[llvm] 4a37b03 - [AArch64][ISel] Add lowering for fixed-width `cttz` intrinsic (#190988)

via llvm-commits llvm-commits at lists.llvm.org
Tue Apr 14 09:09:20 PDT 2026


Author: Harry Ramsey
Date: 2026-04-14T17:09:15+01:00
New Revision: 4a37b03357a9c5a40be292818969523c666c3115

URL: https://github.com/llvm/llvm-project/commit/4a37b03357a9c5a40be292818969523c666c3115
DIFF: https://github.com/llvm/llvm-project/commit/4a37b03357a9c5a40be292818969523c666c3115.diff

LOG: [AArch64][ISel] Add lowering for fixed-width `cttz` intrinsic (#190988)

This patch enables NEON to generate more efficient `cttz` intrinsics by
utilising `rbit` and `ctlz` instructions when they are legal.

# Alive Proof
https://alive2.llvm.org/ce/z/qgrT_7
```
define <8 x i8> @src_v8i8(<8 x i8> %a) {
#0:
  %r = cttz <8 x i8> %a, 1
  ret <8 x i8> %r
}
=>
define <8 x i8> @tgt_v8i8(<8 x i8> %a) {
#0:
  %rbit = bitreverse <8 x i8> %a
  %clz = ctlz <8 x i8> %rbit, 0
  ret <8 x i8> %clz
}
Transformation seems to be correct!


----------------------------------------
define <16 x i8> @src_v16i8(<16 x i8> %a) {
#0:
  %r = cttz <16 x i8> %a, 1
  ret <16 x i8> %r
}
=>
define <16 x i8> @tgt_v16i8(<16 x i8> %a) {
#0:
  %rbit = bitreverse <16 x i8> %a
  %clz = ctlz <16 x i8> %rbit, 0
  ret <16 x i8> %clz
}
Transformation seems to be correct!
```

Added: 
    

Modified: 
    llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    llvm/test/Analysis/CostModel/AArch64/cttz.ll
    llvm/test/CodeGen/AArch64/cttz.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index ece24767bdbb9..9b34d9b385b4e 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -1422,7 +1422,12 @@ AArch64TargetLowering::AArch64TargetLowering(const TargetMachine &TM,
         setOperationAction(ISD::BSWAP, VT, Legal);
       else
         setOperationAction(ISD::BSWAP, VT, Expand);
-      setOperationAction(ISD::CTTZ, VT, Expand);
+
+      if (VT == MVT::v8i8 || VT == MVT::v16i8 || VT == MVT::v8i16 ||
+          VT == MVT::v4i16 || VT == MVT::v2i32 || VT == MVT::v4i32)
+        setOperationAction(ISD::CTTZ, VT, Custom);
+      else
+        setOperationAction(ISD::CTTZ, VT, Expand);
 
       for (MVT InnerVT : MVT::fixedlen_vector_valuetypes()) {
         setTruncStoreAction(VT, InnerVT, Expand);
@@ -11696,7 +11701,9 @@ SDValue AArch64TargetLowering::LowerCTPOP_PARITY(SDValue Op,
 
 SDValue AArch64TargetLowering::LowerCTTZ(SDValue Op, SelectionDAG &DAG) const {
   EVT VT = Op.getValueType();
-  assert(VT.isScalableVector() ||
+  assert(VT.isScalableVector() || VT == MVT::v8i8 || VT == MVT::v16i8 ||
+         VT == MVT::v8i16 || VT == MVT::v4i16 || VT == MVT::v2i32 ||
+         VT == MVT::v4i32 ||
          useSVEForFixedLengthVectorVT(
              VT, /*OverrideNEON=*/Subtarget->useSVEForFixedLengthVectors()));
 

