[llvm] Introducing a new ISD::POISON SDNode to represent the poison value in the IR. (PR #125883)

[zhijian lin via llvm-commits]

================
@@ -2783,6 +2785,7 @@ void DAGTypeLegalizer::PromoteFloatResult(SDNode *N, unsigned ResNo) {
 
     case ISD::SINT_TO_FP:
     case ISD::UINT_TO_FP: R = PromoteFloatRes_XINT_TO_FP(N); break;
+    case ISD::POISON:
----------------
diggerlin wrote:

I delete all the ` case ISD::POISON:` in the file since they are not hit by current  test case. otherwise the patch will be too big. They will be added in a later patch with new test case.

https://github.com/llvm/llvm-project/pull/125883