mips_emul_branch
vaddr_t mips_emul_branch(struct trapframe *, vaddr_t, uint32_t, bool);
ra = mips_emul_branch((struct trapframe *)regs, pc, fpucsr, false);
mips_emul_branch(tf, tf->tf_regs[_R_PC],
reg->r_regs[_R_PC] = mips_emul_branch(tf, pc, 0, false);
va = mips_emul_branch(tf, pc, PCB_FSR(pcb), true);