> Am 26.01.2026 um 19:17 schrieb Andrew Pinski <[email protected]>:
>
> I had noticed there was code that will convert the stride
> to the correct type
> What I didn't realize was the type which it was trying to
> use was stride_type but for this case it should have been using
> the type of the lhs. This fixes that oversight. Note for pointers
> we still want to use stride_type like what is done right above.
>
> I don't have a testcase that does not use LTO though. I didn't figure
> out why this testcase needed LTO though.
>
> Bootstrapped and tested on x86_64-linux-gnu.
Ok
Richard
> PR tree-optimization/123820
>
> gcc/ChangeLog:
>
> * gimple-ssa-strength-reduction.cc (create_add_on_incoming_edge): Use
> the correct type for the stride (lhs if non-pointer).
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/torture/pr123820-1.C: New test.
>
> Signed-off-by: Andrew Pinski <[email protected]>
> ---
> gcc/gimple-ssa-strength-reduction.cc | 5 +--
> gcc/testsuite/g++.dg/torture/pr123820-1.C | 41 +++++++++++++++++++++++
> 2 files changed, 44 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/torture/pr123820-1.C
>
> diff --git a/gcc/gimple-ssa-strength-reduction.cc
> b/gcc/gimple-ssa-strength-reduction.cc
> index f3571e10e90..ced2235498c 100644
> --- a/gcc/gimple-ssa-strength-reduction.cc
> +++ b/gcc/gimple-ssa-strength-reduction.cc
> @@ -2356,10 +2356,11 @@ create_add_on_incoming_edge (slsr_cand_t c, tree
> basis_name,
> }
> else {
> tree stride;
> + tree wanted_type = POINTER_TYPE_P (basis_type) ? c->stride_type :
> basis_type;
>
> - if (!types_compatible_p (TREE_TYPE (c->stride), c->stride_type))
> + if (!types_compatible_p (TREE_TYPE (c->stride), wanted_type))
> {
> - tree cast_stride = make_temp_ssa_name (c->stride_type, NULL,
> + tree cast_stride = make_temp_ssa_name (wanted_type, NULL,
> "slsr");
> cast_stmt = gimple_build_assign (cast_stride, NOP_EXPR,
> c->stride);
> diff --git a/gcc/testsuite/g++.dg/torture/pr123820-1.C
> b/gcc/testsuite/g++.dg/torture/pr123820-1.C
> new file mode 100644
> index 00000000000..3c9d1f0127a
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/torture/pr123820-1.C
> @@ -0,0 +1,41 @@
> +/* { dg-do run } */
> +/* PR tree-optimization/123820 */
> +
> +struct Trit { char value; };
> +
> +struct Matrix {
> + int width;
> + Trit* data;
> +
> + Trit& at(int x, int y) {
> + if (!(x >= y)) __builtin_abort ();
> + return data[y * width];
> + }
> +};
> +
> +
> +Trit set_value;
> +[[gnu::used]]
> +int EmbedPositionDetectionPattern_yStart;
> +
> +[[gnu::used,gnu::noipa]]
> +void EmbedPositionDetectionPattern(Matrix& m) {
> + for (int y = 0; y < 7; ++y)
> + for (int x = 0; x < 7; ++x)
> + m.at(x, EmbedPositionDetectionPattern_yStart + y) = {0};
> +
> + for (int i = 1; i < 8; ++i) {
> + if (i < m.width)
> + m.at(i, 7) = {0};
> +
> + int y = EmbedPositionDetectionPattern_yStart + i;
> + if (7 < m.width && y)
> + m.at(7, y) = {0};
> + }
> +}
> +
> +int main()
> +{
> + return 0;
> +}
> +
> --
> 2.43.0
>
