[llvm] [Mips] Support "$sp" named register (PR #136821)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lldb-remote-linux-win` running on `as-builder-10` while building `llvm` at step 17 "test-check-lldb-api".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/197/builds/11669

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

```
Step 17 (test-check-lldb-api) failure: Test just built components: check-lldb-api completed (failure)
******************** TEST 'lldb-api :: commands/expression/no-deadlock/TestExprDoesntBlock.py' FAILED ********************
Script:
--
C:/Python312/python.exe C:/buildbot/as-builder-10/lldb-x-aarch64/llvm-project/lldb\test\API\dotest.py -u CXXFLAGS -u CFLAGS --env LLVM_LIBS_DIR=C:/buildbot/as-builder-10/lldb-x-aarch64/build/./lib --env LLVM_INCLUDE_DIR=C:/buildbot/as-builder-10/lldb-x-aarch64/build/include --env LLVM_TOOLS_DIR=C:/buildbot/as-builder-10/lldb-x-aarch64/build/./bin --arch aarch64 --build-dir C:/buildbot/as-builder-10/lldb-x-aarch64/build/lldb-test-build.noindex --lldb-module-cache-dir C:/buildbot/as-builder-10/lldb-x-aarch64/build/lldb-test-build.noindex/module-cache-lldb\lldb-api --clang-module-cache-dir C:/buildbot/as-builder-10/lldb-x-aarch64/build/lldb-test-build.noindex/module-cache-clang\lldb-api --executable C:/buildbot/as-builder-10/lldb-x-aarch64/build/./bin/lldb.exe --compiler C:/buildbot/as-builder-10/lldb-x-aarch64/build/./bin/clang.exe --dsymutil C:/buildbot/as-builder-10/lldb-x-aarch64/build/./bin/dsymutil.exe --make C:/ninja/make.exe --llvm-tools-dir C:/buildbot/as-builder-10/lldb-x-aarch64/build/./bin --lldb-obj-root C:/buildbot/as-builder-10/lldb-x-aarch64/build/tools/lldb --lldb-libs-dir C:/buildbot/as-builder-10/lldb-x-aarch64/build/./lib --cmake-build-type Release --platform-url connect://jetson-agx-0086.lab.llvm.org:1234 --platform-working-dir /home/ubuntu/lldb-tests --sysroot c:/buildbot/fs/jetson-agx-ubuntu --env ARCH_CFLAGS=-mcpu=cortex-a78 --platform-name remote-linux --skip-category=lldb-server C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\lldb\test\API\commands\expression\no-deadlock -p TestExprDoesntBlock.py
--
Exit Code: 3221225477

Command Output (stdout):
--
lldb version 22.0.0git (https://github.com/llvm/llvm-project.git revision 13012fe20816c7ce7a4eec62b325a131b6570593)
  clang revision 13012fe20816c7ce7a4eec62b325a131b6570593
  llvm revision 13012fe20816c7ce7a4eec62b325a131b6570593
Setting up remote platform 'remote-linux'

Connecting to remote platform 'remote-linux' at 'connect://jetson-agx-0086.lab.llvm.org:1234'...

Connected.

Setting remote platform working directory to '/home/ubuntu/lldb-tests'...

Skipping the following test categories: lldb-server, libc++, msvcstl, dsym, pdb, gmodules, debugserver, objc, lldb-dap


--
Command Output (stderr):
--
UNSUPPORTED: LLDB (C:\buildbot\as-builder-10\lldb-x-aarch64\build\bin\clang.exe-aarch64) :: test_with_run_command_dsym (TestExprDoesntBlock.ExprDoesntDeadlockTestCase.test_with_run_command_dsym) (test case does not fall in any category of interest for this run) 

PASS: LLDB (C:\buildbot\as-builder-10\lldb-x-aarch64\build\bin\clang.exe-aarch64) :: test_with_run_command_dwarf (TestExprDoesntBlock.ExprDoesntDeadlockTestCase.test_with_run_command_dwarf)

PASS: LLDB (C:\buildbot\as-builder-10\lldb-x-aarch64\build\bin\clang.exe-aarch64) :: test_with_run_command_dwo (TestExprDoesntBlock.ExprDoesntDeadlockTestCase.test_with_run_command_dwo)

----------------------------------------------------------------------

Ran 3 tests in 6.067s



OK (skipped=1)

Windows fatal exception: access violation

Current thread 0x00005618 (most recent call first):
  <no Python frame>
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
Exception Code: 0xC0000005
 #0 0x00007ffed3144902 lldb::SBAttachInfo::UserIDIsValid(void) (C:\buildbot\as-builder-10\lldb-x-aarch64\build\Lib\site-packages\lldb\native\_lldb.cp312-win_amd64.pyd+0xb4902)
 #1 0x00007ffed363501a PyInit__lldb (C:\buildbot\as-builder-10\lldb-x-aarch64\build\Lib\site-packages\lldb\native\_lldb.cp312-win_amd64.pyd+0x5a501a)
 #2 0x00007ffed3635189 PyInit__lldb (C:\buildbot\as-builder-10\lldb-x-aarch64\build\Lib\site-packages\lldb\native\_lldb.cp312-win_amd64.pyd+0x5a5189)
 #3 0x00007ffed38e03bb PyInit__lldb (C:\buildbot\as-builder-10\lldb-x-aarch64\build\Lib\site-packages\lldb\native\_lldb.cp312-win_amd64.pyd+0x8503bb)
...

```

</details>

https://github.com/llvm/llvm-project/pull/136821