diff  --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index ff99eeefde6e3..2c0e42cdc48ee 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -1076,6 +1076,15 @@ AArch64TTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
     }
     break;
   }
+  case Intrinsic::cttz: {
+    auto LT = getTypeLegalizationCost(ICA.getArgTypes()[0]);
+    if (LT.second == MVT::v8i8 || LT.second == MVT::v16i8)
+      return LT.first * 2;
+    if (LT.second == MVT::v4i16 || LT.second == MVT::v8i16 ||
+        LT.second == MVT::v2i32 || LT.second == MVT::v4i32)
+      return LT.first * 3;
+    break;
+  }
   case Intrinsic::experimental_cttz_elts: {
     EVT ArgVT = getTLI()->getValueType(DL, ICA.getArgTypes()[0]);
     if (!getTLI()->shouldExpandCttzElements(ArgVT)) {

diff  --git a/llvm/test/Analysis/CostModel/AArch64/cttz.ll b/llvm/test/Analysis/CostModel/AArch64/cttz.ll
index 6f7810372388a..b890b31f5c5b1 100644
--- a/llvm/test/Analysis/CostModel/AArch64/cttz.ll
+++ b/llvm/test/Analysis/CostModel/AArch64/cttz.ll
@@ -65,7 +65,7 @@ define <2 x i64> @test_cttz_v2i64(<2 x i64> %a) {
 define <2 x i32> @test_cttz_v2i32(<2 x i32> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v2i32'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:10 CodeSize:6 Lat:10 SizeLat:10 for: %cttz = call <2 x i32> @llvm.cttz.v2i32(<2 x i32> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 3 for: %cttz = call <2 x i32> @llvm.cttz.v2i32(<2 x i32> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <2 x i32> %cttz
 ;
   %cttz = call <2 x i32> @llvm.cttz.v2i32(<2 x i32> %a, i1 true)
@@ -75,7 +75,7 @@ define <2 x i32> @test_cttz_v2i32(<2 x i32> %a) {
 define <4 x i32> @test_cttz_v4i32(<4 x i32> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v4i32'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:20 CodeSize:12 Lat:20 SizeLat:20 for: %cttz = call <4 x i32> @llvm.cttz.v4i32(<4 x i32> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 3 for: %cttz = call <4 x i32> @llvm.cttz.v4i32(<4 x i32> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x i32> %cttz
 ;
   %cttz = call <4 x i32> @llvm.cttz.v4i32(<4 x i32> %a, i1 true)
@@ -85,7 +85,7 @@ define <4 x i32> @test_cttz_v4i32(<4 x i32> %a) {
 define <2 x i16> @test_cttz_v2i16(<2 x i16> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v2i16'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:10 CodeSize:6 Lat:10 SizeLat:10 for: %cttz = call <2 x i16> @llvm.cttz.v2i16(<2 x i16> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 3 for: %cttz = call <2 x i16> @llvm.cttz.v2i16(<2 x i16> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <2 x i16> %cttz
 ;
   %cttz = call <2 x i16> @llvm.cttz.v2i16(<2 x i16> %a, i1 true)
@@ -95,7 +95,7 @@ define <2 x i16> @test_cttz_v2i16(<2 x i16> %a) {
 define <4 x i16> @test_cttz_v4i16(<4 x i16> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v4i16'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:20 CodeSize:12 Lat:20 SizeLat:20 for: %cttz = call <4 x i16> @llvm.cttz.v4i16(<4 x i16> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 3 for: %cttz = call <4 x i16> @llvm.cttz.v4i16(<4 x i16> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x i16> %cttz
 ;
   %cttz = call <4 x i16> @llvm.cttz.v4i16(<4 x i16> %a, i1 true)
@@ -105,7 +105,7 @@ define <4 x i16> @test_cttz_v4i16(<4 x i16> %a) {
 define <8 x i16> @test_cttz_v8i16(<8 x i16> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v8i16'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:40 CodeSize:24 Lat:40 SizeLat:40 for: %cttz = call <8 x i16> @llvm.cttz.v8i16(<8 x i16> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 3 for: %cttz = call <8 x i16> @llvm.cttz.v8i16(<8 x i16> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <8 x i16> %cttz
 ;
   %cttz = call <8 x i16> @llvm.cttz.v8i16(<8 x i16> %a, i1 true)
@@ -115,7 +115,7 @@ define <8 x i16> @test_cttz_v8i16(<8 x i16> %a) {
