Intel® C++ Compiler 16.0 User and Reference Guide
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.
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); |
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 |
32-bit scale used to address the loaded FP elements. |
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];
A 128/256-bit vector with unconditionally gathered double-precision FP values.