How is the override mechanism in JvmOverrideFiles.gmk supposed to work?

[Volker Simonis]

Hi,

I've just realized the the override mechanism from
JvmOverrideFiles.gmk isn't really 'overriding' options but just
'appending' new ones.

So for example:

BUILD_LIBJVM_sharedRuntimeTrig.cpp_CXXFLAGS := -DNO_PCH $(CXX_O_FLAG_NONE)

will not replace the CXXFLAGS flags for sharedRuntimeTrig.cpp but only
append the new ones.

The command line will look like this:

.. -O3 -DNO_PCH -O0 ..

Is this the way it is supposed to work?

I think that's a little problematic because if CXX_O_FLAG_NONE is
empty (which seems plausible for "doing no optimizations", the
override mechanism will actually do nothing at all.

Even worse, on AIX we have  CXX_O_FLAG_HIGHEST_JVM="-O3 -qhot=level=1
-qinline -qinlglue" and CXX_O_FLAG_NORM="-O2". So even if "-O2"
overrides "-O3", we still have "-qhot=level=1 -qinline -qinlglue" in
place.

Do we actually have to negate every possible option in
JvmOverrideFiles.gmk if we want to be sure to have correct results.
This makes it impossible to use shortcuts like CXX_O_FLAG_NORM in an
override.

Regards,
Volker