Too slow link in MinGW-w64

[bylee20]

Description

I'm suffer from too slow link in MinGW-w64 environment.

Steps to reproduce

I used very simple main.cpp:

#define CATCH_CONFIG_MAIN
#include "catch.hpp"

And, here's the result:

Well, it takes about 8 seconds to compile the file here, which is totally acceptable considering big header file.

The problem is that it takes another approximately 9 seconds again to create executable with already compiled object file.
As you can see, the link time is even longer than compile time.
This is very annoying because I have to wait 9 seconds at least whenever building executable even though the object file is not changed.
In fact, my actual test project requires me to wait about 1 minute to be linked.

How can I improve link performance, here?
Any suggestion would be nice.

Thank you.

Extra information

• Catch version: v2.1.2
• Operating System: Widows 10, MinGW-w64, 64bit
• Compiler+version: GCC 7.3.0

[alexander-titov]

Hi,

I have a similar problem. I am using Catch under CLion.
Linking time w/ Catch is extremely long (>2 mins for a trivial test).

Example

1. Compiling a trivial main.cpp. Build finished in 772ms

2. Compiling main.cpp with catch.hpp:

    #define CATCH_CONFIG_MAIN
    #include "../Catch2/single_include/catch.hpp"

Build finished in 2m 32s 812ms (!!!)

3. Adding a simple test.cpp:

#include "../Catch2/single_include/catch.hpp"
TEST_CASE( "Simple math", "" ) {
    REQUIRE( 2 + 2 == 4);
}

Build finished in 2m 4s 211ms (!!!)

4. Modifying test.cpp:
   Build finished in 2m 0s 729ms

Most of the time is spent on linking.

Configuration

• Catch: v2.2.1
• OS: Widows 10, MinGW-w64, 64bit
• MinGW: mingw-w64\x86_64-7.2.0-posix-seh-rt_v5-rev1
• Clion: CLion 2017.3.4 Build #CL-173.4674.29
• Compiler+version: GCC 7.2.0

[horenmar]

We have had some issue with link times before, but that was caused by LTO builds.

For non-lto builds, there is not much we can do except concluding that MinGW link times are awful.

[bylee20]

OK. Thanks a lot.

[ghost]

mingw-w64 in version 7.2 and 7.3 LTO is completely broken. Also, the link times are horrible without LTO, to the point of it not being usable. I have to wait 4 minutes for it to link, compared to under MSVC++ the same projects links in less than 20 seconds.

[nano-bot]

The only reasonable for me to use mingw and catch2 is to create a shared library and compile the whole subtree from here https://github.com/catchorg/Catch2/tree/master/include (not a single header file because it's awfully slow). Tests compile and run within milisecond

[snahmad]

Any resolution on this issue?

[ghost]

Not that I am aware of. Hopefully soon, as we're about to move back to Visual Studio.

[maobaoqi]

I have same problem on MSYS2.

[maobaoqi]

The only reasonable for me to use mingw and catch2 is to create a shared library and compile the whole subtree from here https://github.com/catchorg/Catch2/tree/master/include (not a single header file because it's awfully slow). Tests compile and run within milisecond

@nano-bot Hi, How to compile catch2 shared library?

[shreyasbharath]

@nano-bot How'd you go about compiling your shared library?

On a side-note, can we push that shared library to Conan? It'll make consumption a whole lot easier rather than having to build it ourselves.

[Adriankhl]

I am a random guy who was searching for a solution to improve the horrible link time in Mingw. I successfully improve it vastly by using the lld linker -fuse-ld=lld in my own project. I know nothing about this project so it may or may not work.

[ylliu]

where to set

-fuse-ld=lld

?

[dortamiguel]

@Adriankhl where do you set the -fuse-ld=lld ?

[Adriankhl]

@ellipticaldoor It is a compiler flag for gcc: https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html
Therefore, it depends on how your project is built. For plane gcc, here is an example (https://stackoverflow.com/questions/29361801/is-the-lld-linker-a-drop-in-replacement-for-ld-and-gold). Mostly likely, you are working with a build system like cmake, then you have to figure it out how to specify the flag for the system.