[llvm][CodeGen][aarch64] Add contiguous prefetch intrinsics for SVE.

[fpetrogalli]

Summary

The patch covers both register/register and register/immediate addressing modes.

[fpetrogalli]

This is not yet ready to review.

[fpetrogalli]

Replace <n x ... with <vscale x ... in the test.

[fpetrogalli]

The patch now is ready to review. It covers only the contiguous prefetches. I will create a separate revision for the gather prefetches.

[fpetrogalli]

llvm/include/llvm/IR/IntrinsicsAArch64.td

1263–1265

Ideally, I would have liked to define this as something like:

def int_aarch64_sve_prf : Intrinsic<[], [PointerTo<llvm_anyvector_ty>,
                                         LLVMScalarOrSameVectorWidth<0, llvm_i1_ty>,
                                         llvm_i32_ty], [IntrArgMemOnly]>;

For some definition of PointerTo, but I am not aware of anything in the current intrinsic generator that can be used for that.

[sdesmalen]

nit: in the title:
s/continuous/contiguous/

LGTM otherwise

llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

4414

nit: Any reason you're using an anonymous namespace over static for these functions?

4424

nit: you can fold this into the condition above.

4432

instead of 128, can you use AArch64::SVEBitsPerBlock?

[fpetrogalli]

llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

4414

I should have really used static to adhere to the style of the rest of the file... Done.

[fpetrogalli]

Address code review from @sdesmalen.

[andwar]

llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

4415

[nit] corresponding?

4468–4469

What's this check for? Wouldn't some hard-coded null-value be more idiomatic?

llvm/test/CodeGen/AArch64/sve-intrinsics-contiguous-prefetches.ll

101

Would it make sense to add checks for what's expected instead?

[fpetrogalli]

llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

4468–4469

I think EVT() is there to simulate a nullptr, see http://llvm.org/doxygen/ValueTypes_8h_source.html:

struct EVT {
private:
  MVT V = MVT::INVALID_SIMPLE_VALUE_TYPE;
  Type *LLVMTy = nullptr;
 
public:
  constexpr EVT() = default;

Essentially, if statement checks that the MemVT is not { MVT::INVALID_SIMPLE_VALUE_TYPE, nullptr}.

llvm/test/CodeGen/AArch64/sve-intrinsics-contiguous-prefetches.ll

101

I guess you are right. We could miss a failure in the addressing mode generation if we have (at the same time) a failure in the rendering of the immediate constant... quite a remote possibility, which I am sure it will be caught in time in some other tests.

So I think we can leave it as it is.

llvm/include/llvm/IR/IntrinsicsAArch64.td

 
 //
 // Stores
 //
 
 def int_aarch64_sve_stnt1 : AdvSIMD_1Vec_PredStore_Intrinsic;
 
 //
+// Prefetch
+//
+
+def int_aarch64_sve_prf : Intrinsic<[], [llvm_anyvector_ty,
+                                         llvm_ptr_ty,
+                                         llvm_i32_ty], [IntrArgMemOnly]>;
+
+//
 // Scalar to vector operations
 //
 
 def int_aarch64_sve_dup : AdvSIMD_SVE_DUP_Intrinsic;
 
 def int_aarch64_sve_index : AdvSIMD_SVE_Index_Intrinsic;
 
 //

llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

 
 /// createAArch64ISelDag - This pass converts a legalized DAG into a
 /// AArch64-specific DAG, ready for instruction scheduling.
 FunctionPass *llvm::createAArch64ISelDag(AArch64TargetMachine &TM,
                                          CodeGenOpt::Level OptLevel) {
   return new AArch64DAGToDAGISel(TM, OptLevel);
 }
 
