Are literals splatted in SIMD Operations?

Is there any performance difference if I write this

fn multiply_by_two[
    dtype: DType, simd_width: Int
](x: SIMD[dtype, simd_width]) -> SIMD[dtype, simd_width]:
    alias splatted_two = SIMD[dtype, simd_width](2.)
    return splatted_two * x

fn multiply_by_two[
    dtype: DType, simd_width: Int
](x: SIMD[dtype, simd_width]) -> SIMD[dtype, simd_width]:
    alias splatted_two = SIMD[dtype, simd_width](2.)
    return splatted_two * x

instead of this?

fn multiply_by_two[
    dtype: DType, simd_width: Int
](x: SIMD[dtype, simd_width]) -> SIMD[dtype, simd_width]:
    return 2.0 * x

fn multiply_by_two[
    dtype: DType, simd_width: Int
](x: SIMD[dtype, simd_width]) -> SIMD[dtype, simd_width]:
    return 2.0 * x

In other words, is the literal

transformed into a splatted SIMD vector at runtime every time

multiply_by_two

multiply_by_two

is called? Or is this something that the compiler is able to optimize?

Modular•3y ago•

3 replies

Leandro Lacerda

Are literals splatted in SIMD Operations?

Is there any performance difference if I write this

fn multiply_by_two[
    dtype: DType, simd_width: Int
](x: SIMD[dtype, simd_width]) -> SIMD[dtype, simd_width]:
    alias splatted_two = SIMD[dtype, simd_width](2.)
    return splatted_two * x

fn multiply_by_two[
    dtype: DType, simd_width: Int
](x: SIMD[dtype, simd_width]) -> SIMD[dtype, simd_width]:
    alias splatted_two = SIMD[dtype, simd_width](2.)
    return splatted_two * x

instead of this?

fn multiply_by_two[
    dtype: DType, simd_width: Int
](x: SIMD[dtype, simd_width]) -> SIMD[dtype, simd_width]:
    return 2.0 * x

fn multiply_by_two[
    dtype: DType, simd_width: Int
](x: SIMD[dtype, simd_width]) -> SIMD[dtype, simd_width]:
    return 2.0 * x

In other words, is the literal

transformed into a splatted SIMD vector at runtime every time

multiply_by_two

multiply_by_two

is called? Or is this something that the compiler is able to optimize?

Are literals splatted in SIMD Operations?

Similar Threads

Are literals splatted in SIMD Operations?

Similar Threads

Similar Threads

Similar Threads