Treat spilled relocatable operands specially

When RA spills a variable that is known to always contain a compile time constant, we
optimize the fill by reloading the constant using a mov rather than
loading from memory.

However, this optimization is illegal when constant being written in to
spilled variable is a relocatable value. This change prevents spill/fill
optimization for such relocatable operands.

visa/SpillManagerGMRF.h

@@ -800,7 +800,8 @@ static bool immFillCandidate(G4_INST *inst) {
  return inst->opcode() == G4_mov && inst->getExecSize() == g4::SIMD1 &&
  inst->getSrc(0)->isImm() && inst->isWriteEnableInst() &&
  inst->getDst()->getType() == inst->getSrc(0)->getType() &&
- !inst->getPredicate() && !inst->getCondMod() && !inst->getSaturate();
+ !inst->getPredicate() && !inst->getCondMod() && !inst->getSaturate() &&
+ !inst->getSrc(0)->isRelocImm();
 }
 
 G4_SrcRegRegion *getSpillFillHeader(IR_Builder &builder, G4_Declare *decl);