【发布时间】：2021-11-19 05:05:01
【问题描述】：
我写了一个 c++ 类来执行一些多边形操作（计算两个多边形的最小距离和相交面积）。我用g++ 8.3.0 编译它。在没有 -O2 编译器标志的情况下编译时一切正常。当我使用-O2 标志时，在某些情况下会得到错误的结果（例如，边长为1.0 且位于原点的左下角的两个相等正方形的相交区域是-2.0 而不是预期结果1.0。）
我在另一篇 stackoverflow 帖子中读到，这很可能是因为我的代码中存在内存泄漏或其他错误，而这不太可能是编译器错误。我的代码中是否存在这样的错误？
我尝试了什么：
-
我仔细检查了
boost的文档，我正确使用了所有函数和类。 -
我在代码中使用了
cppcheck（没有结果）。 -
我在代码中使用了
clang --analyze（没有结果）。
我错过了什么吗？
#include <iostream>
#include <list>
#include <vector>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/geometries.hpp>
#include <boost/geometry/geometries/linestring.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/multi_point.hpp>
#include <boost/geometry/geometries/multi_polygon.hpp>
#include <boost/assign/std/vector.hpp>
#include <boost/geometry/algorithms/area.hpp>
#include <boost/geometry/algorithms/assign.hpp>
#include <boost/foreach.hpp>
//#include "ndarray.h"
namespace bg = boost::geometry;
// use the following two commands to compile:
//
//WARNING: DO NOT USE O2. IT DESTROYS bg::correct FUNCTIONALITY
// g++ -lboost_system -c -fPIC polygoncalc.cpp -o polygoncalc.o -O2
// g++ -lboost_system -shared -Wl,-soname,libpolygoncalc.so -o libpolygoncalc.so polygoncalc.o -O2
typedef boost::geometry::model::d2::point_xy<double> point_type;
//typedef bg::model::point<double, 2, bg::cs::cartesian> point_type;
typedef bg::model::polygon<point_type> polygon_type;
//typedef std::vector< std::vector<double>> Matrix;
class PolygonCalc{
public:
const double helloworld(){
// std::cout << "Hello World" << std::endl;
return 0.123;
}
double test_calc(){
// Point points[] = {Point(0,0), Point(1,0), Point(1,1), Point(0,1)};
// Point points2[] = {Point(0.5,0.5), Point(1.5,0.5), Point(1.5, 1.5), Point(0.5,1.5)};
polygon_type poly1 {{{0.0, 0.0}, {1.0, 0.0}, {1.0, 1.0}, {0.0, 1.0}}};
polygon_type poly2 {{{5.5, 0.5}, {6.5, 0.5}, {6.5, 1.5}, {5.5, 1.5}}};
// polygon_type poly1 {{{0.0, 1.0}, {1.0, 1.0}, {1.0, 0.0}, {0.0, 0.0}, {0.0, 1.0}}};
// polygon_type poly2 {{{0.5, 1.5}, {1.5, 1.5}, {1.5, 0.5}, {0.5, 0.5}, {0.5, 1.5}}};
bg::correct(poly1);
bg::correct(poly2);
// std::vector<point_type> points1;
// std::vector<point_type> points2;
//
// points1.push_back(point_type(0.0,0.0));
// points1.push_back(point_type(1.0, 0.0));
// points1.push_back(point_type(1.0, 1.0));
// points1.push_back(point_type(0.0, 1.0));
//
// points2.push_back(point_type(0.5, 0.5));
// points2.push_back(point_type(1.5, 0.5));
// points2.push_back(point_type(1.5, 1.5));
// points2.push_back(point_type(0.5, 1.5));
// boost::geometry::read_wkt(
// "POLYGON((2 1.3,2.4 1.7,2.8 1.8,3.4 1.2,3.7 1.6,3.4 2,4.1 3,5.3 2.6,5.4 1.2,4.9 0.8,2.9 0.7,2 1.3)"
// "(4.0 2.0, 4.2 1.4, 4.8 1.9, 4.4 2.2, 4.0 2.0))", poly1);
//
// boost::geometry::read_wkt(
// "POLYGON((4.0 -0.5 , 3.5 1.0 , 2.0 1.5 , 3.5 2.0 , 4.0 3.5 , 4.5 2.0 , 6.0 1.5 , 4.5 1.0 , 4.0 -0.5))", poly2);
// polygon_type poly1;
// polygon_type poly2;
//
// bg::assign_points(poly1, points1);
// bg::assign_points(poly2, points2);
std::deque<polygon_type> output;
bg::intersection(poly1, poly2, output);
// std::cout << bg::area(poly1) <<std::endl;
// std::cout << bg::area(poly2) <<std::endl;
double totalArea = 0.0;
int i = 0;
BOOST_FOREACH(polygon_type const& p, output)
{
// std::cout << i++ << ": " << boost::geometry::area(p) << std::endl;
totalArea += bg::area(p);
}
double d = bg::distance(poly1, poly2);
std::cout << d << std::endl;
return totalArea;
}
int test_nparray(double *A, int n){
// int M, N;
//
// M = poly1.size();
// N = poly1[0].size();
//
// std::cout << M << std::endl << N << std::endl;
int i;
double sum = 0.0;
for (i=0; i<n; i++) {
sum += A[i];
}
