[llvm] [IR2Vec] Initial infrastructure for MIR2Vec (PR #161463)

[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/22457

<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)
...
[1120/1186] Linking CXX executable unittests/Frontend/LLVMFrontendTests
[1121/1186] Building CXX object unittests/ExecutionEngine/MCJIT/CMakeFiles/MCJITTests.dir/MCJITTest.cpp.o
[1122/1186] Building CXX object unittests/CodeGen/CMakeFiles/CodeGenTests.dir/TypeTraitsTest.cpp.o
[1123/1186] Linking CXX executable unittests/Transforms/Coroutines/CoroTests
[1124/1186] Building CXX object unittests/ExecutionEngine/MCJIT/CMakeFiles/MCJITTests.dir/MCJITObjectCacheTest.cpp.o
[1125/1186] Linking CXX executable unittests/Transforms/Instrumentation/InstrumentationTests
[1126/1186] Building CXX object unittests/ExecutionEngine/MCJIT/CMakeFiles/MCJITTests.dir/MCJITMultipleModuleTest.cpp.o
[1127/1186] Linking CXX executable unittests/Passes/PassBuilderBindings/PassesBindingsTests
[1128/1186] Linking CXX executable unittests/Passes/Plugins/PluginsTests
[1129/1186] Building CXX object unittests/CodeGen/CMakeFiles/CodeGenTests.dir/MIR2VecTest.cpp.o
FAILED: unittests/CodeGen/CMakeFiles/CodeGenTests.dir/MIR2VecTest.cpp.o 
/usr/local/bin/c++ -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -D_DEBUG -D_FILE_OFFSET_BITS=64 -D_GLIBCXX_ASSERTIONS -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/tcwg-buildbot/worker/clang-armv8-quick/stage1/unittests/CodeGen -I/home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/unittests/CodeGen -I/home/tcwg-buildbot/worker/clang-armv8-quick/stage1/include -I/home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/include -I/home/tcwg-buildbot/worker/clang-armv8-quick/llvm/third-party/unittest/googletest/include -I/home/tcwg-buildbot/worker/clang-armv8-quick/llvm/third-party/unittest/googlemock/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -std=c++17  -Wno-variadic-macros -Wno-gnu-zero-variadic-macro-arguments -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -Wno-suggest-override -MD -MT unittests/CodeGen/CMakeFiles/CodeGenTests.dir/MIR2VecTest.cpp.o -MF unittests/CodeGen/CMakeFiles/CodeGenTests.dir/MIR2VecTest.cpp.o.d -o unittests/CodeGen/CMakeFiles/CodeGenTests.dir/MIR2VecTest.cpp.o -c /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/unittests/CodeGen/MIR2VecTest.cpp
../llvm/llvm/unittests/CodeGen/MIR2VecTest.cpp:58:5: error: use of undeclared identifier 'LLVMInitializeX86TargetInfo'; did you mean 'LLVMInitializeARMTargetInfo'?
   58 |     LLVMInitializeX86TargetInfo();
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
      |     LLVMInitializeARMTargetInfo
include/llvm/Config/Targets.def:26:1: note: 'LLVMInitializeARMTargetInfo' declared here
   26 | LLVM_TARGET(ARM)
      | ^
../llvm/llvm/include/llvm/Support/TargetSelect.h:24:17: note: expanded from macro 'LLVM_TARGET'
   24 |   LLVM_ABI void LLVMInitialize##TargetName##TargetInfo();
      |                 ^
<scratch space>:101:1: note: expanded from here
  101 | LLVMInitializeARMTargetInfo
      | ^
../llvm/llvm/unittests/CodeGen/MIR2VecTest.cpp:59:5: error: use of undeclared identifier 'LLVMInitializeX86Target'; did you mean 'LLVMInitializeARMTarget'?
   59 |     LLVMInitializeX86Target();
      |     ^~~~~~~~~~~~~~~~~~~~~~~
      |     LLVMInitializeARMTarget
include/llvm/Config/Targets.def:26:1: note: 'LLVMInitializeARMTarget' declared here
   26 | LLVM_TARGET(ARM)
      | ^
../llvm/llvm/include/llvm/Support/TargetSelect.h:28:17: note: expanded from macro 'LLVM_TARGET'
   28 |   LLVM_ABI void LLVMInitialize##TargetName##Target();
      |                 ^
<scratch space>:103:1: note: expanded from here
  103 | LLVMInitializeARMTarget
      | ^
../llvm/llvm/unittests/CodeGen/MIR2VecTest.cpp:60:5: error: use of undeclared identifier 'LLVMInitializeX86TargetMC'; did you mean 'LLVMInitializeARMTargetMC'?
   60 |     LLVMInitializeX86TargetMC();
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~
      |     LLVMInitializeARMTargetMC
include/llvm/Config/Targets.def:26:1: note: 'LLVMInitializeARMTargetMC' declared here
   26 | LLVM_TARGET(ARM)
      | ^
../llvm/llvm/include/llvm/Support/TargetSelect.h:33:17: note: expanded from macro 'LLVM_TARGET'
   33 |   LLVM_ABI void LLVMInitialize##TargetName##TargetMC();
      |                 ^
<scratch space>:105:1: note: expanded from here

```

</details>

https://github.com/llvm/llvm-project/pull/161463