ABataev added inline comments.
================
Comment at: clang/lib/Sema/SemaOpenMP.cpp:1594
+ !Context.getTargetInfo().hasFloat128Type() &&
+ Context.getTargetInfo().getLongDoubleWidth() != 128) ||
(Ty->isIntegerType() && Context.getTypeSize(Ty) == 128 &&
----------------
jdenny wrote:
> ABataev wrote:
> > jdenny wrote:
> > > ABataev wrote:
> > > > jdenny wrote:
> > > > > ABataev wrote:
> > > > > > jdenny wrote:
> > > > > > > ABataev wrote:
> > > > > > > > jdenny wrote:
> > > > > > > > > ABataev wrote:
> > > > > > > > > > Hmm, this look strange, at least. Seems to me, in this case
> > > > > > > > > > the size of the long double is 128 bit (copied from the
> > > > > > > > > > host), but device reports that it does not support 128 bit
> > > > > > > > > > double. Seems to me, it is a problem with the device
> > > > > > > > > > configuration. Why does the host translate long double to
> > > > > > > > > > 128 bit fp, while the device translates it to 64 bit FP?
> > > > > > > > > Sorry, I think I've misunderstood what's happening here, and
> > > > > > > > > my fix is probably wrong.
> > > > > > > > >
> > > > > > > > > For x86_64, the example from my patch summary fails as
> > > > > > > > > described there. Does that work for you?
> > > > > > > > >
> > > > > > > > > For powerpc64le, the reproducer I added to the test suite
> > > > > > > > > fails without this patch. Shouldn't it succeed?
> > > > > > > > Still, seems to me like the problem with the device config, not
> > > > > > > > the original check.
> > > > > > > > Still, seems to me like the problem with the device config, not
> > > > > > > > the original check.
> > > > > > >
> > > > > > > I'm not sure where to begin looking for that. Can you point me
> > > > > > > in the right direction? Thanks.
> > > > > > You need to understand why host and device report different size of
> > > > > > the type. Check how the device is configured in lib/Basic/Targets
> > > > > Thanks for the pointer. I think I understand things a bit better now.
> > > > >
> > > > > Without this patch's fix, the x86_64 example from this patch's
> > > > > summary fails while this patch's new x86_64 test case passes. The
> > > > > difference is the summary's example doesn't specify `-unknown-linux`
> > > > > after `x86_64`, and that's what sets `hasFloat128Type()` to true.
> > > > >
> > > > > `powerpc64le-unknown-linux-gnu` does not have `__float128`, it seems.
> > > > > That's why this patch's new powerpc64le test case fails without this
> > > > > patch's fix.
> > > > >
> > > > > It seems strange to me that the code we're commenting on originally
> > > > > looks for the source type to be either `__float128` or 128-bit `long
> > > > > double`, and it then requires the target to support `__float128`. It
> > > > > doesn't accept 128-bit `long double` support as sufficient. My
> > > > > intention in this patch was to extend it to accept either so that all
> > > > > the examples above compile. Is that too lenient? Am I
> > > > > misinterpreting what's happening?
> > > > >
> > > > > As for your comment about 64-bit floating point in the device
> > > > > translation, I haven't seen that yet. Did I miss it?
> > > > The intention of the original patch is to make host and device to have
> > > > the same float128 and long double types. Device inherits those types
> > > > from the host to be compatible during offloading and to correctly
> > > > mangle functions.
> > > > Without this we just can't generate offloading regions correctly. If
> > > > the host has 128 bit long double, the device also must have 128 bit
> > > > long double.
> > > > If device does not support 128bit floats, in this case device can only
> > > > move the data (do load/stores ops only) and cannot do anything else.
> > > Are you intentionally requiring support for `__float128` when the source
> > > type is 128-bit `long double`? That seems to mean powerpc64le cannot
> > > offload to itself.
> > No, if the host has 128 bit long double, the device must also have 128 bit
> > long double. It has nothing to do with the float128 type itself.
> What if we change the logic to the following?
>
> ```
> (Ty->isFloat128Type() && !Context.getTargetInfo().hasFloat128Type()) ||
> (!Ty->isFloat128Type() && Ty->isRealFloatingType() &&
> Context.getTypeSize(Ty) == 128 &&
> Context.getTargetInfo().getLongDoubleWidth() != 128)
> ```
>
> Maybe there's a more succinct way to check if `Ty` is `long double`....
What if `Ty` is not long double, but some other FP type?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D64289/new/
https://reviews.llvm.org/D64289
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