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SafepointIRVerifier is made unreachable block tolerant
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Authored by yrouban on May 17 2018, 5:04 AM.

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Summary

SafepointIRVerifier crashed while traversing blocks without a DomTreeNode.
This could happen with a custom pipeline or when some optional passes were skipped by OptBisect.

SafepointIRVerifier is fixed to traverse basic blocks that are reachable from entry. Test are added.

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Repository
rL LLVM

Event Timeline

yrouban created this revision.May 17 2018, 5:04 AM
reames accepted this revision.May 17 2018, 9:55 AM

LGTM

This revision is now accepted and ready to land.May 17 2018, 9:55 AM

Without this patch following code leads to a crash

entry:
ptr = getPtr()
br exit

unreachable_bb:
ptr2 = getPtr()
br exit

exit:
p = phi [ptr, entry], [ptr2, unreachable_bb]
v = load p
ret v

But with your patch it's a false-positive. Verifier will report invalid use of poisoned value p here (since unreachable_bb isn't processed and thus ptr2 isn't in its AvailableOut set).
Could you please leave a FIXME about it?

yrouban planned changes to this revision.May 17 2018, 9:47 PM

Good catch Daniil! SafepointIRVerifier crashes with your case. I will improve the patch and add a test.

yrouban updated this revision to Diff 147443.May 18 2018, 12:02 AM
yrouban edited the summary of this revision. (Show Details)

considered a case with unreachable blocks connected to reachable ones

This revision is now accepted and ready to land.May 18 2018, 12:02 AM

LLVM committers, can you integrate this patch, please?

This revision was automatically updated to reflect the committed changes.