On Fri, Nov 21, 2025 at 12:47:22PM +0100, Richard Biener wrote:
> I do wonder if there's a way to figure the number of mask
> arguments we expect for a SIMD clone? Consider
>
> #pragma omp declare simd simdlen(32) inbranch
> int __attribute__((const)) baz ();
>
> where there's only the mask argument or a case with mixed type
> arguments or return?
Given sc->args[i].arg_type == SIMD_CLONE_ARG_TYPE_MASK, if
sc->args[i].vector_type is a VECTOR_TYPE, then easily, divide
the number of lanes handled by that single call (sc->simdlen)
by number of elements in that VECTOR_TYPE.
For integer masks that is harder, I'm afraid you'd need to repeat
what simd_clone_adjust_argument_types did in the sc->inbranch
handling to compute veclen, because orig_type is set in that
case to boolean_type_node and the precision of the INTEGRAL_TYPE_P
vector_type could be larger than veclen.
But we could store the veclen (I think it must be constant in that case)
or k (i.e. the number of the mask arguments) e.g. in
sc->args[i].linear_step.
That is currently documented
/* For arg_type SIMD_CLONE_ARG_TYPE_LINEAR_*CONSTANT_STEP this is
the constant linear step, if arg_type is
SIMD_CLONE_ARG_TYPE_LINEAR_*VARIABLE_STEP, this is index of
the uniform argument holding the step, otherwise 0. */
HOST_WIDE_INT linear_step;
and so it could be reused/abused for one of the veclen or number
of mask arguments, whatever is easier for the vectorizer, if
this comment is adjusted to say what it means for
SIMD_CLONE_ARG_TYPE_MASK and let the code just store it, i.e.
either
--- gcc/omp-simd-clone.cc 2025-04-08 14:08:57.115200232 +0200
+++ gcc/omp-simd-clone.cc 2025-11-21 13:09:10.733282017 +0100
@@ -892,6 +892,7 @@ simd_clone_adjust_argument_types (struct
sc->args[i].orig_type = base_type;
sc->args[i].arg_type = SIMD_CLONE_ARG_TYPE_MASK;
sc->args[i].vector_type = mask_type;
+ sc->args[i].linear_step = k;
}
if (!node->definition)
or = veclen.to_constant (); (though that would need to be conditional
on mask_type being INTEGRAL_TYPE_P or sc->mask_mode != VOIDmode.
Jakub