 define <2 x i8> @test_cttz_v2i8(<2 x i8> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v2i8'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:10 CodeSize:6 Lat:10 SizeLat:10 for: %cttz = call <2 x i8> @llvm.cttz.v2i8(<2 x i8> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 3 for: %cttz = call <2 x i8> @llvm.cttz.v2i8(<2 x i8> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <2 x i8> %cttz
 ;
   %cttz = call <2 x i8> @llvm.cttz.v2i8(<2 x i8> %a, i1 true)
@@ -125,7 +125,7 @@ define <2 x i8> @test_cttz_v2i8(<2 x i8> %a) {
 define <4 x i8> @test_cttz_v4i8(<4 x i8> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v4i8'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:20 CodeSize:12 Lat:20 SizeLat:20 for: %cttz = call <4 x i8> @llvm.cttz.v4i8(<4 x i8> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 3 for: %cttz = call <4 x i8> @llvm.cttz.v4i8(<4 x i8> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x i8> %cttz
 ;
   %cttz = call <4 x i8> @llvm.cttz.v4i8(<4 x i8> %a, i1 true)
@@ -135,7 +135,7 @@ define <4 x i8> @test_cttz_v4i8(<4 x i8> %a) {
 define <8 x i8> @test_cttz_v8i8(<8 x i8> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v8i8'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:40 CodeSize:24 Lat:40 SizeLat:40 for: %cttz = call <8 x i8> @llvm.cttz.v8i8(<8 x i8> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 2 for: %cttz = call <8 x i8> @llvm.cttz.v8i8(<8 x i8> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <8 x i8> %cttz
 ;
   %cttz = call <8 x i8> @llvm.cttz.v8i8(<8 x i8> %a, i1 true)
@@ -145,7 +145,7 @@ define <8 x i8> @test_cttz_v8i8(<8 x i8> %a) {
 define <16 x i8> @test_cttz_v16i8(<16 x i8> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v16i8'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:80 CodeSize:48 Lat:80 SizeLat:80 for: %cttz = call <16 x i8> @llvm.cttz.v16i8(<16 x i8> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 2 for: %cttz = call <16 x i8> @llvm.cttz.v16i8(<16 x i8> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <16 x i8> %cttz
 ;
   %cttz = call <16 x i8> @llvm.cttz.v16i8(<16 x i8> %a, i1 true)
@@ -165,7 +165,7 @@ define <4 x i64> @test_cttz_v4i64(<4 x i64> %a) {
 define <8 x i32> @test_cttz_v8i32(<8 x i32> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v8i32'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:40 CodeSize:24 Lat:40 SizeLat:40 for: %cttz = call <8 x i32> @llvm.cttz.v8i32(<8 x i32> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 6 for: %cttz = call <8 x i32> @llvm.cttz.v8i32(<8 x i32> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <8 x i32> %cttz
 ;
   %cttz = call <8 x i32> @llvm.cttz.v8i32(<8 x i32> %a, i1 true)
@@ -175,7 +175,7 @@ define <8 x i32> @test_cttz_v8i32(<8 x i32> %a) {
 define <16 x i16> @test_cttz_v16i16(<16 x i16> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v16i16'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:80 CodeSize:48 Lat:80 SizeLat:80 for: %cttz = call <16 x i16> @llvm.cttz.v16i16(<16 x i16> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 6 for: %cttz = call <16 x i16> @llvm.cttz.v16i16(<16 x i16> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <16 x i16> %cttz
 ;
   %cttz = call <16 x i16> @llvm.cttz.v16i16(<16 x i16> %a, i1 true)
@@ -185,7 +185,7 @@ define <16 x i16> @test_cttz_v16i16(<16 x i16> %a) {
 define <32 x i8> @test_cttz_v32i8(<32 x i8> %a) {
 ;
 ; CHECK-LABEL: 'test_cttz_v32i8'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:160 CodeSize:96 Lat:160 SizeLat:160 for: %cttz = call <32 x i8> @llvm.cttz.v32i8(<32 x i8> %a, i1 true)
+; CHECK-NEXT:  Cost Model: Found costs of 4 for: %cttz = call <32 x i8> @llvm.cttz.v32i8(<32 x i8> %a, i1 true)
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <32 x i8> %cttz
 ;
   %cttz = call <32 x i8> @llvm.cttz.v32i8(<32 x i8> %a, i1 true)

