Analysis reports for STL implementation comparison (libstdc++, libc++, MS STL)

[honggyukim]

Very recently, microsoft has open-sourced MSVC STL implementation on github.

• https://github.com/microsoft/STL
• https://devblogs.microsoft.com/cppblog/open-sourcing-msvcs-stl

It seems that it can be meaningful to compare the STL implementation for each library.

• GNU libstdc++
• LLVM libc++
• MSVC STL

uftrace can be a useful tool for their analysis.

[namhyung]

Looks like an interesting topic for study.

[lacrimak3]

I want to compare the STL implementation of each library

[honggyukim]

@sungho-yoon Thanks! We first have to make sure that if it's possible to build MS STL in Linux environment. Could you please try it first?

[lacrimak3]

@honggyukim OK I'll try it first

[lacrimak3]

@honggyukim I need some help to analyze stl.
Maybe there is a problem tracing libc++ built-in functions.

Source code

#include <iostream>
using namespace std;

void algorithm_sort(){
    vector<int> a = {5, 4, 3, 2, 1};
    sort(a.begin(), a.end());
}

int main(void){
    algorithm_sort();
    return 0;
}

With g++, libstdc++
Compile option
g++ -pg a.cpp

Compile option
uftrace -t 1us a.out

Result(std::sort())

std::sort() {
            [  3096] |       std::__sort() {
            [  3096] |         std::__final_insertion_sort() {
            [  3096] |           std::__insertion_sort() {
            [  3096] |             std::move_backward() {
   1.300 us [  3096] |               std::__copy_move_backward_a2();
   1.700 us [  3096] |             } /* std::move_backward */
            [  3096] |             std::move_backward() {
   1.100 us [  3096] |               std::__copy_move_backward_a2();
   1.400 us [  3096] |             } /* std::move_backward */
   1.400 us [  3096] |             std::move_backward();
   1.300 us [  3096] |             std::move_backward();
  11.899 us [  3096] |           } /* std::__insertion_sort */
  12.299 us [  3096] |         } /* std::__final_insertion_sort */
  13.599 us [  3096] |       } /* std::__sort */
  13.899 us [  3096] |     } /* 

With clang++, libc++
Compile option
clang++ -pg -stdlib=libc++ a.cpp

Result
uftrace -t 1us a.out

# DURATION     TID     FUNCTION
            [  2978] | main() {
            [  2978] |   algorithm_sort() {
            [  2978] |     std::__1::vector::allocate() {
   1.900 us [  2978] |       operator new();
   5.200 us [  2978] |     } /* std::__1::vector::allocate */
   1.500 us [  2978] |     std::__1::__sort();
   8.700 us [  2978] |   } /* algorithm_sort */
   9.400 us [  2978] | } /* main */

I don't know how to trace libc++ built-in functions. Is there a way to trace it? With Full Dynamic Tracing, the results are same.
Should I rebuild libc++ with -pg option?

[honggyukim]

Sorry for missing to reply this thread. The STL functions inside libstdc++ are mostly provided in its header files, but libc++ provides most of implementation inside the library itself.

So it might not be able to trace many functions inside libc++. The best way to trace it is to recompile libc++ as well. Thanks.