[AArch64][SVE] Fix fptrunc store for fixed len vector

[peterwaller-arm]

Summary

Restrict duplicate FP_EXTEND/FP_TRUNC -> LOAD/STORE DAG combines to only
larger than NEON types, as these are the ones for which there is custom
lowering.

[paulwalker-arm]

llvm/test/CodeGen/AArch64/sve-fpext-load.ll

88–89 ↗

(On Diff #392107)

sve-fixed-length-fp-extend-trunc.ll looks like a better home for this and the test below. In fact I believe we already have the makings of the required tests. See fcvt_v2f32_v2f64 and fcvt_v2f64_v2f32 within that file.

In general we don't use memory for the fixed length tests when the vector types are NEON sized. However, within sve-fixed-length-fp-extend-trunc.ll I think that is a mistake because these tests now validate multiple things, namely operation legalisation as well as the DAGCombines required for good code generation. This is likely how this bug has slipped through so for this patch can you instead update the tests within sve-fixed-length-fp-extend-trunc.ll so they all go through memory (it looks like there only 16 of them)?

[peterwaller-arm]

• Update tests per Paul's comments.

[paulwalker-arm]

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

15989–15990

Looking at the regressions in fcvt_v8f64_v8f32 and fcvt_v16f32_v16f16 I'm wondering if this wants to be >= instead?

[peterwaller-arm]

• Fix regressions per Paul's comment.

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

static SDValue performSTORECombine(SDNode *N,
 
   // If this is an FP_ROUND followed by a store, fold this into a truncating
   // store. We can do this even if this is already a truncstore.
   // We purposefully don't care about legality of the nodes here as we know
   // they can be split down into something legal.
   if (DCI.isBeforeLegalizeOps() && Value.getOpcode() == ISD::FP_ROUND &&
       Value.getNode()->hasOneUse() && ST->isUnindexed() &&
       Subtarget->useSVEForFixedLengthVectors() &&
-      Value.getValueType().isFixedLengthVector())
+      Value.getValueType().isFixedLengthVector() &&
+      Value.getValueType().getFixedSizeInBits() >=
+          Subtarget->getMinSVEVectorSizeInBits())
     return DAG.getTruncStore(Chain, SDLoc(N), Value.getOperand(0), Ptr,
                              ST->getMemoryVT(), ST->getMemOperand());
 
   if (SDValue Split = splitStores(N, DCI, DAG, Subtarget))
     return Split;
 
   if (Subtarget->supportsAddressTopByteIgnored() &&
       performTBISimplification(N->getOperand(2), DCI, DAG))
SDValue performFPExtendCombine(SDNode *N, SelectionDAG &DAG,
   if (N->hasOneUse() && N->use_begin()->getOpcode() == ISD::FP_ROUND)
     return SDValue();
 
   // fold (fpext (load x)) -> (fpext (fptrunc (extload x)))
   // We purposefully don't care about legality of the nodes here as we know
   // they can be split down into something legal.
   if (DCI.isBeforeLegalizeOps() && ISD::isNormalLoad(N0.getNode()) &&
       N0.hasOneUse() && Subtarget->useSVEForFixedLengthVectors() &&
-      VT.isFixedLengthVector()) {
+      VT.isFixedLengthVector() &&
+      VT.getFixedSizeInBits() >= Subtarget->getMinSVEVectorSizeInBits()) {
     LoadSDNode *LN0 = cast<LoadSDNode>(N0);
     SDValue ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, SDLoc(N), VT,
                                      LN0->getChain(), LN0->getBasePtr(),
                                      N0.getValueType(), LN0->getMemOperand());
     DCI.CombineTo(N, ExtLoad);
     DCI.CombineTo(N0.getNode(),
                   DAG.getNode(ISD::FP_ROUND, SDLoc(N0), N0.getValueType(),
                               ExtLoad, DAG.getIntPtrConstant(1, SDLoc(N0))),

llvm/test/CodeGen/AArch64/sve-fixed-length-fp-extend-trunc.ll

 ; Don't use SVE when its registers are no bigger than NEON.
 ; NO_SVE-NOT: ptrue
 
 ;
 ; FCVT H -> S
 ;
 
