Question about TCG liveness_pass_1

[LIU Zhiwei]

Hi Richard,

When I read the tcg code, I find a corner case which may be a bug in 
liveness_pass_1.

I see all TEMP_TBs or global temps are set to TS_DEAD | TS_MEM when 
enter liveness_pass_1. Think about the  sequence.


1)Write_global_temp_0 // 0->TS_DEAD, but not recorded in arg_life

2)INDEX_op_qemu_st   //trigger an exception here.

3)Ref_global_temp_0   // TS_DEAD->0

4)Write_global_temp_0 // TS_DEAD | TS_MEM -> TS_DEAD

As 1) will not write to memory, its register will be reused by the 3).  
I think it may miss a write to global_temp_0 when enter an exception.


Best Regards,
Zhiwei