This was not as straightforward as the C++ backend. CIF has no capability for supporting waiting *for* a specified time as an ALT guard; only waiting until (AFTER, in occam) a specified time. This is further complicated by the fact that when you disable an ALT timer guard in CIF, you have to be able to supply the timeout value that you waited on in the enable sequence.
Therefore, I added a pass that transforms all WaitFor guards into WaitUntil guards, by declaring nonce time variables, getting the time, and adding on the delay that we want to wait for; these actions occur just before the ALT.
This new pass is in the new BackendPasses module, into which I also moved the identifyParProcs pass. I also wrote tests for my new pass that live in the new BackendPassesTest module.
The compiler itself is under the GPLv2+; the support code that gets built into
user programs is under the LGPLv2+. This matches the existing practice for the
KRoC project.
(As with Occade, I've used the new GPLv3-style license header in the source
files, though, since that avoids having to update the FSF's postal address.)
This patch is a bit large, being as it encompasses two major changes:
1. The addition of the first version of a parallel usage checker. The usage checker uses the generics library (like
the other passes) to work out if the parallel usage rules are broken. It mainly consists of:
a) a function used to determine which variables are written to/read from in given bits of code, and
b) a function that applies a) across the members of any par construct in the file, and checks that
the expected usage rules hold
The parallel usage checker is in an early stage, but I think the design is sensible - at least for doing the variable
and array usage. The channel usage checker will require some slightly different functionality, and
I am not considering the abbreviation checker yet.
2. As a consquence of adding a second test file (UsageCheckTest) alongside the first (RainParseTest), I have
created a TestMain class that is intended to run all tests for all parts of Tock. I have also extracted some
useful helper functions (for creating the expected results of tests) into a file named TestUtil. I've also
modified the Makefil accordingly.
There are a few other minor changes to RainParse/RainParseTest that are also included in the patch as separating them
would have been tricky.
