[llvm] [AArch64][SVE][SelectionDAG] Improve codegen for SVE patterns sext(icmp) and zext(icmp) (PR #192052)

via llvm-commits llvm-commits at lists.llvm.org
Tue Apr 14 06:06:47 PDT 2026


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Sushant Gokhale (sushgokh)

<details>
<summary>Changes</summary>

For SVE vectors:

    1. sext(icmp slt) --> max(min(a-b, 0), -1)  --> sclamp(sqsub(a, b), -1, 0)
    2. sext(icmp slt) --> min(max(b-a, 0), 1)  --> sclamp(sqsub(b, a), 0, 1)
    3. zext(icmp ult) --> min(max(b-a, 0), 1)  --> umin(uqsub(b, a), 1)
    4. Let,
       Op = sext(icmp ult(a,b))
       NewOp = umin(uqsub(b, a), 1)

       Then,
       sdot(acc, Op, Op) --> sdot(acc, NewOp, NewOp)

    The other changes follow:
    1. icmp sgt is just inverse of the icmp slt.
    2. udot is similar to sdot


---

Patch is 30.12 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/192052.diff


2 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64ISelLowering.cpp (+96-1) 
- (added) llvm/test/CodeGen/AArch64/sve-icmp-sext-zext.ll (+537) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index ece24767bdbb9..1f83b8cb705ea 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -20941,6 +20941,22 @@ static SDValue performSVEAndCombine(SDNode *N,
   SDValue Src = N->getOperand(0);
   unsigned Opc = Src->getOpcode();
 
+  // and(splat(1), sext(setcc_merge_zero)) -> zext(setcc_merge_zero)
+  SDLoc DL(N);
+  SDValue Op0 = N->getOperand(0);
+  SDValue Op1 = N->getOperand(1);
+  if (Op0.getOpcode() == ISD::SPLAT_VECTOR ||
+      Op1.getOpcode() == ISD::SPLAT_VECTOR) {
+    SDValue NonSplatOp = (Op0.getOpcode() == ISD::SPLAT_VECTOR ? Op1 : Op0);
+    SDValue SplatOp = (Op0.getOpcode() == ISD::SPLAT_VECTOR ? Op0 : Op1);
+    if (NonSplatOp.getOpcode() == ISD::SIGN_EXTEND) {
+      SDValue Compare = NonSplatOp.getOperand(0);
+      if (Compare.getOpcode() == AArch64ISD::SETCC_MERGE_ZERO) {
+        return DAG.getNode(ISD::ZERO_EXTEND, DL, N->getValueType(0), Compare);
+      }
+    }
+  }
+
   // Zero/any extend of an unsigned unpack
   if (Opc == AArch64ISD::UUNPKHI || Opc == AArch64ISD::UUNPKLO) {
     SDValue UnpkOp = Src->getOperand(0);
@@ -20949,7 +20965,6 @@ static SDValue performSVEAndCombine(SDNode *N,
     if (Dup.getOpcode() != ISD::SPLAT_VECTOR)
       return SDValue();
 
