[RISCV] Lower insert subvector shuffles as vslideups

[luke]

Summary

A shuffle with an insert subvector mask is functionally equivalent to:

(insert_subvector v0, (extract_subvector v1, len), index)

We can emulate by doing a vslideup on v1 into the right index, and carefully selecting VL so that we don't overwrite any more destination elements than what we have to.
This avoids the need for a select with a mask.

[reames]

I think you're going one step too far with this patch. Not in the sense that this patch isn't justified - only in the sense you should do a simpler case first.

As highlighted in your test diffs, if you have a suffix of the result vector coming from the second source operand, you can do the operation with a single slideup.

I think you should match this case explicitly above the generic gather/select lowering. Doing so simplifies the test deltas to only the cases where the select is actually needed.

The other option is to add a DAG combine which removes the select afterwards, but I think matching up front is probably the right answer here.

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-shuffles.ll

678

This can be done with a single slide up. You don't need the select here at all.

[reames]

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

3675

I don't have a concrete example, but thinking about it, this seems suspect. You're computing the select condition vector using the elements at the original offsets, but actually selecting between elements which have been slide up or down. That doesn't seem right, we should be having to adjust the select mask too.

[luke]

Rework to only handle inserts of subvectors, and lower them into single vslideups

[luke]

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shufflevector-vnsrl.ll

155

So rd=x0, rs1=x0 means to keep the existing VL. Could that mean these two vsetivli's could be merged into one vsetivli zero, 2, e32, m1, tu, ma, seeing as the second tu trumps the former ta?

[reames]

LGTM w/minor comments.

I'm explicitly okay with the TU/TA issue being handled in a follow up commit.

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

3323

white space on the ", tu," bit

3356

In the case where you're inserting a suffix into the InPlace vector, you don't need the TU here and can use TA instead. (e.g. you slide up into the last 4 elements of a 8 long vector)

We may already catch that via a DAG combine or during vsetvli insertion, not sure.

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-shuffles.ll

648

Please land the test rename separately.

I'd suggest something more generic like concat_4xi8 to avoid the strategy used needing a test rename.

651

This is the TA case I'd mentioned above, looks like we don't catch this.

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shufflevector-vnsrl.ll

155

Yes, though we can also just do better and use a single slidedown to form the shuffle here.

Seems like a reasonable follow up patch.

[luke]

Use a tail agnostic policy if we're inserting at a suffix

[luke]

Remove test rename diff

[luke]

Rebase

[luke]

Closed in 6e9c24edf052756e1f14d6080bf5af7fb75f17e7 and d3e8bd919fbef0392650c27f69c7a79e1b73ca47

[reames]

Looking at some code which benefits from this change, I noticed an opportunity for a follow up.

vsetivli        zero, 4, e8, mf8, ta, ma
vle8.v  v8, (a0)
vle8.v  v10, (a4)
vsetivli        zero, 8, e8, mf2, tu, ma
vslideup.vi     v8, v10, 4

In the snippet above, the vslideup.vi does not need to be tail undisturbed. All of the tail efforts are undef.

Not sure if this makes sense to handle during lowering, or as a general dag combine on vslide.vi when the destination has undef elements. If we do it as a DAG combine, moving the suffix logic from this patch into the same place probably makes sense.

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

SDValue Slidedown =
                     convertToScalableVector(ContainerVT, Src, DAG, Subtarget),
                     DAG.getConstant(NewMask[0], DL, XLenVT), TrueMask, VL);
   return DAG.getNode(
       ISD::EXTRACT_SUBVECTOR, DL, VT,
       convertFromScalableVector(SrcVT, Slidedown, DAG, Subtarget),
       DAG.getConstant(0, DL, XLenVT));
 }
 
