Revert Emit unwinding rules for CE register value

Revert "Emit unwinding rules for CE register value" commit

Author: annkrs

IGC/DebugInfo/DwarfDebug.cpp

@@ -3268,11 +3268,6 @@ void DwarfDebug::writeFDEStackCall(VISAModule *m) {
     }
   };
 
-  auto writeUndefined = [](std::vector<uint8_t> &data, uint32_t srcReg) {
-    write(data, (uint8_t)llvm::dwarf::DW_CFA_undefined);
-    writeULEB128(data, srcReg);
-  };
-
   auto writeSameValue = [](std::vector<uint8_t> &data, uint32_t srcReg) {
     write(data, (uint8_t)llvm::dwarf::DW_CFA_same_value);
     writeULEB128(data, srcReg);
@@ -3403,24 +3398,11 @@ void DwarfDebug::writeFDEStackCall(VISAModule *m) {
   } else {
     if (m->GetType() == VISAModule::ObjectType::KERNEL) {
       // set return location to be undefined in top frame
-      writeUndefined(cfaOps[0], RegisterNumbering::IP);
+      write(cfaOps[0], (uint8_t)llvm::dwarf::DW_CFA_undefined);
+      writeULEB128(cfaOps[0], RegisterNumbering::IP);
     }
   }
 
-  // write channel enable (currently only in -O0)
-  if (CFI.CEOffsetFromFPOff != 0xffff) {
-    write(cfaOps[CFI.CEStoreIP], (uint8_t)llvm::dwarf::DW_CFA_expression);
-    writeULEB128(cfaOps[CFI.CEStoreIP], RegisterNumbering::EMask);
-    writeCFAExpr(cfaOps[CFI.CEStoreIP], CFI.CEOffsetFromFPOff);
-
-    // set EMask to undefined when epilog starts to prevent
-    // dereferencing invalid CFA
-    writeUndefined(cfaOps[CFI.callerbefp.back().end + MovGenInstSizeInBytes],
-                   RegisterNumbering::EMask);
-  } else {
-    writeUndefined(cfaOps[0], RegisterNumbering::EMask);
-  }
-
   // write callee save
   if (CFI.calleeSaveEntry.size() > 0) {
     // set holds any callee save GRF that has been saved already to stack.