-    SDLoc DL(N);
     ConstantSDNode *C = dyn_cast<ConstantSDNode>(Dup->getOperand(0));
     if (!C)
       return SDValue();
@@ -24091,6 +24106,37 @@ static SDValue performIntrinsicCombine(SDNode *N,
   case Intrinsic::aarch64_sve_bsl2n:
   case Intrinsic::aarch64_sve_nbsl:
     return combineSVEBitSel(IID, N, DAG);
+  case Intrinsic::aarch64_sve_udot:
+  case Intrinsic::aarch64_sve_sdot: {
+    // sdot(acc, extend(icmp_ult(A, B)), extend(icmp_ult(A, B)))
+    //  -> sdot(acc, umin(usubsat(B, A)), umin(usubsat(B, A)))
+
+    // sdot(acc, extend(icmp_ugt(A, B)), extend(icmp_ugt(A, B)))
+    //  -> sdot(acc, umin(usubsat(A, B)), umin(usubsat(A, B)))
+    SDValue Extend1 = N->getOperand(2);
+    SDValue Extend2 = N->getOperand(3);
+    if (Extend1 == Extend2 && (Extend1.getOpcode() == ISD::SIGN_EXTEND ||
+                               Extend1.getOpcode() == ISD::ZERO_EXTEND)) {
+      SDValue Compare = Extend1.getOperand(0);
+      if (Compare.getOpcode() != AArch64ISD::SETCC_MERGE_ZERO)
+        break;
+      ISD::CondCode CC = cast<CondCodeSDNode>(Compare.getOperand(3))->get();
+      if (CC != ISD::SETULT && CC != ISD::SETUGT)
+        break;
+      SDLoc DL(N);
+      EVT ResVT = Extend1.getValueType();
+      SDValue A = Compare.getOperand(CC == ISD::SETULT ? 1 : 2);
+      SDValue B = Compare.getOperand(CC == ISD::SETULT ? 2 : 1);
+      SDValue Sub = DAG.getNode(ISD::USUBSAT, DL, ResVT, B, A);
+      SDValue One = DAG.getConstant(1, DL, MVT::i32);
+      SDValue SplatOne = DAG.getSplatVector(ResVT, DL, One);
+      SDValue Min = DAG.getNode(ISD::UMIN, DL, ResVT, Sub, SplatOne);
+      unsigned Opcode = (IID == Intrinsic::aarch64_sve_udot ? AArch64ISD::UDOT
+                                                            : AArch64ISD::SDOT);
+      return DAG.getNode(Opcode, DL, N->getValueType(0), N->getOperand(1), Min,
+                         Min);
+    }
+  }
   }
   return SDValue();
 }
@@ -24422,6 +24468,55 @@ static SDValue performExtendCombine(SDNode *N,
                                     TargetLowering::DAGCombinerInfo &DCI,
                                     SelectionDAG &DAG,
                                     const AArch64Subtarget *Subtarget) {
+  // sext(icmp slt(a, b)) -> sclamp(sqsub(a, b), -1, 0)
+  // sext(icmp sgt(a, b)) -> sclamp(sqsub(b, a), -1, 0)
+  if (N->getOpcode() == ISD::SIGN_EXTEND) {
+    SDValue Compare = N->getOperand(0);
+    if (Compare.getOpcode() == AArch64ISD::SETCC_MERGE_ZERO) {
+      ISD::CondCode CC = cast<CondCodeSDNode>(Compare.getOperand(3))->get();
+      if (Compare.hasOneUse() && Subtarget->hasSVE2p1() &&
+          (CC == ISD::SETLT || CC == ISD::SETGT)) {
+        SDLoc DL(N);
+        SDValue A = Compare.getOperand(CC == ISD::SETLT ? 1 : 2);
+        SDValue B = Compare.getOperand(CC == ISD::SETLT ? 2 : 1);
+        SDValue Sub = DAG.getNode(ISD::SSUBSAT, DL, N->getValueType(0), A, B);
+        SDValue MinusOne = DAG.getSplatVector(
+            N->getValueType(0), DL, DAG.getSignedConstant(-1, DL, MVT::i32));
+        SDValue Zero = DAG.getSplatVector(N->getValueType(0), DL,
+                                          DAG.getConstant(0, DL, MVT::i32));
+        SDValue Sclamp = DAG.getNode(
+            ISD::INTRINSIC_WO_CHAIN, DL, N->getValueType(0),
+            DAG.getConstant(Intrinsic::aarch64_sve_sclamp, DL, MVT::i64), Sub,
+            MinusOne, Zero);
+        return Sclamp;
+      }
+    }
+  }