diff  --git a/llvm/test/CodeGen/AArch64/cttz.ll b/llvm/test/CodeGen/AArch64/cttz.ll
index c9181b4c312d1..86c1aca9ed9e1 100644
--- a/llvm/test/CodeGen/AArch64/cttz.ll
+++ b/llvm/test/CodeGen/AArch64/cttz.ll
@@ -7,15 +7,12 @@ define void @v2i8(ptr %p1) {
 ; CHECK-SD-LABEL: v2i8:
 ; CHECK-SD:       // %bb.0: // %entry
 ; CHECK-SD-NEXT:    ldr h0, [x0]
-; CHECK-SD-NEXT:    movi v1.2s, #1
 ; CHECK-SD-NEXT:    ushll v0.8h, v0.8b, #0
 ; CHECK-SD-NEXT:    ushll v0.4s, v0.4h, #0
 ; CHECK-SD-NEXT:    orr v0.2s, #1, lsl #8
-; CHECK-SD-NEXT:    sub v1.2s, v0.2s, v1.2s
-; CHECK-SD-NEXT:    bic v0.8b, v1.8b, v0.8b
-; CHECK-SD-NEXT:    movi v1.2s, #32
+; CHECK-SD-NEXT:    rev32 v0.8b, v0.8b
+; CHECK-SD-NEXT:    rbit v0.8b, v0.8b
 ; CHECK-SD-NEXT:    clz v0.2s, v0.2s
-; CHECK-SD-NEXT:    sub v0.2s, v1.2s, v0.2s
 ; CHECK-SD-NEXT:    mov s1, v0.s[1]
 ; CHECK-SD-NEXT:    str b0, [x0]
 ; CHECK-SD-NEXT:    stur b1, [x0, #1]
@@ -49,14 +46,11 @@ define void @v3i8(ptr %p1) {
 ; CHECK-SD-NEXT:    sub sp, sp, #16
 ; CHECK-SD-NEXT:    .cfi_def_cfa_offset 16
 ; CHECK-SD-NEXT:    ldr s0, [x0]
-; CHECK-SD-NEXT:    movi v1.4h, #1
 ; CHECK-SD-NEXT:    zip1 v0.8b, v0.8b, v0.8b
 ; CHECK-SD-NEXT:    orr v0.4h, #1, lsl #8
-; CHECK-SD-NEXT:    sub v1.4h, v0.4h, v1.4h
-; CHECK-SD-NEXT:    bic v0.8b, v1.8b, v0.8b
-; CHECK-SD-NEXT:    movi v1.4h, #16
+; CHECK-SD-NEXT:    rev16 v0.8b, v0.8b
+; CHECK-SD-NEXT:    rbit v0.8b, v0.8b
 ; CHECK-SD-NEXT:    clz v0.4h, v0.4h
-; CHECK-SD-NEXT:    sub v0.4h, v1.4h, v0.4h
 ; CHECK-SD-NEXT:    uzp1 v1.8b, v0.8b, v0.8b
 ; CHECK-SD-NEXT:    mov h0, v0.h[2]
 ; CHECK-SD-NEXT:    ushll v1.4s, v1.4h, #0
@@ -101,14 +95,11 @@ define void @v4i8(ptr %p1) {
 ; CHECK-SD-LABEL: v4i8:
 ; CHECK-SD:       // %bb.0: // %entry
 ; CHECK-SD-NEXT:    ldr s0, [x0]
-; CHECK-SD-NEXT:    movi v1.4h, #1
 ; CHECK-SD-NEXT:    ushll v0.8h, v0.8b, #0
 ; CHECK-SD-NEXT:    orr v0.4h, #1, lsl #8
-; CHECK-SD-NEXT:    sub v1.4h, v0.4h, v1.4h
-; CHECK-SD-NEXT:    bic v0.8b, v1.8b, v0.8b
-; CHECK-SD-NEXT:    movi v1.4h, #16
+; CHECK-SD-NEXT:    rev16 v0.8b, v0.8b
+; CHECK-SD-NEXT:    rbit v0.8b, v0.8b
 ; CHECK-SD-NEXT:    clz v0.4h, v0.4h
-; CHECK-SD-NEXT:    sub v0.4h, v1.4h, v0.4h
 ; CHECK-SD-NEXT:    uzp1 v0.8b, v0.8b, v0.8b
 ; CHECK-SD-NEXT:    str s0, [x0]
 ; CHECK-SD-NEXT:    ret
@@ -149,10 +140,8 @@ entry:
