[PATCH] D156477: [RISCVRVVInitUndef] Remove implicit single use assumption for IMPLICIT_DEF

[Philip Reames via Phabricator via llvm-commits]

reames updated this revision to Diff 545696.
reames added a comment.

Change was reverted due to a sanitizer failure - thanks!

It turns out the DeadLaneDetector does an out of bounds access if you query a vreg which didn't exist at population, and there's no clean interface to update it.  For the moment, simply avoid querying newly inserted vregs.

This seems worthy of re-review.  @craig.topper thoughts?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D156477/new/

https://reviews.llvm.org/D156477

Files:
  llvm/lib/Target/RISCV/RISCVRVVInitUndef.cpp
  llvm/test/CodeGen/RISCV/rvv/undef-earlyclobber-chain.ll
  llvm/test/CodeGen/RISCV/rvv/undef-earlyclobber-chain.mir

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