[IR2VecTest] Avoid magic constants

Instead make the members of Vocabulary public. This was causing test
failures with #139357.

Reviewed By: svkeerthy, boomanaiden154

Pull Request: #150878

Author: arichardson

llvm/include/llvm/Analysis/IR2Vec.h

@@ -153,6 +153,7 @@ class Vocabulary {
                     static_cast<unsigned>(OperandKind::MaxOperandKind),
                 "OperandKindNames array size must match MaxOperandKind");
 
+public:
   /// Vocabulary layout constants
 #define LAST_OTHER_INST(NUM) static constexpr unsigned MaxOpcodes = NUM;
 #include "llvm/IR/Instruction.def"
@@ -162,7 +163,6 @@ class Vocabulary {
   static constexpr unsigned MaxOperandKinds =
       static_cast<unsigned>(OperandKind::MaxOperandKind);
 
-public:
   Vocabulary() = default;
   Vocabulary(VocabVector &&Vocab);
 

llvm/unittests/Analysis/IR2VecTest.cpp

@@ -364,9 +364,9 @@ TEST_F(IR2VecTestFixture, GetFunctionVector) {
   EXPECT_TRUE(FuncVec.approximatelyEquals(Embedding(2, 44.4)));
 }
 
-static constexpr unsigned MaxOpcodes = 67;
-static constexpr unsigned MaxTypeIDs = 21;
-static constexpr unsigned MaxOperands = 4;
+static constexpr unsigned MaxOpcodes = Vocabulary::MaxOpcodes;
+static constexpr unsigned MaxTypeIDs = Vocabulary::MaxTypeIDs;
+static constexpr unsigned MaxOperands = Vocabulary::MaxOperandKinds;
 
 TEST(IR2VecVocabularyTest, DummyVocabTest) {
   for (unsigned Dim = 1; Dim <= 10; ++Dim) {