 define <8 x i8> @v8i8(<8 x i8> %d) {
 ; CHECK-SD-LABEL: v8i8:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v1.8b, #1
-; CHECK-SD-NEXT:    sub v1.8b, v0.8b, v1.8b
-; CHECK-SD-NEXT:    bic v0.8b, v1.8b, v0.8b
-; CHECK-SD-NEXT:    cnt v0.8b, v0.8b
+; CHECK-SD-NEXT:    rbit v0.8b, v0.8b
+; CHECK-SD-NEXT:    clz v0.8b, v0.8b
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v8i8:
@@ -170,10 +159,8 @@ entry:
 define <16 x i8> @v16i8(<16 x i8> %d) {
 ; CHECK-SD-LABEL: v16i8:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v1.16b, #1
-; CHECK-SD-NEXT:    sub v1.16b, v0.16b, v1.16b
-; CHECK-SD-NEXT:    bic v0.16b, v1.16b, v0.16b
-; CHECK-SD-NEXT:    cnt v0.16b, v0.16b
+; CHECK-SD-NEXT:    rbit v0.16b, v0.16b
+; CHECK-SD-NEXT:    clz v0.16b, v0.16b
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v16i8:
@@ -191,13 +178,10 @@ entry:
 define <32 x i8> @v32i8(<32 x i8> %d) {
 ; CHECK-SD-LABEL: v32i8:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v2.16b, #1
-; CHECK-SD-NEXT:    sub v3.16b, v0.16b, v2.16b
-; CHECK-SD-NEXT:    sub v2.16b, v1.16b, v2.16b
-; CHECK-SD-NEXT:    bic v0.16b, v3.16b, v0.16b
-; CHECK-SD-NEXT:    bic v1.16b, v2.16b, v1.16b
-; CHECK-SD-NEXT:    cnt v0.16b, v0.16b
-; CHECK-SD-NEXT:    cnt v1.16b, v1.16b
+; CHECK-SD-NEXT:    rbit v0.16b, v0.16b
+; CHECK-SD-NEXT:    rbit v1.16b, v1.16b
+; CHECK-SD-NEXT:    clz v0.16b, v0.16b
+; CHECK-SD-NEXT:    clz v1.16b, v1.16b
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v32i8:
@@ -219,14 +203,11 @@ define void @v2i16(ptr %p1) {
 ; CHECK-SD-LABEL: v2i16:
 ; CHECK-SD:       // %bb.0: // %entry
 ; CHECK-SD-NEXT:    ldr s0, [x0]
-; CHECK-SD-NEXT:    movi v1.2s, #1
 ; CHECK-SD-NEXT:    ushll v0.4s, v0.4h, #0
 ; CHECK-SD-NEXT:    orr v0.2s, #1, lsl #16
-; CHECK-SD-NEXT:    sub v1.2s, v0.2s, v1.2s
-; CHECK-SD-NEXT:    bic v0.8b, v1.8b, v0.8b
-; CHECK-SD-NEXT:    movi v1.2s, #32
+; CHECK-SD-NEXT:    rev32 v0.8b, v0.8b
+; CHECK-SD-NEXT:    rbit v0.8b, v0.8b
 ; CHECK-SD-NEXT:    clz v0.2s, v0.2s
-; CHECK-SD-NEXT:    sub v0.2s, v1.2s, v0.2s
 ; CHECK-SD-NEXT:    mov s1, v0.s[1]
 ; CHECK-SD-NEXT:    str h0, [x0]
 ; CHECK-SD-NEXT:    str h1, [x0, #2]
@@ -260,13 +241,10 @@ entry:
 define void @v3i16(ptr %p1) {
 ; CHECK-SD-LABEL: v3i16:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v0.4h, #1
