[llvm] [utils][UpdateLLCTestChecks] Add MIR support to update_llc_test_checks.py. (PR #164965)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-armv8-quick` running on `linaro-clang-armv8-quick` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/154/builds/23625

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'LLVM :: tools/UpdateTestChecks/update_llc_test_checks/x86-asm-mir-same-prefix.test' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 4
cp -f /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/x86_asm_mir_same_prefix.ll /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/test/tools/UpdateTestChecks/update_llc_test_checks/Output/x86-asm-mir-same-prefix.test.tmp.ll && '/usr/bin/python3.10' /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/utils/update_llc_test_checks.py --llc-binary /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/llc --version=1 /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/test/tools/UpdateTestChecks/update_llc_test_checks/Output/x86-asm-mir-same-prefix.test.tmp.ll 2>&1 | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/tools/UpdateTestChecks/update_llc_test_checks/x86-asm-mir-same-prefix.test --check-prefix=WARNING
# executed command: cp -f /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/x86_asm_mir_same_prefix.ll /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/test/tools/UpdateTestChecks/update_llc_test_checks/Output/x86-asm-mir-same-prefix.test.tmp.ll
# executed command: /usr/bin/python3.10 /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/utils/update_llc_test_checks.py --llc-binary /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/llc --version=1 /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/test/tools/UpdateTestChecks/update_llc_test_checks/Output/x86-asm-mir-same-prefix.test.tmp.ll
# note: command had no output on stdout or stderr
# error: command failed with exit status: 1
# executed command: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/tools/UpdateTestChecks/update_llc_test_checks/x86-asm-mir-same-prefix.test --check-prefix=WARNING
# .---command stderr------------
# | /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/tools/UpdateTestChecks/update_llc_test_checks/x86-asm-mir-same-prefix.test:7:12: error: WARNING: expected string not found in input
# | # WARNING: WARNING: The following prefixes are used for both ASM and MIR output, which will cause FileCheck failures: CHECK
# |            ^
# | <stdin>:1:1: note: scanning from here
# | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/llc: error: unable to get target for 'x86_64', see --version and --triple.
# | ^
# | 
# | Input file: <stdin>
# | Check file: /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/tools/UpdateTestChecks/update_llc_test_checks/x86-asm-mir-same-prefix.test
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |          1: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/llc: error: unable to get target for 'x86_64', see --version and --triple. 
# | check:7     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
# |          2: Error: Failed to update test /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/test/tools/UpdateTestChecks/update_llc_test_checks/Output/x86-asm-mir-same-prefix.test.tmp.ll 
# | check:7     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |          3: Traceback (most recent call last): 
# | check:7     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |          4:  File "/home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/utils/update_llc_test_checks.py", line 373, in main 
# | check:7     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |          5:  update_test(ti) 
# | check:7     ~~~~~~~~~~~~~~~~~
# |          6:  File "/home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/utils/update_llc_test_checks.py", line 145, in update_test 
# | check:7     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |          .
# |          .
# |          .
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/164965