[PATCH] D35082: [OpenCL] Add LangAS::opencl_private to represent private address space in AST

[Anastasia Stulova via Phabricator via cfe-commits]

Anastasia added inline comments.


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Comment at: lib/Sema/SemaDecl.cpp:11846
   // an address space.
   if (T.getAddressSpace() != 0) {
     // OpenCL allows function arguments declared to be an array of a type
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yaxunl wrote:
> Anastasia wrote:
> > Could we use `LangAS::Default` here too?
> done
Sorry, I wasn't clear. I think we could have:

  if (T.getAddressSpace() != LangAS::Default && T.getAddressSpace() != LangAS::opencl_private)

and then original condition. It is a bit clearer I think.


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Comment at: lib/Sema/SemaType.cpp:6969
 
+  if (state.getSema().getLangOpts().OpenCL &&
+      !hasOpenCLAddressSpace && type.getAddressSpace() == 0 &&
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yaxunl wrote:
> Anastasia wrote:
> > Would it be nicer to not append any address space at all neither here nor down at the end of this function and keep it default instead until the Codegen? If it's doable I would very much prefer that. It seems like it would make the implementation potentially a bit cleaner to understand and easier to improve semantical analysis. See one example of improving original type printing in my comment to the test below.
> > 
> > Also there are at least these 3 related bugs open currently:
> > https://bugs.llvm.org//show_bug.cgi?id=33418
> > https://bugs.llvm.org//show_bug.cgi?id=33419
> > https://bugs.llvm.org//show_bug.cgi?id=33420
> > 
> > Does your change address any of those?
> On the contrary, I think using default address space for automatic variable and function parameter will cause ambiguity and inconsistency in AST, making it more difficult to understand and process, and making some bug (e.g. https://bugs.llvm.org//show_bug.cgi?id=33419) unfixable. For example, `private int f(void)` and `int f(void)` will be identical in AST, therefore we cannot diagnose `private int f(void)`.
> 
> With current representation I am able to fix the 3 bugs. I will update the diff.
I don't see why?

`private int f(void)` -> will have an address space attribute in AST as it is provided explicitly.

`int f(void) ` -> will have no address space attribute because it's not provided explicitly and not attached implicitly either.

All I was asking is  not to deduce the address space here if it's not specified explicitly until later step when we need to put it in the IR.


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Comment at: test/SemaOpenCL/access-qualifier.cl:23
 #else
-void myReadWrite(read_write image1d_t); // expected-error {{access qualifier 'read_write' can not be used for '__read_write image1d_t' prior to OpenCL version 2.0}}
+void myReadWrite(read_write image1d_t); // expected-error {{access qualifier 'read_write' can not be used for '__private __read_write image1d_t' prior to OpenCL version 2.0}}
 #endif
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yaxunl wrote:
> Anastasia wrote:
> > Ok, I think that here it would be less confusing not to add any address space since it's missing in the original source.
> Although it looks strange at first sight, `__private __read_write image1d_t` is the true type of the argument. The function argument is allocated from stack and is an l-value. If we take its address, we get a private pointer.
Yes, it is a true type in the Clang internal representation indeed, but not in the original source though. Here we are giving the feedback about the source code so it's nicer to keep it as close to the original as possible. But we are doing similar "magic" for blocks, images and other places, so it's not that critical at the end. Just if it can be avoided it would be better.


https://reviews.llvm.org/D35082