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

[Aidan Goldfarb via llvm-commits]

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@@ -133,13 +134,11 @@ TEST_F(SelectionDAGPatternMatchTest, matchVecShuffle) {
       DAG->getVectorShuffle(VInt32VT, DL, V0, V1, MaskData);
 
   using namespace SDPatternMatch;
+  EXPECT_TRUE(sd_match(VecShuffleWithMask, m_Shuffle(m_Value(), m_Value())));
   EXPECT_TRUE(sd_match(VecShuffleWithMask,
-                       m_Shuffle(m_Value(), m_Value(), CapturedMask)));
+                       m_Shuffle(m_Value(), m_Value(), m_Mask(CapturedMask))));
   EXPECT_TRUE(sd_match(VecShuffleWithMask,
-                       m_ShuffleSpecificMask(m_Value(), m_Value(), MaskData)));
-  EXPECT_FALSE(
-      sd_match(VecShuffleWithMask,
-               m_ShuffleSpecificMask(m_Value(), m_Value(), OtherMaskData)));
+                       m_Shuffle(m_Value(), m_Value(), m_SpecificMask(Mask))));
   EXPECT_TRUE(std::equal(MaskData.begin(), MaskData.end(), CapturedMask.begin(),
                          CapturedMask.end()));
   EXPECT_FALSE(std::equal(OtherMaskData.begin(), OtherMaskData.end(),
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AidanGoldfarb wrote:

I added the test you suggested, which does `MaskData == OtherMaskData` inside of `m_SpecificMask`. However is the other negative test, which does effectively `CaptureMask==OtherMaskData`, not still desired to check that the mask was successfully captured by `m_Mask`? It is tested for equality with the test above `MaskData==CaptureMask`, but in the case of an empty mask or an incorrect equality comparison (as I mistakenly implemented before) should we keep it around? I am not very sure of the coding standards of how much overlap can exist between tests before one is deleted. 
                     

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