Commit 1ebd4a2e authored by Sanjay Patel's avatar Sanjay Patel
Browse files

[DAGCombiner] widen any_ext of popcount based on target support 

This enhances D69127 (rGe6c145e0548e3b3de6eab27e44e1504387cf6b53)
to handle the looser "any_extend" cast in addition to zext.

This is a prerequisite step for canonicalizing in the other direction
(narrow the popcount) in IR - PR43688:
https://bugs.llvm.org/show_bug.cgi?id=43688
parent 35cb3ee4

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

+28 −11
Original line number Diff line number Diff line
@@ -9673,6 +9673,29 @@ static bool isTruncateOf(SelectionDAG &DAG, SDValue N, SDValue &Op, 
  return (Known.Zero | 1).isAllOnesValue();

}













/// Given an extending node with a pop-count operand, if the target does not













/// support a pop-count in the narrow source type but does support it in the













/// destination type, widen the pop-count to the destination type.













static SDValue widenCtPop(SDNode *Extend, SelectionDAG &DAG) {













  assert((Extend->getOpcode() == ISD::ZERO_EXTEND ||













          Extend->getOpcode() == ISD::ANY_EXTEND) && "Expected extend op");

























  SDValue CtPop = Extend->getOperand(0);













  if (CtPop.getOpcode() != ISD::CTPOP || !CtPop.hasOneUse())













    return SDValue();

























  EVT VT = Extend->getValueType(0);













  const TargetLowering &TLI = DAG.getTargetLoweringInfo();













  if (TLI.isOperationLegalOrCustom(ISD::CTPOP, CtPop.getValueType()) ||













      !TLI.isOperationLegalOrCustom(ISD::CTPOP, VT))













    return SDValue();

























  // zext (ctpop X) --> ctpop (zext X)













  SDLoc DL(Extend);













  SDValue NewZext = DAG.getZExtOrTrunc(CtPop.getOperand(0), DL, VT);













  return DAG.getNode(ISD::CTPOP, DL, VT, NewZext);













}



























SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {















  SDValue N0 = N->getOperand(0);















  EVT VT = N->getValueType(0);










@@ -9923,17 +9946,8 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {













  if (SDValue NewVSel = matchVSelectOpSizesWithSetCC(N))















    return NewVSel;



























  // If the target does not support a pop-count in the narrow source type but













  // does support it in the destination type, widen the pop-count to this type:













  // zext (ctpop X) --> ctpop (zext X)













  // TODO: Generalize this to handle starting from anyext.













  if (N0.getOpcode() == ISD::CTPOP && N0.hasOneUse() &&













      !TLI.isOperationLegalOrCustom(ISD::CTPOP, N0.getValueType()) &&













      TLI.isOperationLegalOrCustom(ISD::CTPOP, VT)) {













    SDLoc DL(N);













    SDValue NewZext = DAG.getZExtOrTrunc(N0.getOperand(0), DL, VT);













    return DAG.getNode(ISD::CTPOP, DL, VT, NewZext);













  }













  if (SDValue NewCtPop = widenCtPop(N, DAG))













    return NewCtPop;





























  return SDValue();















}










@@ -10081,6 +10095,9 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {













      return SCC;















  }



























  if (SDValue NewCtPop = widenCtPop(N, DAG))













    return NewCtPop;



























  return SDValue();















}















































llvm/test/CodeGen/PowerPC/popcnt-zext.ll



+4
−4






























Original line number
Diff line number
Diff line








@@ -5,8 +5,8 @@













define i16 @zpop_i8_i16(i8 %x) {















; FAST-LABEL: zpop_i8_i16:















; FAST:       # %bb.0:













; FAST-NEXT:    rlwinm 3, 3, 0, 24, 31













; FAST-NEXT:    popcntw 3, 3













; FAST-NEXT:    clrldi 3, 3, 56













; FAST-NEXT:    popcntd 3, 3















; FAST-NEXT:    blr















;















; SLOW-LABEL: zpop_i8_i16:










@@ -297,8 +297,8 @@ define i64 @popz_i32_i64(i32 %x) {













define i64 @popa_i16_i64(i16 %x) {















; FAST-LABEL: popa_i16_i64:















; FAST:       # %bb.0:













; FAST-NEXT:    rlwinm 3, 3, 0, 16, 31













; FAST-NEXT:    popcntw 3, 3













; FAST-NEXT:    clrldi 3, 3, 48













; FAST-NEXT:    popcntd 3, 3















; FAST-NEXT:    andi. 3, 3, 16















; FAST-NEXT:    blr















;

































llvm/test/CodeGen/PowerPC/popcnt.ll



+4
−4






























Original line number
Diff line number
Diff line








@@ -8,8 +8,8 @@ define i8 @cnt8(i8 %x) nounwind readnone {













  %cnt = tail call i8 @llvm.ctpop.i8(i8 %x)















  ret i8 %cnt















; CHECK-LABEL: @cnt8













; CHECK: rlwinm













; CHECK: popcntw













; CHECK: clrldi













; CHECK: popcntd















; CHECK: blr































; SLOWPC-LABEL: @cnt8









@@ -20,8 +20,8 @@ define i16 @cnt16(i16 %x) nounwind readnone {













  %cnt = tail call i16 @llvm.ctpop.i16(i16 %x)















  ret i16 %cnt















; CHECK-LABEL: @cnt16













; CHECK: rlwinm













; CHECK: popcntw













; CHECK: clrldi













; CHECK: popcntd















; CHECK: blr































; SLOWPC-LABEL: @cnt16