我有此功能代码:
bool interpolate(const Mat &im, float ofsx, float ofsy, float a11, float a12, float a21, float a22, Mat &res)
{
bool ret = false;
// input size (-1 for the safe bilinear interpolation)
const int width = im.cols-1;
const int height = im.rows-1;
// output size
const int halfWidth = res.cols >> 1;
const int halfHeight = res.rows >> 1;
float *out = res.ptr<float>(0);
const float *imptr = im.ptr<float>(0);
for (int j=-halfHeight; j<=halfHeight; ++j)
{
const float rx = ofsx + j * a12;
const float ry = ofsy + j * a22;
#pragma omp simd
for(int i=-halfWidth; i<=halfWidth; ++i, out++)
{
float wx = rx + i * a11;
float wy = ry + i * a21;
const int x = (int) floor(wx);
const int y = (int) floor(wy);
if (x >= 0 && y >= 0 && x < width && y < height)
{
// compute weights
wx -= x; wy -= y;
int rowOffset = y*im.cols;
int rowOffset1 = (y+1)*im.cols;
// bilinear interpolation
*out =
(1.0f - wy) * ((1.0f - wx) * imptr[rowOffset+x] + wx * imptr[rowOffset+x+1]) +
( wy) * ((1.0f - wx) * imptr[rowOffset1+x] + wx * imptr[rowOffset1+x+1]);
} else {
*out = 0;
ret = true; // touching boundary of the input
}
}
}
return ret;
}
是用icpc
编译的代码的一部分和以下选项:
INTEL_OPT=-O3 -simd -xCORE-AVX2 -parallel -qopenmp -fargument-noalias -ansi-alias -no-prec-div -fp-model fast=2 -fma -align -finline-functions
INTEL_PROFILE=-g -qopt-report=5 -Bdynamic -shared-intel -debug inline-debug-info -qopenmp-link dynamic -parallel-source-info=2 -ldl
在优化报告文件(.optr
(中有以下行:
remark #15389: vectorization support: reference *out has unaligned access [ /home/luca/Dropbox/HKUST/CloudCache/cloudcache/CloudCache/Descriptors/hesaff/helpers.cpp(259,14) ]
remark #15389: vectorization support: reference *out has unaligned access [ /home/luca/Dropbox/HKUST/CloudCache/cloudcache/CloudCache/Descriptors/hesaff/helpers.cpp(263,14) ]
remark #15389: vectorization support: reference *out has unaligned access [ /home/luca/Dropbox/HKUST/CloudCache/cloudcache/CloudCache/Descriptors/hesaff/helpers.cpp(263,14) ]
第259和263行是明显更改out
值的第259和263行。
据我所知,这意味着out
是不协调的(这里有更多信息[https://software.intel.com/en-us/articles/fdiag15126],在这里(。
但是,这已经很奇怪了,因为当我在这里发现它时,cv::Mat
对象已经对齐。但这可能是合法的,因为编译器无法知道对齐... 但是,如果我添加以下行,则消息出现的消息将出现:
out
分配为对齐指针:
out = (float*) _mm_malloc(res.cols*res.rows*sizeof(float), 32);
这应该足以告诉编译器数据对齐。我错了吗?否则,我该如何确定out
已经对齐?
编译器看到out++
。它不能保持一致。
(也就是说,它仍然对float*
访问保持一致,但是该消息是指SIMD矢量化,需要更严格的对齐(