+// Because vslideup leaves the destination elements at the start intact, we can
+// use it to perform shuffles that insert subvectors:
+//
+// vector_shuffle v8:v8i8, v9:v8i8, <0, 1, 2, 3, 8, 9, 10, 11>
+// ->
+// vsetvli zero, 8, e8, mf2, tu,ma
+// vslideup.vi v8, v9, 4
+//
+// vector_shuffle v8:v8i8, v9:v8i8 <0, 1, 8, 9, 10, 5, 6, 7>
+// ->
+// vsetvli zero, 5, e8, mf2, tu,ma
+// vslideup.v1 v8, v9, 2
+static SDValue lowerVECTOR_SHUFFLEAsVSlideup(const SDLoc &DL, MVT VT,
+                                             SDValue V1, SDValue V2,
+                                             ArrayRef<int> Mask,
+                                             const RISCVSubtarget &Subtarget,
+                                             SelectionDAG &DAG) {
+  unsigned NumElts = VT.getVectorNumElements();
+  int NumSubElts, Index;
+  if (!ShuffleVectorInst::isInsertSubvectorMask(Mask, NumElts, NumSubElts,
+                                                Index))
+    return SDValue();
+
+  bool OpsSwapped = Mask[Index] < (int)NumElts;
+  SDValue InPlace = OpsSwapped ? V2 : V1;
+  SDValue ToInsert = OpsSwapped ? V1 : V2;
+
+  MVT XLenVT = Subtarget.getXLenVT();
+  MVT ContainerVT = getContainerForFixedLengthVector(DAG, VT, Subtarget);
+  auto TrueMask = getDefaultVLOps(VT, ContainerVT, DL, DAG, Subtarget).first;
+  // We slide up by the index that the subvector is being inserted at, and set
+  // VL to the index + the number of elements being inserted
+  SDValue Slideup = getVSlideup(
+      DAG, Subtarget, DL, ContainerVT,
+      convertToScalableVector(ContainerVT, InPlace, DAG, Subtarget),
+      convertToScalableVector(ContainerVT, ToInsert, DAG, Subtarget),
+      DAG.getConstant(Index, DL, XLenVT), TrueMask,
+      DAG.getConstant(NumSubElts + Index, DL, XLenVT),
+      RISCVII::TAIL_UNDISTURBED_MASK_UNDISTURBED | RISCVII::MASK_AGNOSTIC);
+  return convertFromScalableVector(VT, Slideup, DAG, Subtarget);
+}
+
 // Given two input vectors of <[vscale x ]n x ty>, use vwaddu.vv and vwmaccu.vx
 // to create an interleaved vector of <[vscale x] n*2 x ty>.
 // This requires that the size of ty is less than the subtarget's maximum ELEN.
 static SDValue getWideningInterleave(SDValue EvenV, SDValue OddV, SDLoc &DL,
                                      SelectionDAG &DAG,
                                      const RISCVSubtarget &Subtarget) {
   MVT VecVT = EvenV.getSimpleValueType();
   MVT VecContainerVT = VecVT; // <vscale x n x ty>
if (isInterleaveShuffle(Mask, VT, EvenSrc, OddSrc, Subtarget)) {
     assert(OddSrc >= 0 && "Undef source?");
     OddV = (OddSrc / Size) == 0 ? V1 : V2;
     OddV = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, HalfVT, OddV,
                        DAG.getConstant(OddSrc % Size, DL, XLenVT));
 
     return getWideningInterleave(EvenV, OddV, DL, DAG, Subtarget);
   }
 
+  if (SDValue V =
+          lowerVECTOR_SHUFFLEAsVSlideup(DL, VT, V1, V2, Mask, Subtarget, DAG))
+    return V;
+
   // Detect shuffles which can be re-expressed as vector selects; these are
   // shuffles in which each element in the destination is taken from an element
   // at the corresponding index in either source vectors.
   bool IsSelect = all_of(enumerate(Mask), [&](const auto &MaskIdx) {
     int MaskIndex = MaskIdx.value();
     return MaskIndex < 0 || MaskIdx.index() == (unsigned)MaskIndex % NumElts;
   });
 
static SDValue lowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG,
   unsigned GatherVXOpc = RISCVISD::VRGATHER_VX_VL;
   unsigned GatherVVOpc = RISCVISD::VRGATHER_VV_VL;
   MVT IndexVT = VT.changeTypeToInteger();
   // Since we can't introduce illegal index types at this stage, use i16 and
   // vrgatherei16 if the corresponding index type for plain vrgather is greater
   // than XLenVT.
   if (IndexVT.getScalarType().bitsGT(XLenVT)) {
     GatherVVOpc = RISCVISD::VRGATHEREI16_VV_VL;
     IndexVT = IndexVT.changeVectorElementType(MVT::i16);
   }
 
   MVT IndexContainerVT =
       ContainerVT.changeVectorElementType(IndexVT.getScalarType());
 
   SDValue Gather;
   // TODO: This doesn't trigger for i64 vectors on RV32, since there we
   // encounter a bitcasted BUILD_VECTOR with low/high i32 values.

