[PATCH] Add XINSN macro and use it within NEXT_INSN/PREV_INSN (was Re: [PATCH] Force rtl templates to be inlined)

[David Malcolm]

On Thu, 2014-09-04 at 22:22 +0200, Jakub Jelinek wrote:
> On Thu, Sep 04, 2014 at 04:04:17PM -0400, David Malcolm wrote:
> > --- a/gcc/rtl.h
> > +++ b/gcc/rtl.h
> > @@ -195,6 +195,7 @@ union rtunion
> >    unsigned int rt_uint;
> >    const char *rt_str;
> >    rtx rt_rtx;
> > +  rtx_insn *rt_insn;
> >    rtvec rt_rtvec;
> >    enum machine_mode rt_type;
> >    addr_diff_vec_flags rt_addr_diff_vec_flags;
> > @@ -1208,6 +1209,7 @@ extern void rtl_check_failed_flag (const char *, const_rtx, const char *,
> >  #define XUINT(RTX, N)   (RTL_CHECK2 (RTX, N, 'i', 'n').rt_uint)
> >  #define XSTR(RTX, N)	(RTL_CHECK2 (RTX, N, 's', 'S').rt_str)
> >  #define XEXP(RTX, N)	(RTL_CHECK2 (RTX, N, 'e', 'u').rt_rtx)
> 
> Shouldn't XEXP be changed into RTL_CHECK1 (RTX, N, 'e').rt_rtx
> then and the accessors of first operand of INSN_LIST and only operand of
> LABEL_REF be changed to XINSN too?  Of course doesn't have to be done
> immediately, can be done as a followup.

I suppose so, but I don't see an easy way of locating such XEXP users
beyond building with ENABLE_RTL_CHECKING, and checking on every
configuration, and trying to exercise all code paths.  Can we consider
that a *long-term* followup?

Use of XINSN does introduce a hole in the rtx-classes type-safety
scheme, in that it's only checked with ENABLE_RTL_CHECKING.  I
considered it acceptable in the given patch since the
SET_NEXT_INSN/SET_PREV_INSN lvalue accessors return an rtx_insn *& and
thus will only accept an rtx_insn * as an rvalue - but I'm a bit nervous
about its use elsewhere in the code; I'd rather we used rtx_insn_list
for homogeneous lists of INSN_LIST nodes, and maybe an rtx_label_ref
class for LABEL_REF, and perhaps an rtx_reg_note class for heterogeneous
lists of INSN_LIST/EXPR_LIST/INT_LIST nodes for REG_NOTES.

> > +#define XINSN(RTX, N)	(RTL_CHECK1 (RTX, N, 'u').rt_insn)
> >  #define XVEC(RTX, N)	(RTL_CHECK2 (RTX, N, 'E', 'V').rt_rtvec)
> >  #define XMODE(RTX, N)	(RTL_CHECK1 (RTX, N, 'M').rt_type)
> >  #define XTREE(RTX, N)   (RTL_CHECK1 (RTX, N, 't').rt_tree)
> 
> 	Jakub