[llvm] [utils] Add script to generate elaborated IR and assembly tests (PR #89026)

[Nikita Popov via llvm-commits]

nikic wrote:

It looks like https://lab.llvm.org/buildbot/#/builders/67 has been failing for a long time due to this?
```
# .---command stderr------------
# | /home/buildbot/as-worker-92/clang-with-thin-lto-ubuntu/llvm-project/llvm/test/tools/UpdateTestChecks/update_test_body/gen-fail.test:3:10: error: CHECK: expected string not found in input
# | # CHECK: log
# |          ^
# | <stdin>:1:1: note: scanning from here
# | Traceback (most recent call last):
# | ^
# | <stdin>:1:12: note: possible intended match here
# | Traceback (most recent call last):
# |            ^
# | 
# | Input file: <stdin>
# | Check file: /home/buildbot/as-worker-92/clang-with-thin-lto-ubuntu/llvm-project/llvm/test/tools/UpdateTestChecks/update_test_body/gen-fail.test
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            1: Traceback (most recent call last): 
# | check:3'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
# | check:3'1                ?                        possible intended match
# |            2:  File "/home/buildbot/as-worker-92/clang-with-thin-lto-ubuntu/llvm-project/llvm/utils/update_test_body.py", line 108, in <module> 
# | check:3'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            3:  retcode = process(args, path) 
# | check:3'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            4:  File "/home/buildbot/as-worker-92/clang-with-thin-lto-ubuntu/llvm-project/llvm/utils/update_test_body.py", line 61, in process 
# | check:3'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            5:  check=True, 
# | check:3'0     ~~~~~~~~~~~~~
# |            6:  File "/usr/lib/python3.6/subprocess.py", line 423, in run 
# | check:3'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            .
# |            .
# |            .
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1
```
Unfortunately the backtrace cuts off before we get to the interesting part. 

https://github.com/llvm/llvm-project/pull/89026