knl.ispc

#define int_floor_div_pos_b(a,b) (                 ( (a) - ( ((a)<0) ? ((b)-1) : 0 )  ) / (b)                 )

task void init_knl_inner(uniform int32 const N, uniform float *uniform a)
{
  if (-1 + -8 * ((uniform int32) taskIndex0) + -1 * (varying int32) programIndex + N >= 0)
    for (uniform int32 i = 0; i <= -1 + N; ++i)
      a[8 * i + (((varying int32) programIndex + ((uniform int32) taskIndex0) * 8) % 8) + 8 * N * (((varying int32) programIndex + ((uniform int32) taskIndex0) * 8) / 8)] = 17.0;
}
export void init_knl(uniform int32 const N, uniform float *uniform a)
{
  assert(programCount == 8);
  launch[int_floor_div_pos_b(7 + N, 8)] init_knl_inner(N, a);
}

output

$ ispc --target=avx2-i32x8 knl.ispc -o knl.o
knl.ispc:7:18: Performance Warning: Modulus operator with varying types is very inefficient.
      a[8 * i + (((varying int32) programIndex + ((uniform int32) taskIndex0) * 8) % 8) + 8 * N * (((varying int32) programIndex + ((uniform int32) taskIndex0) * 8) / 8)] = 17.0;
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

knl.ispc:7:7: Performance Warning: Scatter required to store value.
      a[8 * i + (((varying int32) programIndex + ((uniform int32) taskIndex0) * 8) % 8) + 8 * N * (((varying int32) programIndex + ((uniform int32) taskIndex0) * 8) / 8)] = 17.0;
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

try.py

import loopy as lp
import numpy as np


def gen_code(knl):
    knl = lp.preprocess_kernel(knl)
    knl = lp.get_one_scheduled_kernel(knl)
    codegen_result = lp.generate_code_v2(knl)

    return codegen_result.device_code() + "\n" + codegen_result.host_code()


# {{{ settings

if 0:
    DOF_DTYPE = np.float64
    VEC_WIDTH = 4
else:
    DOF_DTYPE = np.float32
    VEC_WIDTH = 8

# }}}


# {{{ kernel creation

def make_init_knl(target):
    knl = lp.make_kernel(
            "{ [i,j]: "
            "0<=i<N and 0<=j<N }",

            """
            a[i,j] = 17
            """,
            target=target,
            name="init_knl",
            default_order="F")

    knl = lp.add_and_infer_dtypes(knl, {"a": DOF_DTYPE})
    knl = lp.set_argument_order(knl, "N,a")

    knl = lp.split_iname(knl, "j", VEC_WIDTH, inner_tag="l.0", outer_tag="g.0")

    knl = lp.split_array_dim(knl, ("a", 1, "F"), VEC_WIDTH,
            auto_split_inames=False)
    knl = lp.tag_data_axes(knl, "a", "N1,N0,N2")

    return knl

# }}}


def main():
    target = lp.ISPCTarget()

    init_knl = make_init_knl(target)
    ispc_code = gen_code(init_knl)

    print(ispc_code)


if __name__ == "__main__":
    main()

# vim: foldmethod=marker