[llvm-bugs] [Bug 47321] New: Simple loop with IO - LLVM much slower than GCC

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47321

            Bug ID: 47321
           Summary: Simple loop with IO - LLVM much slower than GCC
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Loop Optimizer
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

Code:
#include <string>
#include <map>
#include <fstream>
#include <iostream>
int main(int argc, char **argv) {
  if (argc != 2)
    return 1;
  std::string dict = argv[1];
  std::map<unsigned, unsigned> pwd_dist;

  std::ifstream file(dict);
  if (!file.is_open())
    return 1;
  std::string line;
  while (getline(file, line)) {
    unsigned pwd_len = line.length();
    pwd_dist[pwd_len] += 1;
  }
  file.close();

  for (std::map<unsigned, unsigned>::iterator it = pwd_dist.begin();
       it != pwd_dist.end(); it++) {
    std::cout << it->first         // string (key)
              << ':' << it->second ;// string's value
    if (std::next(it) != pwd_dist.end())
       std::cout       << ';';
  }
  return 0;
}

Compiled with -O3.

Clang:
0m1,219s

GCC:
0m0,623s

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