-; CHECK-SD-NEXT:    ldr d1, [x0]
-; CHECK-SD-NEXT:    sub v0.4h, v1.4h, v0.4h
-; CHECK-SD-NEXT:    bic v0.8b, v0.8b, v1.8b
-; CHECK-SD-NEXT:    movi v1.4h, #16
+; CHECK-SD-NEXT:    ldr d0, [x0]
+; CHECK-SD-NEXT:    rev16 v0.8b, v0.8b
+; CHECK-SD-NEXT:    rbit v0.8b, v0.8b
 ; CHECK-SD-NEXT:    clz v0.4h, v0.4h
-; CHECK-SD-NEXT:    sub v0.4h, v1.4h, v0.4h
 ; CHECK-SD-NEXT:    mov h1, v0.h[2]
 ; CHECK-SD-NEXT:    str s0, [x0]
 ; CHECK-SD-NEXT:    str h1, [x0, #4]
@@ -300,12 +278,9 @@ entry:
 define <4 x i16> @v4i16(<4 x i16> %d) {
 ; CHECK-SD-LABEL: v4i16:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v1.4h, #1
-; CHECK-SD-NEXT:    sub v1.4h, v0.4h, v1.4h
-; CHECK-SD-NEXT:    bic v0.8b, v1.8b, v0.8b
-; CHECK-SD-NEXT:    movi v1.4h, #16
+; CHECK-SD-NEXT:    rev16 v0.8b, v0.8b
+; CHECK-SD-NEXT:    rbit v0.8b, v0.8b
 ; CHECK-SD-NEXT:    clz v0.4h, v0.4h
-; CHECK-SD-NEXT:    sub v0.4h, v1.4h, v0.4h
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v4i16:
@@ -324,12 +299,9 @@ entry:
 define <8 x i16> @v8i16(<8 x i16> %d) {
 ; CHECK-SD-LABEL: v8i16:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v1.8h, #1
-; CHECK-SD-NEXT:    sub v1.8h, v0.8h, v1.8h
-; CHECK-SD-NEXT:    bic v0.16b, v1.16b, v0.16b
-; CHECK-SD-NEXT:    movi v1.8h, #16
+; CHECK-SD-NEXT:    rev16 v0.16b, v0.16b
+; CHECK-SD-NEXT:    rbit v0.16b, v0.16b
 ; CHECK-SD-NEXT:    clz v0.8h, v0.8h
-; CHECK-SD-NEXT:    sub v0.8h, v1.8h, v0.8h
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v8i16:
@@ -348,16 +320,12 @@ entry:
 define <16 x i16> @v16i16(<16 x i16> %d) {
 ; CHECK-SD-LABEL: v16i16:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v2.8h, #1
-; CHECK-SD-NEXT:    sub v3.8h, v0.8h, v2.8h
-; CHECK-SD-NEXT:    sub v2.8h, v1.8h, v2.8h
-; CHECK-SD-NEXT:    bic v0.16b, v3.16b, v0.16b
-; CHECK-SD-NEXT:    bic v1.16b, v2.16b, v1.16b
-; CHECK-SD-NEXT:    movi v2.8h, #16
+; CHECK-SD-NEXT:    rev16 v0.16b, v0.16b
+; CHECK-SD-NEXT:    rev16 v1.16b, v1.16b
+; CHECK-SD-NEXT:    rbit v0.16b, v0.16b
+; CHECK-SD-NEXT:    rbit v1.16b, v1.16b
 ; CHECK-SD-NEXT:    clz v0.8h, v0.8h
 ; CHECK-SD-NEXT:    clz v1.8h, v1.8h
-; CHECK-SD-NEXT:    sub v0.8h, v2.8h, v0.8h
-; CHECK-SD-NEXT:    sub v1.8h, v2.8h, v1.8h
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v16i16:
@@ -380,12 +348,9 @@ entry:
 define <2 x i32> @v2i32(<2 x i32> %d) {
