bader marked 3 inline comments as done.
bader added inline comments.

================
Comment at: clang/include/clang/Basic/LangOptions.def:206
 LANGOPT(OpenCLCPlusPlusVersion     , 32, 0, "C++ for OpenCL version")
+ENUM_LANGOPT(SYCLVersion, SYCLVersionList, 4, SYCLVersionList::undefined, 
"Version of the SYCL standard used")
 LANGOPT(NativeHalfType    , 1, 0, "Native half type support")
----------------
Naghasan wrote:
> Ruyk wrote:
> > bader wrote:
> > > All other language options controlling standard versions are added as 
> > > "LANGOPT" i.e. `int`. Why SYCLVersion is different?
> > > @Ruyk, do you think we should convert other options (e.g. `OpenCL`) to 
> > > enums as well?
> > Thats a good point. I don't see strong reasons for the enum, basically I 
> > read the comment in 
> > https://code.woboq.org/llvm/clang/include/clang/Basic/LangOptions.def.html#22
> > 
> > 
> > ```
> > // ENUM_LANGOPT: for options that have enumeration, rather than unsigned, 
> > type.
> > ```
> > 
> > And since there is a known set of SYCL specifications, made more sense to 
> > enumerate it.
> > It also simplifies writing variants to 1.2.1 (e.g. 1.2.1-oneapi) in the 
> > code since then you can add another entry to the enum.
> > 
> > But no strong feelings, so feel free to change it.
> > 
> `int` allows the use of relational operators which should ease version 
> managements.
> 
> As `SYCLVersionList` is a strongly typed enum so this may not be the best, 
> and as the SYCL version are now meant to be a year `int` should do just fine.
Okay. I'll change the type from enum to int.


================
Comment at: clang/include/clang/Driver/Options.td:3401
+def sycl_std_EQ : Joined<["-"], "sycl-std=">, Group<sycl_Group>, 
Flags<[CC1Option]>,
+  HelpText<"SYCL language standard to compile for.">, Values<"1.2.1">;
 
----------------
Naghasan wrote:
> Ruyk wrote:
> > bader wrote:
> > > What do you think we integrate sycl versions to existing clang options 
> > > controlling language version: `-std`.
> > > As far as I can see it's used for all the C/C+ extensions like 
> > > OpenMP/OpenCL/CUDA/HIP/ObjC.
> > > 
> > > If I understand correctly clang supports `-cl-std` only because it's 
> > > required by OpenCL standard. Similar option (i.e. `-sycl-std`) is not 
> > > required by the SYCL specification, so using `-std` is more aligned with 
> > > existing clang design.
> > > 
> > > See clang/include/clang/Basic/LangStandard.h and 
> > > clang/include/clang/Basic/LangStandards.def.
> > In the case of SYCL, you may want to compile your code with C++17 and SYCL 
> > 2015, in which case you need both -std=c++17 and -sycl=sycl-2015 . 
> > SYCL specification mandates a minimum C++ version but users can write code 
> > on newer versions as long as the code in the kernel scope is still valid.
> +1 on this, ComputeCpp used to mix-up both and this proved to be complex to 
> manage. It also integrates better with build systems.
Okay. I'll leave it as a separate option.


