fold-mem-offsets: Fix powerpc64le-linux profiledbootstrap [PR111601]

fold-mem-offsets: Fix powerpc64le-linux profiledbootstrap [PR111601]

The introduction of the fold-mem-offsets pass breaks profiledbootstrap
on powerpc64le-linux.
From what I can see, the pass works one basic block at a time and
will punt on any non-DEBUG_INSN uses outside of the current block
(I believe because of the
          /* This use affects instructions outside of CAN_FOLD_INSNS.  */
          if (!bitmap_bit_p (&can_fold_insns, INSN_UID (use)))
            return 0;
test and can_fold_insns only set in do_analysis (when processing insns in
current bb, cleared at the end) or results of get_single_def_in_bb
(which are checked to be in the same bb).
But, while get_single_def_in_bb checks for
  if (DF_INSN_LUID (def) > DF_INSN_LUID (insn))
    return NULL;
The basic block in the PR in question has:
...
(insn 212 210 215 25 (set (mem/f:DI (reg/v/f:DI 10 10 [orig:152 last_viable ] [152]) [2 *last_viable_336+0 S8 A64])
        (reg/f:DI 9 9 [orig:155 _342 ] [155])) "pr111601.ii":50:17 683 {*movdi_internal64}
     (expr_list:REG_DEAD (reg/v/f:DI 10 10 [orig:152 last_viable ] [152])
        (nil)))
(insn 215 212 484 25 (set (reg:DI 5 5 [226])
        (const_int 0 [0])) "pr111601.ii":52:12 683 {*movdi_internal64}
     (expr_list:REG_EQUIV (const_int 0 [0])
        (nil)))
(insn 484 215 218 25 (set (reg/v/f:DI 10 10 [orig:152 last_viable ] [152])
        (reg/f:DI 9 9 [orig:155 _342 ] [155])) "pr111601.ii":52:12 683 {*movdi_internal64}
     (nil))
...
(insn 564 214 216 25 (set (reg/v/f:DI 10 10 [orig:152 last_viable ] [152])
        (plus:DI (reg/v/f:DI 10 10 [orig:152 last_viable ] [152])
            (const_int 96 [0x60]))) "pr111601.ii":52:12 66 {*adddi3}
     (nil))
(insn 216 564 219 25 (set (mem/f:DI (reg/v/f:DI 10 10 [orig:152 last_viable ] [152]) [2 _343->next+0 S8 A64])
        (reg:DI 5 5 [226])) "pr111601.ii":52:12 683 {*movdi_internal64}
     (expr_list:REG_DEAD (reg:DI 5 5 [226])
        (nil)))
...
and when asking for all uses of %r10 from def 564, it will see uses
in 216 and 212; the former is after the += 96 addition and gets changed
to load from %r10+96 with the addition being dropped, but there is
the other store which is a use across the backedge and when reached
from other edges certainly doesn't have the + 96 addition anywhere,
so the pass doesn't actually change that location.

This patch adds checks from get_single_def_in_bb to get_uses as well,
in particular check that the (regular non-debug) use only appears in the
same basic block as the definition and that it doesn't appear before it (i.e.
use across backedge).

2023-11-29  Jakub Jelinek  <jakub@redhat.com>

	PR bootstrap/111601
	* fold-mem-offsets.cc (get_uses): Ignore DEBUG_INSN uses.  Otherwise,
	punt if use is in a different basic block from INSN or appears before
	INSN in the same basic block.  Formatting fixes.
	(get_single_def_in_bb): Formatting fixes.
	(fold_offsets_1, pass_fold_mem_offsets::execute): Comment formatting
	fixes.

	* g++.dg/opt/pr111601.C: New test.