[cfe-dev] Crash on conditional operation with address_space pointer

[Leonard Chan via cfe-dev]

Does this mean the check during the BitCast codegen shouldn't be there
in the first place?
On Fri, Aug 3, 2018 at 4:28 PM John McCall <rjmccall at apple.com> wrote:
>
> > On Aug 3, 2018, at 7:03 PM, Leonard Chan via cfe-dev <cfe-dev at lists.llvm.org> wrote:
> > Compiling the following causes clang to crash
> >
> > char *cmp(__attribute__((address_space(1))) char *x,
> > __attribute__((address_space(2))) char *y) {
> >  return x < y ? x : y;
> > }
> >
> > with the message: "wrong cast for pointers in different address
> > spaces(must be an address space cast)!"
> >
> > The problem seems to be that BitCast is used when
> > AddressSpaceConversion should be used instead when casting the `y` to
> > a void *. The error is thrown during code gen where a BitCast expects
> > the source and dest address space to be the same.
> >
> > I submitted a patch (https://reviews.llvm.org/D50278) for a fix where
> > we check for differing address spaces in the operands and perform an
> > AddressSpaceConversion cast if anyone wants to review it. It seems
> > that AddressSpaceConversions though were only available when using
> > OpenCL. I'm not familiar with OpenCL and not sure if this was
> > intended, but it fixes the crash while still retaining the warning of
> > using mismatched pointers and all the clang tests pass.
>
> If address spaces 1 and 2 don't overlap — and absent target-specific
> information, the assumption is that they don't — then neither the comparison
> nor the conditional operator here should type-check.
>
> John.