ARM: Fix cttz expansion on vector types.

[logan]

Summary

The 64/128-bit vector types will be treated as legal type when NEON is
enabled, but there was no matching pattern for @llvm.cttz.*()
intrinsics. This commit fix the problem by lowering cttz to ctpop or
ctlz.

[rengolin]

Hi Logan,

The patch looks good, though I was expecting the vector test to be checking instructions as well.

cheers,
--renato

[logan]

Add test cases for 64/128-bit vector types.

[rengolin]

Hi Logan, looks good, thanks!

The cases where you didn't add CHECKs, was it because it didn't use vector instructions? I think it should be fine to check for scalar instructions, like the others, at least to check that the instructions you were expecting got lowered.

Otherwise, LGTM. Thanks!

[logan]

Hi Renato,

I have added the test cases for 64/128-bit vector types. For the other cases I am leaving them unchanged because they are automatically expanded by the code generator and irrelevant to this change. Please have a look again. Thanks.

Logan

[rengolin]

Ok, no problems.

[logan]

Hi Renato,

Thanks for your review. I have committed this as rL242037.

Regarding to your comments on the check lines (for automatically expanded cases), I will try to address them in the different change after I have figured out the pattern for automatic expansion.

Logan

[rengolin]

Perfect, thanks!

lib/Target/ARM/ARMISelLowering.cpp

if (Subtarget->hasNEON()) {
     // NEON does not have single instruction CTPOP for vectors with element
     // types wider than 8-bits.  However, custom lowering can leverage the
     // v8i8/v16i8 vcnt instruction.
     setOperationAction(ISD::CTPOP,      MVT::v2i32, Custom);
     setOperationAction(ISD::CTPOP,      MVT::v4i32, Custom);
     setOperationAction(ISD::CTPOP,      MVT::v4i16, Custom);
     setOperationAction(ISD::CTPOP,      MVT::v8i16, Custom);
 
+    // NEON does not have single instruction CTTZ for vectors.
+    setOperationAction(ISD::CTTZ, MVT::v8i8, Custom);
+    setOperationAction(ISD::CTTZ, MVT::v4i16, Custom);
+    setOperationAction(ISD::CTTZ, MVT::v2i32, Custom);
+    setOperationAction(ISD::CTTZ, MVT::v1i64, Custom);
+
+    setOperationAction(ISD::CTTZ, MVT::v16i8, Custom);
+    setOperationAction(ISD::CTTZ, MVT::v8i16, Custom);
+    setOperationAction(ISD::CTTZ, MVT::v4i32, Custom);
+    setOperationAction(ISD::CTTZ, MVT::v2i64, Custom);
+
+    setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::v8i8, Custom);
+    setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::v4i16, Custom);
+    setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::v2i32, Custom);
+    setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::v1i64, Custom);
+
+    setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::v16i8, Custom);
+    setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::v8i16, Custom);
+    setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::v4i32, Custom);
+    setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::v2i64, Custom);
+
     // NEON only has FMA instructions as of VFP4.
     if (!Subtarget->hasVFP4()) {
       setOperationAction(ISD::FMA, MVT::v2f32, Expand);
       setOperationAction(ISD::FMA, MVT::v4f32, Expand);
     }
 
     setTargetDAGCombine(ISD::INTRINSIC_VOID);
     setTargetDAGCombine(ISD::INTRINSIC_W_CHAIN);
SDValue ARMTargetLowering::LowerFLT_ROUNDS_(SDValue Op,
   SDValue RMODE = DAG.getNode(ISD::SRL, dl, MVT::i32, FltRounds,
                               DAG.getConstant(22, dl, MVT::i32));
   return DAG.getNode(ISD::AND, dl, MVT::i32, RMODE,
                      DAG.getConstant(3, dl, MVT::i32));
 }
 
