On Wed, Dec 20, 2023 at 3:54 AM Alexandre Oliva <ol...@adacore.com> wrote:
>
>
> Builtin expanders for memset and memcpy may involve conditionals and
> loops, but their sequences may be end up emitted in edges. Alas,
> commit_one_edge_insertion rejects sequences that end with a jump, a
> requirement that makes sense for insertions after expand, but not so
> much during expand.
>
> During expand, jumps may appear in the middle of the insert sequence
> as much as in the end, and it's only after committing edge insertions
> out of PHI nodes that we go through the entire function splitting
> blocks where needed, so relax the assert in commit_one_edge_insertion
> so that jumps are accepted during expand even at the end of the
> sequence.
>
> Regstrapping on x86_64-linux-gnu, after testing the testcase with a
> cross compiler to ppc64le-linux-gnu. Ok to install?
OK.
>
> Builtin expanders for memset and memcpy may involve conditionals and
> loops, but their sequences may be end up emitted in edges. Alas,
> commit_one_edge_insertion rejects sequences that end with a jump, a
> requirement that makes sense for insertions after expand, but not so
> much during expand.
>
> During expand, jumps may appear in the middle of the insert sequence
> as much as in the end, and it's only after committing edge insertions
> out of PHI nodes that we go through the entire function splitting
> blocks where needed, so relax the assert in commit_one_edge_insertion
> so that jumps are accepted during expand even at the end of the
> sequence.
>
>
> for gcc/ChangeLog
>
> PR rtl-optimization/113002
> * cfgrtl.cc (commit_one_edge_insertion): Tolerate jumps in the
> inserted sequence during expand.
>
> for gcc/testsuite/ChangeLog
>
> PR rtl-optimization/113002
> * gcc.dg/vect/pr113002.c: New.
> ---
> gcc/cfgrtl.cc | 8 +++++++-
> gcc/testsuite/gcc.dg/vect/pr113002.c | 13 +++++++++++++
> 2 files changed, 20 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.dg/vect/pr113002.c
>
> diff --git a/gcc/cfgrtl.cc b/gcc/cfgrtl.cc
> index 2a3f853eed59b..437eb3a86d5c2 100644
> --- a/gcc/cfgrtl.cc
> +++ b/gcc/cfgrtl.cc
> @@ -2092,7 +2092,13 @@ commit_one_edge_insertion (edge e)
> delete_insn (before);
> }
> else
> - gcc_assert (!JUMP_P (last));
> + /* Some builtin expanders, such as those for memset and memcpy,
> + may generate loops and conditionals, and those may get emitted
> + into edges. That's ok while expanding to rtl, basic block
> + boundaries will be identified and split afterwards. ??? Need
> + we check whether the destination labels of any inserted jumps
> + are also part of the inserted sequence? */
> + gcc_assert (!JUMP_P (last) || currently_expanding_to_rtl);
> }
>
> /* Update the CFG for all queued instructions. */
> diff --git a/gcc/testsuite/gcc.dg/vect/pr113002.c
> b/gcc/testsuite/gcc.dg/vect/pr113002.c
> new file mode 100644
> index 0000000000000..186710f64b422
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/pr113002.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-require-effective-target int128 } */
> +/* { dg-options "-finline-stringops -Os" } */
> +
> +typedef __int128 v64u128 __attribute__((vector_size(64)));
> +int c;
> +v64u128 u;
> +void foo() {
> + if (c)
> + u = (v64u128){0};
> + else
> + u = (v64u128){1};
> +}
>
> --
> Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/
> Free Software Activist GNU Toolchain Engineer
> More tolerance and less prejudice are key for inclusion and diversity
> Excluding neuro-others for not behaving ""normal"" is *not* inclusive