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-buildvec.ll

 ; LMULMAX1-LABEL: hang_when_merging_stores_after_legalization:
 ; LMULMAX1:       # %bb.0:
 ; LMULMAX1-NEXT:    li a0, 2
 ; LMULMAX1-NEXT:    vsetivli zero, 1, e8, mf8, ta, ma
 ; LMULMAX1-NEXT:    vmv.s.x v0, a0
 ; LMULMAX1-NEXT:    vsetivli zero, 4, e32, m1, ta, mu
 ; LMULMAX1-NEXT:    vrgather.vi v12, v8, 0
 ; LMULMAX1-NEXT:    vrgather.vi v12, v9, 3, v0.t
-; LMULMAX1-NEXT:    li a0, 8
-; LMULMAX1-NEXT:    vmv.s.x v0, a0
-; LMULMAX1-NEXT:    vrgather.vi v9, v10, 0
-; LMULMAX1-NEXT:    li a0, 3
-; LMULMAX1-NEXT:    vmv.s.x v8, a0
-; LMULMAX1-NEXT:    vrgather.vi v9, v11, 3, v0.t
-; LMULMAX1-NEXT:    vmv.v.v v0, v8
-; LMULMAX1-NEXT:    vmerge.vvm v8, v9, v12, v0
+; LMULMAX1-NEXT:    vsetivli zero, 3, e32, m1, tu, ma
+; LMULMAX1-NEXT:    vslideup.vi v11, v10, 2
+; LMULMAX1-NEXT:    vsetivli zero, 2, e32, m1, tu, ma
+; LMULMAX1-NEXT:    vslideup.vi v11, v12, 0
+; LMULMAX1-NEXT:    vmv1r.v v8, v11
 ; LMULMAX1-NEXT:    ret
 ;
 ; LMULMAX2-LABEL: hang_when_merging_stores_after_legalization:
 ; LMULMAX2:       # %bb.0:
 ; LMULMAX2-NEXT:    vsetivli zero, 8, e32, m2, ta, mu
 ; LMULMAX2-NEXT:    vid.v v12
 ; LMULMAX2-NEXT:    li a0, 7
 ; LMULMAX2-NEXT:    vmul.vx v14, v12, a0

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-shuffles.ll

entry:
   %1 = shufflevector <16 x i16> %0, <16 x i16> poison, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
   %2 = shufflevector <16 x i16> %0, <16 x i16> poison, <8 x i32> <i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
   %3 = shufflevector <8 x i16> %1, <8 x i16> poison, <4 x i32> <i32 4, i32 5, i32 6, i32 7>
   %4 = shufflevector <8 x i16> %2, <8 x i16> poison, <4 x i32> <i32 0, i32 undef, i32 undef, i32 undef>
   %5 = shufflevector <4 x i16> %3, <4 x i16> %4, <4 x i32> <i32 1, i32 2, i32 3, i32 4>
   ret <4 x i16> %5
 }
 
-define <8 x i8> @merge_start_into_end(<8 x i8> %v, <8 x i8> %w) {
-; CHECK-LABEL: merge_start_into_end:
+define <8 x i8> @slideup_into_end(<8 x i8> %v, <8 x i8> %w) {
+; CHECK-LABEL: slideup_into_end:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetivli zero, 8, e8, mf2, tu, ma
+; CHECK-NEXT:    vslideup.vi v8, v9, 4
+; CHECK-NEXT:    ret
+  %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 9, i32 10, i32 11>
+  ret <8 x i8> %res
+}
+
+define <8 x i8> @slideup_into_end_undef(<8 x i8> %v, <8 x i8> %w) {
+; CHECK-LABEL: slideup_into_end_undef:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetivli zero, 8, e8, mf2, tu, ma
+; CHECK-NEXT:    vslideup.vi v8, v9, 4
+; CHECK-NEXT:    ret
+  %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 undef, i32 10, i32 11>
+  ret <8 x i8> %res
+}
+
+define <8 x i8> @slideup_into_end_undef_at_start(<8 x i8> %v, <8 x i8> %w) {
+; CHECK-LABEL: slideup_into_end_undef_at_start:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetivli zero, 8, e8, mf2, ta, mu
 ; CHECK-NEXT:    vid.v v11
 ; CHECK-NEXT:    vrgather.vv v10, v8, v11
-; CHECK-NEXT:    li a0, 240
+; CHECK-NEXT:    li a0, 224
 ; CHECK-NEXT:    vmv.s.x v0, a0
 ; CHECK-NEXT:    vadd.vi v8, v11, -4
 ; CHECK-NEXT:    vrgather.vv v10, v9, v8, v0.t
 ; CHECK-NEXT:    vmv1r.v v8, v10
 ; CHECK-NEXT:    ret
-  %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 9, i32 10, i32 11>
+  %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 undef, i32 9, i32 10, i32 11>
   ret <8 x i8> %res
 }
 
