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

[Yaxun Liu via Phabricator via cfe-commits]

yaxunl marked 6 inline comments as done.
yaxunl 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
----------------
Anastasia wrote:
> 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.
No. For OpenCL, the condition is on line 11847 and 11848. An array type in other address spaces is allowed.


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Comment at: lib/Sema/SemaType.cpp:6969
 
+  if (state.getSema().getLangOpts().OpenCL &&
+      !hasOpenCLAddressSpace && type.getAddressSpace() == 0 &&
----------------
Anastasia wrote:
> 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.
Clang already deduce global and generic address spaces and use them in the diagnostic messages. I don't see why we can use deduced global and generic address space in diagnostics whereas cannot use deduced private address space in diagnostics. Why users can accept deduced global and generic address spaces but cannot accept deduced private address space?

Automatic variables and function parameters have private address space. This is the reality and as true as a global variable has global or constant address spaces. Not using private address space in diagnostics gives user illusion that automatic variables and function parameters do not have address space, which is not true.

Besides, allowing default address space to represent private address space in AST causes ambiguity in AST. Instead of just check if a type has private address space, now we need to check if a type has private or default address spaces. Also if an expression has default address space, it is not clear if it is an l-value or r-value. This will complicate semantic checking unnecessarily. Also I am not sure if it is acceptable to modify AST between Sema and CodeGen since it seems to change the paradigm of how clang does Sema/CodeGen now.


https://reviews.llvm.org/D35082