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[DAGCombine][RISCV] fold select_cc seteq (and x, 1) 0, 0, -1 -> neg(and(x, 1)) #152062

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[DAGCombine][RISCV] fold select_cc seteq (and x, 1) 0, 0, -1 -> neg(and(x, 1)) #152062

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10 changes: 10 additions & 0 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -28963,6 +28963,16 @@ SDValue DAGCombiner::SimplifySelectCC(const SDLoc &DL, SDValue N0, SDValue N1,
if (SDValue V = foldSelectCCToShiftAnd(DL, N0, N1, N2, N3, CC))
return V;

// fold select_cc seteq (and x, 1), 0, 0, -1 -> neg(and(x, 1))
if (CC == ISD::SETEQ && N0->getOpcode() == ISD::AND &&
N0->getValueType(0) == VT && isNullConstant(N1) &&
isAllOnesConstant(N2) && isOneConstant(N0->getOperand(1))) {
SDValue AndLHS = N0->getOperand(0);
SDValue Neg =
DAG.getNode(ISD::AND, DL, VT, AndLHS, DAG.getConstant(1, DL, VT));
return DAG.getNegative(Neg, DL, VT);
}

// fold (select_cc seteq (and x, y), 0, 0, A) -> (and (sra (shl x)) A)
// where y is has a single bit set.
// A plaintext description would be, we can turn the SELECT_CC into an AND
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16 changes: 7 additions & 9 deletions llvm/test/CodeGen/RISCV/pr148084.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -10,15 +10,14 @@ define fastcc void @search_tx_type() #0 {
; CHECK: # %bb.0: # %._crit_edge.i
; CHECK-NEXT: # %bb.1: # %bb
; CHECK-NEXT: lbu a1, 0(zero)
; CHECK-NEXT: lw a0, 0(zero)
; CHECK-NEXT: lh a2, 0(zero)
; CHECK-NEXT: lw a0, 0(zero)
; CHECK-NEXT: seqz a1, a1
; CHECK-NEXT: srai a3, a0, 63
; CHECK-NEXT: addi a1, a1, -1
; CHECK-NEXT: and a1, a1, a2
; CHECK-NEXT: andi a2, a1, 1
; CHECK-NEXT: addi a2, a2, -1
; CHECK-NEXT: or a3, a3, a0
; CHECK-NEXT: slli a2, a1, 63
; CHECK-NEXT: srai a2, a2, 63
; CHECK-NEXT: srai a3, a0, 63
; CHECK-NEXT: or a2, a2, a3
; CHECK-NEXT: bgez a2, .LBB0_3
; CHECK-NEXT: # %bb.2:
Expand All @@ -36,14 +35,13 @@ define fastcc void @search_tx_type() #0 {
; CHECK-NEXT: # %bb.6: # %bb
; CHECK-NEXT: mv a3, a2
; CHECK-NEXT: .LBB0_7: # %bb
; CHECK-NEXT: andi a5, a1, 8
; CHECK-NEXT: sext.w a4, a3
; CHECK-NEXT: andi a4, a1, 8
; CHECK-NEXT: mv a2, a3
; CHECK-NEXT: beqz a5, .LBB0_9
; CHECK-NEXT: beqz a4, .LBB0_9
; CHECK-NEXT: # %bb.8: # %bb
; CHECK-NEXT: mv a2, a0
; CHECK-NEXT: .LBB0_9: # %bb
; CHECK-NEXT: blt a4, a0, .LBB0_11
; CHECK-NEXT: blt a3, a0, .LBB0_11
; CHECK-NEXT: # %bb.10: # %bb
; CHECK-NEXT: mv a2, a3
; CHECK-NEXT: .LBB0_11: # %bb
Expand Down