[polly] fix(polly/**.py): fix comparison to None (PR #94021)

[Eisuke Kawashima via llvm-commits]

https://github.com/e-kwsm created https://github.com/llvm/llvm-project/pull/94021

from PEP8 (https://peps.python.org/pep-0008/#programming-recommendations):

> Comparisons to singletons like None should always be done with is or is not, never the equality operators.

>From 1f7b14926745f80ec9b0cf82dc3c977b8a11251c Mon Sep 17 00:00:00 2001
From: Eisuke Kawashima <e-kwsm at users.noreply.github.com>
Date: Sat, 11 May 2024 23:57:11 +0900
Subject: [PATCH] fix(polly/**.py): fix comparison to None

from PEP8 (https://peps.python.org/pep-0008/#programming-recommendations):

> Comparisons to singletons like None should always be done with is or
> is not, never the equality operators.
---
 polly/lib/External/isl/interface/python.cc | 2 +-
 polly/lib/External/isl/libisl-gdb.py       | 4 ++--
 polly/lib/External/isl/python/isl.py.top   | 4 ++--
 polly/test/lit.site.cfg.in                 | 2 +-
 polly/utils/pyscop/isl.py                  | 8 ++++----
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/polly/lib/External/isl/interface/python.cc b/polly/lib/External/isl/interface/python.cc
index e4a8288631297..b60bf315ca703 100644
--- a/polly/lib/External/isl/interface/python.cc
+++ b/polly/lib/External/isl/interface/python.cc
@@ -347,7 +347,7 @@ static void print_persistent_callback_failure_check(int indent,
 		printf(fmt, 0);
 		printf(", '%s') and ", callback_name.c_str());
 		printf(fmt, 0);
-		printf(".%s['exc_info'] != None:\n", callback_name.c_str());
+		printf(".%s['exc_info'] is not None:\n", callback_name.c_str());
 		print_indent(indent, "    exc_info = ");
 		printf(fmt, 0);
 		printf(".%s['exc_info'][0]\n", callback_name.c_str());
diff --git a/polly/lib/External/isl/libisl-gdb.py b/polly/lib/External/isl/libisl-gdb.py
index bf01bc583d15d..bdd3949cf89c0 100644
--- a/polly/lib/External/isl/libisl-gdb.py
+++ b/polly/lib/External/isl/libisl-gdb.py
@@ -70,7 +70,7 @@ def invoke(self, arg, from_tty):
         arg = gdb.parse_and_eval(arg)
         printer = str_lookup_function(arg)
 
-        if printer == None:
+        if printer is None:
             print("No isl printer for this type")
             return
 
@@ -90,7 +90,7 @@ def str_lookup_function(val):
     lookup_tag = val.type.target()
     regex = re.compile("^isl_(.*)$")
 
-    if lookup_tag == None:
+    if lookup_tag is None:
         return None
 
     m = regex.match(str(lookup_tag))
diff --git a/polly/lib/External/isl/python/isl.py.top b/polly/lib/External/isl/python/isl.py.top
index d041315d4e11d..9dc47a1a83251 100644
--- a/polly/lib/External/isl/python/isl.py.top
+++ b/polly/lib/External/isl/python/isl.py.top
@@ -3,7 +3,7 @@ from ctypes import *
 from ctypes.util import find_library
 
 isl_dyld_library_path = os.environ.get('ISL_DYLD_LIBRARY_PATH')
-if isl_dyld_library_path != None:
+if isl_dyld_library_path is not None:
     os.environ['DYLD_LIBRARY_PATH'] =  isl_dyld_library_path
 try:
     isl = cdll.LoadLibrary(isl_dlname)
@@ -29,7 +29,7 @@ class Context:
 
     @staticmethod
     def getDefaultInstance():
-        if Context.defaultInstance == None:
+        if Context.defaultInstance is None:
             Context.defaultInstance = Context()
         return Context.defaultInstance
 
diff --git a/polly/test/lit.site.cfg.in b/polly/test/lit.site.cfg.in
index d8a0b6ae3a3b2..f22063e796def 100644
--- a/polly/test/lit.site.cfg.in
+++ b/polly/test/lit.site.cfg.in
@@ -14,7 +14,7 @@ config.extra_paths = "@POLLY_TEST_EXTRA_PATHS@".split(";")
 ## Check the current platform with regex
 import re
 EAT_ERR_ON_X86 = ' '
-if (re.match(r'^x86_64*', '@LLVM_TARGET_TRIPLE@') == None) :
+if (re.match(r'^x86_64*', '@LLVM_TARGET_TRIPLE@') is None) :
   EAT_ERR_ON_X86 = '|| echo \"error is eaten\"'
 
 for arch in config.targets_to_build.split():
diff --git a/polly/utils/pyscop/isl.py b/polly/utils/pyscop/isl.py
index 5eaf7798e20b9..c06b7bca28042 100644
--- a/polly/utils/pyscop/isl.py
+++ b/polly/utils/pyscop/isl.py
@@ -24,7 +24,7 @@ def from_ptr(ptr):
 
     @staticmethod
     def getDefaultInstance():
-        if Context.defaultInstance == None:
+        if Context.defaultInstance is None:
             Context.defaultInstance = Context()
 
         return Context.defaultInstance
@@ -33,12 +33,12 @@ def getDefaultInstance():
 class IslObject:
     def __init__(self, string="", ctx=None, ptr=None):
         self.initialize_isl_methods()
-        if ptr != None:
+        if ptr is not None:
             self.ptr = ptr
             self.ctx = self.get_isl_method("get_ctx")(self)
             return
 
-        if ctx == None:
+        if ctx is None:
             ctx = Context.getDefaultInstance()
 
         self.ctx = ctx
@@ -236,7 +236,7 @@ class Printer:
     FORMAT_EXT_POLYLIB = 6
 
     def __init__(self, ctx=None):
-        if ctx == None:
+        if ctx is None:
             ctx = Context.getDefaultInstance()
 
         self.ctx = ctx