Re: Doubt about Pseudo register uses.

[Chunjiang Li]

Thx.
I also guessed that.
But, for I am a rookie in GCC, I know little about GCC, need advice.

 Ian Lance Taylor <ian@airs.com>:

> Chunjiang Li <chunjiang@nudt.edu.cn> writes:
>
> > I wonder is it true that one Pseudo  register is only corresponding to one
>  basic block?
>
> No, it isn't.
>
> > the reg_info struct is:
> >
> > typedef struct reg_info_def
> > {				/* fields set by reg_scan */
> >   int first_uid;		/* UID of first insn to use (REG n) */
> >   int last_uid;			/* UID of last insn to use (REG n) */
> >
> > 				/* fields set by reg_scan & flow_analysis */
> >   int sets;			/* # of times (REG n) is set */
> >
> > 				/* fields set by flow_analysis */
> >   int refs;			/* # of times (REG n) is used or set */
> >   int freq;			/* # estimated frequency (REG n) is used or set */
> >   int deaths;			/* # of times (REG n) dies */
> >   int live_length;		/* # of instructions (REG n) is live */
> >   int calls_crossed;		/* # of calls (REG n) is live across */
> >   int basic_block;		/* # of basic blocks (REG n) is used in */
> > } reg_info;
> >
> > It seems that one Pseudo register is only used in one basic block.
>
> If the register is used in more than one basic block, the basic_block
> field is set to REG_BLOCK_GLOBAL.  See REG_BASIC_BLOCK in
> basic-block.h and flow.c.
>
> Ian
> 



Creative Compiler Research Group,
National University of Defense Technology, China.