[PATCH] D144008: [DebugMetadata][DwarfDebug] Support function-local static variables in lexical block scopes (7/7)

Mon Mar 13 11:06:17 PDT 2023

dblaikie added a comment.

In D144008#4188878 <https://reviews.llvm.org/D144008#4188878>, @krisb wrote:

> @dblaikie
>
> In D144008#4185551 <https://reviews.llvm.org/D144008#4185551>, @dblaikie wrote:
>
>> @krisb - how's this handle cases of old IR being used in a newer compiler/linker?
>
> There is no backward compatibility, old IR may cause DwarfDebug crash (it asserts that old IR is no longer supported) or miscompilation.
> Implementing AutoUpgrade seems to be quite easy, but as far as I can see almost all the changes in debug metadata before were done w/o backward compatibility, so I haven't considered it yet.

I don't /think/ that's the case - I know Apple used to have a pretty significant dependence on IR upgrading at least invalidating the IR metadata & dropping it (so maybe all you need to do is update the debug info IR verifier so that old IR gets deemed invalid and dropped - not necessarily upgraded).

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