[PATCH] D140478: [RISCV] For Dwarf v5, emit indices into .debug_addr for range list entries

[Sriraman Tallam via Phabricator via llvm-commits]

tmsriram added a comment.

In D140478#4011085 <https://reviews.llvm.org/D140478#4011085>, @dblaikie wrote:

> Is there any mechanism that tests whether a given range bounded by two labels may be subject to linker relaxation? It'd be nice to have that abstraction and use it here (& in some other places in DWARF emission) rather than hardcoding one particular architecture.
>
> The other place this would be needed is in the low/high_pc computation, since currently, even in DWARFv4, the high_pc is encoded as a delta from low_pc, not as a separate relocatable label, so that'd need the same checking.
>
> And I was thinking that PROPELLER needed/was considering doing some linker relaxation too, so could benefit from such an abstraction/hook/check - but maybe they didn't end up needing/using linker relaxation? (@tmsriram - did PROPELLER ever end up needing/using linker relaxation? is that still something under consideration?)

Propeller needs linker relaxation for branch instructions.  Making it a shorter branch when the offset can fit in one byte and flipping branches, from like je to jne to convert and remove a subsequent fallthrough.

I remember dealing with issues regarding low_pc, high_pc. I think you reviewed these patches,  I forget the details now and can take another look to see how this can help.


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