+  // zext(icmp slt(a, b)) -> sclamp(sqsub(b,a), 0, 1)
+  // zext(icmp sgt(a, b)) -> sclamp(sqsub(a,b), 0, 1)
+  if (N->getOpcode() == ISD::ZERO_EXTEND) {
+    SDValue Compare = N->getOperand(0);
+    if (Compare.getOpcode() == AArch64ISD::SETCC_MERGE_ZERO) {
+      ISD::CondCode CC = cast<CondCodeSDNode>(Compare.getOperand(3))->get();
+      if (Compare.hasOneUse() && Subtarget->hasSVE2p1() &&
+          (CC == ISD::SETLT || CC == ISD::SETGT)) {
+        SDLoc DL(N);
+        SDValue A = Compare.getOperand(CC == ISD::SETLT ? 1 : 2);
+        SDValue B = Compare.getOperand(CC == ISD::SETLT ? 2 : 1);
+        SDValue Sub = DAG.getNode(ISD::SSUBSAT, DL, N->getValueType(0), B, A);
+        SDValue One = DAG.getSplatVector(N->getValueType(0), DL,
+                                         DAG.getConstant(1, DL, MVT::i32));
+        SDValue Zero = DAG.getSplatVector(N->getValueType(0), DL,
+                                          DAG.getConstant(0, DL, MVT::i32));
+        SDValue Sclamp = DAG.getNode(
+            ISD::INTRINSIC_WO_CHAIN, DL, N->getValueType(0),
+            DAG.getConstant(Intrinsic::aarch64_sve_sclamp, DL, MVT::i64), Sub,
+            Zero, One);
+        return Sclamp;
+      }
+    }
+  }
+
   // If we see something like (zext (sabd (extract_high ...), (DUP ...))) then
   // we can convert that DUP into another extract_high (of a bigger DUP), which
   // helps the backend to decide that an sabdl2 would be useful, saving a real
diff --git a/llvm/test/CodeGen/AArch64/sve-icmp-sext-zext.ll b/llvm/test/CodeGen/AArch64/sve-icmp-sext-zext.ll
new file mode 100644
index 0000000000000..b53d36e0ee13d
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/sve-icmp-sext-zext.ll
@@ -0,0 +1,537 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc -mtriple=aarch64 -mattr=+dotprod,+sve2p1 --aarch64-sve-vector-bits-min=256 -o - < %s | FileCheck %s
+
+define <vscale x 4 x i32> @test1(<vscale x 16 x i8> %a, <vscale x 16 x i8> %b)
+; CHECK-LABEL: test1:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    uqsub z1.b, z1.b, z0.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+{
+  %1 = icmp ult <vscale x 16 x i8> %a, %b
+  %2 = sext <vscale x 16 x i1> %1 to <vscale x 16 x i8>
+  %3 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %2, <vscale x 16 x i8> %2)
+  ret <vscale x 4 x i32> %3
+}
+
+define <vscale x 4 x i32> @test2(<vscale x 16 x i8> %a, <vscale x 16 x i8> %b)
+; CHECK-LABEL: test2:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    uqsub z1.b, z1.b, z0.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+{
+  %1 = icmp ult <vscale x 16 x i8> %a, %b
+  %2 = zext <vscale x 16 x i1> %1 to <vscale x 16 x i8>
+  %3 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %2, <vscale x 16 x i8> %2)
+  ret <vscale x 4 x i32> %3
+}
+
+define <vscale x 4 x i32> @test3(<vscale x 16 x i8> %a, <vscale x 16 x i8> %b)
+; CHECK-LABEL: test3:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    uqsub z1.b, z1.b, z0.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+{
+  %1 = icmp ult <vscale x 16 x i8> %a, %b
+  %2 = zext <vscale x 16 x i1> %1 to <vscale x 16 x i8>
+  %3 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %2, <vscale x 16 x i8> %2)
+  ret <vscale x 4 x i32> %3
+}
+
+define <vscale x 4 x i32> @test4(<32 x i8> %a, <32 x i8> %b)  {
+; CHECK-LABEL: test4:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $q1 killed $q1 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    ptrue p0.b, vl16
