[OpenMP] Fix for http://bugs.llvm.org/show_bug.cgi?id=32456

[AndreyChurbanov]

Summary

The ittnotify API was mistakenly enabled for static runtime library initially. This fix disables the ittnotify for the static build.

Main problem with ittnotify in static library is impossibility to dynamically detect the presence of the tool at run time once the executable is linked statically, e.g. such interfaces as dlopen, dlsym etc. are inaccessible.

[jlpeyton]

runtime/CMakeLists.txt

311 ↗

(On Diff #93378)

Can you add a message like:
libomp_say("ITT Notify not supported for static libraries - forcing ITT Notify off.")

[AndreyChurbanov]

runtime/CMakeLists.txt

311 ↗

(On Diff #93378)

Is it worth checking if the build is standalone, as we usually keep silence otherwise?
And if ITT notify was already turned off before this setting, we actually do not forcing it off, so no warning needed.

I'd make both checks, like

if(LIBOMP_USE_ITT_NOTIFY AND NOT LIBOMP_ENABLE_SHARED)
  if(${LIBOMP_STANDALONE_BUILD})
    libomp_say("ITT Notify not supported for static libraries - forcing ITT Notify off")
  endif()
  set(LIBOMP_USE_ITT_NOTIFY FALSE)
endif()

Is it better?

[jlpeyton]

runtime/CMakeLists.txt

311 ↗

(On Diff #93378)

I don't think we need to check for the standalone build. Only the block of messages in the # Print configuration after all variables are set. section are kept silent during the LLVM in-tree build. Everything else still prints as normal. The message won't look out of place in an LLVM in-tree build.

[jlpeyton]

runtime/CMakeLists.txt

311 ↗

(On Diff #93378)

Ok, I forgot that libomp_say() prepends the "LIBOMP:" string to the message. You could use:
message(STATUS "ITT Notify not supported for static libraries - forcing ITT Notify off") so now it wouldn't look out of place.

[AndreyChurbanov]

comments addressed

[jlpeyton]

LGTM

openmp/trunk/runtime/CMakeLists.txt

 # Shared library can be switched to a static library
 set(LIBOMP_ENABLE_SHARED TRUE CACHE BOOL
   "Shared library instead of static library?")
 
 if(WIN32 AND NOT LIBOMP_ENABLE_SHARED)
   libomp_error_say("Static libraries requested but not available on Windows")
 endif()
 
+if(LIBOMP_USE_ITT_NOTIFY AND NOT LIBOMP_ENABLE_SHARED)
+  message(STATUS "ITT Notify not supported for static libraries - forcing ITT Notify off")
+  set(LIBOMP_USE_ITT_NOTIFY FALSE)
+endif()
+
 # OMPT-support
 set(LIBOMP_OMPT_DEBUG FALSE CACHE BOOL
   "Trace OMPT initialization?")
 set(LIBOMP_OMPT_SUPPORT FALSE CACHE BOOL
   "OMPT-support?")
 set(LIBOMP_OMPT_BLAME TRUE CACHE BOOL
   "OMPT-blame?")
 set(LIBOMP_OMPT_TRACE TRUE CACHE BOOL