[RISCV] Optimize two source deinterleave2 via ri.vunzip2{a,b} (#142667)

preames · web-flow · commit 88738a74f05b · 2025-06-03T20:18:55.000-07:00
As done for the existing vnsrl cases, we can split a two source
deinterleave2 into two single source deinterleave2 and a slideup.  
We can also use a concat-then-deinterleave2 tactic. Both are equally
valid (except in the m8 source type case), and the 
concat-then-deinterleave2 saves one instruction for fractional LMUL cases.

Additionally, if we happen to know the exact VLEN and our fixed vectors
are an even number of vector registers, we can avoid the need to split or
concat entirely and just use both registers sources.
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -5830,13 +5830,41 @@ static SDValue lowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG,
         Index == 0 ? RISCVISD::RI_VUNZIP2A_VL : RISCVISD::RI_VUNZIP2B_VL;
     if (V2.isUndef())
       return lowerVZIP(Opc, V1, V2, DL, DAG, Subtarget);
+    if (auto VLEN = Subtarget.getRealVLen();
+        VLEN && VT.getSizeInBits().getKnownMinValue() % *VLEN == 0)
+      return lowerVZIP(Opc, V1, V2, DL, DAG, Subtarget);
     if (SDValue Src = foldConcatVector(V1, V2)) {
       EVT NewVT = VT.getDoubleNumVectorElementsVT();
       Src = DAG.getExtractSubvector(DL, NewVT, Src, 0);
       SDValue Res =
           lowerVZIP(Opc, Src, DAG.getUNDEF(NewVT), DL, DAG, Subtarget);
       return DAG.getExtractSubvector(DL, VT, Res, 0);
     }
+    // Deinterleave each source and concatenate them, or concat first, then
+    // deinterleave.
+    if (1 < count_if(Mask,
+                     [&Mask](int Idx) { return Idx < (int)Mask.size(); }) &&
+        1 < count_if(Mask,
+                     [&Mask](int Idx) { return Idx >= (int)Mask.size(); })) {
+
+      const unsigned EltSize = VT.getScalarSizeInBits();
+      const unsigned MinVLMAX = Subtarget.getRealMinVLen() / EltSize;
+      if (NumElts < MinVLMAX) {
+        MVT ConcatVT = VT.getDoubleNumVectorElementsVT();
+        SDValue Concat = DAG.getNode(ISD::CONCAT_VECTORS, DL, ConcatVT, V1, V2);
+        SDValue Res =
+            lowerVZIP(Opc, Concat, DAG.getUNDEF(ConcatVT), DL, DAG, Subtarget);
+        return DAG.getExtractSubvector(DL, VT, Res, 0);
+      }
+
+      SDValue Lo = lowerVZIP(Opc, V1, DAG.getUNDEF(VT), DL, DAG, Subtarget);
+      SDValue Hi = lowerVZIP(Opc, V2, DAG.getUNDEF(VT), DL, DAG, Subtarget);
+
+      MVT SubVT = VT.getHalfNumVectorElementsVT();
+      return DAG.getNode(ISD::CONCAT_VECTORS, DL, VT,
+                         DAG.getExtractSubvector(DL, SubVT, Lo, 0),
+                         DAG.getExtractSubvector(DL, SubVT, Hi, 0));
+    }
   }
 
   if (SDValue V =
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-deinterleave2.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-deinterleave2.ll
