On Thu, Jan 8, 2026 at 2:40 PM Robin Dapp <[email protected]> wrote:
>
> > But that's what types_compatible_p checks. What I'd change is to only
> > verify this if else_value, not when that was determined by the
> > preferred else value hook.
>
>
> The below has been regtested and bootstrapped on x86, power10, aarch64.
> Regtested on riscv64.
LGTM.
Richard.
> Regards
> Robin
>
>
> [PATCH v2] match: Check else value compatibility [PR123268].
>
> In PR123268 we transform x * { 0 or 1, 0 or 1, ... } into
> x & { 0 or -1, 0 or -1, ...} which is a match.pd pattern.
>
> We start out with
> vect_b_28.48_48 = .COND_LEN_MUL ({ -1, -1, -1, -1 }, a, b, { 0.0, 0.0, 0.0,
> 0.0 }, 4, 0);
> and simplify to
>
> _67 = .COND_LEN_AND ({ -1, -1, -1, -1 }, _60, { 4294967295, 0, 0, 0 }, { 0.0,
> 0.0, 0.0, 0.0 }, 4, 0);
>
> where the operation type is int but the else value (that we just copied
> over from the original op) is still float.
>
> In order to catch that, this patch checks if the operation type and the
> else value type are compatible while reassembling the conditional
> operation.
>
> gcc/ChangeLog:
>
> * gimple-match-exports.cc (convert_conditional_op): Check if
> orig_op->type and type of else value match.
> ---
> gcc/gimple-match-exports.cc | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/gcc/gimple-match-exports.cc b/gcc/gimple-match-exports.cc
> index 555e8a967a0..cdd9ae552e2 100644
> --- a/gcc/gimple-match-exports.cc
> +++ b/gcc/gimple-match-exports.cc
> @@ -184,6 +184,13 @@ convert_conditional_op (gimple_match_op *orig_op,
> for (unsigned int i = 0; i < num_ops; ++i)
> new_op->ops[i + 1] = orig_op->ops[i];
> tree else_value = orig_op->cond.else_value;
> + /* Some patterns convert operand types, e.g. from float to int.
> + If we had a real else value before (e.g. float) it won't match
> + the type. Verify that here. */
> + if (else_value
> + && !types_compatible_p (orig_op->type, TREE_TYPE (else_value)))
> + return false;
> +
> if (!else_value)
> else_value = targetm.preferred_else_value (ifn, orig_op->type,
> num_ops, orig_op->ops);
> --
> 2.52.0
>