+namespace {
+/// When \p PredVT is a scalable vector predicate in the form
+/// MVT::nx<M>xi1, it builds the correspondent scalable vector of
+/// integers MVT::nx<M>xi<bits> s.t. M x bits = 128. If the input
+/// PredVT is not in the form MVT::nx<M>xi1, it returns an invalid
+/// EVT.
+EVT getPackedVectorTypeFromPredicateType(LLVMContext &Ctx, EVT PredVT) {
+  if (!PredVT.isScalableVector())
+    return EVT();
+
+  if (PredVT.getVectorElementType() != MVT::i1)
+    return EVT();
+
+  const unsigned NumElts = PredVT.getVectorNumElements();
+
+  if (NumElts != 2 && NumElts != 4 && NumElts != 8 && NumElts != 16)
+    return EVT();
+
+  EVT ScalarVT = EVT::getIntegerVT(Ctx, 128 / NumElts);
+  EVT MemVT = EVT::getVectorVT(Ctx, ScalarVT, NumElts, /*IsScalable=*/true);
+  return MemVT;
+}
+
+/// Return the EVT of the data associated to a memory operation in \p
+/// Root. If such EVT cannot be retrived, it returns an invalid EVT.
+EVT getMemVTFromNode(LLVMContext &Ctx, SDNode *Root) {
+  if (isa<MemSDNode>(Root))
+    return cast<MemSDNode>(Root)->getMemoryVT();
+
+  const unsigned Opcode = Root->getOpcode();
+  if (Opcode != ISD::INTRINSIC_VOID)
+    return EVT();
+
+  const unsigned IntNo =
+      cast<ConstantSDNode>(Root->getOperand(1))->getZExtValue();
+  if (IntNo != Intrinsic::aarch64_sve_prf)
+    return EVT();
+
+  // We are using an SVE prefetch intrinsic. Type must be inferred
+  // from the width of the predicate.
+  return getPackedVectorTypeFromPredicateType(
+      Ctx, Root->getOperand(2)->getValueType(0));
+}
+} // end anonymous namespace
+
 /// SelectAddrModeIndexedSVE - Attempt selection of the addressing mode:
 /// Base + OffImm * sizeof(MemVT) for Min >= OffImm <= Max
 /// where Root is the memory access using N for its address.
 template <int64_t Min, int64_t Max>
 bool AArch64DAGToDAGISel::SelectAddrModeIndexedSVE(SDNode *Root, SDValue N,
                                                    SDValue &Base,
                                                    SDValue &OffImm) {
-  assert(isa<MemSDNode>(Root) && "Invalid node.");
+  const EVT MemVT = getMemVTFromNode(*(CurDAG->getContext()), Root);
 
-  EVT MemVT = cast<MemSDNode>(Root)->getMemoryVT();
+  if (MemVT == EVT())
+    return false;
 
   if (N.getOpcode() != ISD::ADD)
     return false;
 
   SDValue VScale = N.getOperand(1);
   if (VScale.getOpcode() != ISD::VSCALE)
     return false;
 

llvm/lib/Target/AArch64/AArch64SVEInstrInfo.td

let Predicates = [HasSVE] in {
   defm PRFD_PRI : sve_mem_prfm_si<0b11, "prfd">;
 
   // Contiguous prefetch (register + register)
   def PRFB_PRR : sve_mem_prfm_ss<0b001, "prfb", GPR64NoXZRshifted8>;
   def PRFH_PRR : sve_mem_prfm_ss<0b011, "prfh", GPR64NoXZRshifted16>;
   def PRFS_PRR : sve_mem_prfm_ss<0b101, "prfw", GPR64NoXZRshifted32>;
   def PRFD_PRR : sve_mem_prfm_ss<0b111, "prfd", GPR64NoXZRshifted64>;
 