@@ -1364,13 +1364,11 @@ define <4 x i64> @unzip2a_dual_v4i64(<4 x i64> %a, <4 x i64> %b) {
 ;
 ; ZIP-LABEL: unzip2a_dual_v4i64:
 ; ZIP:       # %bb.0: # %entry
-; ZIP-NEXT:    vsetivli zero, 4, e64, m1, ta, mu
-; ZIP-NEXT:    vmv.v.i v0, 8
-; ZIP-NEXT:    vslideup.vi v10, v9, 2
-; ZIP-NEXT:    vslideup.vi v10, v9, 1, v0.t
-; ZIP-NEXT:    vmv.v.i v0, 12
-; ZIP-NEXT:    ri.vunzip2a.vv v11, v8, v9
-; ZIP-NEXT:    vmerge.vvm v8, v11, v10, v0
+; ZIP-NEXT:    vsetivli zero, 4, e64, m1, ta, ma
+; ZIP-NEXT:    ri.vunzip2a.vv v11, v9, v10
+; ZIP-NEXT:    ri.vunzip2a.vv v9, v8, v10
+; ZIP-NEXT:    vslideup.vi v9, v11, 2
+; ZIP-NEXT:    vmv.v.v v8, v9
 ; ZIP-NEXT:    ret
 entry:
   %c = shufflevector <4 x i64> %a, <4 x i64> %b, <4 x i32> <i32 0, i32 2, i32 4, i32 6>
@@ -1502,16 +1500,11 @@ define <16 x i64> @unzip2a_dual_v16i64(<16 x i64> %a, <16 x i64> %b) {
 ; ZIP-LABEL: unzip2a_dual_v16i64:
 ; ZIP:       # %bb.0: # %entry
 ; ZIP-NEXT:    vsetivli zero, 8, e64, m2, ta, ma
-; ZIP-NEXT:    ri.vunzip2a.vv v16, v8, v10
-; ZIP-NEXT:    vsetivli zero, 16, e16, m1, ta, ma
-; ZIP-NEXT:    vid.v v8
-; ZIP-NEXT:    li a0, -256
-; ZIP-NEXT:    vadd.vv v8, v8, v8
-; ZIP-NEXT:    vmv.s.x v0, a0
-; ZIP-NEXT:    vadd.vi v8, v8, -16
-; ZIP-NEXT:    vsetvli zero, zero, e64, m4, ta, mu
-; ZIP-NEXT:    vrgatherei16.vv v16, v12, v8, v0.t
-; ZIP-NEXT:    vmv.v.v v8, v16
+; ZIP-NEXT:    ri.vunzip2a.vv v16, v12, v14
+; ZIP-NEXT:    ri.vunzip2a.vv v12, v8, v10
+; ZIP-NEXT:    vsetivli zero, 16, e64, m4, ta, ma
+; ZIP-NEXT:    vslideup.vi v12, v16, 8
+; ZIP-NEXT:    vmv.v.v v8, v12
 ; ZIP-NEXT:    ret
 entry:
   %c = shufflevector <16 x i64> %a, <16 x i64> %b, <16 x i32> <i32 0, i32 2, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14, i32 16, i32 18, i32 20, i32 22, i32 24, i32 26, i32 28, i32 30>
@@ -1557,13 +1550,9 @@ define <4 x i64> @unzip2a_dual_v4i64_exact(<4 x i64> %a, <4 x i64> %b) vscale_ra
 ;
 ; ZIP-LABEL: unzip2a_dual_v4i64_exact:
 ; ZIP:       # %bb.0: # %entry
-; ZIP-NEXT:    vsetivli zero, 4, e64, m1, ta, mu
-; ZIP-NEXT:    vmv.v.i v0, 8
-; ZIP-NEXT:    vslideup.vi v10, v9, 2
-; ZIP-NEXT:    vslideup.vi v10, v9, 1, v0.t
-; ZIP-NEXT:    vmv.v.i v0, 12
-; ZIP-NEXT:    ri.vunzip2a.vv v11, v8, v9
-; ZIP-NEXT:    vmerge.vvm v8, v11, v10, v0
+; ZIP-NEXT:    vsetivli zero, 4, e64, m1, ta, ma
+; ZIP-NEXT:    ri.vunzip2a.vv v10, v8, v9
+; ZIP-NEXT:    vmv.v.v v8, v10
 ; ZIP-NEXT:    ret
 entry:
   %c = shufflevector <4 x i64> %a, <4 x i64> %b, <4 x i32> <i32 0, i32 2, i32 4, i32 6>
@@ -1609,13 +1598,10 @@ define <4 x i64> @unzip2a_dual_v4i64_exact_nf2(<4 x i64> %a, <4 x i64> %b) vscal
 ;
 ; ZIP-LABEL: unzip2a_dual_v4i64_exact_nf2:
 ; ZIP:       # %bb.0: # %entry
-; ZIP-NEXT:    vsetivli zero, 4, e64, m1, ta, mu
-; ZIP-NEXT:    vmv.v.i v0, 8
-; ZIP-NEXT:    vslideup.vi v10, v9, 2
