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Re: [PATCH 007/236] New function: for_each_rtx_in_insn


On Tue, 2014-08-12 at 15:08 -0600, Jeff Law wrote:
> On 08/06/14 11:19, David Malcolm wrote:
> > gcc/
> > 	* rtl.h (for_each_rtx_in_insn): New function.
> > 	* rtlanal.c (for_each_rtx_in_insn): Likewise.
> OK.  Note that we're moving away from for_each_rtx...   I haven't 
> looked, but there's a reasonable chance we may not need it after Richard 
> S.'s work is committed.  Something to watch.

CCing Richard S, as a "heads up".

Richard, for context, the patch in this thread is this one:
https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00494.html

which adds a "for_each_rtx_in_insn" function, to work on a top-level
insn node, as part of a big cleanup I'm working on that distinguishes
between insn nodes vs arbitrary rtx nodes:
https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00498.html

I believe that your rtl-iter reworking:
 https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00133.html
hasn't landed in trunk yet (I don't see an rtl-iter.h there yet).

Summary of notes below: I think our patch series are mostly compatible,
but I think there's a conflict between them in rtlanal.c to do with
for_each_inc_dec, at patch 176 in my kit vs patch 40 of your kit.  I
think it's resolvable, though.

More detailed notes follow:

My reading of Richard's patch series is that it optimizes many specific
for_each_rtx implementations, but keeps the existing generic one around.

Some notes on all of the places in which I've made use of the new
"for_each_rtx_in_insn" in my patchkit:

cfgcleanup.c:1728:		  for_each_rtx_in_insn (&BB_END (bb1), replace_label, &rr);
cfgcleanup.c:1742:		  for_each_rtx_in_insn (&BB_END (bb1), replace_label, &rr);
  (both in outgoing_edges_match; I don't think Richard's patchkit
touches this one).


cfgcleanup.c:2002:		for_each_rtx_in_insn (&insn, replace_label, &rr);
  (in try_crossjump_to_edge; likewise, I don't think Richard's kit
touches this)


ira.c:3350:	for_each_rtx_in_insn (&insn, set_paradoxical_subreg,
  ...in update_equiv_regs, the use added in my
"[PATCH 191/236] Remove DF_REF_INSN scaffolding":
https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00554.html

It looks like Richard's
"[PATCH 25/50] ira.c:set_paradoxical_subreg": 
https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00161.html
optimizes the current code, and my reading of his patch is that it's
compatible with my patchkit; the for_each_rtx_in_insn can be eliminated.
Hence, depending on whose patch goes in first, the other patch will need
some fixup, but I think it will be trivial to fixup.


rtlanal.c:3103:  return for_each_rtx_in_insn (insn, for_each_inc_dec_find_mem, &data);
  ...in for_each_inc_dec, the use added in my:
"[PATCH 176/236] cselib and incdec":
https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00711.html

Looks like Richard's
"[PATCH 40/50] rtlanal.c:for_each_inc_dec":
https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00177.html
optimizes this.

Merging these looks more involved: in my patch series I establish that
the first param to for_each_inc_dec is an rtx_insn **, which may cause
type issues in Richard's new code as is - but perhaps may allow some
simplification?  Given that the loc passed in is an insn, am I right in
thinking we're only interested in MEM within the PATTERN of insn, right?
Also, am I right in thinking that that particular callback can't modify
the ptr that's passed in (I don't see writes back to *r)?  If so, that
suggests that we can lose an indirection from the first param, and
simply work on PATTERN (insn).


config/i386/i386.c:46886:            for_each_rtx_in_insn (&insn, (rtx_function) ix86_loop_memcount,
  (in ix86_loop_unroll_adjust)

config/s390/s390.c:11820:            for_each_rtx_in_insn (&insn, (rtx_function) check_dpu, &mem_count);
  (in s390_loop_unroll_adjust)

(as far as I can see Richard's patches don't touch the config subdirs).


Hope this is sane
Dave



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