 ; Don't use SVE for 64-bit vectors.
-define <2 x float> @fcvt_v2f16_v2f32(<2 x half> %op1) #0 {
+define void @fcvt_v2f16_v2f32(<2 x half>* %a, <2 x float>* %b) #0 {
 ; CHECK-LABEL: fcvt_v2f16_v2f32:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr s0, [x0]
 ; CHECK-NEXT:    fcvtl v0.4s, v0.4h
-; CHECK-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-NEXT:    str d0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <2 x half>, <2 x half>* %a
   %res = fpext <2 x half> %op1 to <2 x float>
-  ret <2 x float> %res
+  store <2 x float> %res, <2 x float>* %b
+  ret void
 }
 
 ; Don't use SVE for 128-bit vectors.
-define <4 x float> @fcvt_v4f16_v4f32(<4 x half> %op1) #0 {
+define void @fcvt_v4f16_v4f32(<4 x half>* %a, <4 x float>* %b) #0 {
 ; CHECK-LABEL: fcvt_v4f16_v4f32:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr d0, [x0]
 ; CHECK-NEXT:    fcvtl v0.4s, v0.4h
+; CHECK-NEXT:    str q0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <4 x half>, <4 x half>* %a
   %res = fpext <4 x half> %op1 to <4 x float>
-  ret <4 x float> %res
+  store <4 x float> %res, <4 x float>* %b
+  ret void
 }
 
 define void @fcvt_v8f16_v8f32(<8 x half>* %a, <8 x float>* %b) #0 {
 ; CHECK-LABEL: fcvt_v8f16_v8f32:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.s, vl8
 ; CHECK-NEXT:    ld1sh { z0.s }, p0/z, [x0]
 ; CHECK-NEXT:    fcvt z0.s, p0/m, z0.h
; VBITS_GE_2048-NEXT:    ret
   ret void
 }
 
 ;
 ; FCVT H -> D
 ;
 
 ; Don't use SVE for 64-bit vectors.
-define <1 x double> @fcvt_v1f16_v1f64(<1 x half> %op1) #0 {
+define void @fcvt_v1f16_v1f64(<1 x half>* %a, <1 x double>* %b) #0 {
 ; CHECK-LABEL: fcvt_v1f16_v1f64:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr h0, [x0]
 ; CHECK-NEXT:    fcvt d0, h0
+; CHECK-NEXT:    str d0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <1 x half>, <1 x half>* %a
   %res = fpext <1 x half> %op1 to <1 x double>
-  ret <1 x double> %res
+  store <1 x double> %res, <1 x double>* %b
+  ret void
 }
 
 ; v2f16 is not legal for NEON, so use SVE
-define <2 x double> @fcvt_v2f16_v2f64(<2 x half> %op1) #0 {
+define void @fcvt_v2f16_v2f64(<2 x half>* %a, <2 x double>* %b) #0 {
 ; CHECK-LABEL: fcvt_v2f16_v2f64:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    // kill: def $d0 killed $d0 def $z0
+; CHECK-NEXT:    ldr s0, [x0]
 ; CHECK-NEXT:    ptrue p0.d, vl4
 ; CHECK-NEXT:    uunpklo z0.s, z0.h
 ; CHECK-NEXT:    uunpklo z0.d, z0.s
 ; CHECK-NEXT:    fcvt z0.d, p0/m, z0.h
-; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0
+; CHECK-NEXT:    str q0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <2 x half>, <2 x half>* %a
   %res = fpext <2 x half> %op1 to <2 x double>
-  ret <2 x double> %res
+  store <2 x double> %res, <2 x double>* %b
+  ret void
 }
 
 define void @fcvt_v4f16_v4f64(<4 x half>* %a, <4 x double>* %b) #0 {
 ; CHECK-LABEL: fcvt_v4f16_v4f64:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.d, vl4
 ; CHECK-NEXT:    ld1sh { z0.d }, p0/z, [x0]
 ; CHECK-NEXT:    fcvt z0.d, p0/m, z0.h
; VBITS_GE_2048-NEXT:    ret
   ret void
 }
 
