On Fri, Dec 12, 2025 at 12:57 PM Robin Dapp <[email protected]> wrote:
>
> Hi,
>
> In the PR we extract non-existent bits/elements from a vector. This is
> because we use TYPE_SIZE (vectype) for a boolean vector which returns 8
> instead of 4 for RVV's vector (4) <signed-boolean:1>.
>
> The patch uses TYPE_VECTOR_SUBPARTS instead and multiplies its result
> with vector_element_bits to get the proper number of elements and size.
>
> Bootstrapped and regtested on x86 and power10. Regtested on riscv64 and
> aarch64.
OK.
> Regards
> Robin
>
> PR tree-optimization/123097
>
> gcc/ChangeLog:
>
> * tree-vect-loop.cc (vect_create_epilog_for_reduction):
> Calculate vector size by number of elements * bit size per
> element.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/rvv/autovec/pr123097-run.c: New test.
> * gcc.target/riscv/rvv/autovec/pr123097.c: New test.
> ---
> .../riscv/rvv/autovec/pr123097-run.c | 19 ++++++++++++++++++
> .../gcc.target/riscv/rvv/autovec/pr123097.c | 20 +++++++++++++++++++
> gcc/tree-vect-loop.cc | 12 +++++------
> 3 files changed, 45 insertions(+), 6 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123097-run.c
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123097.c
>
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123097-run.c
> b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123097-run.c
> new file mode 100644
> index 00000000000..f536c82bcb9
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123097-run.c
> @@ -0,0 +1,19 @@
> +/* { dg-do run } */
> +/* { dg-require-effective-target riscv_v_ok } */
> +/* { dg-options "-O3 -march=rv64gcv -mabi=lp64d" } */
> +
> +long long a;
> +int b[22];
> +_Bool c[22];
> +
> +int main() {
> + for (long f=0; f<10; ++f)
> + b[f] = c[f] = 1;
> + for (int f=0; f<5; f++)
> + for( int g=0; g<5; g++)
> + c[g*2] &= (_Bool)b[2*f];
> + for (long f=0; f<2; ++f)
> + a ^= c[f];
> + if (a != 0)
> + __builtin_abort ();
> +}
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123097.c
> b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123097.c
> new file mode 100644
> index 00000000000..7f1538940d2
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123097.c
> @@ -0,0 +1,20 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -march=rv64gcv -mabi=lp64d -fdump-tree-optimized" } */
> +
> +long long a;
> +int b[22];
> +_Bool c[22];
> +
> +int main() {
> + for (long f=0; f<10; ++f)
> + b[f] = c[f] = 1;
> + for (int f=0; f<5; f++)
> + for( int g=0; g<5; g++)
> + c[g*2] &= (_Bool)b[2*f];
> + for (long f=0; f<2; ++f)
> + a ^= c[f];
> + if (a != 0)
> + __builtin_abort ();
> +}
> +
> +/* { dg-final { scan-tree-dump-not "BIT_FIELD_REF <\\{ -1, -1, -1, -1 \\},"
> "optimized" } } */
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index f9dd88ed824..02ff28d522f 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -5972,13 +5972,11 @@ vect_create_epilog_for_reduction (loop_vec_info
> loop_vinfo,
>
> if (reduce_with_shift && (!slp_reduc || group_size == 1))
> {
> - tree bitsize = TYPE_SIZE (TREE_TYPE (vectype1));
> - int element_bitsize = tree_to_uhwi (bitsize);
> + int element_bitsize = vector_element_bits (vectype1);
> /* Enforced by vectorizable_reduction, which disallows SLP
> reductions
> for variable-length vectors and also requires direct target
> support
> for loop reductions. */
> - int vec_size_in_bits = tree_to_uhwi (TYPE_SIZE (vectype1));
> - int nelements = vec_size_in_bits / element_bitsize;
> + int nelements = TYPE_VECTOR_SUBPARTS (vectype1).to_constant ();
> vec_perm_builder sel;
> vec_perm_indices indices;
>
> @@ -6019,7 +6017,8 @@ vect_create_epilog_for_reduction (loop_vec_info
> loop_vinfo,
> "extract scalar result\n");
>
> new_temp = gimple_build (&stmts, BIT_FIELD_REF, TREE_TYPE
> (vectype1),
> - new_temp, bitsize, bitsize_zero_node);
> + new_temp, bitsize_int (element_bitsize),
> + bitsize_zero_node);
> new_temp = gimple_convert (&stmts, scalar_type, new_temp);
> gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);
> scalar_results.safe_push (new_temp);
> @@ -6041,8 +6040,9 @@ vect_create_epilog_for_reduction (loop_vec_info
> loop_vinfo,
> "Reduce using scalar code.\n");
>
> tree compute_type = TREE_TYPE (vectype1);
> - unsigned vec_size_in_bits = tree_to_uhwi (TYPE_SIZE (vectype1));
> unsigned element_bitsize = vector_element_bits (vectype1);
> + unsigned vec_size_in_bits = element_bitsize
> + * TYPE_VECTOR_SUBPARTS (vectype1).to_constant ();
> tree bitsize = bitsize_int (element_bitsize);
> gimple_seq stmts = NULL;
> FOR_EACH_VEC_ELT (reduc_inputs, i, vec_temp)
> --
> 2.51.1
>