+; CHECK-NEXT:    // kill: def $q3 killed $q3 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    // kill: def $q2 killed $q2 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    splice z0.b, p0, { z0.b, z1.b }
+; CHECK-NEXT:    splice z1.b, p0, { z2.b, z3.b }
+; CHECK-NEXT:    uqsub z1.b, z1.b, z0.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+  %1 = icmp ult <32 x i8> %a, %b
+  %2 = sext <32 x i1> %1 to <32 x i8>
+  %3 = tail call <vscale x 16 x i8> @llvm.vector.insert.nxv16i8.v32i8(<vscale x 16 x i8> poison, <32 x i8> %2, i64 0)
+  %4 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %3, <vscale x 16 x i8> %3)
+  ret <vscale x 4 x i32> %4
+}
+
+define <vscale x 4 x i32> @test5(<32 x i8> %a, <32 x i8> %b)  {
+; CHECK-LABEL: test5:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $q1 killed $q1 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    ptrue p0.b, vl16
+; CHECK-NEXT:    // kill: def $q3 killed $q3 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    // kill: def $q2 killed $q2 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    splice z0.b, p0, { z0.b, z1.b }
+; CHECK-NEXT:    splice z1.b, p0, { z2.b, z3.b }
+; CHECK-NEXT:    uqsub z1.b, z1.b, z0.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+  %1 = icmp ult <32 x i8> %a, %b
+  %2 = zext <32 x i1> %1 to <32 x i8>
+  %3 = tail call <vscale x 16 x i8> @llvm.vector.insert.nxv16i8.v32i8(<vscale x 16 x i8> poison, <32 x i8> %2, i64 0)
+  %4 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %3, <vscale x 16 x i8> %3)
+  ret <vscale x 4 x i32> %4
+}
+
+define <vscale x 4 x i32> @test6(<32 x i8> %a, <32 x i8> %b)  {
+; CHECK-LABEL: test6:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $q1 killed $q1 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    ptrue p0.b, vl16
+; CHECK-NEXT:    // kill: def $q3 killed $q3 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    // kill: def $q2 killed $q2 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    splice z0.b, p0, { z0.b, z1.b }
+; CHECK-NEXT:    splice z1.b, p0, { z2.b, z3.b }
+; CHECK-NEXT:    uqsub z1.b, z1.b, z0.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+  %1 = icmp ult <32 x i8> %a, %b
+  %2 = zext <32 x i1> %1 to <32 x i8>
+  %3 = tail call <vscale x 16 x i8> @llvm.vector.insert.nxv16i8.v32i8(<vscale x 16 x i8> poison, <32 x i8> %2, i64 0)
+  %4 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %3, <vscale x 16 x i8> %3)
+  ret <vscale x 4 x i32> %4
+}
+
+define <vscale x 4 x i32> @test7(<vscale x 16 x i8> %a, <vscale x 16 x i8> %b)
+; CHECK-LABEL: test7:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    uqsub z1.b, z0.b, z1.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+{
+  %1 = icmp ugt <vscale x 16 x i8> %a, %b
+  %2 = sext <vscale x 16 x i1> %1 to <vscale x 16 x i8>
+  %3 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %2, <vscale x 16 x i8> %2)
+  ret <vscale x 4 x i32> %3
+}
+
+define <vscale x 4 x i32> @test8(<vscale x 16 x i8> %a, <vscale x 16 x i8> %b)
+; CHECK-LABEL: test8:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    uqsub z1.b, z0.b, z1.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+{
+  %1 = icmp ugt <vscale x 16 x i8> %a, %b
+  %2 = zext <vscale x 16 x i1> %1 to <vscale x 16 x i8>
+  %3 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %2, <vscale x 16 x i8> %2)
+  ret <vscale x 4 x i32> %3
+}
