[llvm] [MIPS]Remove unnecessary SLL instructions on MIPS64el (PR #109386)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lldb-x86_64-debian` running on `lldb-x86_64-debian` while building `llvm` at step 6 "test".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/162/builds/21788

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

```
Step 6 (test) failure: build (failure)
...
UNSUPPORTED: lldb-shell :: ScriptInterpreter/Python/Crashlog/interactive_crashlog_json.test (2881 of 2890)
UNSUPPORTED: lldb-shell :: ScriptInterpreter/Lua/watchpoint_callback.test (2882 of 2890)
UNSUPPORTED: lldb-shell :: ScriptInterpreter/Lua/partial_statements.test (2883 of 2890)
PASS: lldb-api :: tools/lldb-server/TestLldbGdbServer.py (2884 of 2890)
PASS: lldb-api :: api/multithreaded/TestMultithreaded.py (2885 of 2890)
PASS: lldb-api :: terminal/TestEditlineCompletions.py (2886 of 2890)
PASS: lldb-api :: commands/process/attach/TestProcessAttach.py (2887 of 2890)
PASS: lldb-api :: repl/clang/TestClangREPL.py (2888 of 2890)
PASS: lldb-api :: tools/lldb-dap/attach/TestDAP_attachByPortNum.py (2889 of 2890)
TIMEOUT: lldb-api :: tools/lldb-dap/breakpoint/TestDAP_setExceptionBreakpoints.py (2890 of 2890)
******************** TEST 'lldb-api :: tools/lldb-dap/breakpoint/TestDAP_setExceptionBreakpoints.py' FAILED ********************
Script:
--
/usr/bin/python3 /home/worker/2.0.1/lldb-x86_64-debian/llvm-project/lldb/test/API/dotest.py -u CXXFLAGS -u CFLAGS --env LLVM_LIBS_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/./lib --env LLVM_INCLUDE_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/include --env LLVM_TOOLS_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/./bin --arch x86_64 --build-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex --lldb-module-cache-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/module-cache-lldb/lldb-api --clang-module-cache-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/module-cache-clang/lldb-api --executable /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/lldb --compiler /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/clang --dsymutil /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/dsymutil --make /usr/bin/gmake --llvm-tools-dir /home/worker/2.0.1/lldb-x86_64-debian/build/./bin --lldb-obj-root /home/worker/2.0.1/lldb-x86_64-debian/build/tools/lldb --lldb-libs-dir /home/worker/2.0.1/lldb-x86_64-debian/build/./lib -t /home/worker/2.0.1/lldb-x86_64-debian/llvm-project/lldb/test/API/tools/lldb-dap/breakpoint -p TestDAP_setExceptionBreakpoints.py
--
Exit Code: -9
Timeout: Reached timeout of 600 seconds

Command Output (stdout):
--
lldb version 21.0.0git (https://github.com/llvm/llvm-project.git revision 69f3552d5ee27b4a2fb160600564d3d4d3c3868b)
  clang revision 69f3552d5ee27b4a2fb160600564d3d4d3c3868b
  llvm revision 69f3552d5ee27b4a2fb160600564d3d4d3c3868b

--
Command Output (stderr):
--
Change dir to: /home/worker/2.0.1/lldb-x86_64-debian/llvm-project/lldb/test/API/tools/lldb-dap/breakpoint
runCmd: settings clear --all

output: 

runCmd: settings set symbols.enable-external-lookup false

output: 

runCmd: settings set target.inherit-tcc true

output: 

runCmd: settings set target.disable-aslr false

output: 

runCmd: settings set target.detach-on-error false

output: 

runCmd: settings set target.auto-apply-fixits false

```

</details>

https://github.com/llvm/llvm-project/pull/109386