void marked an inline comment as done.
void added inline comments.
================
Comment at: llvm/lib/CodeGen/MachineVerifier.cpp:701
+ } else if (MBB->succ_size() == LandingPadSuccs.size() ||
+ MBB->succ_size() == IndirectPadSuccs.size()) {
// It's possible that the block legitimately ends with a noreturn
----------------
jyknight wrote:
> This isn't correct.
>
> This line here, is looking at a block which doesn't end in a jump to a
> successor. So, it's trying to verify that the successor list makes sense in
> that context.
>
> The unstated assumption in the code is that the only successors will be
> landing pads. Instead of actually checking each one, instead it just checks
> that the count is the number of landing pads, with the assumption that all
> the successors should be landing pads, and that all the landing pads should
> be successors.
>
> The next clause is then checking for the case where there's a fallthrough to
> the next block. In that case, the successors should've been all the landing
> pads, and the single fallthrough block.
>
> Adding similar code to check for the number of callbr targets doesn't really
> make sense. It's certainly not the case that all callbr targets are targets
> of all
> callbr instructions. And even if it was, this still wouldn't be counting
> things correctly.
>
>
> However -- I think i'd expect analyzeBranch to error out (returning true)
> when confronted by a callbr instruction, because it cannot actually tell
> what's going on there. If that were the case, nothing in this block should
> even be invoked. But I guess that's probably not happening, due to the
> terminator being followed by non-terminators.
>
> That seems likely to be a problem that needs to be fixed. (And if that is
> fixed, I think the changes here aren't needed anymore)
>
>
Your comment is very confusing. Could you please give an example of where this
fails?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D69868/new/
https://reviews.llvm.org/D69868
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