 ;
 ; FCVT S -> D
 ;
 
 ; Don't use SVE for 64-bit vectors.
-define <1 x double> @fcvt_v1f32_v1f64(<1 x float> %op1) #0 {
+define void @fcvt_v1f32_v1f64(<1 x float>* %a, <1 x double>* %b) #0 {
 ; CHECK-LABEL: fcvt_v1f32_v1f64:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr s0, [x0]
 ; CHECK-NEXT:    fcvtl v0.2d, v0.2s
-; CHECK-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-NEXT:    str d0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <1 x float>, <1 x float>* %a
   %res = fpext <1 x float> %op1 to <1 x double>
-  ret <1 x double> %res
+  store <1 x double> %res, <1 x double>* %b
+  ret void
 }
 
 ; Don't use SVE for 128-bit vectors.
-define <2 x double> @fcvt_v2f32_v2f64(<2 x float> %op1) #0 {
+define void @fcvt_v2f32_v2f64(<2 x float>* %a, <2 x double>* %b) #0 {
 ; CHECK-LABEL: fcvt_v2f32_v2f64:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr d0, [x0]
 ; CHECK-NEXT:    fcvtl v0.2d, v0.2s
+; CHECK-NEXT:    str q0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <2 x float>, <2 x float>* %a
   %res = fpext <2 x float> %op1 to <2 x double>
-  ret <2 x double> %res
+  store <2 x double> %res, <2 x double>* %b
+  ret void
 }
 
 define void @fcvt_v4f32_v4f64(<4 x float>* %a, <4 x double>* %b) #0 {
 ; CHECK-LABEL: fcvt_v4f32_v4f64:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.d, vl4
 ; CHECK-NEXT:    ld1sw { z0.d }, p0/z, [x0]
 ; CHECK-NEXT:    fcvt z0.d, p0/m, z0.s

 ;
 ; VBITS_GE_512-LABEL: fcvt_v8f32_v8f64:
 ; VBITS_GE_512:       // %bb.0:
 ; VBITS_GE_512-NEXT:    ptrue p0.d, vl8
 ; VBITS_GE_512-NEXT:    ld1sw { z0.d }, p0/z, [x0]
 ; VBITS_GE_512-NEXT:    fcvt z0.d, p0/m, z0.s
 ; VBITS_GE_512-NEXT:    st1d { z0.d }, p0, [x1]
 ; VBITS_GE_512-NEXT:    ret
-
   %op1 = load <8 x float>, <8 x float>* %a
   %res = fpext <8 x float> %op1 to <8 x double>
   store <8 x double> %res, <8 x double>* %b
   ret void
 }
 
 define void @fcvt_v16f32_v16f64(<16 x float>* %a, <16 x double>* %b) #0 {
 ; VBITS_GE_1024-LABEL: fcvt_v16f32_v16f64:
; VBITS_GE_2048-NEXT:    ret
   ret void
 }
 
 ;
 ; FCVT S -> H
 ;
 
 ; Don't use SVE for 64-bit vectors.
-define <2 x half> @fcvt_v2f32_v2f16(<2 x float> %op1) #0 {
+define void @fcvt_v2f32_v2f16(<2 x float>* %a, <2 x half>* %b) #0 {
 ; CHECK-LABEL: fcvt_v2f32_v2f16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    // kill: def $d0 killed $d0 def $q0
+; CHECK-NEXT:    ldr d0, [x0]
 ; CHECK-NEXT:    fcvtn v0.4h, v0.4s
+; CHECK-NEXT:    str s0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <2 x float>, <2 x float>* %a
   %res = fptrunc <2 x float> %op1 to <2 x half>
-  ret <2 x half> %res
+  store <2 x half> %res, <2 x half>* %b
+  ret void
 }
 