 define <8 x i8> @merge_start_into_end_non_contiguous(<8 x i8> %v, <8 x i8> %w) {
 ; CHECK-LABEL: merge_start_into_end_non_contiguous:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetivli zero, 8, e8, mf2, ta, mu
 ; CHECK-NEXT:    vid.v v11
 ; CHECK-NEXT:    vrgather.vv v10, v8, v11
 ; CHECK-NEXT:    li a0, 144
 ; CHECK-NEXT:    vmv.s.x v0, a0
 ; CHECK-NEXT:    vadd.vi v8, v11, -4
 ; CHECK-NEXT:    vrgather.vv v10, v9, v8, v0.t
 ; CHECK-NEXT:    vmv1r.v v8, v10
 ; CHECK-NEXT:    ret
   %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 5, i32 6, i32 11>
   ret <8 x i8> %res
 }
 
-define <8 x i8> @merge_end_into_end(<8 x i8> %v, <8 x i8> %w) {
-; CHECK-LABEL: merge_end_into_end:
+define <8 x i8> @slideup_end_into_end(<8 x i8> %v, <8 x i8> %w) {
+; CHECK-LABEL: slideup_end_into_end:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    li a0, 15
-; CHECK-NEXT:    vsetivli zero, 8, e8, mf2, ta, ma
-; CHECK-NEXT:    vmv.s.x v0, a0
-; CHECK-NEXT:    vmerge.vvm v8, v9, v8, v0
+; CHECK-NEXT:    vsetivli zero, 4, e8, mf2, tu, ma
+; CHECK-NEXT:    vslideup.vi v9, v8, 0
+; CHECK-NEXT:    vmv1r.v v8, v9
 ; CHECK-NEXT:    ret
   %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 12, i32 13, i32 14, i32 15>
   ret <8 x i8> %res
 }
 
-define <8 x i8> @merge_start_into_middle(<8 x i8> %v, <8 x i8> %w) {
-; CHECK-LABEL: merge_start_into_middle:
+define <8 x i8> @slideup_into_middle(<8 x i8> %v, <8 x i8> %w) {
+; CHECK-LABEL: slideup_into_middle:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vsetivli zero, 8, e8, mf2, ta, mu
-; CHECK-NEXT:    vid.v v11
-; CHECK-NEXT:    vrgather.vv v10, v8, v11
-; CHECK-NEXT:    li a0, 30
-; CHECK-NEXT:    vmv.s.x v0, a0
-; CHECK-NEXT:    vadd.vi v8, v11, -1
-; CHECK-NEXT:    vrgather.vv v10, v9, v8, v0.t
-; CHECK-NEXT:    vmv1r.v v8, v10
+; CHECK-NEXT:    vsetivli zero, 5, e8, mf2, tu, ma
+; CHECK-NEXT:    vslideup.vi v8, v9, 1
 ; CHECK-NEXT:    ret
   %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 0, i32 8, i32 9, i32 10, i32 11, i32 5, i32 6, i32 7>
   ret <8 x i8> %res
 }
 
-define <8 x i8> @merge_start_into_start(<8 x i8> %v, <8 x i8> %w) {
-; CHECK-LABEL: merge_start_into_start:
+define <8 x i8> @slideup_start_into_start(<8 x i8> %v, <8 x i8> %w) {
+; CHECK-LABEL: slideup_start_into_start:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    li a0, 240
-; CHECK-NEXT:    vsetivli zero, 8, e8, mf2, ta, ma
-; CHECK-NEXT:    vmv.s.x v0, a0
-; CHECK-NEXT:    vmerge.vvm v8, v9, v8, v0
+; CHECK-NEXT:    vsetivli zero, 4, e8, mf2, tu, ma
+; CHECK-NEXT:    vslideup.vi v8, v9, 0
 ; CHECK-NEXT:    ret
   %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 8, i32 9, i32 10, i32 11, i32 4, i32 5, i32 6, i32 7>
   ret <8 x i8> %res
 }
 
 define <8 x i8> @merge_slidedown(<8 x i8> %v, <8 x i8> %w) {
 ; CHECK-LABEL: merge_slidedown:
 ; CHECK:       # %bb.0:

