[llvm/utils] Enable fpcmp

[taewookoh]

Summary

fpcmp is useful for comparing floating point values within noise margin, but currently not built. This diff enables fpcmp.

[lattner]

I don't think that fpcmp by itself will help, we need to integrate this with filecheck. We aren't using one-or-the-other right? We need CHECK: labels with magic regex's.

[taewookoh]

That would be great but I think fpcmp can be used as is by providing reference input file to it (and not using FileCheck). Does this make sense to you?

[lattner]

I don't think it will be super helpful for our use-cases, because we don't want to have a full reference output we diff against, we want CHECK: style tests.

I didn't realize that fpcmp wasn't built when I mentioned it. If this is the case, maybe we should just delete it from the LLVM tree as dead code :)

llvm/CMakeLists.txt

 add_subdirectory(include/llvm)
 
 add_subdirectory(lib)
 
 if( LLVM_INCLUDE_UTILS )
   add_subdirectory(utils/FileCheck)
   add_subdirectory(utils/PerfectShuffle)
   add_subdirectory(utils/count)
+  add_subdirectory(utils/fpcmp)
   add_subdirectory(utils/not)
   add_subdirectory(utils/yaml-bench)
 else()
   if ( LLVM_INCLUDE_TESTS )
     message(FATAL_ERROR "Including tests when not building utils will not work.
     Either set LLVM_INCLUDE_UTILS to On, or set LLVM_INCLUDE_TESTS to Off.")
   endif()
 endif()

llvm/utils/fpcmp/CMakeLists.txt

+add_llvm_utility(fpcmp
+  fpcmp.cpp
+  )
+
+target_link_libraries(fpcmp PRIVATE LLVMSupport)