[llvm] [RFC] Memory Model Relaxation Annotations (PR #78569)

[Kamau Bridgeman via llvm-commits]

kamaub wrote:

This change appears to have broken several buildbots:
https://lab.llvm.org/buildbot/#/builders/36/builds/44839
https://lab.llvm.org/buildbot/#/builders/57/builds/34531
https://lab.llvm.org/buildbot/#/builders/214/builds/11990

With the error: 
```
FAILED: lib/IR/CMakeFiles/LLVMCore.dir/Verifier.cpp.o 
ccache /home/docker/llvm-external-buildbots/clang.16.0.1/bin/clang++ --gcc-toolchain=/gcc-toolchain/usr -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/lib/IR -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/lib/IR -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror -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 -fPIC  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -MD -MT lib/IR/CMakeFiles/LLVMCore.dir/Verifier.cpp.o -MF lib/IR/CMakeFiles/LLVMCore.dir/Verifier.cpp.o.d -o lib/IR/CMakeFiles/LLVMCore.dir/Verifier.cpp.o -c /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/lib/IR/Verifier.cpp
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/lib/IR/Verifier.cpp:4854:14: error: unused variable 'IsLeaf' [-Werror,-Wunused-variable]
  const auto IsLeaf = [](const Metadata *CurMD) {
             ^
1 error generated.
```

The bot that builds and uses lld also catches this failure:
```
FAILED: unittests/IR/CMakeFiles/IRTests.dir/MemoryModelRelaxationAnnotationsTest.cpp.o 
ccache /home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/install/stage1/bin/clang++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/build/stage2/unittests/IR -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/unittests/IR -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/build/stage2/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/third-party/unittest/googletest/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/third-party/unittest/googlemock/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror -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/IR/CMakeFiles/IRTests.dir/MemoryModelRelaxationAnnotationsTest.cpp.o -MF unittests/IR/CMakeFiles/IRTests.dir/MemoryModelRelaxationAnnotationsTest.cpp.o.d -o unittests/IR/CMakeFiles/IRTests.dir/MemoryModelRelaxationAnnotationsTest.cpp.o -c /home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/unittests/IR/MemoryModelRelaxationAnnotationsTest.cpp
In file included from /home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/unittests/IR/MemoryModelRelaxationAnnotationsTest.cpp:13:
/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:1379:11: error: comparison of integers of different signs: 'const unsigned int' and 'const int' [-Werror,-Wsign-compare]
 1379 |   if (lhs == rhs) {
      |       ~~~ ^  ~~~
/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:1398:12: note: in instantiation of function template specialization 'testing::internal::CmpHelperEQ<unsigned int, int>' requested here
 1398 |     return CmpHelperEQ(lhs_expression, rhs_expression, lhs, rhs);
      |            ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/unittests/IR/MemoryModelRelaxationAnnotationsTest.cpp:61:3: note: in instantiation of function template specialization 'testing::internal::EqHelper::Compare<unsigned int, int, nullptr>' requested here
   61 |   EXPECT_EQ(SingleMD->getNumOperands(), 2);
      |   ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:1869:54: note: expanded from macro 'EXPECT_EQ'
 1869 |   EXPECT_PRED_FORMAT2(::testing::internal::EqHelper::Compare, val1, val2)
      |                                                      ^
1 error generated.
``` 
which does not appear to be caused by the other change in that changeset.

Please investigate and fix this or revert your change if it will keep the bots red for 24 hours.

Let me know if there is anyway I can assist, thank you.

https://github.com/llvm/llvm-project/pull/78569