[PATCH] D104827: [DebugInfo] Enforce implicit constraints on `distinct` MDNodes

Thu Jul 8 12:36:18 PDT 2021

dexonsmith removed a reviewer: dexonsmith.
dexonsmith added a comment.

In D104827#2855970 <https://reviews.llvm.org/D104827#2855970>, @dexonsmith wrote:

> That looks bad — best to revert while that's investigated.

Oops... I had misread this comment:

In D104827#2854825 <https://reviews.llvm.org/D104827#2854825>, @uabelho wrote:

> We've noticed that this patch changes things so bcfiles created with the patch cannot be parsed with binaries built before it.

I don't think we have any guarantees about reading new bitcode with old readers. There's some machinery for a high-level version check to get a nice error (checking `MODULE_CODE_VERSION`) but I think that's it. (I thought this was saying the new reader couldn't read the old bitcode, in which case there'd be a missing bitcode upgrade.)

In D104827#2864582 <https://reviews.llvm.org/D104827#2864582>, @scott.linder wrote:

> Any thoughts on where to go from here, and whether this patch should be blocked on these fixes?

Assuming IIUC now, the patch can probably land as-is... but probably makes sense to investigate the LLDB issue first. @JDevlieghere, could the failing LLDB test somehow be reading a new bitcode file with an old reader, or is that something different?

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https://reviews.llvm.org/D104827