pxli168 added inline comments.

================
Comment at: lib/CodeGen/CGOpenCLRuntime.cpp:108
@@ +107,3 @@
+    PipeTy = llvm::PointerType::get(llvm::StructType::create(
+      CGM.getLLVMContext(), "opencl.pipe_t"), PipeAddrSpc);
+  }
----------------
pekka.jaaskelainen wrote:
> pxli168 wrote:
> > pekka.jaaskelainen wrote:
> > > I'm not sure if touching the built-in fingerprints for this is a good 
> > > idea. It might lead to problems and confusion. Cannot one pass pipes as 
> > > arguments to user functions too? Are the fingerprints of those functions 
> > > then modified accordingly? It might become messy.
> > > 
> > > Because the packet size is known at host side, the pipes can be 
> > > implemented as structs which holds the packet size as one of the member 
> > > variables. The problem with this approach is how to exploit wider 
> > > reads/writes instead of a scalar read/write loop + unpack/pack in case of 
> > > vector datatypes. 
> > > 
> > > If the size is known only at runtime, one cannot easily generate vector 
> > > reads/writes even if the element is a vector datatype and it would be 
> > > efficient to keep the packet in a vector register as long as possible. 
> > > For helping this I'd add a metadata which can be utilized at compile time 
> > > to make reading/writing from the pipe faster.  But in a way that is 
> > > already an optimization, not a requirement, to make pipes work.
> > > 
> > > The reading itself is platform dependent as the pipe can be even a 
> > > hardware FIFO accessed using special instructions.
> > This is what I'm worry about, I don't think we need to give much 
> > information about an opaque type in OpenCL.
> > 
> > Actually we can get the element type from the metadata, and I think we can 
> > leave the optimization to the backend and let platform to choose which way 
> > to use for read/write pipe.
> > 
> > And I think the built-in function support for the pipe in OpenCL-C is not 
> > necessary in the clang, what do you think? Though it can do some check in 
> > Sema check, they can also be done in some llvm pass in backend. If the 
> > built-in is really needed, I will send another patch based on this included 
> > built-in support for pipe.
> > 
> > Thank you.
> As far as I've understood, no there's no need to add built-in function 
> awareness to the frontend for this case. Sema checking/diagnostics is needed 
> to ensure pipes are used only as function arguments, not local variables, for 
> example. Is this patch missing it?
I think there are a lot of Sema checking about OpenCL2.0 are missing, the pipe 
could not be a local variable is just one, there are also some check are 
missing for reserve_id_t in my tests these days. 
My plan is to use a patch to cover all these missing Sema check for OpenCL. 
That would be a hard work with the OpenCL Specification and would take a lot of 
time and may delay this patch, so could you accept this patch first and let me 
to finish the missing Sema check later to make sure cover more missing part.


http://reviews.llvm.org/D15603



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