Use NEON vmin/vmax instructions for floating-point selects.
Radar 7461718.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96572 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index adf1644..ecc8289 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -294,6 +294,7 @@
setTargetDAGCombine(ISD::SIGN_EXTEND);
setTargetDAGCombine(ISD::ZERO_EXTEND);
setTargetDAGCombine(ISD::ANY_EXTEND);
+ setTargetDAGCombine(ISD::SELECT_CC);
}
computeRegisterProperties();
@@ -544,6 +545,8 @@
case ARMISD::VZIP: return "ARMISD::VZIP";
case ARMISD::VUZP: return "ARMISD::VUZP";
case ARMISD::VTRN: return "ARMISD::VTRN";
+ case ARMISD::FMAX: return "ARMISD::FMAX";
+ case ARMISD::FMIN: return "ARMISD::FMIN";
}
}
@@ -3856,23 +3859,97 @@
return SDValue();
}
+/// PerformSELECT_CCCombine - Target-specific DAG combining for ISD::SELECT_CC
+/// to match f32 max/min patterns to use NEON vmax/vmin instructions.
+static SDValue PerformSELECT_CCCombine(SDNode *N, SelectionDAG &DAG,
+ const ARMSubtarget *ST) {
+ // If the target supports NEON, try to use vmax/vmin instructions for f32
+ // selects like "x < y ? x : y". Unless the FiniteOnlyFPMath option is set,
+ // be careful about NaNs: NEON's vmax/vmin return NaN if either operand is
+ // a NaN; only do the transformation when it matches that behavior.
+
+ // For now only do this when using NEON for FP operations; if using VFP, it
+ // is not obvious that the benefit outweighs the cost of switching to the
+ // NEON pipeline.
+ if (!ST->hasNEON() || !ST->useNEONForSinglePrecisionFP() ||
+ N->getValueType(0) != MVT::f32)
+ return SDValue();
+
+ SDValue CondLHS = N->getOperand(0);
+ SDValue CondRHS = N->getOperand(1);
+ SDValue LHS = N->getOperand(2);
+ SDValue RHS = N->getOperand(3);
+ ISD::CondCode CC = cast<CondCodeSDNode>(N->getOperand(4))->get();
+
+ unsigned Opcode = 0;
+ bool IsReversed;
+ if (LHS == CondLHS && RHS == CondRHS) {
+ IsReversed = false; // x CC y ? x : y
+ } else if (LHS == CondRHS && RHS == CondLHS) {
+ IsReversed = true ; // x CC y ? y : x
+ } else {
+ return SDValue();
+ }
+
+ switch (CC) {
+ default: break;
+ case ISD::SETOLT:
+ case ISD::SETOLE:
+ case ISD::SETLT:
+ case ISD::SETLE:
+ // This can be vmin if we can prove that the LHS is not a NaN.
+ // (If either operand is NaN, the comparison will be false and the result
+ // will be the RHS, which matches vmin if RHS is the NaN.)
+ if (DAG.isKnownNeverNaN(LHS))
+ Opcode = IsReversed ? ARMISD::FMAX : ARMISD::FMIN;
+ break;
+
+ case ISD::SETULT:
+ case ISD::SETULE:
+ // Likewise, for ULT/ULE we need to know that RHS is not a NaN.
+ if (DAG.isKnownNeverNaN(RHS))
+ Opcode = IsReversed ? ARMISD::FMAX : ARMISD::FMIN;
+ break;
+
+ case ISD::SETOGT:
+ case ISD::SETOGE:
+ case ISD::SETGT:
+ case ISD::SETGE:
+ // This can be vmax if we can prove that the LHS is not a NaN.
+ // (If either operand is NaN, the comparison will be false and the result
+ // will be the RHS, which matches vmax if RHS is the NaN.)
+ if (DAG.isKnownNeverNaN(LHS))
+ Opcode = IsReversed ? ARMISD::FMIN : ARMISD::FMAX;
+ break;
+
+ case ISD::SETUGT:
+ case ISD::SETUGE:
+ // Likewise, for UGT/UGE we need to know that RHS is not a NaN.
+ if (DAG.isKnownNeverNaN(RHS))
+ Opcode = IsReversed ? ARMISD::FMIN : ARMISD::FMAX;
+ break;
+ }
+
+ if (!Opcode)
+ return SDValue();
+ return DAG.getNode(Opcode, N->getDebugLoc(), N->getValueType(0), LHS, RHS);
+}
+
SDValue ARMTargetLowering::PerformDAGCombine(SDNode *N,
DAGCombinerInfo &DCI) const {
switch (N->getOpcode()) {
default: break;
- case ISD::ADD: return PerformADDCombine(N, DCI);
- case ISD::SUB: return PerformSUBCombine(N, DCI);
+ case ISD::ADD: return PerformADDCombine(N, DCI);
+ case ISD::SUB: return PerformSUBCombine(N, DCI);
case ARMISD::VMOVRRD: return PerformVMOVRRDCombine(N, DCI);
- case ISD::INTRINSIC_WO_CHAIN:
- return PerformIntrinsicCombine(N, DCI.DAG);
+ case ISD::INTRINSIC_WO_CHAIN: return PerformIntrinsicCombine(N, DCI.DAG);
case ISD::SHL:
case ISD::SRA:
- case ISD::SRL:
- return PerformShiftCombine(N, DCI.DAG, Subtarget);
+ case ISD::SRL: return PerformShiftCombine(N, DCI.DAG, Subtarget);
case ISD::SIGN_EXTEND:
case ISD::ZERO_EXTEND:
- case ISD::ANY_EXTEND:
- return PerformExtendCombine(N, DCI.DAG, Subtarget);
+ case ISD::ANY_EXTEND: return PerformExtendCombine(N, DCI.DAG, Subtarget);
+ case ISD::SELECT_CC: return PerformSELECT_CCCombine(N, DCI.DAG, Subtarget);
}
return SDValue();
}