Index: llvm/lib/Target/AArch64/AArch64ISelLowering.h
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelLowering.h
+++ llvm/lib/Target/AArch64/AArch64ISelLowering.h
@@ -415,12 +415,14 @@
 // Any instruction that defines a 32-bit result zeros out the high half of the
 // register. Truncate can be lowered to EXTRACT_SUBREG. CopyFromReg may
 // be copying from a truncate. But any other 32-bit operation will zero-extend
-// up to 64 bits.
+// up to 64 bits. AssertSext/AssertZext aren't saying anything about the upper
+// 32 bits, they're probably just qualifying a CopyFromReg.
 // FIXME: X86 also checks for CMOV here. Do we need something similar?
 static inline bool isDef32(const SDNode &N) {
   unsigned Opc = N.getOpcode();
   return Opc != ISD::TRUNCATE && Opc != TargetOpcode::EXTRACT_SUBREG &&
-         Opc != ISD::CopyFromReg;
+         Opc != ISD::CopyFromReg && Opc != ISD::AssertSext &&
+         Opc != ISD::AssertZext;
 }
 
 } // end anonymous namespace
Index: llvm/test/CodeGen/AArch64/arm64-assert-zext-sext.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/arm64-assert-zext-sext.ll
@@ -0,0 +1,101 @@
+; RUN: llc -O2 -mtriple=aarch64-linux-gnu < %s | FileCheck %s
+
+%struct.a = type { i32 }
+
+@a = internal unnamed_addr global i1 false, align 8
+@b = common local_unnamed_addr global i32 0, align 4
+@e = common local_unnamed_addr global i32 0, align 4
+@d = common local_unnamed_addr global i32 0, align 4
+@.str = private unnamed_addr constant [6 x i8] c"%llu\0A\00", align 1
+@g = global i32 193, align 4
+@f = local_unnamed_addr global i8* bitcast (i32* @g to i8*), align 8
+@j = common global i32 0, align 4
+@k = global i16* bitcast (i32* @j to i16*), align 8
+@n = local_unnamed_addr global i32** bitcast (i16** @k to i32**), align 8
+@m = common local_unnamed_addr global %struct.a zeroinitializer, align 4
+
+declare i32 @printf(i8* nocapture readonly, ...) local_unnamed_addr
+
+define i32 @assertzext() local_unnamed_addr {
+entry:
+  %.b = load i1, i1* @a, align 8
+  %i = select i1 %.b, i64 0, i64 66296709418
+  store i1 true, i1* @a, align 8
+  %conv.i = trunc i64 %i to i32
+  %.pr.i = load i32, i32* @b, align 4
+  %cmp11.i = icmp eq i32 %.pr.i, 0
+  br i1 %cmp11.i, label %end, label %for.body.lr.ph.i
+
+for.body.lr.ph.i:                                 ; preds = %entry
+  %i1 = load i32, i32* @e, align 4
+  %sext.i = and i64 %i, 1872199978
+  %inc.i.peel = add nsw i32 %.pr.i, 1
+  %cmp.i.peel = icmp eq i32 %inc.i.peel, 0
+  br i1 %cmp.i.peel, label %for.cond.for.end_crit_edge.i, label %for.body.i
+
+for.body.i:                                       ; preds = %for.body.i, %for.body.lr.ph.i
+  %i2 = phi i32 [ %inc.i, %for.body.i ], [ %inc.i.peel, %for.body.lr.ph.i ]
+  %inc.i = add nsw i32 %i2, 1
+  %cmp.i = icmp eq i32 %inc.i, 0
+  br i1 %cmp.i, label %for.cond.for.end_crit_edge.i, label %for.body.i
+
+for.cond.for.end_crit_edge.i:                     ; preds = %for.body.i, %for.body.lr.ph.i
+  %n.012.i.lcssa = phi i64 [ %sext.i, %for.body.lr.ph.i ], [ 0, %for.body.i ]
+  %conv2.i = sext i32 %i1 to i64
+  %i3 = inttoptr i64 %conv2.i to i64*
+  store i64 %n.012.i.lcssa, i64* %i3, align 8
+  store i32 0, i32* @b, align 4
+  br label %end
+
+end:                                              ; preds = %for.cond.for.end_crit_edge.i, %entry