+multiclass sve_prefetch<SDPatternOperator prefetch, ValueType PredTy, Instruction RegImmInst, Instruction RegRegInst, int scale, ComplexPattern AddrCP> {
+    // reg + imm
+    let AddedComplexity = 2 in {
+      def _reg_imm : Pat<(prefetch (PredTy PPR_3b:$gp), (am_sve_indexed_s6 GPR64sp:$base, simm6s1:$offset), (i32 sve_prfop:$prfop)),
+                         (RegImmInst sve_prfop:$prfop, PPR_3b:$gp, GPR64:$base, simm6s1:$offset)>;
+    }
+
+    // reg + reg
+    let AddedComplexity = 1 in {
+      def _reg_reg : Pat<(prefetch (PredTy PPR_3b:$gp), (AddrCP GPR64sp:$base, GPR64:$index), (i32 sve_prfop:$prfop)),
+                         (RegRegInst sve_prfop:$prfop, PPR_3b:$gp, GPR64:$base, GPR64:$index)>;
+    }
+
+    // default fallback
+    def _default : Pat<(prefetch  (PredTy PPR_3b:$gp), GPR64:$base, (i32 sve_prfop:$prfop)),
+                       (RegImmInst sve_prfop:$prfop, PPR_3b:$gp, GPR64:$base, (i64 0))>;
+  }
+
+  defm : sve_prefetch<int_aarch64_sve_prf, nxv16i1, PRFB_PRI, PRFB_PRR, 0, am_sve_regreg_lsl0>;
+  defm : sve_prefetch<int_aarch64_sve_prf, nxv8i1,  PRFH_PRI, PRFH_PRR, 1, am_sve_regreg_lsl1>;
+  defm : sve_prefetch<int_aarch64_sve_prf, nxv4i1,  PRFW_PRI, PRFS_PRR, 2, am_sve_regreg_lsl2>;
+  defm : sve_prefetch<int_aarch64_sve_prf, nxv2i1,  PRFD_PRI, PRFD_PRR, 3, am_sve_regreg_lsl3>;
+
   // Gather prefetch using scaled 32-bit offsets, e.g.
   //    prfh pldl1keep, p0, [x0, z0.s, uxtw #1]
   defm PRFB_S : sve_mem_32b_prfm_sv_scaled<0b00, "prfb", ZPR32ExtSXTW8Only,  ZPR32ExtUXTW8Only>;
   defm PRFH_S : sve_mem_32b_prfm_sv_scaled<0b01, "prfh", ZPR32ExtSXTW16, ZPR32ExtUXTW16>;
   defm PRFW_S : sve_mem_32b_prfm_sv_scaled<0b10, "prfw", ZPR32ExtSXTW32, ZPR32ExtUXTW32>;
   defm PRFD_S : sve_mem_32b_prfm_sv_scaled<0b11, "prfd", ZPR32ExtSXTW64, ZPR32ExtUXTW64>;
 
   // Gather prefetch using unpacked, scaled 32-bit offsets, e.g.

llvm/lib/Target/AArch64/SVEInstrFormats.td

 
 multiclass sve_mem_64b_prfm_vi<bits<2> msz, string asm, Operand imm_ty> {
   def NAME : sve_mem_64b_prfm_vi<msz, asm, imm_ty>;
 
   def : InstAlias<asm # "\t$prfop, $Pg, [$Zn]",
                   (!cast<Instruction>(NAME) sve_prfop:$prfop, PPR3bAny:$Pg, ZPR64:$Zn, 0), 1>;
 }
 
-
 //===----------------------------------------------------------------------===//
 // SVE Compute Vector Address Group
 //===----------------------------------------------------------------------===//
 
 class sve_int_bin_cons_misc_0_a<bits<2> opc, bits<2> msz, string asm,
                                 ZPRRegOp zprty, RegisterOperand zprext>
 : I<(outs zprty:$Zd), (ins zprty:$Zn, zprext:$Zm),
   asm, "\t$Zd, [$Zn, $Zm]",
: I<(outs ZPR8:$Zdn), (ins ZPR8:$_Zdn),
   let Inst{9-5}   = 0b00000;
   let Inst{4-0}   = Zdn;
 
   let Constraints = "$Zdn = $_Zdn";
 }
 
 /// Addressing modes
 def am_sve_indexed_s4 :ComplexPattern<i64, 2, "SelectAddrModeIndexedSVE<-8,7>", [], [SDNPWantRoot]>;
+def am_sve_indexed_s6 :ComplexPattern<i64, 2, "SelectAddrModeIndexedSVE<-32,31>", [], [SDNPWantRoot]>;
 
 def am_sve_regreg_lsl0 : ComplexPattern<i64, 2, "SelectSVERegRegAddrMode<0>", []>;
 def am_sve_regreg_lsl1 : ComplexPattern<i64, 2, "SelectSVERegRegAddrMode<1>", []>;
 def am_sve_regreg_lsl2 : ComplexPattern<i64, 2, "SelectSVERegRegAddrMode<2>", []>;
 def am_sve_regreg_lsl3 : ComplexPattern<i64, 2, "SelectSVERegRegAddrMode<3>", []>;

