Developer Guide and Reference

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_mm_i64gather_pd, _mm256_i64gather_pd

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

Syntax

extern __m128d _mm_i64gather_pd(double const * base, __m128i vindex, const int scale);
extern __m256d _mm256_mask_i64gather_pd(double const * base, __m128i vindex, const int scale);
Arguments
base
the base address used to reference the loaded FP elements.
vindex
the vector of qword indices used to reference the loaded FP elements.
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 load 2/4 packed double-precision floating-point values from memory using qword indices and updates the destination operand.
Below is the pseudo-code for the intrinsics:
_mm_i64gather_pd()
:
result[63:0] = mem[base+vindex[63:0]*scale]; result[127:64] = mem[base+vindex[127:64]*scale];
_mm256_i64gather_pd()
:
result[63:0] = mem[base+vindex[63:0]*scale]; result[127:64] = mem[base+vindex[127:64]*scale]; result[191:128] = mem[base+vindex[191:128]*scale]; result[255:192] = mem[base+vindex[255:192]*scale];
Returns
A 128/256-bit vector with unconditionally gathered double-precision FP values.