Add OpenCL Model

[tonghaining]

No description provided.

[hernanponcedeleon]

A few comments based on a quick look to the changes. Will take a closer look next week

[hernanponcedeleon]

There is something about the overall code that I don't like (I am probably the one the blame about this).

I think the reason we have C and OpenCL things mixed in a bad way now is because we have very few OpenCL tests and we wanted to use the C litmus tests we have to validate OpenCL model: the OpenCL model is an extension of the C model and thus we should get the same results on pure C programs.

We should rather port our C litmus the OpenCL syntax (which is pretty much the same except the syntax will explicitly state the scopes and the address space, avoiding the need to do this magic in the parser).

What about the following:

• Litmus intended to be run wrt opencl.cat should have OpenCL in the first line
• Litmus having OpenCL int he first line should have @ for the threads to explicitly state the hierarchy
• For Litmus having OpenCL in the first line, we add scopes, address spaces, and any other opencl tag which are explicitly stated in the syntax and we default to some specific ones when not explicitly stated. This should make the porting og C litmus so OpenCL easy (just change the first line and add @wg0, dev0 to all tests). Otherwise, we request explicit mention of the needed tags. This might make the porting harder and I am not sure it has any benefit.
• We use the same visitor for litmus having C and OpenCL in the first line. Most of the visitor methods will be the same, execpt that depending on the first line, we might need to add some tags. But at least this should result in cleaner code about the usage of Thread or ScopedThread

[tonghaining]

Sounds good to me.

• For Litmus having OpenCL in the first line, we add scopes, address spaces, and any other opencl tag which are explicitly stated in the syntax and we default to some specific ones when not explicitly stated. This should make the porting og C litmus so OpenCL easy (just change the first line and add @wg0, dev0 to all tests). Otherwise, we request explicit mention of the needed tags. This might make the porting harder and I am not sure it has any benefit.

One more change we need is to add "global" for all variables for C litmus

[hernanponcedeleon]

Comment about the code. I still have not check in detail the cat models and the tests.

[hernanponcedeleon]

We are almost there ;)

Please answer the review with new commits (i.e. do not rebase) so it is easier to review the next time (otherwise I need to go over a large diff)

[hernanponcedeleon]

Btw ... Don't forget to add opencl as a target in the README

[hernanponcedeleon]

Unless @ThomasHaas has more comments, I can merge once the CI passes