[PATCH] D62450: [DAGCombine] x ==/!= c -> (x - c) ==/!= 0 iff '-c' can be folded into the x node.

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri created this revision.
lebedev.ri added reviewers: efriedma, craig.topper, spatel, RKSimon.
lebedev.ri added a project: LLVM.
Herald added subscribers: kristof.beyls, javed.absar.
lebedev.ri added a parent revision: D62392: [DAGCombine][ARM] (sub Carry, X)  ->  (addcarry (sub 0, X), 0, Carry)  fold.
lebedev.ri added a child revision: D62294: [DAGCombine] (x - C) - y  ->  (x - y) - C  fold.

This fold, helps recover from the rest of the D62266 <https://reviews.llvm.org/D62266> ARM regressions.
https://rise4fun.com/Alive/TvpC

Note that while the fold is quite flexible, i'we restricted it
to the single interesting pattern at the moment.


Repository:
  rL LLVM

https://reviews.llvm.org/D62450

Files:
  include/llvm/CodeGen/TargetLowering.h
  lib/CodeGen/SelectionDAG/TargetLowering.cpp
  test/CodeGen/ARM/addsubcarry-promotion.ll

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