 static SDValue LowerCTTZ(SDNode *N, SelectionDAG &DAG,
                          const ARMSubtarget *ST) {
-  EVT VT = N->getValueType(0);
   SDLoc dl(N);
+  EVT VT = N->getValueType(0);
+  if (VT.isVector()) {
+    assert(ST->hasNEON());
+
+    // Compute the least significant set bit: LSB = X & -X
+    SDValue X = N->getOperand(0);
+    SDValue NX = DAG.getNode(ISD::SUB, dl, VT, getZeroVector(VT, DAG, dl), X);
+    SDValue LSB = DAG.getNode(ISD::AND, dl, VT, X, NX);
+
+    EVT ElemTy = VT.getVectorElementType();
+
+    if (ElemTy == MVT::i8) {
+      // Compute with: cttz(x) = ctpop(lsb - 1)
+      SDValue One = DAG.getNode(ARMISD::VMOVIMM, dl, VT,
+                                DAG.getTargetConstant(1, dl, ElemTy));
+      SDValue Bits = DAG.getNode(ISD::SUB, dl, VT, LSB, One);
+      return DAG.getNode(ISD::CTPOP, dl, VT, Bits);
+    }
+
+    if ((ElemTy == MVT::i16 || ElemTy == MVT::i32) &&
+        (N->getOpcode() == ISD::CTTZ_ZERO_UNDEF)) {
+      // Compute with: cttz(x) = (width - 1) - ctlz(lsb), if x != 0
+      unsigned NumBits = ElemTy.getSizeInBits();
+      SDValue WidthMinus1 =
+          DAG.getNode(ARMISD::VMOVIMM, dl, VT,
+                      DAG.getTargetConstant(NumBits - 1, dl, ElemTy));
+      SDValue CTLZ = DAG.getNode(ISD::CTLZ, dl, VT, LSB);
+      return DAG.getNode(ISD::SUB, dl, VT, WidthMinus1, CTLZ);
+    }
+
+    // Compute with: cttz(x) = ctpop(lsb - 1)
+
+    // Since we can only compute the number of bits in a byte with vcnt.8, we
+    // have to gather the result with pairwise addition (vpaddl) for i16, i32,
+    // and i64.
+
+    // Compute LSB - 1.
+    SDValue Bits;
+    if (ElemTy == MVT::i64) {
+      // Load constant 0xffff'ffff'ffff'ffff to register.
+      SDValue FF = DAG.getNode(ARMISD::VMOVIMM, dl, VT,
+                               DAG.getTargetConstant(0x1eff, dl, MVT::i32));
+      Bits = DAG.getNode(ISD::ADD, dl, VT, LSB, FF);
+    } else {
+      SDValue One = DAG.getNode(ARMISD::VMOVIMM, dl, VT,
+                                DAG.getTargetConstant(1, dl, ElemTy));
+      Bits = DAG.getNode(ISD::SUB, dl, VT, LSB, One);
+    }
+
+    // Count #bits with vcnt.8.
+    EVT VT8Bit = VT.is64BitVector() ? MVT::v8i8 : MVT::v16i8;
+    SDValue BitsVT8 = DAG.getNode(ISD::BITCAST, dl, VT8Bit, Bits);
+    SDValue Cnt8 = DAG.getNode(ISD::CTPOP, dl, VT8Bit, BitsVT8);
+
+    // Gather the #bits with vpaddl (pairwise add.)
+    EVT VT16Bit = VT.is64BitVector() ? MVT::v4i16 : MVT::v8i16;
+    SDValue Cnt16 = DAG.getNode(ISD::INTRINSIC_WO_CHAIN, dl, VT16Bit,
+        DAG.getTargetConstant(Intrinsic::arm_neon_vpaddlu, dl, MVT::i32),
+        Cnt8);
+    if (ElemTy == MVT::i16)
+      return Cnt16;
+
+    EVT VT32Bit = VT.is64BitVector() ? MVT::v2i32 : MVT::v4i32;
+    SDValue Cnt32 = DAG.getNode(ISD::INTRINSIC_WO_CHAIN, dl, VT32Bit,
+        DAG.getTargetConstant(Intrinsic::arm_neon_vpaddlu, dl, MVT::i32),
+        Cnt16);
+    if (ElemTy == MVT::i32)
+      return Cnt32;
+
+    assert(ElemTy == MVT::i64);
+    SDValue Cnt64 = DAG.getNode(ISD::INTRINSIC_WO_CHAIN, dl, VT,
+        DAG.getTargetConstant(Intrinsic::arm_neon_vpaddlu, dl, MVT::i32),
+        Cnt32);
+    return Cnt64;
+  }
 
