I have a .dll compiled with various optimization flags using g++, how do I dynamically link it to my application?

Question

I have a .dll library on Windows which I compiled using mingw g++ on the command line with various flags to optimize it, but I need to link it to my project so that the .dll is required to run the compiled .exe (as far as I understand, this is implicit/dynamic linking). This is originally a macOS project, so I can't figure out how to link it to my Visual Studio project since it seems I need a .lib file.

The way I create the .dll file is by inputting this command in cmd inside the lib folder :

g++ -shared -DNDEBUG -IC:\Users\luis.lopez\Documents\libraries\eigen\ -march=native -ftree-vectorize -ffast-math -fstrict-aliasing -O3 -fomit-frame-pointer -fopenmp -o libfoo.dll foolibrary.cpp

Is there a way for me to create the .lib file while maintaining these compilation flags?

If you compiled that lib yourself you have access to the source code. Why don't you recompile the DLL with VS? — Chnossos, Feb 08 '21 at 15:56
I have various optimization flags that are available in the g++ compiler, not sure how I would do that with the VS compiler. — Luis Angel Urena Lopez, Feb 08 '21 at 15:59
Type "msvc " in Google. You'll find an equivalent for [most](https://learn.microsoft.com/en-us/cpp/build/reference/o-options-optimize-code) if not all. — Chnossos, Feb 08 '21 at 16:08

score 0 · Answer 1 · answered Feb 11 '21 at 18:28

0

You can add -Wl,--output-def,libfoo.def to generate libfoo.def. Then you should be able to generate an MSVC .lib file, see: How to generate an import library (LIB-file) from a DLL?

But to properly port to Windows you need to make sure the symbols are in fact exported by the library using __declspec(dllexport) and imported using __declspec(dllimport) by the code using the library, see for example: linkage between dllimport and dllexport

answered Feb 11 '21 at 18:28

Brecht Sanders

6,215
1
16
40

I'm using `-Wl,--out-implib,libcafx_dll.lib` flag and it makes the .lib directly. Is there any benefit to doing a .def first? – Luis Angel Urena Lopez Feb 11 '21 at 19:53
In the method I described you are sure the .lib file is generated by MSVC tools, but that works too. – Brecht Sanders Feb 11 '21 at 20:09

I have a .dll compiled with various optimization flags using g++, how do I dynamically link it to my application?

1 Answers1