[llvm] Add SD matchers and unit test coverage for ISD::VECTOR_SHUFFLE (PR #119592)

[Min-Yih Hsu via llvm-commits]

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@@ -119,6 +119,33 @@ TEST_F(SelectionDAGPatternMatchTest, matchValueType) {
   EXPECT_FALSE(sd_match(Op2, m_ScalableVectorVT()));
 }
 
+TEST_F(SelectionDAGPatternMatchTest, matchVecShuffle) {
+  SDLoc DL;
+  auto Int32VT = EVT::getIntegerVT(Context, 32);
+  auto VInt32VT = EVT::getVectorVT(Context, Int32VT, 4);
+  SmallVector<int, 4> MaskData = {2, 0, 3, 1};
+  SmallVector<int, 4> otherMaskData = {1, 2, 3, 4};
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mshockwave wrote:

nit: can we use `const std::array<int, 4>` here instead of SmallVector?

https://github.com/llvm/llvm-project/pull/119592