   if (!ST->hasV6T2Ops())
     return SDValue();
 
   SDValue rbit = DAG.getNode(ARMISD::RBIT, dl, VT, N->getOperand(0));
   return DAG.getNode(ISD::CTLZ, dl, VT, rbit);
 }
 
case ISD::INTRINSIC_WO_CHAIN: return LowerINTRINSIC_WO_CHAIN(Op, DAG,
                                                                Subtarget);
   case ISD::BITCAST:       return ExpandBITCAST(Op.getNode(), DAG);
   case ISD::SHL:
   case ISD::SRL:
   case ISD::SRA:           return LowerShift(Op.getNode(), DAG, Subtarget);
   case ISD::SHL_PARTS:     return LowerShiftLeftParts(Op, DAG);
   case ISD::SRL_PARTS:
   case ISD::SRA_PARTS:     return LowerShiftRightParts(Op, DAG);
-  case ISD::CTTZ:          return LowerCTTZ(Op.getNode(), DAG, Subtarget);
+  case ISD::CTTZ:
+  case ISD::CTTZ_ZERO_UNDEF: return LowerCTTZ(Op.getNode(), DAG, Subtarget);
   case ISD::CTPOP:         return LowerCTPOP(Op.getNode(), DAG, Subtarget);
   case ISD::SETCC:         return LowerVSETCC(Op, DAG);
   case ISD::ConstantFP:    return LowerConstantFP(Op, DAG, Subtarget);
   case ISD::BUILD_VECTOR:  return LowerBUILD_VECTOR(Op, DAG, Subtarget);
   case ISD::VECTOR_SHUFFLE: return LowerVECTOR_SHUFFLE(Op, DAG);
   case ISD::INSERT_VECTOR_ELT: return LowerINSERT_VECTOR_ELT(Op, DAG);
   case ISD::EXTRACT_VECTOR_ELT: return LowerEXTRACT_VECTOR_ELT(Op, DAG);
   case ISD::CONCAT_VECTORS: return LowerCONCAT_VECTORS(Op, DAG);

