Fix the issue that flag register should not be propagated to ternary instruction

Flag register is not allowed in any operand of ternary instruction. So, shouldn't
propagate flag register to ternary instruction.

Author: fangliu2020

visa/G4_IR.cpp

@@ -7975,6 +7975,10 @@ bool G4_INST::canSrcBeFlagForPropagation(Gen4_Operand_Number opndNum) const {
   if (!isLogic())
     return false;
 
+  // flag register is not allowed in ternary instruction
+  if (getNumSrc() == 3)
+    return false;
+
   // For non-commutative opcodes, only src0 can be flag. Otherwise, HWConformity
   // may generate more mov instructions to fix the illegal flag reg operand.
   // For commutative opcodes, it is fine to have flag reg on non-src0 sources as

visa/G4_Verifier.cpp

@@ -465,6 +465,12 @@ void G4Verifier::verifyOpnd(G4_Operand *opnd, G4_INST *inst) {
       }
     }
   } else {
+    // Only valid ARF type are NULL and Accumulator for ternary instructions
+    if (inst->getNumSrc() == 3) {
+      if (opnd->isAreg() && !opnd->isNullReg() && !opnd->isAccReg())
+        vISA_ASSERT(false, "Not allowed ARF in ternary instruction");
+    }
+
     if (opnd->isSrcRegRegion() && opnd->isRightBoundSet()) {
       G4_SrcRegRegion newRgn(*(opnd->asSrcRegRegion()));