[llvm] [Xtensa] Implement lowering SELECT_CC, SETCC. (PR #97017)

[Andrei Safronov via llvm-commits]

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@@ -697,6 +718,126 @@ const char *XtensaTargetLowering::getTargetNodeName(unsigned Opcode) const {
     return "XtensaISD::PCREL_WRAPPER";
   case XtensaISD::RET:
     return "XtensaISD::RET";
+  case XtensaISD::SELECT_CC:
+    return "XtensaISD::SELECT_CC";
   }
   return nullptr;
 }
+
+//===----------------------------------------------------------------------===//
+// Custom insertion
+//===----------------------------------------------------------------------===//
+
+static int GetBranchKind(int Cond, bool &BrInv) {
+  switch (Cond) {
+  case ISD::SETEQ:
+    return Xtensa::BEQ;
+  case ISD::SETNE:
+    return Xtensa::BNE;
+  case ISD::SETLT:
+    return Xtensa::BLT;
+  case ISD::SETLE:
+    BrInv = true;
+    return Xtensa::BGE;
+  case ISD::SETGT:
+    BrInv = true;
+    return Xtensa::BLT;
+  case ISD::SETGE:
+    return Xtensa::BGE;
+  case ISD::SETULT:
+    return Xtensa::BLTU;
+  case ISD::SETULE:
+    BrInv = true;
----------------
andreisfr wrote:

I added patterns for brcc with  ULE and UGT codes:
[ brcc operation](https://github.com/llvm/llvm-project/blob/ac634c8b08adef1da8114821fbb7ad8a70e994a2/llvm/lib/Target/Xtensa/XtensaInstrInfo.td#L419)
And the same approach is used in lowering SELECTCC. 
So, your suggestion is to remove such ULE/UGT handling in code and use setCondCodeAction(CC, Expand) instead?

https://github.com/llvm/llvm-project/pull/97017