 ; Don't use SVE for 128-bit vectors.
-define <4 x half> @fcvt_v4f32_v4f16(<4 x float> %op1) #0 {
+define void @fcvt_v4f32_v4f16(<4 x float>* %a, <4 x half>* %b) #0 {
 ; CHECK-LABEL: fcvt_v4f32_v4f16:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr q0, [x0]
 ; CHECK-NEXT:    fcvtn v0.4h, v0.4s
+; CHECK-NEXT:    str d0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <4 x float>, <4 x float>* %a
   %res = fptrunc <4 x float> %op1 to <4 x half>
-  ret <4 x half> %res
+  store <4 x half> %res, <4 x half>* %b
+  ret void
 }
 
-define <8 x half> @fcvt_v8f32_v8f16(<8 x float>* %a) #0 {
+define void @fcvt_v8f32_v8f16(<8 x float>* %a, <8 x half>* %b) #0 {
 ; CHECK-LABEL: fcvt_v8f32_v8f16:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.s, vl8
 ; CHECK-NEXT:    ld1w { z0.s }, p0/z, [x0]
-; CHECK-NEXT:    ptrue p0.s
 ; CHECK-NEXT:    fcvt z0.h, p0/m, z0.s
-; CHECK-NEXT:    uzp1 z0.h, z0.h, z0.h
-; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0
+; CHECK-NEXT:    st1h { z0.s }, p0, [x1]
 ; CHECK-NEXT:    ret
   %op1 = load <8 x float>, <8 x float>* %a
   %res = fptrunc <8 x float> %op1 to <8 x half>
-  ret <8 x half> %res
+  store <8 x half> %res, <8 x half>* %b
+  ret void
 }
 
 define void @fcvt_v16f32_v16f16(<16 x float>* %a, <16 x half>* %b) #0 {
 ; Ensure sensible type legalisation
 ; VBITS_EQ_256-LABEL: fcvt_v16f32_v16f16:
 ; VBITS_EQ_256:       // %bb.0:
 ; VBITS_EQ_256-NEXT:    mov x8, #8
 ; VBITS_EQ_256-NEXT:    ptrue p0.s, vl8
; VBITS_GE_2048-NEXT:    ret
   ret void
 }
 
 ;
 ; FCVT D -> H
 ;
 
 ; Don't use SVE for 64-bit vectors.
-define <1 x half> @fcvt_v1f64_v1f16(<1 x double> %op1) #0 {
+define void @fcvt_v1f64_v1f16(<1 x double>* %a, <1 x half>* %b) #0 {
 ; CHECK-LABEL: fcvt_v1f64_v1f16:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr d0, [x0]
 ; CHECK-NEXT:    fcvt h0, d0
+; CHECK-NEXT:    str h0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <1 x double>, <1 x double>* %a
   %res = fptrunc <1 x double> %op1 to <1 x half>
-  ret <1 x half> %res
+  store <1 x half> %res, <1 x half>* %b
+  ret void
 }
 
 ; v2f16 is not legal for NEON, so use SVE
-define <2 x half> @fcvt_v2f64_v2f16(<2 x double> %op1) #0 {
+define void @fcvt_v2f64_v2f16(<2 x double>* %a, <2 x half>* %b) #0 {
 ; CHECK-LABEL: fcvt_v2f64_v2f16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    // kill: def $q0 killed $q0 def $z0
+; CHECK-NEXT:    ldr q0, [x0]
 ; CHECK-NEXT:    ptrue p0.d
 ; CHECK-NEXT:    fcvt z0.h, p0/m, z0.d
 ; CHECK-NEXT:    uzp1 z0.s, z0.s, z0.s
 ; CHECK-NEXT:    uzp1 z0.h, z0.h, z0.h
-; CHECK-NEXT:    // kill: def $d0 killed $d0 killed $z0
+; CHECK-NEXT:    str s0, [x1]
 ; CHECK-NEXT:    ret
+  %op1 = load <2 x double>, <2 x double>* %a
   %res = fptrunc <2 x double> %op1 to <2 x half>
-  ret <2 x half> %res
+  store <2 x half> %res, <2 x half>* %b
+  ret void
 }
 
