[all-commits] [llvm/llvm-project] a6f79b: [InstCombine] avoid infinite loops with select/icm...

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  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a6f79b56711e009440d00685e36c1fb919659202
      https://github.com/llvm/llvm-project/commit/a6f79b56711e009440d00685e36c1fb919659202
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2021-05-04 (Tue, 04 May 2021)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/test/Transforms/InstCombine/icmp-dom.ll

  Log Message:
  -----------
  [InstCombine] avoid infinite loops with select/icmp transforms

This fixes https://llvm.org/PR48900 , but as seen in the
regression tests prevents some optimizations.

There are a few options to restore those (switch to min/max
intrinsics, add larger pattern matching for select with
dominating condition, improve CVP), but we need to prevent
the bug 1st.