doloop: Fix up doloop df use [PR116799]

doloop: Fix up doloop df use [PR116799]

The following testcases are miscompiled on s390x-linux, because the
doloop_optimize
  /* Ensure that the new sequence doesn't clobber a register that
     is live at the end of the block.  */
  {
    bitmap modified = BITMAP_ALLOC (NULL);

    for (rtx_insn *i = doloop_seq; i != NULL; i = NEXT_INSN (i))
      note_stores (i, record_reg_sets, modified);

    basic_block loop_end = desc->out_edge->src;
    bool fail = bitmap_intersect_p (df_get_live_out (loop_end), modified);
check doesn't work as intended.
The problem is that it uses df, but the df analysis was only done using
  iv_analysis_loop_init (loop);
->
  df_analyze_loop (loop);
which computes df inside on the bbs of the loop.
While loop_end bb is inside of the loop, df_get_live_out computed that
way includes registers set in the loop and used at the start of the next
iteration, but doesn't include registers set in the loop (or before the
loop) and used after the loop.

The following patch fixes that by doing whole function df_analyze first,
changes the loop iteration mode from 0 to LI_ONLY_INNERMOST (on many
targets which use can_use_doloop_if_innermost target hook a so are known
to only handle innermost loops) or LI_FROM_INNERMOST (I think only bfin
actually allows non-innermost loops) and checking not just
df_get_live_out (loop_end) (that is needed for something used by the
next iteration), but also df_get_live_in (desc->out_edge->dest),
i.e. what will be used after the loop.  df of such a bb shouldn't
be affected by the df_analyze_loop and so should be from df_analyze
of the whole function.

2024-12-05  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/113994
	PR rtl-optimization/116799
	* loop-doloop.cc: Include targhooks.h.
	(doloop_optimize): Also punt on intersection of modified
	with df_get_live_in (desc->out_edge->dest).
	(doloop_optimize_loops): Call df_analyze.  Use
	LI_ONLY_INNERMOST or LI_FROM_INNERMOST instead of 0 as
	second loops_list argument.

	* gcc.c-torture/execute/pr116799.c: New test.
	* g++.dg/torture/pr113994.C: New test.

(cherry picked from commit 0eed81612ad6eac2bec60286348a103d4dc02a5a)