[BOLT][UTILS] Usability improvements for nfc-check-setup

[Amir]

Summary

1. Stash local changes before checkout.
2. Print a message that the source repository revision has been changed, with instructions to switch back.
3. Make the script executable.
4. Print sample instructions how to run bolt tests.
5. Assume that llvm-bolt-wrapper script is in the same source directory.

[Amir]

Stash changes before checkout

[rafauler]

LGTM, thanks!

Btw, the stashed changes can't be recovered by any of the commands listed in your print statement, right? You would need to run git stash apply

[Amir]

In D126941#3557170, @rafauler wrote:

LGTM, thanks!

Btw, the stashed changes can't be recovered by any of the commands listed in your print statement, right? You would need to run git stash apply

Right, I didn't provide commands to restore, assuming the user would know how to do that. I don't feel like making the script more complex for now, but if/when I forget what to do with the stash next time I use this script, I'll add that :)

bolt/utils/nfc-check-setup.py

 #!/usr/bin/env python3
 import argparse
 import os
 import re
 import shlex
 import subprocess
 import sys
 import textwrap
 
+def get_git_ref_or_rev(dir: str) -> str:
+    # Run 'git symbolic-ref -q --short HEAD || git rev-parse --short HEAD'
+    cmd_ref = 'git symbolic-ref -q --short HEAD'
+    ref = subprocess.run(shlex.split(cmd_ref), cwd=dir, text=True,
+                         stdout=subprocess.PIPE)
+    if not ref.returncode:
+        return ref.stdout.strip()
+    cmd_rev = 'git rev-parse --short HEAD'
+    return subprocess.check_output(shlex.split(cmd_rev), cwd=dir,
+                                   text=True).strip()
+
 
 def main():
     parser = argparse.ArgumentParser(description=textwrap.dedent('''
             This script builds two versions of BOLT (with the current and
             previous revision) and sets up symlink for llvm-bolt-wrapper.
             Passes the options through to llvm-bolt-wrapper.
             '''))
     parser.add_argument('build_dir', nargs='?', default=os.getcwd(),
                         help='Path to BOLT build directory, default is current directory')
     args, wrapper_args = parser.parse_known_args()
     bolt_path = f'{args.build_dir}/bin/llvm-bolt'
 
     source_dir = None
     # find the repo directory
     with open(f'{args.build_dir}/CMakeCache.txt') as f:
         for line in f:
             m = re.match(r'LLVM_SOURCE_DIR:STATIC=(.*)', line)
             if m:
                 source_dir = m.groups()[0]
     if not source_dir:
         sys.exit("Source directory is not found")
 
-    wrapper_path = os.path.abspath(
-        f'{source_dir}/../bolt/utils/llvm-bolt-wrapper.py')
+    script_dir = os.path.dirname(os.path.abspath(__file__))
+    wrapper_path = f'{script_dir}/llvm-bolt-wrapper.py'
     # build the current commit
     subprocess.run(shlex.split("cmake --build . --target llvm-bolt"),
                    cwd=args.build_dir)
     # rename llvm-bolt
     os.replace(bolt_path, f'{bolt_path}.new')
+    # memorize the old hash for logging
+    old_ref = get_git_ref_or_rev(source_dir)
+
+    # save local changes before checkout
+    subprocess.run(shlex.split("git stash"), cwd=source_dir)
     # check out the previous commit
-    subprocess.run(shlex.split("git checkout -f HEAD^"),
-                   cwd=source_dir)
+    subprocess.run(shlex.split("git checkout -f HEAD^"), cwd=source_dir)
+    # get the parent commit hash for logging
+    new_ref = get_git_ref_or_rev(source_dir)
     # build the previous commit
     subprocess.run(shlex.split("cmake --build . --target llvm-bolt"),
                    cwd=args.build_dir)
     # rename llvm-bolt
     os.replace(bolt_path, f'{bolt_path}.old')
     # set up llvm-bolt-wrapper.ini
     ini = subprocess.check_output(
         shlex.split(
             f"{wrapper_path} {bolt_path}.old {bolt_path}.new") + wrapper_args,
         text=True)
     with open(f'{args.build_dir}/bin/llvm-bolt-wrapper.ini', 'w') as f:
         f.write(ini)
     # symlink llvm-bolt-wrapper
     os.symlink(wrapper_path, bolt_path)
+    print(f"The repository {source_dir} has been switched from rev {old_ref} "
+          f"to {new_ref}. Local changes were stashed. Switch back using\n\t"
+          f"git checkout {old_ref}\n"
+          "Current build directory is ready to run BOLT tests, e.g.\n\t"
+          "bin/llvm-lit -sv tools/bolt/test\nor\n\t"
+          "bin/llvm-lit -sv tools/bolttests")
 
 
 if __name__ == "__main__":
     main()