[all-commits] [llvm/llvm-project] b3f0c2: [Analysis] simplify propagation of FMF in recurren...

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  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b3f0c2653b61377413c02ce6f6cdeb452c9a8e79
      https://github.com/llvm/llvm-project/commit/b3f0c2653b61377413c02ce6f6cdeb452c9a8e79
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2021-03-03 (Wed, 03 Mar 2021)

  Changed paths:
    M llvm/lib/Analysis/IVDescriptors.cpp

  Log Message:
  -----------
  [Analysis] simplify propagation of FMF in recurrences; NFC

This is a mess, but this is hopefully no-functional-change.
The 'Prev' descriptor is only used for min/max recurrences
or when starting a match from a phi, so it should not be a
factor when propagating FMF for fmul/fadd.

The API is confusing (and should be reduced in subsequent steps)
because the "UnsafeAlgebraInst" appears to actually be a placeholder
for a recurrence that does NOT have FMF, but we still want to
treat it as reassociative.