[Utils] Improved chunk-print-before-all.py script

[dbakunevich]

Summary

As part of this patch, the ability to work with dump files
containing ir after passes received using the -print-after-all
option was added to script chunk-print-before-all.py.
The names of the output files have also been changed.

Before: chunk-NUM.ll
Now: NUM-STAGE-PASS_NAME.ll

NUM - sequence number of the pass operation.
STAGE - stage of the pass operation (for example: before, after, dump).
PASS_NAME - the name of the pass.

[apilipenko]

llvm/utils/chunk-print-before-all.py

1–2

Update the comment

42–47

Extract into a helper and add a comment on what this code is doing?

[apilipenko]

llvm/utils/chunk-print-before-all.py

16–20

This should do the trick:

return re.split(' |<', short_line)[0]

llvm/utils/chunk-print-before-all.py

 #!/usr/bin/env python
 
 # Given a -print-before-all and/or -print-after-all -print-module-scope log from 
 # an opt invocation, chunk it into a series of individual IR files, one for each 
 # pass invocation. If the log ends with an obvious stack trace, try to split off 
 # a separate "crashinfo.txt" file leaving only the valid input IR in the last 
 # chunk. Files are written to current working directory.
 
 import sys
+import re
 
 chunk_id = 0
 
 # This function gets the pass name from the following line:
 # *** IR Dump Before/After PASS_NAME... ***
 def get_pass_name(line, prefix):
     short_line = line[line.find(prefix) + len(prefix) + 1:]
     return re.split(' |<', short_line)[0]
 
 def print_chunk(lines, prefix, pass_name):
     global chunk_id
     fname = str(chunk_id) + "-" + prefix + "-" + pass_name + ".ll"
     chunk_id = chunk_id + 1
     print("writing chunk " + fname + " (" + str(len(lines)) + " lines)")
     with open(fname, "w") as f:
         f.writelines(lines)
 
 is_dump = False
 cur = []
 for line in sys.stdin:
     if line.startswith("*** IR Dump Before "):
         if len(cur) != 0:
             print_chunk(cur, "before", pass_name)
             cur = []
         cur.append("; " + line)
         pass_name = get_pass_name(line, "Before")
     elif line.startswith("*** IR Dump After "):
         if len(cur) != 0:
             print_chunk(cur, "after", pass_name)
             cur = []
         cur.append("; " + line)
         pass_name = get_pass_name(line, "After")
     elif line.startswith("Stack dump:"):
         print_chunk(cur, "crash", pass_name)
         cur = []
         cur.append(line)
         is_dump = True
     else:
         cur.append(line)
 
 if is_dump:
     print("writing crashinfo.txt (" + str(len(cur)) + " lines)")
     with open("crashinfo.txt", "w") as f:
         f.writelines(cur)
 else:
     print_chunk(cur, "last", pass_name)