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

[Leonard Chan via cfe-dev]

Oh I see. I misinterpreted a few things. I'll change the patch to
print something from err_typecheck_incompatible_address_space instead
in addition to raising the warning.
On Fri, Aug 3, 2018 at 4:57 PM John McCall <rjmccall at apple.com> wrote:
>
> > On Aug 3, 2018, at 7:56 PM, Leonard Chan <leonardchan at google.com> wrote:
> > Oh. Should an error be printed here instead, or it's fine to let it
> > crash I suppose since the code shouldn't be generate in the first
> > place?
> >
> > It seems that at least 3 tests expect this conditional operator to
> > print a "pointer type mismatch" warning.
>
> The compiler should definitely never crash.  That sounds like the right diagnostic
> we should be emitting, except I don't think it can be just a warning for an
> address-space mismatch.
>
> John.
>
> > On Fri, Aug 3, 2018 at 4:50 PM John McCall <rjmccall at apple.com> wrote:
> >>
> >>> On Aug 3, 2018, at 7:42 PM, Leonard Chan <leonardchan at google.com> wrote:
> >>> Does this mean the check during the BitCast codegen shouldn't be there
> >>> in the first place?
> >>
> >> We should not be generating code for this program, correct.
> >>
> >> John.
> >>
> >>> 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.
> >>
>