[llvm] [AArch64] AArch64TargetLowering::computeKnownBitsForTargetNode - add support for AArch64ISD::MOV/MVN constants (PR #154039)

[Yatao Wang via llvm-commits]

================
@@ -318,6 +318,118 @@ TEST_F(AArch64SelectionDAGTest, ComputeKnownBits_UADDO_CARRY) {
   EXPECT_EQ(Known.One, APInt(8, 0x86));
 }
 
+// Piggy-backing on the AArch64 tests to verify SelectionDAG::computeKnownBits.
+TEST_F(AArch64SelectionDAGTest, ComputeKnownBits_MOVI) {
+  SDLoc Loc;
+  auto IntSca32VT = MVT::i32;
+  auto Int8Vec8VT = MVT::v8i8;
+  auto Int16Vec8VT = MVT::v16i8;
+  auto Int4Vec16VT = MVT::v4i16;
+  auto Int8Vec16VT = MVT::v8i16;
+  auto Int2Vec32VT = MVT::v2i32;
+  auto Int4Vec32VT = MVT::v4i32;
+  auto IntVec64VT = MVT::v1i64;
+  auto Int2Vec64VT = MVT::v2i64;
+  auto N0 = DAG->getConstant(0x000000A5, Loc, IntSca32VT);
+  KnownBits Known;
+
+  auto OpMOVIedit64 = DAG->getNode(AArch64ISD::MOVIedit, Loc, IntVec64VT, N0);
+  Known = DAG->computeKnownBits(OpMOVIedit64);
+  EXPECT_EQ(Known.Zero, APInt(64, 0x00FF00FFFF00FF00));
+  EXPECT_EQ(Known.One, APInt(64, 0xFF00FF0000FF00FF));
+
+  auto OpMOVIedit128 = DAG->getNode(AArch64ISD::MOVIedit, Loc, Int2Vec64VT, N0);
+  Known = DAG->computeKnownBits(OpMOVIedit128);
+  EXPECT_EQ(Known.Zero, APInt(64, 0x00FF00FFFF00FF00));
+  EXPECT_EQ(Known.One, APInt(64, 0xFF00FF0000FF00FF));
+
+  auto N1 = DAG->getConstant(264, Loc, IntSca32VT);
+  auto OpMOVImsl64 =
+      DAG->getNode(AArch64ISD::MOVImsl, Loc, Int2Vec32VT, N0, N1);
+  Known = DAG->computeKnownBits(OpMOVImsl64);
+  EXPECT_EQ(Known.Zero, APInt(32, 0xFFFF5A00));
+  EXPECT_EQ(Known.One, APInt(32, 0x0000A5FF));
+
+  auto N2 = DAG->getConstant(272, Loc, IntSca32VT);
+  auto OpMOVImsl128 =
+      DAG->getNode(AArch64ISD::MOVImsl, Loc, Int4Vec32VT, N0, N2);
+  Known = DAG->computeKnownBits(OpMOVImsl128);
+  EXPECT_EQ(Known.Zero, APInt(32, 0xFF5A0000));
+  EXPECT_EQ(Known.One, APInt(32, 0x00A5FFFF));
+
+  auto OpMVNImsl64 =
+      DAG->getNode(AArch64ISD::MVNImsl, Loc, Int2Vec32VT, N0, N2);
+  Known = DAG->computeKnownBits(OpMVNImsl64);
+  EXPECT_EQ(Known.Zero, APInt(32, 0x00A50000));
+  EXPECT_EQ(Known.One, APInt(32, 0xFF5AFFFF));
+
+  auto OpMVNImsl128 =
+      DAG->getNode(AArch64ISD::MVNImsl, Loc, Int4Vec32VT, N0, N1);
+  Known = DAG->computeKnownBits(OpMVNImsl128);
+  EXPECT_EQ(Known.Zero, APInt(32, 0x0000A500));
+  EXPECT_EQ(Known.One, APInt(32, 0xFFFF5AFF));
+
+  auto N3 = DAG->getConstant(0, Loc, IntSca32VT);
+  auto OpMOVIshift2Vec32 =
+      DAG->getNode(AArch64ISD::MOVIshift, Loc, Int2Vec32VT, N0, N3);
+  Known = DAG->computeKnownBits(OpMOVIshift2Vec32);
+  EXPECT_EQ(Known.Zero, APInt(32, 0xFFFFFF5A));
+  EXPECT_EQ(Known.One, APInt(32, 0x000000A5));
+
+  auto N4 = DAG->getConstant(24, Loc, IntSca32VT);
+  auto OpMOVIshift4Vec32 =
+      DAG->getNode(AArch64ISD::MOVIshift, Loc, Int4Vec32VT, N0, N4);
+  Known = DAG->computeKnownBits(OpMOVIshift4Vec32);
+  EXPECT_EQ(Known.Zero, APInt(32, 0x5AFFFFFF));
+  EXPECT_EQ(Known.One, APInt(32, 0xA5000000));
+
+  auto OpMVNIshift2Vec32 =
+      DAG->getNode(AArch64ISD::MVNIshift, Loc, Int2Vec32VT, N0, N4);
+  Known = DAG->computeKnownBits(OpMVNIshift2Vec32);
+  EXPECT_EQ(Known.Zero, APInt(32, 0xA5FFFFFF));
+  EXPECT_EQ(Known.One, APInt(32, 0x5A000000));
+
+  auto OpMVNIshift4Vec32 =
+      DAG->getNode(AArch64ISD::MVNIshift, Loc, Int4Vec32VT, N0, N3);
+  Known = DAG->computeKnownBits(OpMVNIshift4Vec32);
+  EXPECT_EQ(Known.Zero, APInt(32, 0x000000A5));
+  EXPECT_EQ(Known.One, APInt(32, 0xFFFFFF5A));
+
+  auto OpMOVIshift4Vec16 =
+      DAG->getNode(AArch64ISD::MOVIshift, Loc, Int4Vec16VT, N0, N3);
+  Known = DAG->computeKnownBits(OpMOVIshift4Vec16);
+  EXPECT_EQ(Known.One, APInt(16, 0x00A5));
+  EXPECT_EQ(Known.Zero, APInt(16, 0xFF5A));
+
+  auto OpMOVIshift8Vec16 =
+      DAG->getNode(AArch64ISD::MOVIshift, Loc, Int8Vec16VT, N0, N1);
----------------
ningxinr wrote:

Initially I picked this 264 and 272 from [tryAdvSIMDModImm321s in AArch64ISelLowering.cpp](https://github.com/llvm/llvm-project/blob/344793e513b272e3f6bff018844da46eee440fe6/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp#L14563) for MOVImsl and MVNImsl. In the code MOVIshift uses 8 instead of 264, but it didn't complain when I give it 264. 

Let me change the constants and their names to reflect the actual usage in the code and make it a bit easier to read. Thanks!

https://github.com/llvm/llvm-project/pull/154039