[llvm] [GISel] Add KnownFPClass Analysis to GISelValueTrackingPass (PR #134611)

[Matt Arsenault via llvm-commits]

================
@@ -762,6 +764,32 @@ struct CompareOp_match {
   }
 };
 
+template <typename LHS_P, typename Test_P, unsigned Opcode>
+struct ClassifyOp_match {
+  LHS_P L;
+  Test_P T;
+
+  ClassifyOp_match(const LHS_P &LHS, const Test_P &Tst) : L(LHS), T(Tst) {}
+
+  template <typename OpTy>
+  bool match(const MachineRegisterInfo &MRI, OpTy &&Op) {
+    MachineInstr *TmpMI;
+    if (!mi_match(Op, MRI, m_MInstr(TmpMI)) || TmpMI->getOpcode() != Opcode)
+      return false;
+
+    Register LHS = TmpMI->getOperand(1).getReg();
+    if (!L.match(MRI, LHS))
+      return false;
+
+    FPClassTest TmpClass =
+        static_cast<FPClassTest>(TmpMI->getOperand(2).getImm());
+    if (T.match(MRI, TmpClass))
+      return true;
+
+    return false;
----------------
arsenm wrote:

```suggestion
    return T.match(MRI, TmpClass);
```

https://github.com/llvm/llvm-project/pull/134611