[all-commits] [llvm/llvm-project] 1eb753: [MCA][RegisterFile] Consistently update the PRF in...

[Andrea Di Biagio via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1eb75362c9903fcaa8b5ceb28ab36234ddda0cca
      https://github.com/llvm/llvm-project/commit/1eb75362c9903fcaa8b5ceb28ab36234ddda0cca
  Author: Andrea Di Biagio <andrea.dibiagio at sony.com>
  Date:   2021-08-26 (Thu, 26 Aug 2021)

  Changed paths:
    M llvm/lib/MCA/HardwareUnits/RegisterFile.cpp

  Log Message:
  -----------
  [MCA][RegisterFile] Consistently update the PRF in the presence of multiple writes to the same register.

My last change to the RegisterFile (PR51495) has introduced a bug in the logic
that allocates physical registers in the PRF.

In some cases, this bug could have triggered a nasty unsigned wrap in the number
of allocated registers, thus resulting in mca being stuck forever in a loop of
PRF availability checks.