[PATCH] D80077: [LiveVariables] Don't set undef reg PHI used as live for FromMBB

[Zhang Kang via Phabricator via llvm-commits]

ZhangKang added a comment.

@bjope , we can use below command to reproduce the error:

  llc -mtriple=aarch64-linux-gnu shrink-wrap.ll  -o stop-before.processimpdefs.mir -verify-machineinstrs -stop-before=processimpdefs
  llc -mtriple=aarch64-linux-gnu stop-before.processimpdefs.mir -verify-machineinstrs -run-pass=processimpdefs,livevars,machine-loops,phi-node-elimination,twoaddressinstruction

Then ,we will get below error:

  *** Bad machine code: LiveVariables: Block should not be in AliveBlocks ***
  - function:    func
  - basic block: %bb.19  (0x1001cf4fde0)
  Virtual register %59 is not needed live through the block.
  LLVM ERROR: Found 1 machine code errors.
  PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace.
  Stack dump:

But the `stop-before.processimpdefs.mir` has more than 500 lines, I am using butpoint to reduce the case, but it doesn't narrow down it.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D80077/new/

https://reviews.llvm.org/D80077