Further insn-attrtab.c speedup

Hi!

This patch implements get_attr_* (insn) caching in insn-attrtab.c.
insn-attrtab.c contains stuff like:
    case 1685:  /* *vec_extractv2di_1_rex64 */
    case 1684:  /* *vec_extractv2di_1_rex64_avx */
      extract_constrain_insn_cached (insn);
      if (!((1 << which_alternative) & 0x7))
        {
          return 1;
        }
      else if (get_attr_memory (insn) == MEMORY_BOTH)
        {
          return 3;
        }
      else if (get_attr_memory (insn) == MEMORY_LOAD)
        {
          return 2;
        }
      else if (get_attr_memory (insn) == MEMORY_NONE)
        {
          return 1;
        }
      else
        {
          return 0;
        }
and get_attr_memory isn't pure (as it can call extract_insn_cached
or extract_constrain_insn_cached, recog_memoized, etc.).
This patch instead emits
  enum attr_memory cached_memory ATTRIBUTE_UNUSED;
...
    case 1685:  /* *vec_extractv2di_1_rex64 */
    case 1684:  /* *vec_extractv2di_1_rex64_avx */
      extract_constrain_insn_cached (insn);
      if (!((1 << which_alternative) & 0x7))
        {
          return 1;
        }
      else if ((cached_memory = get_attr_memory (insn)) == MEMORY_BOTH)
        {
          return 3;
        }
      else if (cached_memory == MEMORY_LOAD)
        {
          return 2;
        }
      else if (cached_memory == MEMORY_NONE)
        {
          return 1;
        }
      else
        {
          return 0;
        }
Similar for conditions like if (something && (((get_attr_memory (insn) == MEMORY_BOTH) || (get_attr_memory (insn) == MEMORY_LOAD))))
it emits if (something && ((((cached_memory = get_attr_memory (insn)) == MEMORY_BOTH || (cached_memory == MEMORY_LOAD))))
The resulting insn-attrtab.c compiled with -Wuninitialized, so I hope I've done
all the conditions when the cached attribute can be used finally right.

The patch initially scans all the conditions in a function and checks
which if..else if..else blocks check the same attribute more than once,
for such attributes emits cached_<attributename> vars at the start of
the function.  Then for each block figures again which attributes would
be good to cache there, and for those when not proven to be already cached
emits the (cached_XXX = get_attr_XXX (insn)) == YYY form, otherwise
cached_XXX == YYY form.  write_test_expr tracks 3 different sets of attributes
that are known to be cached: one set is what can be cached during the current
write_test_expr call - anything that is known to be cached before the if (resp.
else if) and in || (resp. &&) series operands after it has been set.
The second set which it tracks is which attributes are known to be set
for when the whole if/else if condition evaluates to 1 (i.e. what
is known to be set inside of the then block) and another set
what is known to be set in else if/else block after it.
Say (cached_XXX = get_attr_XXX (insn)) == YYY right after if (
will known to be set in both places, for
if (something && (cached_XXX = get_attr_XXX (insn)) == YYY)
only in the then block and
if (something || (cached_XXX = get_attr_XXX (insn)) == YYY)
only in the else block.
if ((something || (cached_XXX = get_attr_XXX (insn)) == YYY) && something2)
in neither.

The patch is on top of the latest genattrtab speedup patch.

Bootstrapped/regtested on x86_64-linux and i686-linux.
Compared to vanilla trunk, in gcc/*.o only
bt-load.o cc1-checksum.o cc1obj-checksum.o cc1objplus-checksum.o
cc1plus-checksum.o cfgexpand.o haifa-sched.o insn-attrtab.o
insn-automata.o sel-sched-ir.o
(i.e. checksums, insn-attrtab itself and what includes changed insn-attr.h)
changed. insn-attrtab.o .text sizes:
	vanilla		genattrtab_speedup_only	both_patches
x86_64	1003956		635929			573453
i686	864342		535461			475104

Ok to commit (assuming the speedup patch is approved; except for the
make_automaton_attrs hunk it would apply even to vanilla genattrtab.c though)?

2010-06-18  Jakub Jelinek  <jakub@redhat.com>

	* Makefile.in (build/genattrtab.o): Depend on vecprim.h.
	* genattrtab.c: Include vecprim.h.
	(cached_attrs, cached_attr_count, attrs_seen_once,
	attrs_seen_more_than_once, attrs_to_cache, attrs_cached_inside,
	attrs_cached_after): New variables.
	(find_attrs_to_cache): New function.
	(FLG_BITWISE, FLG_AFTER, FLG_INSIDE, FLG_OUTSIDE_AND): Define.
	(write_test_expr): Add attrs_cached argument, return it too,
	attempt to cache non-const attributes used more than once in
	a single case handling.
	(write_attr_get): Use find_attrs_to_cache, for caching candidates
	emit cached_* variables.  Adjust write_attr_set callers.
	(write_attr_set): Add attrs_cached attribute, use find_attrs_to_cache
	to find attributes that should be cached in this block.  Adjust
	write_test_expr callers.
	(write_attr_case): Clear attrs_to_cache.  Adjust write_attr_set
	callers.
	(make_automaton_attrs): Adjust write_test_expr caller.

	Jakub

Further insn-attrtab.c speedup

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