reorg.c (fill_slots_from_thread): Reinstate code typoed out in "Remove CC0".

The typo here, is obviously mistaken removal of lines next
to a line that was validly removed.  Targets affected are
those with a delay-slot *and* defining TARGET_FLAGS_REGNUM.
In-tree, a git-grep says the only ones matching are CRIS,
h8300 and visium.  The code removal has the effect of
wrong-code, not reverting the effect of r11-2814.

I'm "guessing" it was the effect of an incorrect conflict
resolution in preparatory work for the r12-440 /
bd1cd0d0e0fe / "Remove CC0" commit, when rebasing a related
branch, and not testing any of the affected targets.  Either
way, the effect was a btest-gcc.sh state of "regress-1152"
for cris-elf.  FWIW, I wrote the removed code (sans the
validly removed cc0 line), a part of what was committed at
2020-08-24 as 0e6c51de8ec47 / r11-2814.

This commit gets cris-elf test-results back to a sane state
(tested at 0ffdbc85d9a6 / r12-761).

gcc:
	* reorg.c (fill_slots_from_thread): Reinstate code typoed out in
	"Remove CC0".

diff --git a/gcc/reorg.c b/gcc/reorg.c
index 4595f9a..7f06a6f 100644 (file)
--- a/gcc/reorg.c
+++ b/gcc/reorg.c
@@ -2375,6 +2375,16 @@ fill_slots_from_thread (rtx_jump_insn *insn, rtx condition,
       if (! insn_references_resource_p (trial, &set, true)
          && ! insn_sets_resource_p (trial, filter_flags ? &fset : &set, true)
          && ! insn_sets_resource_p (trial, &needed, true)
+         /* If we're handling sets to the flags register specially, we
+            only allow an insn into a delay-slot, if it either:
+            - doesn't set the flags register,
+            - the "set" of the flags register isn't used (clobbered),
+            - insns between the delay-slot insn and the trial-insn
+            as accounted in "set", have not affected the flags register.  */
+         && (! filter_flags
+             || ! insn_sets_resource_p (trial, &flags_res, true)
+             || find_regno_note (trial, REG_UNUSED, targetm.flags_regnum)
+             || ! TEST_HARD_REG_BIT (set.regs, targetm.flags_regnum))
          && ! can_throw_internal (trial))
        {
          rtx_insn *prior_insn;