 
 ; This shouldn't generate a vmerge because the elements of %w are not consecutive
 define <8 x i8> @unmergable(<8 x i8> %v, <8 x i8> %w) {
 ; CHECK-LABEL: unmergable:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetivli zero, 8, e8, mf2, ta, mu
 ; CHECK-NEXT:    vid.v v10
 ; CHECK-NEXT:    vadd.vi v11, v10, 2
-; CHECK-NEXT:    lui a0, %hi(.LCPI44_0)
-; CHECK-NEXT:    addi a0, a0, %lo(.LCPI44_0)
+; CHECK-NEXT:    lui a0, %hi(.LCPI46_0)
+; CHECK-NEXT:    addi a0, a0, %lo(.LCPI46_0)
 ; CHECK-NEXT:    vle8.v v12, (a0)
 ; CHECK-NEXT:    li a0, 234
 ; CHECK-NEXT:    vmv.s.x v0, a0
 ; CHECK-NEXT:    vrgather.vv v10, v8, v11
 ; CHECK-NEXT:    vrgather.vv v10, v9, v12, v0.t
 ; CHECK-NEXT:    vmv1r.v v8, v10
 ; CHECK-NEXT:    ret
   %res = shufflevector <8 x i8> %v, <8 x i8> %w, <8 x i32> <i32 2, i32 9, i32 4, i32 11, i32 6, i32 13, i32 8, i32 15>
   ret <8 x i8> %res
 }

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shufflevector-vnsrl.ll

 ; V-NEXT:    vnsrl.wi v8, v8, 0
 ; V-NEXT:    vse32.v v8, (a1)
 ; V-NEXT:    ret
 ;
 ; ZVE32F-LABEL: vnsrl_0_i32:
 ; ZVE32F:       # %bb.0: # %entry
 ; ZVE32F-NEXT:    vsetivli zero, 4, e32, m1, ta, ma
 ; ZVE32F-NEXT:    vle32.v v8, (a0)
-; ZVE32F-NEXT:    vsetivli zero, 2, e32, m1, ta, mu
+; ZVE32F-NEXT:    vsetivli zero, 2, e32, m1, ta, ma
 ; ZVE32F-NEXT:    vslidedown.vi v9, v8, 2
-; ZVE32F-NEXT:    li a0, 2
-; ZVE32F-NEXT:    vmv.s.x v0, a0
-; ZVE32F-NEXT:    vrgather.vi v10, v8, 0
-; ZVE32F-NEXT:    vrgather.vi v10, v9, 0, v0.t
-; ZVE32F-NEXT:    vse32.v v10, (a1)
+; ZVE32F-NEXT:    vsetvli zero, zero, e32, m1, tu, ma
+; ZVE32F-NEXT:    vslideup.vi v8, v9, 1
+; ZVE32F-NEXT:    vse32.v v8, (a1)
 ; ZVE32F-NEXT:    ret
 entry:
   %0 = load <4 x i32>, ptr %in, align 4
   %shuffle.i5 = shufflevector <4 x i32> %0, <4 x i32> poison, <2 x i32> <i32 0, i32 2>
   store <2 x i32> %shuffle.i5, ptr %out, align 4
   ret void
 }
 

