================
@@ -21471,6 +21471,53 @@ bool isHalvingTruncateOfLegalScalableType(EVT SrcVT,
EVT DstVT) {
(SrcVT == MVT::nxv2i64 && DstVT == MVT::nxv2i32);
}
+// Combine store (trunc X to <3 x i8>) to sequence of ST1.b.
+static SDValue combineI8TruncStore(StoreSDNode *ST, SelectionDAG &DAG,
+ const AArch64Subtarget *Subtarget) {
+ SDValue Value = ST->getValue();
+ EVT ValueVT = Value.getValueType();
+
+ if (ST->isVolatile() || !Subtarget->isLittleEndian() ||
+ Value.getOpcode() != ISD::TRUNCATE ||
+ ValueVT != EVT::getVectorVT(*DAG.getContext(), MVT::i8, 3))
+ return SDValue();
+
+ assert(ST->getOffset().isUndef() && "undef offset expected");
+ SDLoc DL(ST);
+ auto WideVT = EVT::getVectorVT(
+ *DAG.getContext(),
+ Value->getOperand(0).getValueType().getVectorElementType(), 4);
+ SDValue UndefVector = DAG.getUNDEF(WideVT);
+ SDValue WideTrunc = DAG.getNode(
+ ISD::INSERT_SUBVECTOR, DL, WideVT,
+ {UndefVector, Value->getOperand(0), DAG.getVectorIdxConstant(0, DL)});
+ SDValue Cast = DAG.getNode(
+ ISD::BITCAST, DL, WideVT.getSizeInBits() == 64 ? MVT::v8i8 : MVT::v16i8,
+ WideTrunc);
+
+ MachineFunction &MF = DAG.getMachineFunction();
+ SDValue Chain = ST->getChain();
+ MachineMemOperand *MMO = ST->getMemOperand();
+ unsigned IdxScale = WideVT.getScalarSizeInBits() / 8;
+ SDValue E2 = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, MVT::i8, Cast,
+ DAG.getConstant(2 * IdxScale, DL, MVT::i64));
+ TypeSize Offset2 = TypeSize::getFixed(2);
+ SDValue Ptr2 = DAG.getMemBasePlusOffset(ST->getBasePtr(), Offset2, DL);
+ Chain = DAG.getStore(Chain, DL, E2, Ptr2, MF.getMachineMemOperand(MMO, 2,
1));
+
+ SDValue E1 = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, MVT::i8, Cast,
+ DAG.getConstant(1 * IdxScale, DL, MVT::i64));
+ TypeSize Offset1 = TypeSize::getFixed(1);
+ SDValue Ptr1 = DAG.getMemBasePlusOffset(ST->getBasePtr(), Offset1, DL);
+ Chain = DAG.getStore(Chain, DL, E1, Ptr1, MF.getMachineMemOperand(MMO, 1,
1));
+
+ SDValue E0 = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, MVT::i8, Cast,
+ DAG.getConstant(0, DL, MVT::i64));
+ Chain = DAG.getStore(Chain, DL, E0, ST->getBasePtr(), ST->getMemOperand());
----------------
fhahn wrote:
Updated, thanks!
https://github.com/llvm/llvm-project/pull/78637
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