[all-commits] [llvm/llvm-project] 814172: Use a stable-sort when combining bases

[Sterling-Augustine via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 81417261a15f46284f2613118120d7d6de2bc02d
      https://github.com/llvm/llvm-project/commit/81417261a15f46284f2613118120d7d6de2bc02d
  Author: Sterling Augustine <saugustine at google.com>
  Date:   2022-03-17 (Thu, 17 Mar 2022)

  Changed paths:
    M llvm/lib/Target/ARM/ARMISelLowering.cpp

  Log Message:
  -----------
  Use a stable-sort when combining bases

While experimenting with different algorithms for std::sort
I discovered that combine-vmovdrr.ll fails if this sort is not
stable.

I suspect that the test is too stringent in its check--the resultant
code looks functionally identical to me under both stable and unstable
sorting, but a generic fix is quite a bit more difficult to implement.

Thanks to scw at google.com for finding the proper fix.

Differential Revision: https://reviews.llvm.org/D121870