 ; V-NEXT:    vnsrl.wi v8, v8, 0
 ; V-NEXT:    vse32.v v8, (a1)
 ; V-NEXT:    ret
 ;
 ; ZVE32F-LABEL: vnsrl_0_float:
 ; ZVE32F:       # %bb.0: # %entry
 ; ZVE32F-NEXT:    vsetivli zero, 4, e32, m1, ta, ma
 ; ZVE32F-NEXT:    vle32.v v8, (a0)
-; ZVE32F-NEXT:    vsetivli zero, 2, e32, m1, ta, mu
+; ZVE32F-NEXT:    vsetivli zero, 2, e32, m1, ta, ma
 ; ZVE32F-NEXT:    vslidedown.vi v9, v8, 2
-; ZVE32F-NEXT:    li a0, 2
-; ZVE32F-NEXT:    vmv.s.x v0, a0
-; ZVE32F-NEXT:    vrgather.vi v10, v8, 0
-; ZVE32F-NEXT:    vrgather.vi v10, v9, 0, v0.t
-; ZVE32F-NEXT:    vse32.v v10, (a1)
+; ZVE32F-NEXT:    vsetvli zero, zero, e32, m1, tu, ma
+; ZVE32F-NEXT:    vslideup.vi v8, v9, 1
+; ZVE32F-NEXT:    vse32.v v8, (a1)
 ; ZVE32F-NEXT:    ret
 entry:
   %0 = load <4 x float>, ptr %in, align 4
   %shuffle.i5 = shufflevector <4 x float> %0, <4 x float> poison, <2 x i32> <i32 0, i32 2>
   store <2 x float> %shuffle.i5, ptr %out, align 4
   ret void
 }
 
entry:
   ret void
 }
 
 define void @vnsrl_0_i64(ptr %in, ptr %out) {
 ; V-LABEL: vnsrl_0_i64:
 ; V:       # %bb.0: # %entry
 ; V-NEXT:    vsetivli zero, 4, e64, m1, ta, ma
 ; V-NEXT:    vle64.v v8, (a0)
-; V-NEXT:    vsetivli zero, 2, e64, m1, ta, mu
+; V-NEXT:    vsetivli zero, 2, e64, m1, ta, ma
 ; V-NEXT:    vslidedown.vi v9, v8, 2
-; V-NEXT:    li a0, 2
-; V-NEXT:    vmv.s.x v0, a0
-; V-NEXT:    vrgather.vi v10, v8, 0
-; V-NEXT:    vrgather.vi v10, v9, 0, v0.t
-; V-NEXT:    vse64.v v10, (a1)
+; V-NEXT:    vsetvli zero, zero, e64, m1, tu, ma
+; V-NEXT:    vslideup.vi v8, v9, 1
+; V-NEXT:    vse64.v v8, (a1)
 ; V-NEXT:    ret
 ;
 ; ZVE32F-LABEL: vnsrl_0_i64:
 ; ZVE32F:       # %bb.0: # %entry
 ; ZVE32F-NEXT:    ld a2, 16(a0)
 ; ZVE32F-NEXT:    ld a0, 0(a0)
 ; ZVE32F-NEXT:    sd a2, 8(a1)
 ; ZVE32F-NEXT:    sd a0, 0(a1)
entry:
   ret void
 }
 
 define void @vnsrl_0_double(ptr %in, ptr %out) {
 ; V-LABEL: vnsrl_0_double:
 ; V:       # %bb.0: # %entry
 ; V-NEXT:    vsetivli zero, 4, e64, m1, ta, ma
 ; V-NEXT:    vle64.v v8, (a0)
-; V-NEXT:    vsetivli zero, 2, e64, m1, ta, mu
+; V-NEXT:    vsetivli zero, 2, e64, m1, ta, ma
 ; V-NEXT:    vslidedown.vi v9, v8, 2
-; V-NEXT:    li a0, 2
-; V-NEXT:    vmv.s.x v0, a0
-; V-NEXT:    vrgather.vi v10, v8, 0
-; V-NEXT:    vrgather.vi v10, v9, 0, v0.t
-; V-NEXT:    vse64.v v10, (a1)
+; V-NEXT:    vsetvli zero, zero, e64, m1, tu, ma
+; V-NEXT:    vslideup.vi v8, v9, 1
+; V-NEXT:    vse64.v v8, (a1)
 ; V-NEXT:    ret
 ;
 ; ZVE32F-LABEL: vnsrl_0_double:
 ; ZVE32F:       # %bb.0: # %entry
 ; ZVE32F-NEXT:    ld a2, 16(a0)
 ; ZVE32F-NEXT:    ld a0, 0(a0)
 ; ZVE32F-NEXT:    sd a2, 8(a1)
 ; ZVE32F-NEXT:    sd a0, 0(a1)

llvm/test/CodeGen/RISCV/rvv/vector-deinterleave-fixed.ll

 %retval = call {<4 x i32>, <4 x i32>} @llvm.experimental.vector.deinterleave2.v8i32(<8 x i32> %vec)
 ret {<4 x i32>, <4 x i32>} %retval
 }
 
