyObject *str1, PyObject *str2, Py_ssize_t str2_length) {
     // This helper function only exists to deduplicate code in CPyStr_Equal and CPyStr_EqualLiteral
     Py_ssize_t str1_length = PyUnicode_GET_LENGTH(str1);
     if (str1_length != str2_length)

From ef0a46e50f7594c876949b4a66eba816d11cca7b Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Tue, 14 Oct 2025 06:09:32 -0400
Subject: [PATCH 24/26] Update irbuild-str.test

---
 mypyc/test-data/irbuild-str.test | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/mypyc/test-data/irbuild-str.test b/mypyc/test-data/irbuild-str.test
index 3fa39819498de..75c3689aa2dc6 100644
--- a/mypyc/test-data/irbuild-str.test
+++ b/mypyc/test-data/irbuild-str.test
@@ -740,3 +740,16 @@ L2:
 L3:
     keep_alive x
     return r2
+
+[case testStrEqLiteral]
+from typing import Final
+literal: Final = "literal"
+def literal_rhs(x: str) -> bool:
+    return x == literal
+def literal_lhs(x: str) -> bool:
+    return literal == x
+[out]
+def literal_rhs(x):
+L0:
+def literal_lhs(x):
+L0:

From 60c093f17efef7b929fa82c509807915ddc228b0 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Tue, 14 Oct 2025 06:11:43 -0400
Subject: [PATCH 25/26] Update irbuild-str.test

---
 mypyc/test-data/irbuild-str.test | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mypyc/test-data/irbuild-str.test b/mypyc/test-data/irbuild-str.test
index 75c3689aa2dc6..cc2b5576f7fc4 100644
--- a/mypyc/test-data/irbuild-str.test
+++ b/mypyc/test-data/irbuild-str.test
@@ -748,8 +748,15 @@ def literal_rhs(x: str) -> bool:
     return x == literal
 def literal_lhs(x: str) -> bool:
     return literal == x
+def literal_both() -> bool:
+    return literal == "literal"
 [out]
 def literal_rhs(x):
+    x :: str
 L0:
 def literal_lhs(x):
+    x :: str
+L0:
+def literal_both():
+    r0 :: bool
 L0:

From e494f0c376f08a37b7836811e5de09f9512a29df Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Tue, 14 Oct 2025 06:32:41 -0400
Subject: [PATCH 26/26] Update irbuild-str.test

---
 mypyc/test-data/irbuild-str.test | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/mypyc/test-data/irbuild-str.test b/mypyc/test-data/irbuild-str.test
index cc2b5576f7fc4..056f120c7bac0 100644
--- a/mypyc/test-data/irbuild-str.test
+++ b/mypyc/test-data/irbuild-str.test
@@ -752,11 +752,22 @@ def literal_both() -> bool:
     return literal == "literal"
 [out]
 def literal_rhs(x):
-    x :: str
+    x, r0 :: str
+    r1 :: bool
 L0:
+    r0 = 'literal'
+    r1 = CPyStr_EqualLiteral(x, r0, 7)
+    return r1
 def literal_lhs(x):
-    x :: str
+    x, r0 :: str
+    r1 :: bool
 L0:
+    r0 = 'literal'
+    r1 = CPyStr_EqualLiteral(x, r0, 7)
+    return r1
 def literal_both():
-    r0 :: bool
+    r0, r1 :: str
 L0:
+    r0 = 'literal'
+    r1 = 'literal'
+    return 1