test/CodeGen/ARM/cttz.ll

+; RUN: llc < %s -mtriple arm-eabi -mattr=+v6t2 | FileCheck %s
+; RUN: llc < %s -mtriple arm-eabi -mattr=+v6t2 -mattr=+neon | FileCheck %s
+
+; This test checks the @llvm.cttz.* intrinsics for integers.
+
+declare i8 @llvm.cttz.i8(i8, i1)
+declare i16 @llvm.cttz.i16(i16, i1)
+declare i32 @llvm.cttz.i32(i32, i1)
+declare i64 @llvm.cttz.i64(i64, i1)
+
+;------------------------------------------------------------------------------
+
+define i8 @test_i8(i8 %a) {
+; CHECK-LABEL: test_i8:
+; CHECK: orr [[REG:r[0-9]+]], [[REG]], #256
+; CHECK: rbit
+; CHECK: clz
+  %tmp = call i8 @llvm.cttz.i8(i8 %a, i1 false)
+  ret i8 %tmp
+}
+
+define i16 @test_i16(i16 %a) {
+; CHECK-LABEL: test_i16:
+; CHECK: orr [[REG:r[0-9]+]], [[REG]], #65536
+; CHECK: rbit
+; CHECK: clz
+  %tmp = call i16 @llvm.cttz.i16(i16 %a, i1 false)
+  ret i16 %tmp
+}
+
+define i32 @test_i32(i32 %a) {
+; CHECK-LABEL: test_i32:
+; CHECK: rbit
+; CHECK: clz
+  %tmp = call i32 @llvm.cttz.i32(i32 %a, i1 false)
+  ret i32 %tmp
+}
+
+define i64 @test_i64(i64 %a) {
+; CHECK-LABEL: test_i64:
+; CHECK: rbit
+; CHECK: rbit
+; CHECK: cmp
+; CHECK: clz
+; CHECK: add
+; CHECK: clzne
+  %tmp = call i64 @llvm.cttz.i64(i64 %a, i1 false)
+  ret i64 %tmp
+}
+
+;------------------------------------------------------------------------------
+
+define i8 @test_i8_zero_undef(i8 %a) {
+; CHECK-LABEL: test_i8_zero_undef:
+; CHECK-NOT: orr
+; CHECK: rbit
+; CHECK: clz
+  %tmp = call i8 @llvm.cttz.i8(i8 %a, i1 true)
+  ret i8 %tmp
+}
+
+define i16 @test_i16_zero_undef(i16 %a) {
+; CHECK-LABEL: test_i16_zero_undef:
+; CHECK-NOT: orr
+; CHECK: rbit
+; CHECK: clz
+  %tmp = call i16 @llvm.cttz.i16(i16 %a, i1 true)
+  ret i16 %tmp
+}
+
+
+define i32 @test_i32_zero_undef(i32 %a) {
+; CHECK-LABEL: test_i32_zero_undef:
+; CHECK: rbit
+; CHECK: clz
+  %tmp = call i32 @llvm.cttz.i32(i32 %a, i1 true)
+  ret i32 %tmp
+}
+
+define i64 @test_i64_zero_undef(i64 %a) {
+; CHECK-LABEL: test_i64_zero_undef:
+; CHECK: rbit
+; CHECK: rbit
+; CHECK: cmp
+; CHECK: clz
+; CHECK: add
+; CHECK: clzne
+  %tmp = call i64 @llvm.cttz.i64(i64 %a, i1 true)
+  ret i64 %tmp
+}

