Revert 4334892e7b "[DAGCombine][ARM] x ==/!= c -> (x - c) ==/!= 0 iff '-c' can be folded into the x node."

This broke various Windows builds, see comments on the Phabricator
review.

This also reverts the follow-up 20bf0cf.

> Summary:
> This fold, helps recover from the rest of the D62266 ARM regressions.
> https://rise4fun.com/Alive/TvpC
>
> Note that while the fold is quite flexible, i've restricted it
> to the single interesting pattern at the moment.
>
> Reviewers: efriedma, craig.topper, spatel, RKSimon, deadalnix
>
> Reviewed By: deadalnix
>
> Subscribers: javed.absar, kristof.beyls, llvm-commits
>
> Tags: #llvm
>
> Differential Revision: https://reviews.llvm.org/D62450

1 files changed, 0 insertions, 65 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 5af2663d29e..9ab1324533f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -3045,66 +3045,6 @@ SDValue TargetLowering::foldSetCCWithBinOp(EVT VT, SDValue N0, SDValue N1,
   return DAG.getSetCC(DL, VT, X, YShl1, Cond);
 }
 
-/// x ==/!= c  ->  (x - c) ==/!= 0  iff '-c' can be folded into the x node.
-SDValue TargetLowering::optimizeSetCCToComparisonWithZero(
-    EVT SCCVT, SDValue N0, ConstantSDNode *N1C, ISD::CondCode Cond,
-    DAGCombinerInfo &DCI, const SDLoc &DL) const {
-  assert((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
-         "Only for equality-comparisons.");
-
-  // The constant we are comparing with must be a non-zero, non-opaque constant.
-  if (N1C->isNullValue() || N1C->isOpaque())
-    return SDValue();
-
-  // LHS should not be used elsewhere, to avoid creating an extra node.
-  if (!N0.hasOneUse())
-    return SDValue();
-
-  // Will we able to fold the '-c' into 'x' node?
-  bool IsAdd;
-  switch (N0.getOpcode()) {
-  default:
-    return SDValue(); // Don't know about that node.
-  case ISD::ADD:
-  case ISD::SUB:
-    return SDValue(); // Let's not touch these.
-  case ISD::ADDCARRY:
-    IsAdd = true;
-    break;
-  case ISD::SUBCARRY:
-    IsAdd = false;
-    break;
-  }
-
-  // Second operand must be a non-opaque constant.
-  ConstantSDNode *N01C = isConstOrConstSplat(N0.getOperand(1));
-  if (!N01C || N01C->isOpaque())
-    return SDValue();
-
-  // And let's be even more specific for now, it must be a zero constant.
-  // It is possible to relax this requirement, but a precise cost-model needed.
-  if (!N01C->isNullValue())
-    return SDValue();
-
-  SelectionDAG &DAG = DCI.DAG;
-  EVT OpVT = N0.getValueType();
-
-  // (y + N01C) - N1C = y + (N01C - N1C)
-  // (y - N01C) - N1C = y - (N01C + N1C)
-  SDValue NewC = DAG.FoldConstantArithmetic(IsAdd ? ISD::SUB : ISD::ADD, DL,
-                                            OpVT, N01C, N1C);
-  assert(NewC && "Constant-folding failed!");
-
-  SmallVector<SDValue, 3> N0Ops(N0.getNode()->ops().begin(),
-                                N0.getNode()->ops().end());
-  N0Ops[1] = NewC;
-
-  N0 = DAG.getNode(N0.getOpcode(), DL, N0->getVTList(), N0Ops);
-
-  SDValue Zero = DAG.getConstant(0, DL, OpVT);
-  return DAG.getSetCC(DL, SCCVT, N0, Zero, Cond);
-}
-
 /// Try to simplify a setcc built with the specified operands and cc. If it is
 /// unable to simplify it, return a null SDValue.
 SDValue TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
@@ -3638,11 +3578,6 @@ SDValue TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
           return CC;
     }
 
-    if (Cond == ISD::SETEQ || Cond == ISD::SETNE)
-      if (SDValue CC =
-              optimizeSetCCToComparisonWithZero(VT, N0, N1C, Cond, DCI, dl))
-        return CC;
-
     // If we have "setcc X, C0", check to see if we can shrink the immediate
     // by changing cc.
     // TODO: Support this for vectors after legalize ops.