Scrub FileCheck regex delimiters from test checks

[greened]

Summary

It's quite common for ScalarEvolution to emit a "{{" sequence, which FileCheck
will interpret as the start of a regular expression. Escape such patterns so
that we can correctly match them in the auto-generated checks.

[RKSimon]

Is there a suitable test case change?

[greened]

In D67728#1674499, @RKSimon wrote:

Is there a suitable test case change?

Are there tests for this tool? I ran into this issue with some downstream testing. I could mock-up a testcase but where does it go?

[xbolva00]

I could mock-up a testcase but where does it go?

As you mentioned SCEV, you can add new/update test for SCEV. But I dont think this "step" is required.

[greened]

In D67728#1678378, @xbolva00 wrote:

I could mock-up a testcase but where does it go?

As you mentioned SCEV, you can add new/update test for SCEV. But I dont think this "step" is required.

So, that leaves me with a question. What else needs to be done before getting this committed?

[greened]

In D67728#1686494, @greened wrote:

In D67728#1678378, @xbolva00 wrote:

I could mock-up a testcase but where does it go?

As you mentioned SCEV, you can add new/update test for SCEV. But I dont think this "step" is required.

So, that leaves me with a question. What else needs to be done before getting this committed?

Ping.

[MaskRay]

In D67728#1675450, @greened wrote:

In D67728#1674499, @RKSimon wrote:

Is there a suitable test case change?

Are there tests for this tool? I ran into this issue with some downstream testing. I could mock-up a testcase but where does it go?

You can attach a minimalist example with generated CHECK lines before/after this change in the summary. Logic in this script is very tricky and such examples in the git logs will be very helpful to a future poor soul hacking the source.

[RKSimon]

@greened reverse ping

llvm/utils/UpdateTestChecks/common.py

 MARCH_ARG_RE = re.compile(r'-march[= ]([^ ]+)')
 
 SCRUB_LEADING_WHITESPACE_RE = re.compile(r'^(\s+)')
 SCRUB_WHITESPACE_RE = re.compile(r'(?!^(|  \w))[ \t]+', flags=re.M)
 SCRUB_TRAILING_WHITESPACE_RE = re.compile(r'[ \t]+$', flags=re.M)
 SCRUB_KILL_COMMENT_RE = re.compile(r'^ *#+ +kill:.*\n')
 SCRUB_LOOP_COMMENT_RE = re.compile(
     r'# =>This Inner Loop Header:.*|# in Loop:.*', flags=re.M)
-
+SCRUB_FILECHECK_REGEX_RE = re.compile(r'{{')
+SCRUB_FILECHECK_REGEX_REPLACEMENT = r'{{[{][{]}}'
 
 def error(msg, test_file=None):
   if test_file:
     msg = '{}: {}'.format(msg, test_file)
   print('ERROR: {}'.format(msg), file=sys.stderr)
 
 def warn(msg, test_file=None):
   if test_file:
     msg = '{}: {}'.format(msg, test_file)
   print('WARNING: {}'.format(msg), file=sys.stderr)
 
 def scrub_body(body):
   # Scrub runs of whitespace out of the assembly, but leave the leading
   # whitespace in place.
   body = SCRUB_WHITESPACE_RE.sub(r' ', body)
   # Expand the tabs used for indentation.
   body = string.expandtabs(body, 2)
   # Strip trailing whitespace.
   body = SCRUB_TRAILING_WHITESPACE_RE.sub(r'', body)
+  # Munge anything that could be interpreted as a FileCheck regexp.
+  body = SCRUB_FILECHECK_REGEX_RE.sub(SCRUB_FILECHECK_REGEX_REPLACEMENT, body)
   return body
 
 def do_scrub(body, scrubber, scrubber_args, extra):
   if scrubber_args:
     local_args = copy.deepcopy(scrubber_args)
     local_args[0].extra_scrub = extra
     return scrubber(body, *local_args)
   return scrubber(body, *scrubber_args)