-define <4 x half> @fcvt_v4f64_v4f16(<4 x double>* %a) #0 {
+define void @fcvt_v4f64_v4f16(<4 x double>* %a, <4 x half>* %b) #0 {
 ; CHECK-LABEL: fcvt_v4f64_v4f16:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.d, vl4
 ; CHECK-NEXT:    ld1d { z0.d }, p0/z, [x0]
-; CHECK-NEXT:    ptrue p0.d
 ; CHECK-NEXT:    fcvt z0.h, p0/m, z0.d
-; CHECK-NEXT:    uzp1 z0.s, z0.s, z0.s
-; CHECK-NEXT:    uzp1 z0.h, z0.h, z0.h
-; CHECK-NEXT:    // kill: def $d0 killed $d0 killed $z0
+; CHECK-NEXT:    st1h { z0.d }, p0, [x1]
 ; CHECK-NEXT:    ret
   %op1 = load <4 x double>, <4 x double>* %a
   %res = fptrunc <4 x double> %op1 to <4 x half>
-  ret <4 x half> %res
+  store <4 x half> %res, <4 x half>* %b
+  ret void
 }
 
-define <8 x half> @fcvt_v8f64_v8f16(<8 x double>* %a) #0 {
+define void @fcvt_v8f64_v8f16(<8 x double>* %a, <8 x half>* %b) #0 {
 ; Ensure sensible type legalisation
 ; VBITS_EQ_256-LABEL: fcvt_v8f64_v8f16:
 ; VBITS_EQ_256:       // %bb.0:
 ; VBITS_EQ_256-NEXT:    mov x8, #4
 ; VBITS_EQ_256-NEXT:    ptrue p0.d, vl4
 ; VBITS_EQ_256-NEXT:    ld1d { z0.d }, p0/z, [x0, x8, lsl #3]
 ; VBITS_EQ_256-NEXT:    ld1d { z1.d }, p0/z, [x0]
 ; VBITS_EQ_256-NEXT:    ptrue p0.d
 ; VBITS_EQ_256-NEXT:    fcvt z0.h, p0/m, z0.d
 ; VBITS_EQ_256-NEXT:    fcvt z1.h, p0/m, z1.d
 ; VBITS_EQ_256-NEXT:    uzp1 z0.s, z0.s, z0.s
 ; VBITS_EQ_256-NEXT:    uzp1 z1.s, z1.s, z1.s
-; VBITS_EQ_256-NEXT:    uzp1 z2.h, z0.h, z0.h
-; VBITS_EQ_256-NEXT:    uzp1 z0.h, z1.h, z1.h
-; VBITS_EQ_256-NEXT:    mov v0.d[1], v2.d[0]
-; VBITS_EQ_256-NEXT:    // kill: def $q0 killed $q0 killed $z0
+; VBITS_EQ_256-NEXT:    uzp1 z0.h, z0.h, z0.h
+; VBITS_EQ_256-NEXT:    uzp1 z1.h, z1.h, z1.h
+; VBITS_EQ_256-NEXT:    mov v1.d[1], v0.d[0]
+; VBITS_EQ_256-NEXT:    str q1, [x1]
 ; VBITS_EQ_256-NEXT:    ret
 ;
 ; VBITS_GE_512-LABEL: fcvt_v8f64_v8f16:
 ; VBITS_GE_512:       // %bb.0:
 ; VBITS_GE_512-NEXT:    ptrue p0.d, vl8
 ; VBITS_GE_512-NEXT:    ld1d { z0.d }, p0/z, [x0]
-; VBITS_GE_512-NEXT:    ptrue p0.d
 ; VBITS_GE_512-NEXT:    fcvt z0.h, p0/m, z0.d
-; VBITS_GE_512-NEXT:    uzp1 z0.s, z0.s, z0.s
-; VBITS_GE_512-NEXT:    uzp1 z0.h, z0.h, z0.h
-; VBITS_GE_512-NEXT:    // kill: def $q0 killed $q0 killed $z0
+; VBITS_GE_512-NEXT:    st1h { z0.d }, p0, [x1]
 ; VBITS_GE_512-NEXT:    ret
   %op1 = load <8 x double>, <8 x double>* %a
   %res = fptrunc <8 x double> %op1 to <8 x half>
-  ret <8 x half> %res
+  store <8 x half> %res, <8 x half>* %b
+  ret void
 }
 
