[Beignet] [PATCH V2] GBE: optimize IMM handling for SEL/SEL_CMP/CMP.

[Song, Ruiling]

> +    }
> +    // If it's a compare instruction, theoritically, we can easily revert the condition code to
> +    // switch the two operands. But we can't do that for float due to the NaN's exist.
> +    // For a normal select instruction, we can always inverse the predication to switch the two
> +    // operands' position.
> +    else if (OCL_OPTIMIZE_IMMEDIATE && dag0 != NULL &&
> +             dag0->insn.getOpcode() == OP_LOADI && canGetRegisterFromImmediate(dag0->insn) &&
> +             ((dag.insn.isMemberOf<CompareInstruction>() && type != TYPE_FLOAT && type != TYPE_DOUBLE) ||
> +              (dag.insn.isMemberOf<SelectInstruction>()) ||
> +              (dag.insn.getOpcode() == OP_ORD))) {
Why do we need to optimize for OP_ORD here?

    } else if(opcode == OP_ORD) {
          sel.push();
            sel.CMP(GEN_CONDITIONAL_EQ, src0, src0, tmpDst);
            sel.curr.predicate = GEN_PREDICATE_NORMAL;
            sel.curr.flagGen = 1;
            sel.CMP(GEN_CONDITIONAL_EQ, src1, src1, tmpDst);
          sel.pop();

seems that OP_ORD cannot accept immediate operand.

> +      const auto &childInsn = cast<LoadImmInstruction>(dag0->insn);
> +      src0 = this->selReg(dag.insn.getSrc(src1Index), type);
> +      src1 = getRegisterFromImmediate(childInsn.getImmediate(), type);
> +      inverse = true;
> +      if (dag1) dag1->isRoot = 1;