test/CodeGen/ARM/cttz_vector.ll

+; RUN: llc < %s -mtriple armv7-linux-gnueabihf -mattr=+neon | FileCheck %s
+
+; This test checks the @llvm.cttz.* intrinsics for vectors.
+
+declare <1 x i8> @llvm.cttz.v1i8(<1 x i8>, i1)
+declare <2 x i8> @llvm.cttz.v2i8(<2 x i8>, i1)
+declare <4 x i8> @llvm.cttz.v4i8(<4 x i8>, i1)
+declare <8 x i8> @llvm.cttz.v8i8(<8 x i8>, i1)
+declare <16 x i8> @llvm.cttz.v16i8(<16 x i8>, i1)
+
+declare <1 x i16> @llvm.cttz.v1i16(<1 x i16>, i1)
+declare <2 x i16> @llvm.cttz.v2i16(<2 x i16>, i1)
+declare <4 x i16> @llvm.cttz.v4i16(<4 x i16>, i1)
+declare <8 x i16> @llvm.cttz.v8i16(<8 x i16>, i1)
+
+declare <1 x i32> @llvm.cttz.v1i32(<1 x i32>, i1)
+declare <2 x i32> @llvm.cttz.v2i32(<2 x i32>, i1)
+declare <4 x i32> @llvm.cttz.v4i32(<4 x i32>, i1)
+
+declare <1 x i64> @llvm.cttz.v1i64(<1 x i64>, i1)
+declare <2 x i64> @llvm.cttz.v2i64(<2 x i64>, i1)
+
+;------------------------------------------------------------------------------
+
+define void @test_v1i8(<1 x i8>* %p) {
+; CHECK-LABEL: test_v1i8
+  %a = load <1 x i8>, <1 x i8>* %p
+  %tmp = call <1 x i8> @llvm.cttz.v1i8(<1 x i8> %a, i1 false)
+  store <1 x i8> %tmp, <1 x i8>* %p
+  ret void
+}
+
+define void @test_v2i8(<2 x i8>* %p) {
+; CHECK-LABEL: test_v2i8:
+  %a = load <2 x i8>, <2 x i8>* %p
+  %tmp = call <2 x i8> @llvm.cttz.v2i8(<2 x i8> %a, i1 false)
+  store <2 x i8> %tmp, <2 x i8>* %p
+  ret void
+}
+
+define void @test_v4i8(<4 x i8>* %p) {
+; CHECK-LABEL: test_v4i8:
+  %a = load <4 x i8>, <4 x i8>* %p
+  %tmp = call <4 x i8> @llvm.cttz.v4i8(<4 x i8> %a, i1 false)
+  store <4 x i8> %tmp, <4 x i8>* %p
+  ret void
+}
+
+define void @test_v8i8(<8 x i8>* %p) {
+; CHECK-LABEL: test_v8i8:
+  %a = load <8 x i8>, <8 x i8>* %p
+  %tmp = call <8 x i8> @llvm.cttz.v8i8(<8 x i8> %a, i1 false)
+  store <8 x i8> %tmp, <8 x i8>* %p
+  ret void
+}
+
+define void @test_v16i8(<16 x i8>* %p) {
+; CHECK-LABEL: test_v16i8:
+  %a = load <16 x i8>, <16 x i8>* %p
+  %tmp = call <16 x i8> @llvm.cttz.v16i8(<16 x i8> %a, i1 false)
+  store <16 x i8> %tmp, <16 x i8>* %p
+  ret void
+}
+
+define void @test_v1i16(<1 x i16>* %p) {
+; CHECK-LABEL: test_v1i16:
+  %a = load <1 x i16>, <1 x i16>* %p
+  %tmp = call <1 x i16> @llvm.cttz.v1i16(<1 x i16> %a, i1 false)
+  store <1 x i16> %tmp, <1 x i16>* %p
+  ret void
+}
+
+define void @test_v2i16(<2 x i16>* %p) {
+; CHECK-LABEL: test_v2i16:
+  %a = load <2 x i16>, <2 x i16>* %p
+  %tmp = call <2 x i16> @llvm.cttz.v2i16(<2 x i16> %a, i1 false)
+  store <2 x i16> %tmp, <2 x i16>* %p
+  ret void
+}
+
+define void @test_v4i16(<4 x i16>* %p) {
+; CHECK-LABEL: test_v4i16:
+  %a = load <4 x i16>, <4 x i16>* %p