llvm/test/CodeGen/AArch64/sve-intrinsics-contiguous-prefetches.ll

+; RUN: llc -mtriple=aarch64-linux-gnu -mattr=+sve < %s | FileCheck %s
+
+;
+; Testing prfop encodings
+;
+define void @test_svprf_pldl1strm(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pldl1strm
+; CHECK: prfb pldl1strm, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 1)
+  ret void
+}
+
+define void @test_svprf_pldl2keep(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pldl2keep
+; CHECK: prfb pldl2keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 2)
+  ret void
+}
+
+define void @test_svprf_pldl2strm(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pldl2strm
+; CHECK: prfb pldl2strm, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 3)
+  ret void
+}
+
+define void @test_svprf_pldl3keep(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pldl3keep
+; CHECK: prfb pldl3keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 4)
+  ret void
+}
+
+define void @test_svprf_pldl3strm(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pldl3strm
+; CHECK: prfb pldl3strm, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 5)
+  ret void
+}
+
+define void @test_svprf_pstl1keep(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pstl1keep
+; CHECK: prfb pstl1keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 8)
+  ret void
+}
+
+define void @test_svprf_pstl1strm(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pstl1strm
+; CHECK: prfb pstl1strm, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 9)
+  ret void
+}
+
+define void @test_svprf_pstl2keep(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pstl2keep
+; CHECK: prfb pstl2keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 10)
+  ret void
+}
+
+define void @test_svprf_pstl2strm(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pstl2strm
+; CHECK: prfb pstl2strm, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 11)
+  ret void
+}
+
+define void @test_svprf_pstl3keep(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pstl3keep
+; CHECK: prfb pstl3keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 12)
+  ret void
+}
+
+define void @test_svprf_pstl3strm(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprf_pstl3strm
+; CHECK: prfb pstl3strm, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 13)
+  ret void
+}
+
+;
+; Testing imm limits of SI form
+;
+
+define void @test_svprf_vnum_under(<vscale x 16 x i1> %pg, <vscale x 16 x i8>* %base) {
+; CHECK-LABEL: test_svprf_vnum_under
+; CHECK-NOT: prfb pstl3strm, p0, [x0, #-33, mul vl]
+entry:
+  %gep = getelementptr inbounds <vscale x 16 x i8>, <vscale x 16 x i8>* %base, i64 -33, i64 0
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %gep, i32 13)
+  ret void
+}
+
+define void @test_svprf_vnum_min(<vscale x 16 x i1> %pg, <vscale x 16 x i8>* %base) {
+; CHECK-LABEL: test_svprf_vnum_min
+; CHECK: prfb pstl3strm, p0, [x0, #-32, mul vl]
+entry:
+  %gep = getelementptr inbounds <vscale x 16 x i8>, <vscale x 16 x i8>* %base, i64 -32, i64 0
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %gep, i32 13)
+  ret void
+}
+
+define void @test_svprf_vnum_over(<vscale x 16 x i1> %pg, <vscale x 16 x i8>* %base) {
+; CHECK-LABEL: test_svprf_vnum_over
+; CHECK-NOT: prfb pstl3strm, p0, [x0, #32, mul vl]
+entry:
+  %gep = getelementptr inbounds <vscale x 16 x i8>, <vscale x 16 x i8>* %base, i64 32, i64 0
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %gep, i32 13)
+  ret void
+}
+
+define void @test_svprf_vnum_max(<vscale x 16 x i1> %pg, <vscale x 16 x i8>* %base) {
+; CHECK-LABEL: test_svprf_vnum_max
+; CHECK: prfb pstl3strm, p0, [x0, #31, mul vl]
+entry:
+  %gep = getelementptr inbounds <vscale x 16 x i8>, <vscale x 16 x i8>* %base, i64 31, i64 0
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %gep, i32 13)
+  ret void
+}
+
+;
+; scalar contiguous
+;
+
