--- /dev/null
+// RUN: not llvm-mc -triple=aarch64 -show-encoding -mattr=+sve2 2>&1 < %s| FileCheck %s
+
+
+// ------------------------------------------------------------------------- //
+// Invalid element widths.
+
+ext z0.h, { z1.h, z2.h }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: invalid element width
+// CHECK-NEXT: ext z0.h, { z1.h, z2.h }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+ext z0.s, { z1.s, z2.s }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: invalid element width
+// CHECK-NEXT: ext z0.s, { z1.s, z2.s }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+ext z0.d, { z1.d, z2.d }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: invalid element width
+// CHECK-NEXT: ext z0.d, { z1.d, z2.d }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+
+// ------------------------------------------------------------------------- //
+// Invalid immediate range.
+
+ext z0.b, { z1.b, z2.b }, #-1
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: immediate must be an integer in range [0, 255].
+// CHECK-NEXT: ext z0.b, { z1.b, z2.b }, #-1
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+ext z0.b, { z1.b, z2.b }, #256
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: immediate must be an integer in range [0, 255].
+// CHECK-NEXT: ext z0.b, { z1.b, z2.b }, #256
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+
+// --------------------------------------------------------------------------//
+// Invalid vector list.
+
+ext z0.b, { }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: vector register expected
+// CHECK-NEXT: ext z0.b, { }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+ext z0.b, { z1.b }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: invalid operand for instruction
+// CHECK-NEXT: ext z0.b, { z1.b }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+ext z0.b, { z1.b, z2.b, z3.b }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: invalid operand for instruction
+// CHECK-NEXT: ext z0.b, { z1.b, z2.b, z3.b }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+ext z0.b, { z1.b, z2.h }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: mismatched register size suffix
+// CHECK-NEXT: ext z0.b, { z1.b, z2.h }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+ext z0.b, { z1.b, z31.b }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: registers must be sequential
+// CHECK-NEXT: ext z0.b, { z1.b, z31.b }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+ext z0.b, { v0.4b, v1.4b }, #0
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: invalid operand for instruction
+// CHECK-NEXT: ext z0.b, { v0.4b, v1.4b }, #0
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+
+// --------------------------------------------------------------------------//
+// Negative tests for instructions that are incompatible with movprfx
+
+movprfx z31, z6
+ext z31.b, { z30.b, z31.b }, #255
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: instruction is unpredictable when following a movprfx, suggest replacing movprfx with mov
+// CHECK-NEXT: ext z31.b, { z30.b, z31.b }, #255
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+movprfx z31.b, p0/z, z6.b
+ext z31.b, { z30.b, z31.b }, #255
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: instruction is unpredictable when following a movprfx, suggest replacing movprfx with mov
+// CHECK-NEXT: ext z31.b, { z30.b, z31.b }, #255
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
--- /dev/null
+// RUN: llvm-mc -triple=aarch64 -show-encoding -mattr=+sve2 < %s \
+// RUN: | FileCheck %s --check-prefixes=CHECK-ENCODING,CHECK-INST
+// RUN: not llvm-mc -triple=aarch64 -show-encoding < %s 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK-ERROR
+// RUN: llvm-mc -triple=aarch64 -filetype=obj -mattr=+sve2 < %s \
+// RUN: | llvm-objdump -d -mattr=+sve2 - | FileCheck %s --check-prefix=CHECK-INST
+// RUN: llvm-mc -triple=aarch64 -filetype=obj -mattr=+sve2 < %s \
+// RUN: | llvm-objdump -d - | FileCheck %s --check-prefix=CHECK-UNKNOWN
+
+ext z0.b, { z1.b, z2.b }, #0
+// CHECK-INST: ext z0.b, { z1.b, z2.b }, #0
+// CHECK-ENCODING: [0x20,0x00,0x60,0x05]
+// CHECK-ERROR: instruction requires: sve2
+// CHECK-UNKNOWN: 20 00 60 05 <unknown>
+
+ext z31.b, { z30.b, z31.b }, #255
+// CHECK-INST: ext z31.b, { z30.b, z31.b }, #255
+// CHECK-ENCODING: [0xdf,0x1f,0x7f,0x05]
+// CHECK-ERROR: instruction requires: sve2
+// CHECK-UNKNOWN: df 1f 7f 05 <unknown>