[all-commits] [llvm/llvm-project] 5b24d4: TailDuplication: do not remove trivial PHIs from a...

[Tim Northover via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 5b24d421064743fcb67be82cf1578cc3aa502faf
      https://github.com/llvm/llvm-project/commit/5b24d421064743fcb67be82cf1578cc3aa502faf
  Author: Tim Northover <tnorthover at apple.com>
  Date:   2023-01-09 (Mon, 09 Jan 2023)

  Changed paths:
    M llvm/lib/CodeGen/TailDuplicator.cpp
    A llvm/test/CodeGen/AArch64/taildup-addrtaken.mir

  Log Message:
  -----------
  TailDuplication: do not remove trivial PHIs from addr-taken blocks.

Unlike an anonymous block, it will not be removed even though we've resolved
all valid paths to get here. So removing a PHI can leave vregs with no
definition, violating SSA. Instead, this converts it to an IMPLICIT_DEF.