Intel® C++ Compiler 16.0 User and Reference Guide
Gathers 2/4 quadword values from memory referenced by the given base address, qword indices, and scale. The corresponding Intel® AVX2 instruction is VPGATHERQQ.
extern __m128i _mm_i64gather_epi64(__int64 const * base, __m128i vindex, const int scale); |
extern __m128i _mm256_i64gather_epi64(__int64 const * base, __m256i vindex, const int scale); |
base |
the base address used to reference the loaded qword elements. |
vindex |
the vector of qword indices used to reference the loaded qword elements. |
scale |
32-bit scale used to address the loaded dword elements; it is multiplied by the corresponding element from 'vindex'. |
The intrinsics load 2/4 quadword values from memory using the base address, qword indices, and 64-bit scale.
Below is the pseudo-code for the intrinsics:
_mm_i64gather_epi64():
result[63:0] = mem[base+vindex[63:0]*scale]; result[127:64] = mem[base+vindex[127:64]*scale];
_mm256_i64gather_epi64():
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 integer64 values.