+  %n.0.lcssa.i = phi i32 [ 0, %for.cond.for.end_crit_edge.i ], [ %conv.i, %entry ]
+  %call.i = tail call i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([6 x i8], [6 x i8]* @.str, i64 0, i64 0), i32 %n.0.lcssa.i)
+  %conv4.i = sext i32 %n.0.lcssa.i to i64
+  %call5.i = tail call i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([6 x i8], [6 x i8]* @.str, i64 0, i64 0), i64 %conv4.i)
+  ret i32 0
+; CHECK-LABEL: end
+; CHECK:       mov     w{{[0-9]+}}, w{{[0-9]+}}
+; CHECK:       bl      printf
+; CHECK:       mov     w{{[0-9]+}}, w{{[0-9]+}}
+; CHECK:       bl      printf
+}
+
+declare i64 @test(i64)
+
+define i32 @assertsext() {
+entry:
+  %i = load i8*, i8** @f, align 8
+  %i1 = load i8, i8* %i, align 1
+  %conv.i.i = sext i8 %i1 to i32
+  %i2 = load i32, i32* getelementptr inbounds (%struct.a, %struct.a* @m, i64 0, i32 0), align 4
+  %mul = mul nsw i32 %i2, %conv.i.i
+  %xor = xor i32 %mul, 3
+  %tobool = icmp eq i32 %xor, 0
+  br i1 %tobool, label %t.exit, label %land.end
+
+land.end:                                         ; preds = %entry
+  %conv1 = zext i32 %conv.i.i to i64
+  %conv.i.i.i = sext i32 %xor to i64
+  %div.i7 = udiv i64 2036854775807, %conv1
+  %cmp = icmp slt i64 %div.i7, %conv.i.i.i
+  %spec.select = select i1 %cmp, i32 1, i32 %conv.i.i
+  br label %t.exit
+; CHECK-LABEL: land.end
+; CHECK:       mov     w{{[0-9]+}}, w{{[0-9]+}}
+; CHECK:       udiv    x{{[0-9]+}}, x{{[0-9]+}}, x{{[0-9]+}}
+
+t.exit:                                           ; preds = %land.end, %entry
+  %i3 = phi i32 [ %conv.i.i, %entry ], [ %spec.select, %land.end ]
+  %conv3.i.i.i = trunc i32 %i3 to i16
+  %i4 = load i16*, i16** @k, align 8
+  store i16 %conv3.i.i.i, i16* %i4, align 2
+  %i5 = load i32**, i32*** @n, align 8
+  %i6 = load i32*, i32** %i5, align 8
+  %i7 = load i32, i32* %i6, align 4
+  %xor.i.i = xor i32 %i7, 8
+  store i32 %xor.i.i, i32* %i6, align 4
+  %call2.i = tail call i64 bitcast (i64 (i64)* @test to i64 (i32)*)(i32 undef)
+  %i8 = load i32, i32* @j, align 4
+  %call1 = tail call i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([6 x i8], [6 x i8]* @.str, i64 0, i64 0), i32 %i8)
+  ret i32 0
+}
Index: llvm/test/CodeGen/AArch64/shift_minsize.ll
===================================================================
--- llvm/test/CodeGen/AArch64/shift_minsize.ll
+++ llvm/test/CodeGen/AArch64/shift_minsize.ll
@@ -59,7 +59,7 @@
 ; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
 ; CHECK-NEXT:    .cfi_offset w30, -16
-; CHECK-NEXT:    // kill: def $w2 killed $w2 def $x2
+; CHECK-NEXT:    mov w2, w2
 ; CHECK-NEXT:    bl __ashlti3
 ; CHECK-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
 ; CHECK-NEXT:    ret
@@ -86,7 +86,7 @@
 ; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
 ; CHECK-NEXT:    .cfi_offset w30, -16
-; CHECK-NEXT:    // kill: def $w2 killed $w2 def $x2
+; CHECK-NEXT:    mov w2, w2
 ; CHECK-NEXT:    bl __ashrti3
 ; CHECK-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
 ; CHECK-NEXT:    ret
@@ -112,7 +112,7 @@
 ; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
 ; CHECK-NEXT:    .cfi_offset w30, -16
-; CHECK-NEXT:    // kill: def $w2 killed $w2 def $x2
+; CHECK-NEXT:    mov w2, w2
 ; CHECK-NEXT:    bl __lshrti3
 ; CHECK-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
 ; CHECK-NEXT:    ret