This is an unavoidably invasive commit, because it affects the unit tests
(which formerly exited using stop()), the test harness Verilog generator
(since it is no longer necessary), and the DRAM model (since it is no
longer connected). However, this should substantially reduce the effort
of building test harnesses in the future, since manual or semi-automatic
Verilog writing should no longer be necessary. Furthermore, there is now
very little duplication of effort between the Verilator and VCS test
harnesses.
This commit removes support for DRAMsim, which is a bit of an unfortunate
consequence. The main blocker is the lack of Verilog parameterization for
BlackBox. It would be straightforward to revive DRAMsim once support for
that feature is added to Chisel and FIRRTL. But that might not even be
necessary, as we move towards synthesizable DRAM models and FAME-1
transformations.
This allows users to specify if they want to build RocketChip against
Chisel 2 or 3. Since Chisel 3 is now open source we can add these
submodule pointers directly to avoid a fork of upstream.
All 'addon' subprojects now have their sources aggregated into the addons subproject. This is done via a source copy (so that sbt will only rebuild sources that actually changed). To prevent caching issues the addons/src directory is CLEARED and then refilled every time addons is compiled. Thus, it is CRUCIAL NO SOURCES ARE MANUALLY ADDED TO addons/src AS THEY WILL BE WIPED BY addons/prepare. Due to sbt source caching, sbt will still be able to tell which sources have changed. (Strangely, sbt would not cache sources in extra unmanaged source directories and thus would always recompile them.) Also, cleaned up project/build.scala a bit to remove some warnings: Added import scala.language/postFixOps (so make! at the bottom no longer errors) and .toURI.toURL (as straight .toURL has been deprecated by the java standard library).
