[llvm] [AIX] Use internal lit shell for TableGen instead of a global setting (PR #113627)

[Abhina Sree via llvm-commits]

https://github.com/abhina-sree created https://github.com/llvm/llvm-project/pull/113627

This is to address the latest lit regressions https://lab.llvm.org/buildbot/#/builders/64/builds/1285 caused by using the internal lit shell. This change will limit using the internal lit shell to TableGen on AIX so we do not hit these regressions.

>From 3c2ea230bb446f3355383e205ae379ef5bb146c1 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Thu, 24 Oct 2024 19:51:50 -0400
Subject: [PATCH 1/2] Revert "[lit][aix] Always use internal lit shell on AIX
 (#113355)"

This reverts commit 4583dbc7b85d25bdda652ad1afe5ec3e95183a16.
---
 llvm/utils/lit/lit/llvm/config.py | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/llvm/utils/lit/lit/llvm/config.py b/llvm/utils/lit/lit/llvm/config.py
index 1ef5796cd32e44..5f762ec7f3514a 100644
--- a/llvm/utils/lit/lit/llvm/config.py
+++ b/llvm/utils/lit/lit/llvm/config.py
@@ -57,13 +57,6 @@ def __init__(self, lit_config, config):
                 self.lit_config.note("using lit tools: {}".format(path))
                 lit_path_displayed = True
 
-        if platform.system() == "AIX":
-            # Diff on AIX doesn't have all the required features (see
-            # https://github.com/llvm/llvm-project/pull/108871 and
-            # https://github.com/llvm/llvm-project/pull/112997#issuecomment-2429656192)
-            # so always use the internal shell.
-            self.use_lit_shell = True
-
         if platform.system() == "OS/390":
             self.with_environment("_BPXK_AUTOCVT", "ON")
             self.with_environment("_TAG_REDIR_IN", "TXT")

>From a7a85bfbec84a775df9c232b1c78c6249a3c95d4 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Thu, 24 Oct 2024 19:52:20 -0400
Subject: [PATCH 2/2] Use internal lit shell for TableGen only

---
 llvm/test/TableGen/lit.local.cfg | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/llvm/test/TableGen/lit.local.cfg b/llvm/test/TableGen/lit.local.cfg
index 0e827479cd4123..1993ff5f16cbee 100644
--- a/llvm/test/TableGen/lit.local.cfg
+++ b/llvm/test/TableGen/lit.local.cfg
@@ -1,2 +1,8 @@
+import lit.formats
+
 config.suffixes = [".td"]
 config.excludes = ["Common", "Inputs"]
+
+# AIX 'diff' command doesn't support --strip-trailing-cr, but the internal
+# python implementation does, so use that for cross platform compatibility
+config.test_format = lit.formats.ShTest()