 define void @fcvt_v16f64_v16f16(<16 x double>* %a, <16 x half>* %b) #0 {
 ; VBITS_GE_1024-LABEL: fcvt_v16f64_v16f16:
 ; VBITS_GE_1024:       // %bb.0:
 ; VBITS_GE_1024-NEXT:    ptrue p0.d, vl16
 ; VBITS_GE_1024-NEXT:    ld1d { z0.d }, p0/z, [x0]
 ; VBITS_GE_1024-NEXT:    fcvt z0.h, p0/m, z0.d
; VBITS_GE_2048-NEXT:    ret
   ret void
 }
 
 ;
 ; FCVT D -> S
 ;
 
 ; Don't use SVE for 64-bit vectors.
-define <1 x float> @fcvt_v1f64_v1f32(<1 x double> %op1) #0 {
+define void @fcvt_v1f64_v1f32(<1 x double> %op1, <1 x float>* %b) #0 {
 ; CHECK-LABEL: fcvt_v1f64_v1f32:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    // kill: def $d0 killed $d0 def $q0
 ; CHECK-NEXT:    fcvtn v0.2s, v0.2d
+; CHECK-NEXT:    str s0, [x0]
 ; CHECK-NEXT:    ret
   %res = fptrunc <1 x double> %op1 to <1 x float>
-  ret <1 x float> %res
+  store <1 x float> %res, <1 x float>* %b
+  ret void
 }
 
 ; Don't use SVE for 128-bit vectors.
-define <2 x float> @fcvt_v2f64_v2f32(<2 x double> %op1) #0 {
+define void @fcvt_v2f64_v2f32(<2 x double> %op1, <2 x float>* %b) #0 {
 ; CHECK-LABEL: fcvt_v2f64_v2f32:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    fcvtn v0.2s, v0.2d
+; CHECK-NEXT:    str d0, [x0]
 ; CHECK-NEXT:    ret
   %res = fptrunc <2 x double> %op1 to <2 x float>
-  ret <2 x float> %res
+  store <2 x float> %res, <2 x float>* %b
+  ret void
 }
 
-define <4 x float> @fcvt_v4f64_v4f32(<4 x double>* %a) #0 {
+define void @fcvt_v4f64_v4f32(<4 x double>* %a, <4 x float>* %b) #0 {
 ; CHECK-LABEL: fcvt_v4f64_v4f32:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.d, vl4
 ; CHECK-NEXT:    ld1d { z0.d }, p0/z, [x0]
-; CHECK-NEXT:    ptrue p0.d
 ; CHECK-NEXT:    fcvt z0.s, p0/m, z0.d
-; CHECK-NEXT:    uzp1 z0.s, z0.s, z0.s
-; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0
+; CHECK-NEXT:    st1w { z0.d }, p0, [x1]
 ; CHECK-NEXT:    ret
   %op1 = load <4 x double>, <4 x double>* %a
   %res = fptrunc <4 x double> %op1 to <4 x float>
-  ret <4 x float> %res
+  store <4 x float> %res, <4 x float>* %b
+  ret void
 }
 
 define void @fcvt_v8f64_v8f32(<8 x double>* %a, <8 x float>* %b) #0 {
 ; Ensure sensible type legalisation
 ; VBITS_EQ_256-LABEL: fcvt_v8f64_v8f32:
 ; VBITS_EQ_256:       // %bb.0:
 ; VBITS_EQ_256-NEXT:    mov x8, #4
 ; VBITS_EQ_256-NEXT:    ptrue p0.d, vl4