 define {<2 x i64>, <2 x i64>} @vector_deinterleave_v2i64_v4i64(<4 x i64> %vec) {
 ; CHECK-LABEL: vector_deinterleave_v2i64_v4i64:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetivli zero, 2, e64, m2, ta, ma
-; CHECK-NEXT:    vslidedown.vi v12, v8, 2
+; CHECK-NEXT:    vslidedown.vi v10, v8, 2
 ; CHECK-NEXT:    li a0, 2
 ; CHECK-NEXT:    vmv.s.x v0, a0
 ; CHECK-NEXT:    vsetivli zero, 2, e64, m1, ta, mu
-; CHECK-NEXT:    vrgather.vi v10, v8, 0
-; CHECK-NEXT:    vrgather.vi v10, v12, 0, v0.t
 ; CHECK-NEXT:    vrgather.vi v9, v8, 1
-; CHECK-NEXT:    vrgather.vi v9, v12, 1, v0.t
-; CHECK-NEXT:    vmv.v.v v8, v10
+; CHECK-NEXT:    vrgather.vi v9, v10, 1, v0.t
+; CHECK-NEXT:    vsetvli zero, zero, e64, m1, tu, ma
+; CHECK-NEXT:    vslideup.vi v8, v10, 1
 ; CHECK-NEXT:    ret
 %retval = call {<2 x i64>, <2 x i64>} @llvm.experimental.vector.deinterleave2.v4i64(<4 x i64> %vec)
 ret {<2 x i64>, <2 x i64>} %retval
 }
 
 declare {<16 x i1>, <16 x i1>} @llvm.experimental.vector.deinterleave2.v32i1(<32 x i1>)
 declare {<16 x i8>, <16 x i8>} @llvm.experimental.vector.deinterleave2.v32i8(<32 x i8>)
 declare {<8 x i16>, <8 x i16>} @llvm.experimental.vector.deinterleave2.v16i16(<16 x i16>)

 %retval = call {<4 x float>, <4 x float>} @llvm.experimental.vector.deinterleave2.v8f32(<8 x float> %vec)
 ret  {<4 x float>, <4 x float>} %retval
 }
 
 define {<2 x double>, <2 x double>} @vector_deinterleave_v2f64_v4f64(<4 x double> %vec) {
 ; CHECK-LABEL: vector_deinterleave_v2f64_v4f64:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetivli zero, 2, e64, m2, ta, ma
-; CHECK-NEXT:    vslidedown.vi v12, v8, 2
+; CHECK-NEXT:    vslidedown.vi v10, v8, 2
 ; CHECK-NEXT:    li a0, 2
 ; CHECK-NEXT:    vmv.s.x v0, a0
 ; CHECK-NEXT:    vsetivli zero, 2, e64, m1, ta, mu
-; CHECK-NEXT:    vrgather.vi v10, v8, 0
-; CHECK-NEXT:    vrgather.vi v10, v12, 0, v0.t
 ; CHECK-NEXT:    vrgather.vi v9, v8, 1
-; CHECK-NEXT:    vrgather.vi v9, v12, 1, v0.t
-; CHECK-NEXT:    vmv.v.v v8, v10
+; CHECK-NEXT:    vrgather.vi v9, v10, 1, v0.t
+; CHECK-NEXT:    vsetvli zero, zero, e64, m1, tu, ma
+; CHECK-NEXT:    vslideup.vi v8, v10, 1
 ; CHECK-NEXT:    ret
 %retval = call {<2 x double>, <2 x double>} @llvm.experimental.vector.deinterleave2.v4f64(<4 x double> %vec)
 ret {<2 x double>, <2 x double>} %retval
 }
 
 declare {<2 x half>,<2 x half>} @llvm.experimental.vector.deinterleave2.v4f16(<4 x half>)
 declare {<4 x half>, <4 x half>} @llvm.experimental.vector.deinterleave2.v8f16(<8 x half>)
 declare {<2 x float>, <2 x float>} @llvm.experimental.vector.deinterleave2.v4f32(<4 x float>)
 declare {<8 x half>, <8 x half>} @llvm.experimental.vector.deinterleave2.v16f16(<16 x half>)
 declare {<4 x float>, <4 x float>} @llvm.experimental.vector.deinterleave2.v8f32(<8 x float>)
 declare {<2 x double>, <2 x double>} @llvm.experimental.vector.deinterleave2.v4f64(<4 x double>)