+define void @test_svprfb(<vscale x 16 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprfb
+; CHECK: prfb pldl1keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %base, i32 0)
+  ret void
+}
+
+define void @test_svprfh(<vscale x 8 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprfh
+; CHECK: prfh pldl1keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv8i1(<vscale x 8 x i1> %pg, i8* %base, i32 0)
+  ret void
+}
+
+define void @test_svprfw(<vscale x 4 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprfw
+; CHECK: prfw pldl1keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv4i1(<vscale x 4 x i1> %pg, i8* %base, i32 0)
+  ret void
+}
+
+define void @test_svprfd(<vscale x 2 x i1> %pg, i8* %base) {
+; CHECK-LABEL: test_svprfd
+; CHECK: prfd pldl1keep, p0, [x0]
+entry:
+  tail call void @llvm.aarch64.sve.prf.nxv2i1(<vscale x 2 x i1> %pg, i8* %base, i32 0)
+  ret void
+}
+
+;
+; scalar + imm contiguous
+;
+; imm form of prfb is tested above
+
+define void @test_svprfh_vnum(<vscale x 8 x i1> %pg, <vscale x 8 x i16>* %base) {
+; CHECK-LABEL: test_svprfh_vnum
+; CHECK: prfh pstl3strm, p0, [x0, #31, mul vl]
+entry:
+  %gep = getelementptr <vscale x 8 x i16>, <vscale x 8 x i16>* %base, i64 31
+  %addr = bitcast <vscale x 8 x i16>* %gep to i8*
+  tail call void @llvm.aarch64.sve.prf.nxv8i1(<vscale x 8 x i1> %pg, i8* %addr, i32 13)
+  ret void
+}
+
+define void @test_svprfw_vnum(<vscale x 4 x i1> %pg, <vscale x 4 x i32>* %base) {
+; CHECK-LABEL: test_svprfw_vnum
+; CHECK: prfw pstl3strm, p0, [x0, #31, mul vl]
+entry:
+  %gep = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* %base, i64 31
+  %addr = bitcast <vscale x 4 x i32>* %gep to i8*
+  tail call void @llvm.aarch64.sve.prf.nxv4i1(<vscale x 4 x i1> %pg, i8* %addr, i32 13)
+  ret void
+}
+
+define void @test_svprfd_vnum(<vscale x 2 x i1> %pg, <vscale x 2 x i64>* %base) {
+; CHECK-LABEL: test_svprfd_vnum
+; CHECK: prfd pstl3strm, p0, [x0, #31, mul vl]
+entry:
+  %gep = getelementptr <vscale x 2 x i64>, <vscale x 2 x i64>* %base, i64 31
+  %addr = bitcast <vscale x 2 x i64>* %gep to i8*
+  tail call void @llvm.aarch64.sve.prf.nxv2i1(<vscale x 2 x i1> %pg, i8* %addr, i32 13)
+  ret void
+}
+
+;
+; scalar + scaled scalar contiguous
+;
+
+define void @test_svprfb_ss(<vscale x 16 x i1> %pg, i8* %base, i64 %offset) {
+; CHECK-LABEL: test_svprfb_ss
+; CHECK: prfb pstl3strm, p0, [x0, x1]
+entry:
+  %addr = getelementptr i8, i8* %base, i64 %offset
+  tail call void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1> %pg, i8* %addr, i32 13)
+  ret void
+}
+
+define void @test_svprfh_ss(<vscale x 8 x i1> %pg, i16* %base, i64 %offset) {
+; CHECK-LABEL: test_svprfh_ss
+; CHECK: prfh pstl3strm, p0, [x0, x1, lsl #1]
+entry:
+  %gep = getelementptr i16, i16* %base, i64 %offset
+  %addr = bitcast i16* %gep to i8*
+  tail call void @llvm.aarch64.sve.prf.nxv8i1(<vscale x 8 x i1> %pg, i8* %addr, i32 13)
+  ret void
+}
+
+define void @test_svprfw_ss(<vscale x 4 x i1> %pg, i32* %base, i64 %offset) {
+; CHECK-LABEL: test_svprfw_ss
+; CHECK: prfw pstl3strm, p0, [x0, x1, lsl #2]
+entry:
+  %gep = getelementptr i32, i32* %base, i64 %offset
+  %addr = bitcast i32* %gep to i8*
+  tail call void @llvm.aarch64.sve.prf.nxv4i1(<vscale x 4 x i1> %pg, i8* %addr, i32 13)
+  ret void
+}
+
+define void @test_svprfd_ss(<vscale x 2 x i1> %pg, i64* %base, i64 %offset) {
+; CHECK-LABEL: test_svprfd_ss
+; CHECK: prfd pstl3strm, p0, [x0, x1, lsl #3]
+entry:
+  %gep = getelementptr i64, i64* %base, i64 %offset
+  %addr = bitcast i64* %gep to i8*
+  tail call void @llvm.aarch64.sve.prf.nxv2i1(<vscale x 2 x i1> %pg, i8* %addr, i32 13)
+  ret void
+}
+
+
+declare void @llvm.aarch64.sve.prf.nxv16i1(<vscale x 16 x i1>, i8*, i32)
+declare void @llvm.aarch64.sve.prf.nxv8i1(<vscale x 8 x i1>,  i8*, i32)
+declare void @llvm.aarch64.sve.prf.nxv4i1(<vscale x 4 x i1>,  i8*, i32)
+declare void @llvm.aarch64.sve.prf.nxv2i1(<vscale x 2 x i1>,  i8*, i32)