[TableGen] Add `countRendererFns` to `InstructionOperandMatcher`

[Pierre-vh]

Summary

Without it, the count of renderer functions is inaccurate and, in some
edge cases (like the patterns added in D134354), we can actually
go out of bounds (run out of pre-allocated renderer function spaces
in the GISel state)

llvm/test/TableGen/GlobalISelEmitter.td

 // CHECK-NEXT:    bool testImmPredicate_I64(unsigned PredicateID, int64_t Imm) const override;
 // CHECK-NEXT:    bool testImmPredicate_APInt(unsigned PredicateID, const APInt &Imm) const override;
 // CHECK-NEXT:    bool testImmPredicate_APFloat(unsigned PredicateID, const APFloat &Imm) const override;
 // CHECK-NEXT:    const int64_t *getMatchTable() const override;
 // CHECK-NEXT:    bool testMIPredicate_MI(unsigned PredicateID, const MachineInstr &MI, const std::array<const MachineOperand *, 3> &Operands) const override;
 // CHECK-NEXT:  #endif // ifdef GET_GLOBALISEL_TEMPORARIES_DECL
 
 // CHECK-LABEL: #ifdef GET_GLOBALISEL_TEMPORARIES_INIT
-// CHECK-NEXT:    , State(2),
+// CHECK-NEXT:    , State(3),
 // CHECK-NEXT:    ISelInfo(TypeObjects, NumTypeObjects, FeatureBitsets, ComplexPredicateFns, CustomRenderers)
 // CHECK-NEXT:  #endif // ifdef GET_GLOBALISEL_TEMPORARIES_INIT
 
 // CHECK-LABEL: enum SubtargetFeatureBits : uint8_t {
 // CHECK-NEXT:    Feature_HasABit = 0,
 // CHECK-NEXT:    Feature_HasBBit = 1,
 // CHECK-NEXT:    Feature_HasCBit = 2,
 // CHECK-NEXT:  };

llvm/utils/TableGen/GlobalISelEmitter.cpp

if (B.OperandPredicateMatcher::isHigherPriorityThan(*this))
       return false;
 
     if (const InstructionOperandMatcher *BP =
             dyn_cast<InstructionOperandMatcher>(&B))
       if (InsnMatcher->isHigherPriorityThan(*BP->InsnMatcher))
         return true;
     return false;
   }
+
+  /// Report the maximum number of temporary operands needed by the predicate
+  /// matcher.
+  unsigned countRendererFns() const override {
+    return InsnMatcher->countRendererFns();
+  }
 };
 
 void InstructionMatcher::optimize() {
   SmallVector<std::unique_ptr<PredicateMatcher>, 8> Stash;
   const auto &OpcMatcher = getOpcodeMatcher();
 
   Stash.push_back(predicates_pop_front());
   if (Stash.back().get() == &OpcMatcher) {