-; ZIP-NEXT:    vslideup.vi v10, v9, 1, v0.t
-; ZIP-NEXT:    vmv.v.i v0, 12
-; ZIP-NEXT:    ri.vunzip2a.vv v11, v8, v9
-; ZIP-NEXT:    vmerge.vvm v8, v11, v10, v0
+; ZIP-NEXT:    vsetivli zero, 8, e64, m1, ta, ma
+; ZIP-NEXT:    vslideup.vi v8, v9, 4
+; ZIP-NEXT:    ri.vunzip2a.vv v9, v8, v10
+; ZIP-NEXT:    vmv.v.v v8, v9
 ; ZIP-NEXT:    ret
 entry:
   %c = shufflevector <4 x i64> %a, <4 x i64> %b, <4 x i32> <i32 0, i32 2, i32 4, i32 6>
@@ -1740,39 +1726,111 @@ define <16 x i64> @unzip2a_dual_v16i64_exact(<16 x i64> %a, <16 x i64> %b) vscal
 ;
 ; ZIP-LABEL: unzip2a_dual_v16i64_exact:
 ; ZIP:       # %bb.0: # %entry
-; ZIP-NEXT:    vsetivli zero, 4, e64, m1, ta, mu
-; ZIP-NEXT:    vslideup.vi v18, v15, 2
-; ZIP-NEXT:    vmv.v.i v16, 8
-; ZIP-NEXT:    vmv.v.i v17, 12
-; ZIP-NEXT:    vslideup.vi v20, v13, 2
-; ZIP-NEXT:    vmv.v.v v0, v16
-; ZIP-NEXT:    vslideup.vi v18, v15, 1, v0.t
-; ZIP-NEXT:    ri.vunzip2a.vv v15, v14, v19
-; ZIP-NEXT:    vmv.v.v v0, v17
-; ZIP-NEXT:    vmerge.vvm v15, v15, v18, v0
-; ZIP-NEXT:    vmv.v.v v0, v16
-; ZIP-NEXT:    vslideup.vi v20, v13, 1, v0.t
-; ZIP-NEXT:    ri.vunzip2a.vv v14, v12, v13
-; ZIP-NEXT:    vslideup.vi v12, v11, 2
-; ZIP-NEXT:    vslideup.vi v18, v9, 2
-; ZIP-NEXT:    vmv.v.v v0, v17
-; ZIP-NEXT:    vmerge.vvm v14, v14, v20, v0
-; ZIP-NEXT:    li a0, -256
-; ZIP-NEXT:    ri.vunzip2a.vv v20, v10, v13
-; ZIP-NEXT:    ri.vunzip2a.vv v10, v8, v19
-; ZIP-NEXT:    vmv.v.v v0, v16
-; ZIP-NEXT:    vslideup.vi v12, v11, 1, v0.t
-; ZIP-NEXT:    vmv.v.v v0, v17
-; ZIP-NEXT:    vmerge.vvm v13, v20, v12, v0
-; ZIP-NEXT:    vmv.v.v v0, v16
-; ZIP-NEXT:    vslideup.vi v18, v9, 1, v0.t
-; ZIP-NEXT:    vmv.v.v v0, v17
-; ZIP-NEXT:    vmerge.vvm v12, v10, v18, v0
-; ZIP-NEXT:    vmv.s.x v0, a0
 ; ZIP-NEXT:    vsetivli zero, 16, e64, m4, ta, ma
-; ZIP-NEXT:    vmerge.vvm v8, v12, v12, v0
+; ZIP-NEXT:    ri.vunzip2a.vv v16, v8, v12
+; ZIP-NEXT:    vmv.v.v v8, v16
 ; ZIP-NEXT:    ret
 entry:
   %c = shufflevector <16 x i64> %a, <16 x i64> %b, <16 x i32> <i32 0, i32 2, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14, i32 16, i32 18, i32 20, i32 22, i32 24, i32 26, i32 28, i32 30>
   ret <16 x i64> %c
 }
+
+define <4 x i64> @unzip2b_dual_v4i64(<4 x i64> %a, <4 x i64> %b) {
+; V-LABEL: unzip2b_dual_v4i64:
+; V:       # %bb.0: # %entry
+; V-NEXT:    vsetivli zero, 4, e64, m1, ta, mu
+; V-NEXT:    vmv.v.i v0, 2
+; V-NEXT:    vslidedown.vi v10, v8, 1
+; V-NEXT:    vslidedown.vi v10, v8, 2, v0.t
+; V-NEXT:    vmv.v.i v0, 4
+; V-NEXT:    vmv1r.v v8, v9
+; V-NEXT:    vslideup.vi v8, v9, 1, v0.t
+; V-NEXT:    vmv.v.i v0, 12
+; V-NEXT:    vmerge.vvm v8, v10, v8, v0
+; V-NEXT:    ret
+;
+; ZVE32F-LABEL: unzip2b_dual_v4i64:
+; ZVE32F:       # %bb.0: # %entry
+; ZVE32F-NEXT:    ld a3, 8(a2)
+; ZVE32F-NEXT:    ld a2, 24(a2)
+; ZVE32F-NEXT:    ld a4, 8(a1)
+; ZVE32F-NEXT:    ld a1, 24(a1)
