BPF_ZEXT_REG
*to++ = BPF_ZEXT_REG(BPF_REG_AX);
zext_patch[1] = BPF_ZEXT_REG(0);
insns[i++] = BPF_ZEXT_REG(R0); /* Zext always inserted by verifier */
insns[i++] = BPF_ZEXT_REG(R0); /* Zext always inserted by verifier */
insn[i++] = BPF_ZEXT_REG(R0);