g++ 为 std::bitset 分配内存不足

Question

Here I'm allocating 10^9 bits:

#include <bitset>
#include <iostream>

const int N = 1000000000;
std::bitset<N> b;

int main()
{
    std::cout << sizeof(b) << std::endl;
}

I get cc1plus.exe: out of memory allocating 268439551 bytes .

But when I do

#include <bitset>
#include <iostream>

const int N = 1000000000;
int l[N/32];

int main()
{
    std::cout << sizeof(l) << std::endl;
}

The 125000000 bytes (125 MB) are allocated fine. If I change N to a different power of 10 I see both sizeof are the same. I don't even see where the 268439551 byte limit is coming from, since that's 268.4 MB and I have about 4 GB RAM free. Even on a 32 bit system ~200 MB should not be causing a problem, and somehow the byte limit is reached. What's causing the problem here?

Using gcc 4.8.3 on Windows 8.1 with 8 GB RAM.

Answer 1

This seems to be a bug with GCC for c++11: Gcc uses large amounts of memory and processor power with large C++11 bitsets . Compiling with -std=c++98 was a temporary workaround for me.