[PATCH] D54029: [RISCV] Properly evaluate fixup_riscv_pcrel_lo12

[Lewis Revill via Phabricator via llvm-commits]

lewis-revill added a comment.

In D54029#1407041 <https://reviews.llvm.org/D54029#1407041>, @lewis-revill wrote:

> In D54029#1404753 <https://reviews.llvm.org/D54029#1404753>, @apazos wrote:
>
> > Hi James, I encountered another case not handled yet in this patch. It produces the error: could not find corresponding %pcrel_hi
> >
> >   .option push
> >   .option norelax
> >   la gp, __global_pointer$
> >   .option pop
> >   la sp, _sp
>
>
> This also occurs when you manually expand la.
>
> Regardless I believe the problem is caused because `EmitLabel` doesn't have any checks for whether a new data fragment should be introduced, whereas `EmitInstToData` does. So when the `.Lpcrel_hiX` label is expanded/parsed it's parent fragment is the one before the directive changed the STI flags, but the `auipc` and its `%pcrel_hi` fixup is located in the fragment after.
>
> When `getPCRelHiFixup()` searches for the `%pcrel_hi` it fails to find it since it uses the fragment & offset of the label to search, whereas the fixup is in another fragment.
>
> This is just from some initial debugging, so I'm not sure whether this is the only issue and/or what the best solution would be.


Sure enough, threading through an `MCSubtargetInfo` to `EmitLabel` and checking for `CanReuseDataFragment` before inserting the label into the current section fixes the issue.


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