+  %tmp = call <4 x i16> @llvm.cttz.v4i16(<4 x i16> %a, i1 false)
+  store <4 x i16> %tmp, <4 x i16>* %p
+  ret void
+}
+
+define void @test_v8i16(<8 x i16>* %p) {
+; CHECK-LABEL: test_v8i16:
+  %a = load <8 x i16>, <8 x i16>* %p
+  %tmp = call <8 x i16> @llvm.cttz.v8i16(<8 x i16> %a, i1 false)
+  store <8 x i16> %tmp, <8 x i16>* %p
+  ret void
+}
+
+define void @test_v1i32(<1 x i32>* %p) {
+; CHECK-LABEL: test_v1i32:
+  %a = load <1 x i32>, <1 x i32>* %p
+  %tmp = call <1 x i32> @llvm.cttz.v1i32(<1 x i32> %a, i1 false)
+  store <1 x i32> %tmp, <1 x i32>* %p
+  ret void
+}
+
+define void @test_v2i32(<2 x i32>* %p) {
+; CHECK-LABEL: test_v2i32:
+  %a = load <2 x i32>, <2 x i32>* %p
+  %tmp = call <2 x i32> @llvm.cttz.v2i32(<2 x i32> %a, i1 false)
+  store <2 x i32> %tmp, <2 x i32>* %p
+  ret void
+}
+
+define void @test_v4i32(<4 x i32>* %p) {
+; CHECK-LABEL: test_v4i32:
+  %a = load <4 x i32>, <4 x i32>* %p
+  %tmp = call <4 x i32> @llvm.cttz.v4i32(<4 x i32> %a, i1 false)
+  store <4 x i32> %tmp, <4 x i32>* %p
+  ret void
+}
+
+define void @test_v1i64(<1 x i64>* %p) {
+; CHECK-LABEL: test_v1i64:
+  %a = load <1 x i64>, <1 x i64>* %p
+  %tmp = call <1 x i64> @llvm.cttz.v1i64(<1 x i64> %a, i1 false)
+  store <1 x i64> %tmp, <1 x i64>* %p
+  ret void
+}
+
+define void @test_v2i64(<2 x i64>* %p) {
+; CHECK-LABEL: test_v2i64:
+  %a = load <2 x i64>, <2 x i64>* %p
+  %tmp = call <2 x i64> @llvm.cttz.v2i64(<2 x i64> %a, i1 false)
+  store <2 x i64> %tmp, <2 x i64>* %p
+  ret void
+}
+
+;------------------------------------------------------------------------------
+
+define void @test_v1i8_zero_undef(<1 x i8>* %p) {
+; CHECK-LABEL: test_v1i8_zero_undef
+  %a = load <1 x i8>, <1 x i8>* %p
+  %tmp = call <1 x i8> @llvm.cttz.v1i8(<1 x i8> %a, i1 true)
+  store <1 x i8> %tmp, <1 x i8>* %p
+  ret void
+}
+
+define void @test_v2i8_zero_undef(<2 x i8>* %p) {
+; CHECK-LABEL: test_v2i8_zero_undef:
+  %a = load <2 x i8>, <2 x i8>* %p
+  %tmp = call <2 x i8> @llvm.cttz.v2i8(<2 x i8> %a, i1 true)
+  store <2 x i8> %tmp, <2 x i8>* %p
+  ret void
+}
+
+define void @test_v4i8_zero_undef(<4 x i8>* %p) {
+; CHECK-LABEL: test_v4i8_zero_undef:
+  %a = load <4 x i8>, <4 x i8>* %p
+  %tmp = call <4 x i8> @llvm.cttz.v4i8(<4 x i8> %a, i1 true)
+  store <4 x i8> %tmp, <4 x i8>* %p
+  ret void
+}
+
+define void @test_v8i8_zero_undef(<8 x i8>* %p) {
+; CHECK-LABEL: test_v8i8_zero_undef:
+  %a = load <8 x i8>, <8 x i8>* %p
+  %tmp = call <8 x i8> @llvm.cttz.v8i8(<8 x i8> %a, i1 true)
+  store <8 x i8> %tmp, <8 x i8>* %p
+  ret void
+}
+
+define void @test_v16i8_zero_undef(<16 x i8>* %p) {
+; CHECK-LABEL: test_v16i8_zero_undef:
+  %a = load <16 x i8>, <16 x i8>* %p
