[llvm] 25aac60 - [lit] Use text mode when opening text files on z/OS (#217434)

[via llvm-commits]

Author: Abhina Sree
Date: 2026-09-22T08:52:51-04:00
New Revision: 25aac605a4f1fc72bd1dcf0bb8d64fbfe2db3aa9

URL: https://github.com/llvm/llvm-project/commit/25aac605a4f1fc72bd1dcf0bb8d64fbfe2db3aa9
DIFF: https://github.com/llvm/llvm-project/commit/25aac605a4f1fc72bd1dcf0bb8d64fbfe2db3aa9.diff

LOG: [lit] Use text mode when opening text files on z/OS (#217434)

On z/OS, we rely on autoconversion to read files correctly, and this
requires files to be opened as text.

The following change https://github.com/llvm/llvm-project/pull/208024
changed the streams to be read and piped as binary resulting in some
test regressions due to unreadable output. This patch restores the
functionality of opening and reading as a text stream.

Added: 
    

Modified: 
    llvm/utils/lit/lit/TestRunner.py
    llvm/utils/lit/lit/builtin_commands/cat.py
    llvm/utils/lit/lit/builtin_commands/diff.py

Removed: 
    


################################################################################
diff  --git a/llvm/utils/lit/lit/TestRunner.py b/llvm/utils/lit/lit/TestRunner.py
index 1d4480f81f873..425255125db9c 100644
--- a/llvm/utils/lit/lit/TestRunner.py
+++ b/llvm/utils/lit/lit/TestRunner.py
@@ -5,6 +5,7 @@
 import io
 import os
 import pathlib
+import platform
 import re
 import shlex
 import signal
@@ -404,7 +405,8 @@ def _make_out_sink(stdout: int | TextIO, is_last: bool) -> IO[bytes] | None:
         last stage or a non-pipe target, which don't need this sink.
     """
     if stdout == subprocess.PIPE and not is_last:
-        return tempfile.SpooledTemporaryFile(max_size=1 << 20)
+        _mode = "w+" if platform.system() == "OS/390" else "w+b"
+        return tempfile.SpooledTemporaryFile(max_size=1 << 20, mode=_mode)
     return None
 
 

diff  --git a/llvm/utils/lit/lit/builtin_commands/cat.py b/llvm/utils/lit/lit/builtin_commands/cat.py
index bfd6e86f46bdb..2882b79f572fd 100644
--- a/llvm/utils/lit/lit/builtin_commands/cat.py
+++ b/llvm/utils/lit/lit/builtin_commands/cat.py
@@ -90,8 +90,17 @@ def run(argv, stdin, stdout, stderr, cwd):
 
         if show_nonprinting:
             contents = convertToCaretAndMNotation(contents)
-        elif is_text:
-            contents = contents.encode()
+
+        # Determine if stdout expects text or binary
+        mode = getattr(stdout, "mode", "b")
+        is_text_output = "b" not in mode
+
+        if is_text_output:
+            if isinstance(contents, bytes):
+                contents = contents.decode()
+        else:
+            if isinstance(contents, str):
+                contents = contents.encode()
         stdout.write(contents)
     return 0
 

diff  --git a/llvm/utils/lit/lit/builtin_commands/
diff .py b/llvm/utils/lit/lit/builtin_commands/
diff .py
index 3a85d2210705f..7f286fd5e16be 100644
--- a/llvm/utils/lit/lit/builtin_commands/
diff .py
+++ b/llvm/utils/lit/lit/builtin_commands/
diff .py
@@ -5,6 +5,7 @@
 import os
 import re
 import sys
+import platform
 
 # 
diff .py runs in two modes during the in-process migration:
 #   - In-process: imported as 'lit.builtin_commands.
diff ', so __package__ is
@@ -63,11 +64,22 @@ def getDirTree(path, basedir=""):
 def compareTwoFiles(flags, filepaths, stdin, stdout):
     filelines = []
     for file in filepaths:
+        is_text = False
         if file == "-":
             filelines.append(stdin.readlines())
         else:
-            with open(file, "rb") as file_bin:
-                filelines.append(file_bin.readlines())
+            if platform.system() == "OS/390":
+                try:
+                    with open(file, "r") as file_text:
+                        filelines.append(
+                            file_text.read().encode().splitlines(keepends=True)
+                        )
+                        is_text = True
+                except:
+                    pass
+            if not is_text:
+                with open(file, "rb") as file_bin:
+                    filelines.append(file_bin.readlines())
 
     try:
         return compareTwoTextFiles(