+
+define <vscale x 4 x i32> @test9(<vscale x 16 x i8> %a, <vscale x 16 x i8> %b)
+; CHECK-LABEL: test9:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    uqsub z1.b, z0.b, z1.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+{
+  %1 = icmp ugt <vscale x 16 x i8> %a, %b
+  %2 = zext <vscale x 16 x i1> %1 to <vscale x 16 x i8>
+  %3 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %2, <vscale x 16 x i8> %2)
+  ret <vscale x 4 x i32> %3
+}
+
+define <vscale x 4 x i32> @test10(<32 x i8> %a, <32 x i8> %b)  {
+; CHECK-LABEL: test10:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $q3 killed $q3 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q1 killed $q1 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    ptrue p0.b, vl16
+; CHECK-NEXT:    // kill: def $q2 killed $q2 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    splice z2.b, p0, { z2.b, z3.b }
+; CHECK-NEXT:    splice z0.b, p0, { z0.b, z1.b }
+; CHECK-NEXT:    uqsub z1.b, z0.b, z2.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+  %1 = icmp ugt <32 x i8> %a, %b
+  %2 = sext <32 x i1> %1 to <32 x i8>
+  %3 = tail call <vscale x 16 x i8> @llvm.vector.insert.nxv16i8.v32i8(<vscale x 16 x i8> poison, <32 x i8> %2, i64 0)
+  %4 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %3, <vscale x 16 x i8> %3)
+  ret <vscale x 4 x i32> %4
+}
+
+define <vscale x 4 x i32> @test11(<32 x i8> %a, <32 x i8> %b)  {
+; CHECK-LABEL: test11:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $q3 killed $q3 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q1 killed $q1 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    ptrue p0.b, vl16
+; CHECK-NEXT:    // kill: def $q2 killed $q2 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    splice z2.b, p0, { z2.b, z3.b }
+; CHECK-NEXT:    splice z0.b, p0, { z0.b, z1.b }
+; CHECK-NEXT:    uqsub z1.b, z0.b, z2.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+  %1 = icmp ugt <32 x i8> %a, %b
+  %2 = zext <32 x i1> %1 to <32 x i8>
+  %3 = tail call <vscale x 16 x i8> @llvm.vector.insert.nxv16i8.v32i8(<vscale x 16 x i8> poison, <32 x i8> %2, i64 0)
+  %4 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %3, <vscale x 16 x i8> %3)
+  ret <vscale x 4 x i32> %4
+}
+
+define <vscale x 4 x i32> @test12(<32 x i8> %a, <32 x i8> %b)  {
+; CHECK-LABEL: test12:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $q3 killed $q3 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q1 killed $q1 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    ptrue p0.b, vl16
+; CHECK-NEXT:    // kill: def $q2 killed $q2 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    splice z2.b, p0, { z2.b, z3.b }
+; CHECK-NEXT:    splice z0.b, p0, { z0.b, z1.b }
+; CHECK-NEXT:    uqsub z1.b, z0.b, z2.b
+; CHECK-NEXT:    movi v0.2d, #0000000000000000
+; CHECK-NEXT:    umin z1.b, z1.b, #1
+; CHECK-NEXT:    sdot z0.s, z1.b, z1.b
+; CHECK-NEXT:    ret
+  %1 = icmp ugt <32 x i8> %a, %b
+  %2 = zext <32 x i1> %1 to <32 x i8>
+  %3 = tail call <vscale x 16 x i8> @llvm.vector.insert.nxv16i8.v32i8(<vscale x 16 x i8> poison, <32 x i8> %2, i64 0)
+  %4 = tail call <vscale x 4 x i32> @llvm.aarch64.sve.sdot.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 16 x i8> %3, <vscale x 16 x i8> %3)
+  ret <vscale x 4 x i32> %4
+}
+
+define <vscale x 16 x i8> @test13(<vscale x 16 x i8> %0, <vscale x 16 x i8> %1)  {
+; CHECK-LABEL: test13:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    movi v2.2d, #0000000000000000