+  %tmp = call <16 x i8> @llvm.cttz.v16i8(<16 x i8> %a, i1 true)
+  store <16 x i8> %tmp, <16 x i8>* %p
+  ret void
+}
+
+define void @test_v1i16_zero_undef(<1 x i16>* %p) {
+; CHECK-LABEL: test_v1i16_zero_undef:
+  %a = load <1 x i16>, <1 x i16>* %p
+  %tmp = call <1 x i16> @llvm.cttz.v1i16(<1 x i16> %a, i1 true)
+  store <1 x i16> %tmp, <1 x i16>* %p
+  ret void
+}
+
+define void @test_v2i16_zero_undef(<2 x i16>* %p) {
+; CHECK-LABEL: test_v2i16_zero_undef:
+  %a = load <2 x i16>, <2 x i16>* %p
+  %tmp = call <2 x i16> @llvm.cttz.v2i16(<2 x i16> %a, i1 true)
+  store <2 x i16> %tmp, <2 x i16>* %p
+  ret void
+}
+
+define void @test_v4i16_zero_undef(<4 x i16>* %p) {
+; CHECK-LABEL: test_v4i16_zero_undef:
+  %a = load <4 x i16>, <4 x i16>* %p
+  %tmp = call <4 x i16> @llvm.cttz.v4i16(<4 x i16> %a, i1 true)
+  store <4 x i16> %tmp, <4 x i16>* %p
+  ret void
+}
+
+define void @test_v8i16_zero_undef(<8 x i16>* %p) {
+; CHECK-LABEL: test_v8i16_zero_undef:
+  %a = load <8 x i16>, <8 x i16>* %p
+  %tmp = call <8 x i16> @llvm.cttz.v8i16(<8 x i16> %a, i1 true)
+  store <8 x i16> %tmp, <8 x i16>* %p
+  ret void
+}
+
+define void @test_v1i32_zero_undef(<1 x i32>* %p) {
+; CHECK-LABEL: test_v1i32_zero_undef:
+  %a = load <1 x i32>, <1 x i32>* %p
+  %tmp = call <1 x i32> @llvm.cttz.v1i32(<1 x i32> %a, i1 true)
+  store <1 x i32> %tmp, <1 x i32>* %p
+  ret void
+}
+
+define void @test_v2i32_zero_undef(<2 x i32>* %p) {
+; CHECK-LABEL: test_v2i32_zero_undef:
+  %a = load <2 x i32>, <2 x i32>* %p
+  %tmp = call <2 x i32> @llvm.cttz.v2i32(<2 x i32> %a, i1 true)
+  store <2 x i32> %tmp, <2 x i32>* %p
+  ret void
+}
+
+define void @test_v4i32_zero_undef(<4 x i32>* %p) {
+; CHECK-LABEL: test_v4i32_zero_undef:
+  %a = load <4 x i32>, <4 x i32>* %p
+  %tmp = call <4 x i32> @llvm.cttz.v4i32(<4 x i32> %a, i1 true)
+  store <4 x i32> %tmp, <4 x i32>* %p
+  ret void
+}
+
+define void @test_v1i64_zero_undef(<1 x i64>* %p) {
+; CHECK-LABEL: test_v1i64_zero_undef:
+  %a = load <1 x i64>, <1 x i64>* %p
+  %tmp = call <1 x i64> @llvm.cttz.v1i64(<1 x i64> %a, i1 true)
+  store <1 x i64> %tmp, <1 x i64>* %p
+  ret void
+}
+
+define void @test_v2i64_zero_undef(<2 x i64>* %p) {
+; CHECK-LABEL: test_v2i64_zero_undef:
+  %a = load <2 x i64>, <2 x i64>* %p
+  %tmp = call <2 x i64> @llvm.cttz.v2i64(<2 x i64> %a, i1 true)
+  store <2 x i64> %tmp, <2 x i64>* %p
+  ret void
+}

test/CodeGen/ARM/ctz.ll

-; RUN: llc -mtriple=arm-eabi -mattr=+v6t2 %s -o - | FileCheck %s
-
-declare i32 @llvm.cttz.i32(i32, i1)
-
-define i32 @f1(i32 %a) {
-; CHECK-LABEL: f1:
-; CHECK: rbit
-; CHECK: clz
-  %tmp = call i32 @llvm.cttz.i32( i32 %a, i1 true )
-  ret i32 %tmp
-}