# _mm_mask_i64gather_pd, _mm256_mask_i64gather_pd

Gathers 2/4 packed double-precision floating point values from memory referenced by the given base address, qword indices and scale, and using the given double precision FP mask values. The corresponding Intel® AVX2 instruction is `VGATHERQPD`.

## Syntax

extern __m128d _mm_mask_i64gather_pd(__m128d def_vals, double const * base, __m128i vindex __m128d vmask, const int scale);

extern __m256d _mm256_mask_i64gather_pd(__m256d def_vals, double const * base, __m128i vindex __m256d vmask, const int scale);

## Arguments

def_vals | the vector of double-precision FP values copied to the destination when the corresponding element of the double-precision FP mask is '0'.
base | the base address used to reference the loaded FP elements.
vindex | the vector of qword indices used to reference the loaded FP elements.
vmask | the vector of FP elements used as a vector mask; only the most significant bit of each data element is used as a mask.
scale | The compilation time literal constant, which is used as the vector indices scale to address the loaded elements. Possible values are one of the following: 1, 2, 4, 8.

## Description

The intrinsics conditionally load 2/4 packed double-precision floating-point values from memory using qword indices according to mask values.

Below is the pseudo-code for the intrinsics:

`_mm_mask_i64gather_pd()`:

    result[63:0] = (vmask[63]==1) ? (mem[base+vindex[63:0]*scale]) : (def_vals[63:0]);
    result[127:64] = (vmask[127]==1) ? (mem[base+vindex[127:64]*scale]) : (def_vals[127:64]);

`_mm256_mask_i64gather_pd()`:

    result[63:0] = (vmask[63]==1) ? (mem[base+vindex[63:0]*scale]) : (def_vals[63:0]);
    result[127:64] = (vmask[127]==1) ? (mem[base+vindex[127:64]*scale]) : (def_vals[127:64]);
    result[191:128] = (vmask[191]==1) ? (mem[base+vindex[191:128]*scale]) : (def_vals[191:128]);
    result[255:192] = (vmask[255]==1) ? (mem[base+vindex[255:192]*scale]) : (def_vals[255:192]);

## Returns

A 128/256-bit vector with conditionally gathered double-precision values.

Parent topic: Intrinsics for GATHER Operations