================
Comment at: clang/lib/Frontend/CompilerInvocation.cpp:2548
+  Opts.SYCL = Args.hasFlag(options::OPT_fsycl, options::OPT_fno_sycl, false);
+  Opts.SYCLIsDevice = Args.hasArg(options::OPT_fsycl_is_device);
+  if (Opts.SYCL || Opts.SYCLIsDevice) {
----------------
Naghasan wrote:
> bader wrote:
> > ABataev wrote:
> > > bader wrote:
> > > > ABataev wrote:
> > > > > bader wrote:
> > > > > > ABataev wrote:
> > > > > > > bader wrote:
> > > > > > > > ABataev wrote:
> > > > > > > > > bader wrote:
> > > > > > > > > > ABataev wrote:
> > > > > > > > > > > This option also must be controlled by `-fsycl`:
> > > > > > > > > > > ```
> > > > > > > > > > > Opts.SYCLIsDevice =  Opts.SYCL && 
> > > > > > > > > > > Args.hasArg(options::OPT_fsycl_is_device);
> > > > > > > > > > > 
> > > > > > > > > > > ```
> > > > > > > > > > Does it really has to? This logic is already present in the 
> > > > > > > > > > driver and it makes front-end tests verbose `%clang_cc1 
> > > > > > > > > > -fsycl -fsycl-is-device`.
> > > > > > > > > > Can `-fsycl-is-device` imply `-fsycl`?
> > > > > > > > > > Looking how CUDA/OpenMP options are handled, not all of 
> > > > > > > > > > them are processed using this pattern.
> > > > > > > > > In general, this is how we handle it in OpenMP. Cuda works 
> > > > > > > > > differently, because it has its own kind of files (.cu) and 
> > > > > > > > > Cuda is triggered by the language switch (-x cu). Seems to 
> > > > > > > > > me, you're using something close to OpenMP model, no? Or do 
> > > > > > > > > you want to define your own language kind just like Cuda?
> > > > > > > > I applied you suggest, although I don't fully understand the 
> > > > > > > > need of using two options instead of two. I would prefer having 
> > > > > > > > following code:
> > > > > > > > ```
> > > > > > > > Opts.SYCLIsDevice = Args.hasArg(options::OPT_fsycl_is_device);
> > > > > > > > Opts.SYCL = Args.hasArg(options::OPT_fsycl) || 
> > > > > > > > Opts.SYCLIsDevice; // -fsycl-is-device enable SYCL mode as well
> > > > > > > > ```
> > > > > > > I'm not quite familiar with SYCL model, maybe this the right 
> > > > > > > approach. You'd better try to provide more details. Are there any 
> > > > > > > differences between just SYCL and SYCL-device compilation modes? 
> > > > > > > How do you see the compilation sequence in general? At first 
> > > > > > > you're going to compile the host version of the code, then the 
> > > > > > > device? OR something different?
> > > > > > I think SYCL model is quite similar to OpenMP model. One 
> > > > > > significant difference might be that to implement standard SYCL 
> > > > > > functionality we don't need any modifications for the host 
> > > > > > compiler. AFAIK, OpenMP compiler has to support OpenMP pragmas. 
> > > > > > We have a few attributes for Intel FPGA devices, which we can't 
> > > > > > pre-process with `__SYCL_DEVICE_ONLY__` macro and we have added 
> > > > > > "SYCL-host" mode to suppress compiler warnings about attributes 
> > > > > > ignored on the host. I think there might be other options how this 
> > > > > > can be achieved w/o adding new compilation mode and use regular C++ 
> > > > > > front-end as SYCL host compiler.
> > > > > > I think there is a difference between SYCL and SYCL-device modes, 
> > > > > > but it's mostly changes the compilation workflow in the driver, but 
> > > > > > not in the front-end. In SYCL-device mode, driver invokes only one 
> > > > > > front-end instance to generate offload code. In SYCL mode, driver 
> > > > > > invokes multiple front-end instances: one in SYCL-device mode and 
> > > > > > one in regular C++ mode (to be accurate we use SYCL-host mode, but 
> > > > > > as I mentioned above I don't think it really needed).
> > > > > > I hope it makes it clear now. Let me know if you have any other 
> > > > > > questions.
> > > > > > 
> > > > > > Do I understand it correctly that OpenMP option enables OpenMP 
> > > > > > mode, which is equivalent of "SYCL-host" mode and enabling both 
> > > > > > OpenMP and OpenMPIsDevice is required for enabling OpenMP mode, 
> > > > > > which is similar to SYCL-device mode?
> > > > > > If so, can we assume that OpenMPIsDevice implies that OpenMP option 
> > > > > > is also set (implicitly)?
> > > > > > Do I understand it correctly that OpenMP option enables OpenMP 
> > > > > > mode, which is equivalent of "SYCL-host" mode and enabling both 
> > > > > > OpenMP and OpenMPIsDevice is required for enabling OpenMP mode, 
> > > > > > which is similar to SYCL-device mode?
> > > > > 
> > > > > Well, for driver you need to pass `-fopenmp 
> > > > > -fopenmp-target=<list_of_targets>` to enable the compilation with 
> > > > > offloading support. In the frontend the host part is compiled with 
> > > > > `-fopenmp` only (+ aux-triple, probably), for devices - `-fopenmp 
> > > > > -fopenmp-is-device`. Without `-fopenmp` `-fopenmp-is-device` is just 
> > > > > ignored.
> > > > What is the reason to require the driver to pass both options for the 
> > > > devices? It sounds like `-fopenmp-is-device` should be enough to 
> > > > differentiate from the host part (`-fopenmp` only). Right?
> > > We treat a little bit differently. `-fopenmp` turns support for OpenMP, 
> > > while `-fopenmp-is-device` turns processing for device compilation.
> > I'm okay to use OpenMP way to treat front-end options as they impact only 
> > clang developers (more verbose LIT test + a little bit more logic in the 
> > code), but I'd like to keep driver options handling simpler for clang users.
> > We can discuss this later, when `-fsycl-device-only` driver option is added.
> > 
> > Do you have any other comments to this change?
> > 
> > BTW, thanks a lot for take your time to review SYCL patches - it's highly 
> > appreciated!
> ```
> We treat a little bit differently. -fopenmp turns support for OpenMP, while 
> -fopenmp-is-device turns processing for device compilation.
> ```
> 
> Seems to me that SYCL is kind of an hybrid here.
> 
> @bader do you plan on raising kernel specific diagnostics even on the host 
> side ? In this case reusing this model will fully make sense.
> do you plan on raising kernel specific diagnostics even on the host side ? In 
> this case reusing this model will fully make sense.

Not sure I understand the question. Why would we need raising kernel specific 
diagnostics on the host side? Is it against the SYCL design principal?


Repository:
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  https://reviews.llvm.org/D72857/new/

https://reviews.llvm.org/D72857



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