Fix unassigned add handling in aarch64

Author: chansuke

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -5711,13 +5711,17 @@ SDValue AArch64TargetLowering::LowerINTRINSIC_WO_CHAIN(SDValue Op,
   case Intrinsic::aarch64_neon_urhadd:
   case Intrinsic::aarch64_neon_shadd:
   case Intrinsic::aarch64_neon_uhadd: {
+    bool IsUnsignedAdd = IntNo == Intrinsic::aarch64_neon_uhadd;
     bool IsSignedAdd = (IntNo == Intrinsic::aarch64_neon_srhadd ||
                         IntNo == Intrinsic::aarch64_neon_shadd);
     bool IsRoundingAdd = (IntNo == Intrinsic::aarch64_neon_srhadd ||
                           IntNo == Intrinsic::aarch64_neon_urhadd);
-    unsigned Opcode = IsSignedAdd
-                          ? (IsRoundingAdd ? ISD::AVGCEILS : ISD::AVGFLOORS)
-                          : (IsRoundingAdd ? ISD::AVGCEILU : ISD::AVGFLOORU);
+    unsigned Opcode;
+    if (IsUnsignedAdd) {
+      Opcode = IsRoundingAdd ? ISD::AVGCEILU : ISD::AVGFLOORU;
+    } else {
+      Opcode = IsRoundingAdd ? ISD::AVGCEILS : ISD::AVGFLOORS;
+    }
     return DAG.getNode(Opcode, dl, Op.getValueType(), Op.getOperand(1),
                        Op.getOperand(2));
   }

llvm/test/CodeGen/AArch64/aarch64-non-negative-args.ll

@@ -0,0 +1,13 @@
+; RUN: llc -mtriple=aarch64-unknown-linux-gnu < %s | FileCheck %s
+
+define <8 x i16> @uhadd_in_disguise(<8 x i16> %a0, <8 x i16> %a1) {
+; CHECK-LABEL: uhadd_in_disguise:
+; CHECK:       and
+; CHECK-NEXT:  uhadd
+; CHECK-NEXT:  ret
+  %m0 = and <8 x i16> %a0, <i16 510, i16 510, i16 510, i16 510, i16 510, i16 510, i16 510, i16 510>
+  %m1 = and <8 x i16> %a1, <i16 510, i16 510, i16 510, i16 510, i16 510, i16 510, i16 510, i16 510>
+  %r = call <8 x i16> @llvm.aarch64.neon.shadd.v8i16(<8 x i16> %m0, <8 x i16> %m1)
+  ret <8 x i16> %r
+}
+declare <8 x i16> @llvm.aarch64.neon.shadd.v8i16(<8 x i16>, <8 x i16>)