`UA` verification error during breakdown experiments

[blackgeorge-boom]

When applying only a few of the LLVM modifications, ua does not verify.

To reproduce, compile LLVM without the TableGen flags:

cmake \
  -G Ninja \
  -DBUILD_SHARED_LIBS=On \
  -DLLVM_ENABLE_ASSERTIONS=On \
  -DLLVM_TARGETS_TO_BUILD="X86;AArch64" \
  -DLLVM_ENABLE_SPHINX=Off \
  -DLLVM_ENABLE_THREADS=On \
  -DLLVM_INSTALL_UTILS=On \
  -DLIBCXX_ENABLE_EXCEPTIONS=On \
  -DLIBCXX_ENABLE_RTTI=On \
  -DLLVM_OPTIMIZED_TABLEGEN=On \
  -DLLVM_UNIFICO_TABLEGEN_FEATURES="" \ <------
  -DLLVM_ENABLE_PROJECTS="clang" \
  -DCMAKE_BUILD_TYPE=RelWithDebInfo \
  -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}" \
  "~/llvm-project/llvm"

Then, compile keeping only the alignment flags.

[blackgeorge-boom]

In the same setting, it seems that removing the reg-scavenging-slot flag lead to a compilation error (potentially different issue).