As reported on https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116372,
this change restores bootstrap.
Committing as obvious.
--Philipp.
On Tue, 20 Aug 2024 at 21:57, Manolis Tsamis <manolis.tsa...@vrull.eu> wrote:
>
> Now that more operations are allowed for noce_convert_multiple_sets, it is
> possible that the same register appears multiple times as target in a
> basic block. After noce_convert_multiple_sets_1 is called we potentially
> also emit register moves from temporaries back to the original targets.
> In some cases where the target registers overlap with the block's condition,
> these register moves may overwrite intermediate variables because they're
> emitted after the if-converted code. To address this issue we now iterate
> backwards and keep track of seen registers when emitting these final register
> moves.
>
> Fix-up for the recent ifcvt commit 72c9b5f4
>
> PR rtl-optimization/116372
> PR rtl-optimization/116405
>
> gcc/ChangeLog:
>
> * ifcvt.cc (noce_convert_multiple_sets): Iterate backwards and track
> target registers.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/pr116372.c: New test.
> * gcc.dg/pr116405.c: New test.
>
> Signed-off-by: Manolis Tsamis <manolis.tsa...@vrull.eu>
> ---
>
> gcc/ifcvt.cc | 22 ++++++++++++++++++----
> gcc/testsuite/gcc.dg/pr116372.c | 13 +++++++++++++
> gcc/testsuite/gcc.dg/pr116405.c | 17 +++++++++++++++++
> 3 files changed, 48 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/pr116372.c
> create mode 100644 gcc/testsuite/gcc.dg/pr116405.c
>
> diff --git a/gcc/ifcvt.cc b/gcc/ifcvt.cc
> index da59c907891..36de036661b 100644
> --- a/gcc/ifcvt.cc
> +++ b/gcc/ifcvt.cc
> @@ -3515,10 +3515,24 @@ noce_convert_multiple_sets (struct noce_if_info
> *if_info)
> given an empty BB to convert, and we can't handle that. */
> gcc_assert (!insn_info.is_empty ());
>
> - /* Now fixup the assignments. */
> - for (unsigned i = 0; i < insn_info.length (); i++)
> - if (insn_info[i]->target != insn_info[i]->temporary)
> - noce_emit_move_insn (insn_info[i]->target, insn_info[i]->temporary);
> + /* Now fixup the assignments.
> + PR116405: Iterate in reverse order and keep track of the targets so that
> + a move does not overwrite a subsequent value when multiple instructions
> + have the same target. */
> + unsigned i;
> + noce_multiple_sets_info *info;
> + bitmap set_targets = BITMAP_ALLOC (®_obstack);
> + FOR_EACH_VEC_ELT_REVERSE (insn_info, i, info)
> + {
> + gcc_checking_assert (REG_P (info->target));
> +
> + if (info->target != info->temporary
> + && !bitmap_bit_p (set_targets, REGNO (info->target)))
> + noce_emit_move_insn (info->target, info->temporary);
> +
> + bitmap_set_bit (set_targets, REGNO (info->target));
> + }
> + BITMAP_FREE (set_targets);
>
> /* Actually emit the sequence if it isn't too expensive. */
> rtx_insn *seq = get_insns ();
> diff --git a/gcc/testsuite/gcc.dg/pr116372.c b/gcc/testsuite/gcc.dg/pr116372.c
> new file mode 100644
> index 00000000000..e9878ac5042
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr116372.c
> @@ -0,0 +1,13 @@
> +/* PR rtl-optimization/116372 */
> +/* { dg-do run } */
> +/* { dg-options "-O1" } */
> +/* { dg-additional-options "-march=z13" { target s390x-*-* } } */
> +
> +long x = -0x7fffffff - 1;
> +int main (void)
> +{
> + long y = x % (-0xf - 1);
> + if (-0x7fffffff - 1 + y == x == 0)
> + __builtin_abort ();
> + return 0;
> +}
> diff --git a/gcc/testsuite/gcc.dg/pr116405.c b/gcc/testsuite/gcc.dg/pr116405.c
> new file mode 100644
> index 00000000000..9223f15a298
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr116405.c
> @@ -0,0 +1,17 @@
> +/* PR rtl-optimization/116405 */
> +/* { dg-do run } */
> +/* { dg-options "-O2 -fno-ssa-phiopt -fno-tree-dce" } */
> +
> +int printf(const char *, ...);
> +int a, b = 2, c = 1;
> +unsigned d, e;
> +int main() {
> + L:
> + a = -1 / c;
> + d = ~(b && (c && ~e) & b);
> + printf("0\n");
> + c = 0;
> + if (d != -1)
> + goto L;
> + return 0;
> +}
> --
> 2.34.1
>
