[llvm] [VP][RISCV] Add a vp.load.ff intrinsic for fault only first load. (PR #128593)

[Luke Lau via llvm-commits]

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@@ -11966,6 +11973,57 @@ SDValue RISCVTargetLowering::lowerMaskedLoad(SDValue Op,
   return DAG.getMergeValues({Result, Chain}, DL);
 }
 
+SDValue RISCVTargetLowering::lowerLoadFF(SDValue Op, SelectionDAG &DAG) const {
+  assert(Op.getResNo() == 0);
+  SDLoc DL(Op);
+  MVT VT = Op.getSimpleValueType();
+
+  const auto *VPLoadFF = cast<VPLoadFFSDNode>(Op);
+  EVT MemVT = VPLoadFF->getMemoryVT();
+  MachineMemOperand *MMO = VPLoadFF->getMemOperand();
+  SDValue Chain = VPLoadFF->getChain();
+  SDValue BasePtr = VPLoadFF->getBasePtr();
+
+  SDValue Mask = VPLoadFF->getMask();
+  SDValue VL = VPLoadFF->getVectorLength();
+
+  bool IsUnmasked = ISD::isConstantSplatVectorAllOnes(Mask.getNode());
+
+  MVT XLenVT = Subtarget.getXLenVT();
+
+  MVT ContainerVT = VT;
+  if (VT.isFixedLengthVector()) {
+    ContainerVT = getContainerForFixedLengthVector(VT);
+    if (!IsUnmasked) {
+      MVT MaskVT = getMaskTypeFor(ContainerVT);
+      Mask = convertToScalableVector(MaskVT, Mask, DAG, Subtarget);
+    }
+  }
+
+  unsigned IntID =
+      IsUnmasked ? Intrinsic::riscv_vleff : Intrinsic::riscv_vleff_mask;
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lukel97 wrote:

I think the vleff pseudos are marked with RISCVMaskedPseudo. If you only emit riscv_vleff_mask here does RISCVVectorPeephole convert it to the unmasked pseudo?

https://github.com/llvm/llvm-project/pull/128593