+; CHECK-NEXT:    sqsub z0.b, z0.b, z1.b
+; CHECK-NEXT:    mov z1.b, #-1 // =0xffffffffffffffff
+; CHECK-NEXT:    sclamp z0.b, z1.b, z2.b
+; CHECK-NEXT:    ret
+entry:
+  %2 = icmp slt <vscale x 16 x i8> %0, %1
+  %3 = sext <vscale x 16 x i1> %2 to <vscale x 16 x i8>
+  ret <vscale x 16 x i8> %3
+}
+
+define <vscale x 16 x i8> @test14(<32 x i8> %0, <32 x i8> %1)  {
+; CHECK-LABEL: test14:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    // kill: def $q3 killed $q3 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q1 killed $q1 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    ptrue p0.b, vl16
+; CHECK-NEXT:    // kill: def $q2 killed $q2 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    splice z2.b, p0, { z2.b, z3.b }
+; CHECK-NEXT:    splice z0.b, p0, { z0.b, z1.b }
+; CHECK-NEXT:    movi v1.2d, #0000000000000000
+; CHECK-NEXT:    sqsub z0.b, z0.b, z2.b
+; CHECK-NEXT:    mov z2.b, #-1 // =0xffffffffffffffff
+; CHECK-NEXT:    sclamp z0.b, z2.b, z1.b
+; CHECK-NEXT:    ret
+entry:
+  %2 = icmp slt <32 x i8> %0, %1
+  %3 = sext <32 x i1> %2 to <32 x i8>
+  %4 = tail call <vscale x 16 x i8> @llvm.vector.insert.nxv16i8.v32i8(<vscale x 16 x i8> poison, <32 x i8> %3, i64 0)
+  ret <vscale x 16 x i8> %4
+}
+
+; FIXME: Lower this sequence to sqsub/sclamp
+define <vscale x 16 x i8> @test15(<vscale x 16 x i8> %0, <vscale x 16 x i8> %1)  {
+; CHECK-LABEL: test15:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    ptrue p0.b
+; CHECK-NEXT:    cmpgt p1.b, p0/z, z1.b, z0.b
+; CHECK-NEXT:    mov z1.b, #1 // =0x1
+; CHECK-NEXT:    mov z0.b, p1/z, #-1 // =0xffffffffffffffff
+; CHECK-NEXT:    add z0.b, p1/m, z0.b, z1.b
+; CHECK-NEXT:    ret
+entry:
+  %2 = icmp slt <vscale x 16 x i8> %0, %1
+  %3 = sext <vscale x 16 x i1> %2 to <vscale x 16 x i8>
+  %4 = zext <vscale x 16 x i1> %2 to <vscale x 16 x i8>
+  %5 = add <vscale x 16 x i8> %3, %4
+  ret <vscale x 16 x i8> %5
+}
+
+define <vscale x 16 x i8> @test16(<vscale x 16 x i8> %0, <vscale x 16 x i8> %1)  {
+; CHECK-LABEL: test16:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    movi v2.2d, #0000000000000000
+; CHECK-NEXT:    sqsub z0.b, z1.b, z0.b
+; CHECK-NEXT:    mov z1.b, #-1 // =0xffffffffffffffff
+; CHECK-NEXT:    sclamp z0.b, z1.b, z2.b
+; CHECK-NEXT:    ret
+entry:
+  %2 = icmp sgt <vscale x 16 x i8> %0, %1
+  %3 = sext <vscale x 16 x i1> %2 to <vscale x 16 x i8>
+  ret <vscale x 16 x i8> %3
+}
+
+define <vscale x 16 x i8> @test17(<32 x i8> %0, <32 x i8> %1)  {
+; CHECK-LABEL: test17:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    // kill: def $q1 killed $q1 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    ptrue p0.b, vl16
+; CHECK-NEXT:    // kill: def $q3 killed $q3 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0_z1 def $z0_z1
+; CHECK-NEXT:    // kill: def $q2 killed $q2 killed $z2_z3 def $z2_z3
+; CHECK-NEXT:    splice z0.b, p0, { z0.b, z1.b }
+; CHECK-NEXT:    splice z1.b, p0, { z2.b, z3.b }
+; CHECK-NEXT:    mov z2.b, #-1 // =0xffffffffffffffff
+; CHECK-NEXT:    sqsub z0.b, z1.b, z0.b
+; CHECK-NEXT:    movi v1.2d, #0000000000000000
+; CHECK-NEXT:    sclamp z0.b, z2.b, z1.b
+; CHECK-NEXT:    ret
+entry:
+  %2 = icmp sgt <32 x i8> %0, %1
+  %3 = sext <32 x i1> %2 to <32 x i8>
+  %4 = tail call <vscale x 16 x i...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/192052


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