std::cout << "n: " << n << std::endl;
std::cout << sum / n << std::endl;
return n;
}
double min_poly_distance(double *poly1x, double *poly1y, double *poly2x, double *poly2y, int m, int n){
int i;
std::vector<point_type> points1;
std::vector<point_type> points2;
for (i=0; i<m; i++) {
points1.push_back(point_type(poly1x[i], poly1y[i]));
// std::cout << poly1x[i] << " " << poly1y[i] << std::endl;
}
for (i=0; i<n; i++) {
points2.push_back(point_type(poly2x[i], poly2y[i]));
}
polygon_type poly1;
polygon_type poly2;
bg::assign_points(poly1, points1);
bg::assign_points(poly2, points2);
bg::correct(poly1);
bg::correct(poly2);
std::deque<polygon_type> output;
bg::intersection(poly1, poly2, output);
double totalArea = 0.0;
BOOST_FOREACH(polygon_type const& p, output)
{
totalArea += bg::area(p);
}
if (totalArea > 0.0){
return 0.0;
}
return bg::distance(poly1, poly2);
}
double poly_intersection_area(double *poly1x, double *poly1y, double *poly2x, double *poly2y, int m, int n){
int i;
std::vector<point_type> points1;
std::vector<point_type> points2;
for (i=0; i<m; i++) {
points1.push_back(point_type(poly1x[i], poly1y[i]));
// std::cout << poly1x[i] << " " << poly1y[i] << std::endl;
}
for (i=0; i<n; i++) {
points2.push_back(point_type(poly2x[i], poly2y[i]));
}
polygon_type poly1;
polygon_type poly2;
bg::assign_points(poly1, points1);
bg::assign_points(poly2, points2);
bg::correct(poly1);
bg::correct(poly2);
std::deque<polygon_type> output;
bg::intersection(poly1, poly2, output);
double totalArea = 0.0;
BOOST_FOREACH(polygon_type const& p, output)
{
totalArea += bg::area(p);
}
return totalArea;
}
double poly_intersection_area_ratio(double *poly1x, double *poly1y, double *poly2x, double *poly2y, int m, int n){
int i;
std::vector<point_type> points1;
std::vector<point_type> points2;
for (i=0; i<m; i++) {
points1.push_back(point_type(poly1x[i], poly1y[i]));
// std::cout << poly1x[i] << " " << poly1y[i] << std::endl;
}
for (i=0; i<n; i++) {
points2.push_back(point_type(poly2x[i], poly2y[i]));
}
polygon_type poly1;
polygon_type poly2;
bg::assign_points(poly1, points1);
bg::assign_points(poly2, points2);
bg::correct(poly1);
bg::correct(poly2);
std::deque<polygon_type> output;
bg::intersection(poly1, poly2, output);
double totalArea = 0.0;
BOOST_FOREACH(polygon_type const& p, output)
{
totalArea += bg::area(p);
}
double area1 = bg::area(poly1);
double area2 = bg::area(poly2);
if (area1 > area2) {
return totalArea / area2;
} else {
return totalArea / area1;
}
return totalArea;
}
};
extern "C" {
PolygonCalc* PolygonCalc_new(){ return new PolygonCalc; }
const double PolygonCalc_helloworld(PolygonCalc* polygoncalc){ return polygoncalc->helloworld(); }
double PolygonCalc_test_calc(PolygonCalc* polygoncalc){ return polygoncalc->test_calc(); }
int PolygonCalc_test_nparray(double *A, int n, PolygonCalc* polygoncalc){ return polygoncalc->test_nparray(A, n); }
double PolygonCalc_min_poly_distance(double *poly1x, double *poly1y, double *poly2x, double *poly2y, int m, int n, PolygonCalc* polygoncalc){
return polygoncalc->min_poly_distance(poly1x, poly1y, poly2x, poly2y, m, n);
}
double PolygonCalc_poly_intersection_area(double *poly1x, double *poly1y, double *poly2x, double *poly2y, int m, int n, PolygonCalc* polygoncalc){
return polygoncalc->poly_intersection_area(poly1x, poly1y, poly2x, poly2y, m, n);
}
double PolygonCalc_poly_intersection_area_ratio(double *poly1x, double *poly1y, double *poly2x, double *poly2y, int m, int n, PolygonCalc* polygoncalc){
return polygoncalc->poly_intersection_area_ratio(poly1x, poly1y, poly2x, poly2y, m, n);
}
}
【问题讨论】：
标签： c++ memory-leaks g++ compiler-optimization