[llvm] [TableGen] Add a field to filter out GenericTable entries (PR #65458)

[Wang Pengcheng via llvm-commits]

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@@ -734,22 +738,25 @@ irrelevant.
 
   def ATable : GenericTable {
     let FilterClass = "AEntry";
+    let FilterClassField = "IsNeeded";
     let Fields = ["Str", "Val1", "Val2"];
     let PrimaryKey = ["Val1", "Val2"];
     let PrimaryKeyName = "lookupATableByValues";
   }
 
-  class AEntry<string str, int val1, int val2> {
+  class AEntry<string str, int val1, int val2, bit isNeeded> {
     string Str = str;
     bits<8> Val1 = val1;
     bits<10> Val2 = val2;
+    bit IsNeeded = isNeeded;
   }
 
-  def : AEntry<"Bob",   5, 3>;
-  def : AEntry<"Carol", 2, 6>;
-  def : AEntry<"Ted",   4, 4>;
-  def : AEntry<"Alice", 4, 5>;
-  def : AEntry<"Costa", 2, 1>;
+  def : AEntry<"Bob",   5, 3, 1>;
+  def : AEntry<"Carol", 2, 6, 1>;
+  def : AEntry<"Ted",   4, 4, 1>;
+  def : AEntry<"Alice", 4, 5, 1>;
+  def : AEntry<"Costa", 2, 1, 1>;
+  def : AEntry<"Dale",  2, 1, 0>;
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wangpc-pp wrote:

Yes! We won't generate unneeded C++ fields because these C++ fields are specified by `Fields`.

https://github.com/llvm/llvm-project/pull/65458