Intel® C++ Compiler Classic Developer Guide and Reference

ID 767249
Date 12/16/2022
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

<span class='option'>_mm_i64gather_epi32,_mm256_i64gather_epi32</span>

Gathers 2/4 doubleword values from memory referenced by the given base address, qword indices, and scale. The corresponding Intel® AVX2 instruction is VPGATHERQD.

Syntax

extern __m128i _mm_i64gather_epi32(int const * base, __m128i vindex, const int scale);

extern __m128i _mm256_i64gather_epi32(int const * base, __m256i vindex, const int scale);

Arguments

base

the base address used to reference the loaded dword elements.

vindex

the vector of qword indices used to reference the loaded dword 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 doubleword values from memory using the base address, qword indices, and 32-bit scale. The intrinsic _mm_i64gather_epi32() also sets the upper 64-bits of the result to '0'.

Below is the pseudo-code for the intrinsics:

_mm_i64gather_epi32():

result[31:0] = mem[base+vindex[63:0]*scale];
result[63:32] = mem[base+vindex[127:64]*scale];
result[127:64] = 0;

_mm256_i64gather_epi32():

result[31:0] = mem[base+vindex[63:0]*scale];
result[63:32] = mem[base+vindex[127:64]*scale];
result[95:64] = mem[base+vindex[191:128]*scale];
result[127:96] = mem[base+vindex[255:192]*scale];
Returns

A 128/256-bit vector with unconditionally gathered integer32 values.