On Wed, Aug 21, 2024 at 8:37 AM Robin Dapp <rdapp....@gmail.com> wrote:
>
> Hi,
>
> in get_best_extraction_insn we use smallest_int_mode_for_size with
> struct_bits as size argument. In PR115495 struct_bits = 256 and we
> don't have a mode for that. This patch just bails for such cases.
>
> This does not happen on the current trunk anymore (so the test passes
> unpatched) but we've seen it internally. Does it still make sense
> to install it (and backport to 14)?
>
> Bootstrapped and regtested on x86 and aarch64. Regtested on rv64gcv.
>
> Regards
> Robin
>
> PR middle-end/115495
>
> gcc/ChangeLog:
>
> * optabs-query.cc (get_best_extraction_insn): Return if
> smallest_int_mode_for_size might not find a mode.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/rvv/autovec/pr115495.c: New test.
> ---
> gcc/optabs-query.cc | 4 ++++
> gcc/testsuite/gcc.target/riscv/rvv/autovec/pr115495.c | 9 +++++++++
> 2 files changed, 13 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/pr115495.c
>
> diff --git a/gcc/optabs-query.cc b/gcc/optabs-query.cc
> index 93c1d7b8485..dc2690e720f 100644
> --- a/gcc/optabs-query.cc
> +++ b/gcc/optabs-query.cc
> @@ -208,6 +208,10 @@ get_best_extraction_insn (extraction_insn *insn,
> machine_mode field_mode)
> {
> opt_scalar_int_mode mode_iter;
> +
> + if (maybe_gt (struct_bits, GET_MODE_PRECISION (MAX_MODE_INT)))
> + return false;
> +
> FOR_EACH_MODE_FROM (mode_iter, smallest_int_mode_for_size (struct_bits))
I think we instead should change this iteration to use FOR_EACH_MODE_IN_CLASS
(like smallest_mode_for_size does) and skip to small modes?
> {
> scalar_int_mode mode = mode_iter.require ();
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr115495.c
> b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr115495.c
> new file mode 100644
> index 00000000000..bbf4d720f63
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr115495.c
> @@ -0,0 +1,9 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64gcv_zvl256b -mabi=lp64d -O3" } */
> +
> +extern short a[];
> +short b;
> +int main() {
> + for (char c = 0; c < 18; c += 1)
> + a[c + 0] = b;
> +}
> --
> 2.46.0
>
