Index: llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -3960,7 +3960,6 @@
 SDValue DAGTypeLegalizer::WidenVecRes_EXTRACT_SUBVECTOR(SDNode *N) {
   EVT      VT = N->getValueType(0);
   EVT      WidenVT = TLI.getTypeToTransformTo(*DAG.getContext(), VT);
-  unsigned WidenNumElts = WidenVT.getVectorNumElements();
   SDValue  InOp = N->getOperand(0);
   SDValue  Idx  = N->getOperand(1);
   SDLoc dl(N);
@@ -3975,7 +3974,12 @@
   if (IdxVal == 0 && InVT == WidenVT)
     return InOp;
 
+  if (VT.isScalableVector())
+    report_fatal_error("Don't know how to widen the result of "
+                       "EXTRACT_SUBVECTOR for scalable vectors");
+
   // Check if we can extract from the vector.
+  unsigned WidenNumElts = WidenVT.getVectorNumElements();
   unsigned InNumElts = InVT.getVectorNumElements();
   if (IdxVal % WidenNumElts == 0 && IdxVal + WidenNumElts < InNumElts)
     return DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, WidenVT, InOp, Idx);
Index: llvm/test/CodeGen/AArch64/sve-calling-convention-mixed.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-calling-convention-mixed.ll
+++ llvm/test/CodeGen/AArch64/sve-calling-convention-mixed.ll
@@ -198,6 +198,18 @@
   ret <vscale x 1 x i32> %1
 }
 
+
+define <vscale x 1 x i32> @foo8(<vscale x 1 x i32> %a, <vscale x 1 x i32> %b) {
+; CHECK-LABEL: foo8:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    add z0.s, z0.s, z1.s
+; CHECK-NEXT:    ret
+entry:
+  %c = add <vscale x 1 x i32> %a, %b
+  ret <vscale x 1 x i32> %c
+}
+
+
 declare float @callee1(float, <vscale x 8 x double>, <vscale x 8 x double>, <vscale x 2 x double>)
 declare float @callee2(i32, i32, i32, i32, i32, i32, i32, i32, float, <vscale x 8 x double>, <vscale x 8 x double>)
 declare float @callee3(float, float, <vscale x 8 x double>, <vscale x 6 x double>, <vscale x 2 x double>)
Index: llvm/test/CodeGen/AArch64/sve-extract-vector.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-extract-vector.ll
+++ llvm/test/CodeGen/AArch64/sve-extract-vector.ll
@@ -105,7 +105,30 @@
   ret <16 x i8> %retval
 }
 
+
+; Extracting illegal subvectors
+
+define <vscale x 1 x i32> @extract_nxv1i32_nxv4i32(<vscale x 4 x i32> %vec) nounwind {
+; CHECK-LABEL: extract_nxv1i32_nxv4i32:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ret
+  %retval = call <vscale x 1 x i32> @llvm.experimental.vector.extract.nxv1i32.nxv4i32(<vscale x 4 x i32> %vec, i64 0)
+  ret <vscale x 1 x i32> %retval
+}
+
+define <vscale x 1 x i16> @extract_nxv1i16_nxv6i16(<vscale x 6 x i16> %vec) nounwind {
+; CHECK-LABEL: extract_nxv1i16_nxv6i16:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ret
+  %retval = call <vscale x 1 x i16> @llvm.experimental.vector.extract.nxv1i16.nxv6i16(<vscale x 6 x i16> %vec, i64 0)
+  ret <vscale x 1 x i16> %retval
+}
+
+
 declare <2 x i64> @llvm.experimental.vector.extract.v2i64.nxv2i64(<vscale x 2 x i64>, i64)
 declare <4 x i32> @llvm.experimental.vector.extract.v4i32.nxv4i32(<vscale x 4 x i32>, i64)
 declare <8 x i16> @llvm.experimental.vector.extract.v8i16.nxv8i16(<vscale x 8 x i16>, i64)
 declare <16 x i8> @llvm.experimental.vector.extract.v16i8.nxv16i8(<vscale x 16 x i8>, i64)
+
+declare <vscale x 1 x i32> @llvm.experimental.vector.extract.nxv1i32.nxv4i32(<vscale x 4 x i32>, i64)
+declare <vscale x 1 x i16> @llvm.experimental.vector.extract.nxv1i16.nxv6i16(<vscale x 6 x i16>, i64)