 ; CHECK-SD-LABEL: v2i32:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v1.2s, #1
-; CHECK-SD-NEXT:    sub v1.2s, v0.2s, v1.2s
-; CHECK-SD-NEXT:    bic v0.8b, v1.8b, v0.8b
-; CHECK-SD-NEXT:    movi v1.2s, #32
+; CHECK-SD-NEXT:    rev32 v0.8b, v0.8b
+; CHECK-SD-NEXT:    rbit v0.8b, v0.8b
 ; CHECK-SD-NEXT:    clz v0.2s, v0.2s
-; CHECK-SD-NEXT:    sub v0.2s, v1.2s, v0.2s
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v2i32:
@@ -405,12 +370,9 @@ entry:
 define <3 x i32> @v3i32(<3 x i32> %d) {
 ; CHECK-SD-LABEL: v3i32:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v1.4s, #1
-; CHECK-SD-NEXT:    sub v1.4s, v0.4s, v1.4s
-; CHECK-SD-NEXT:    bic v0.16b, v1.16b, v0.16b
-; CHECK-SD-NEXT:    movi v1.4s, #32
+; CHECK-SD-NEXT:    rev32 v0.16b, v0.16b
+; CHECK-SD-NEXT:    rbit v0.16b, v0.16b
 ; CHECK-SD-NEXT:    clz v0.4s, v0.4s
-; CHECK-SD-NEXT:    sub v0.4s, v1.4s, v0.4s
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v3i32:
@@ -434,12 +396,9 @@ entry:
 define <4 x i32> @v4i32(<4 x i32> %d) {
 ; CHECK-SD-LABEL: v4i32:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v1.4s, #1
-; CHECK-SD-NEXT:    sub v1.4s, v0.4s, v1.4s
-; CHECK-SD-NEXT:    bic v0.16b, v1.16b, v0.16b
-; CHECK-SD-NEXT:    movi v1.4s, #32
+; CHECK-SD-NEXT:    rev32 v0.16b, v0.16b
+; CHECK-SD-NEXT:    rbit v0.16b, v0.16b
 ; CHECK-SD-NEXT:    clz v0.4s, v0.4s
-; CHECK-SD-NEXT:    sub v0.4s, v1.4s, v0.4s
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v4i32:
@@ -459,16 +418,12 @@ entry:
 define <8 x i32> @v8i32(<8 x i32> %d) {
 ; CHECK-SD-LABEL: v8i32:
 ; CHECK-SD:       // %bb.0: // %entry
-; CHECK-SD-NEXT:    movi v2.4s, #1
-; CHECK-SD-NEXT:    sub v3.4s, v0.4s, v2.4s
-; CHECK-SD-NEXT:    sub v2.4s, v1.4s, v2.4s
-; CHECK-SD-NEXT:    bic v0.16b, v3.16b, v0.16b
-; CHECK-SD-NEXT:    bic v1.16b, v2.16b, v1.16b
-; CHECK-SD-NEXT:    movi v2.4s, #32
+; CHECK-SD-NEXT:    rev32 v0.16b, v0.16b
+; CHECK-SD-NEXT:    rev32 v1.16b, v1.16b
+; CHECK-SD-NEXT:    rbit v0.16b, v0.16b
+; CHECK-SD-NEXT:    rbit v1.16b, v1.16b
 ; CHECK-SD-NEXT:    clz v0.4s, v0.4s
 ; CHECK-SD-NEXT:    clz v1.4s, v1.4s
-; CHECK-SD-NEXT:    sub v0.4s, v2.4s, v0.4s
-; CHECK-SD-NEXT:    sub v1.4s, v2.4s, v1.4s
 ; CHECK-SD-NEXT:    ret
 ;
 ; CHECK-GI-LABEL: v8i32:


        


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