openmp g ++错误:折叠的循环未完全嵌套 [英] openmp g++ error: collapsed loops not perfectly nested

问题描述

我尝试编译

#include <omp.h>

using namespace std;

vector< vector<int> > multiplyMatrixes(const vector< vector<int> > &a, const vector<     vector<int> > &b, int aHeight, int aWidth, int bHeight, int bWidth) {
    vector < vector<int> > c(aHeight, vector<int>(bWidth, 0));
    #pragma omp parallel for collapse(2)
    for(int row = 0; row < aHeight; row++) {
            for(int col = 0; col < bWidth; col++) {
                   int value = 0;
                   for(int i = 0; i < aWidth; i++) {
                          value += a[row][i] * b[i][col];
                   }
                   c[row][col] = value;
                   cout<<"Tread #"<<omp_get_thread_num()<<"\n";
            }
            std::cout<<'\n';
    }
    return c;
}

int main() {}

使用'g ++ -fopenmp hello.cpp -o hello'命令，gcc版本为4.7，但我得到以下提示 'hello.cpp:19:17:错误:折叠的循环未完全嵌套" 是什么意思?

with 'g++ -fopenmp hello.cpp -o hello' command, gcc version is 4.7, but i get following 'hello.cpp:19:17: error: collapsed loops not perfectly nested' What does it mean?

推荐答案

在错误中进行搜索会发现循环必须完全嵌套；也就是说，在折叠的循环之间没有中间代码，也没有任何OpenMP编译指示"

Googling for the error finds "The loops must be perfectly nested; that is, there is no intervening code nor any OpenMP pragma between the loops which are collapsed"

我认为这意味着不允许在for(i)循环之前和之后的代码.

I think that means the code before and after the for(i) loop is not allowed.

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