UMA: Add ability to override flags from command line

[dnakamura]

Add ability to set/unset flags from the command line when invoking uma,
without having to modify the relevant buildspec file.

Signed-off-by: Devin Nakamura [email protected]

[rservant]

The changes to UMA look good.

[DanHeidinga]

This is a cool hack @dnakamura! Can you provide some additional rationale for this change?

As you're well aware, UMA is something we'd like to replace with CMAKE. Is this something to ease the transition from UMA to CMAKE?

[dnakamura]

Yes this is really to make life easier during the transition period. Currently I have cmake build run conditionally on the presence of the build_cmake flag, which needs to be set in the appropriate buildspec file. This means i need to maintain a long running branch which keeps the modified buildspec (which we obviously don't want to merge until cmake is ready for prime time).

In addition the openj9-openjdk-jdk9 build scripts need to take a different approach when building a cmake enabled build vs a non-cmake eanabled build. However there is no infrastructure there for parsing out the buildspecs, so it makes it much more difficult to enable the conditional behavior. Rather than have to pull that information up into the build/configure scripts, it seemed much easier to push it down into uma, overriding values in the build spec. The next step is to add an option to the configure script, --with-cmake. The presence/absence of this flag determines if uma is called with -D build_cmake or -U build_cmake respectively. This allows the cmake changes to live side by side with the current build system in master, and would allow anyone to test them without having to apply any patches to the repo

[DanHeidinga]

Thanks @dnakamura. Can you open a longer running issue to track the work / document the plan for the transition from UMA to cmake and link this PR from the issue?

[genie-openj9]

Can one of the admins verify this patch?