+; ZVE32F-NEXT:    vsetivli zero, 8, e32, m1, ta, mu
+; ZVE32F-NEXT:    vmv.v.i v0, 15
+; ZVE32F-NEXT:    srli a5, a2, 32
+; ZVE32F-NEXT:    srli a6, a3, 32
+; ZVE32F-NEXT:    srli a7, a1, 32
+; ZVE32F-NEXT:    srli t0, a4, 32
+; ZVE32F-NEXT:    vmv.v.x v8, a4
+; ZVE32F-NEXT:    vmv.v.x v9, a3
+; ZVE32F-NEXT:    vslide1down.vx v8, v8, t0
+; ZVE32F-NEXT:    vslide1down.vx v9, v9, a6
+; ZVE32F-NEXT:    vslide1down.vx v8, v8, a1
+; ZVE32F-NEXT:    vslide1down.vx v9, v9, a2
+; ZVE32F-NEXT:    vslide1down.vx v8, v8, a7
+; ZVE32F-NEXT:    vslide1down.vx v9, v9, a5
+; ZVE32F-NEXT:    vslidedown.vi v9, v8, 4, v0.t
+; ZVE32F-NEXT:    vse32.v v9, (a0)
+; ZVE32F-NEXT:    ret
+;
+; ZIP-LABEL: unzip2b_dual_v4i64:
+; ZIP:       # %bb.0: # %entry
+; ZIP-NEXT:    vsetivli zero, 4, e64, m1, ta, ma
+; ZIP-NEXT:    ri.vunzip2b.vv v11, v9, v10
+; ZIP-NEXT:    ri.vunzip2b.vv v9, v8, v10
+; ZIP-NEXT:    vslideup.vi v9, v11, 2
+; ZIP-NEXT:    vmv.v.v v8, v9
+; ZIP-NEXT:    ret
+entry:
+  %c = shufflevector <4 x i64> %a, <4 x i64> %b, <4 x i32> <i32 1, i32 3, i32 5, i32 7>
+  ret <4 x i64> %c
+}
+
+define <4 x i64> @unzip2b_dual_v4i64_exact(<4 x i64> %a, <4 x i64> %b) vscale_range(4,4) {
+; V-LABEL: unzip2b_dual_v4i64_exact:
+; V:       # %bb.0: # %entry
+; V-NEXT:    vsetivli zero, 4, e64, m1, ta, mu
+; V-NEXT:    vmv.v.i v0, 2
+; V-NEXT:    vslidedown.vi v10, v8, 1
+; V-NEXT:    vslidedown.vi v10, v8, 2, v0.t
+; V-NEXT:    vmv.v.i v0, 4
+; V-NEXT:    vmv1r.v v8, v9
+; V-NEXT:    vslideup.vi v8, v9, 1, v0.t
+; V-NEXT:    vmv.v.i v0, 12
+; V-NEXT:    vmerge.vvm v8, v10, v8, v0
+; V-NEXT:    ret
+;
+; ZVE32F-LABEL: unzip2b_dual_v4i64_exact:
+; ZVE32F:       # %bb.0: # %entry
+; ZVE32F-NEXT:    ld a3, 8(a2)
+; ZVE32F-NEXT:    ld a2, 24(a2)
+; ZVE32F-NEXT:    ld a4, 8(a1)
+; ZVE32F-NEXT:    ld a1, 24(a1)
+; ZVE32F-NEXT:    vsetivli zero, 8, e32, m1, ta, mu
+; ZVE32F-NEXT:    vmv.v.i v0, 15
+; ZVE32F-NEXT:    srli a5, a2, 32
+; ZVE32F-NEXT:    srli a6, a3, 32
+; ZVE32F-NEXT:    srli a7, a1, 32
+; ZVE32F-NEXT:    srli t0, a4, 32
+; ZVE32F-NEXT:    vmv.v.x v8, a4
+; ZVE32F-NEXT:    vmv.v.x v9, a3
+; ZVE32F-NEXT:    vslide1down.vx v8, v8, t0
+; ZVE32F-NEXT:    vslide1down.vx v9, v9, a6
+; ZVE32F-NEXT:    vslide1down.vx v8, v8, a1
+; ZVE32F-NEXT:    vslide1down.vx v9, v9, a2
+; ZVE32F-NEXT:    vslide1down.vx v8, v8, a7
+; ZVE32F-NEXT:    vslide1down.vx v9, v9, a5
+; ZVE32F-NEXT:    vslidedown.vi v9, v8, 4, v0.t
+; ZVE32F-NEXT:    vs1r.v v9, (a0)
+; ZVE32F-NEXT:    ret
+;
+; ZIP-LABEL: unzip2b_dual_v4i64_exact:
+; ZIP:       # %bb.0: # %entry
+; ZIP-NEXT:    vsetivli zero, 4, e64, m1, ta, ma
+; ZIP-NEXT:    ri.vunzip2b.vv v10, v8, v9
+; ZIP-NEXT:    vmv.v.v v8, v10
+; ZIP-NEXT:    ret
+entry:
+  %c = shufflevector <4 x i64> %a, <4 x i64> %b, <4 x i32> <i32 1, i32 3, i32 5, i32 7>
+  ret <4 x i64> %c
+}
