Remove check for single use in ShrinkDemandedConstant

This removes check for single use from general ShrinkDemandedConstant
to the BE because of the AArch64 regression after D56289/rL350475.

After several hours of experiments I did not come up with a testcase
failing on any other targets if check is not performed.

Moreover, direct call to ShrinkDemandedConstant is not really needed
and superceed by SimplifyDemandedBits.

Differential Revision: https://reviews.llvm.org/D56406

llvm-svn: 350684

Author: rampitec

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -350,9 +350,6 @@ bool TargetLowering::ShrinkDemandedConstant(SDValue Op, const APInt &Demanded,
   SDLoc DL(Op);
   unsigned Opcode = Op.getOpcode();
 
-  if (!Op.hasOneUse())
-    return false;
-
   // Do target-specific constant optimization.
   if (targetShrinkDemandedConstant(Op, Demanded, TLO))
     return TLO.New.getNode();

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

@@ -8586,8 +8586,7 @@ SDValue SITargetLowering::performCvtF32UByteNCombine(SDNode *N,
   TargetLowering::TargetLoweringOpt TLO(DAG, !DCI.isBeforeLegalize(),
                                         !DCI.isBeforeLegalizeOps());
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
-  if (TLI.ShrinkDemandedConstant(Src, Demanded, TLO) ||
-      TLI.SimplifyDemandedBits(Src, Demanded, Known, TLO)) {
+  if (TLI.SimplifyDemandedBits(Src, Demanded, Known, TLO)) {
     DCI.CommitTargetLoweringOpt(TLO);
   }