[PATCH] D136395: Add the ability to verify the .debug_aranges section.

Fri Oct 21 13:34:35 PDT 2022

dblaikie added a comment.

In D136395#3875783 <https://reviews.llvm.org/D136395#3875783>, @ayermolo wrote:

> In D136395#3873072 <https://reviews.llvm.org/D136395#3873072>, @dblaikie wrote:
>
>> If possible, I'd rather not add this - I think .debug_aranges should be removed (it's already been off-by-default for a decade in Clang) in favor of using CU-level address ranges. They're cheap-enough to parse that it doesn't substantially change the performance of tools so far as I'm aware and they save space by not duplicating the address range information in two places.
>>
>> Adding a verifier feels like endorsing/encouraging/maintaining `.debug_aranges` which seems like the wrong direction we should be going.
>
> Can you elaborate on why they should be removed. Is it because of the aforementioned duplication of information, or are there other reasons also?

Yeah, basically only that - they're redundant, and maintaining different paths is a burden (verifying them, fixing bugs in them, having tools that either consume one or the other or both, etc) - having a single way to represent things would be better for the DWARF ecosystem of consumers and producers.

(also aranges haven't been updated to benefit from the more compact/fewer-relocation-using encoding of .debug_rnglists introduced in DWARFv5 - so it's bigger/less efficient now as well)

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https://reviews.llvm.org/D136395