[all-commits] [llvm/llvm-project] 100843: Revert "[InstCombine] do not exclude min/max from ...

[RotateRight via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 1008435f3d47ac0f49690c52cb8ae3af6e3b9c4b
      https://github.com/llvm/llvm-project/commit/1008435f3d47ac0f49690c52cb8ae3af6e3b9c4b
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2020-04-02 (Thu, 02 Apr 2020)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/test/Transforms/InstCombine/adjust-for-minmax.ll
    M llvm/test/Transforms/InstCombine/select_meta.ll

  Log Message:
  -----------
  Revert "[InstCombine] do not exclude min/max from icmp with casted operand fold"

This reverts commit f2fbdf76d8d07f6a0fbd97825cbc533660d64a37.
As noted in the post-commit thread:
https://reviews.llvm.org/rGf2fbdf76d8d0
...this can obscure a min/max pattern where the components
have extra uses. We can show that the problem is independent
of this change with a slightly modified source example, so
this revert just delays/reduces the need to fix the real
problem.

We need to improve our analysis of negation or -- more
generally -- subtraction using patches like D77230 or D68408.