I have a C++ library built in Visual Studio 2017 which uses AVX-512 intrinsics. I need to link the library to VS2008 C++ code. The library is used to extract lines from an image. All the intrinsic instructions are encapsulated within the library. VS2008 code passes in char* data, LineSpec (structure with 4 floats) and char* result, which gets filled with extracted lines.
I am unable to link the library due to error C1083: Cannot open include file: immintrin.h. I am also unable to build the library in VS2017 using VS2008 tool-set for the same reason.
The goal is to increase extraction speed with AVX-512 instructions while compiling the rest of the code with VS2008. I am new to intrinsics and mixing platforms. Do you have any suggestion on how to use the library in VS2008?
You can't
To call a function that uses ymm registers the compilers need to emit instructions to prepare those according to the ABI. But AVX-512 didn't exist in 2008, thus there's no way for VS2008 to know about the ABI or AVX-512 instructions
And then when linking you also need to know about the instruction set to know which address to fix, although this might be easier to solve with the offset stored in the object code
In short you need to update the compiler instead of using a decade-old one
Related
I'm trying out the clang32 compiler coming with C++ builder 10.2. Builder don't yet have any good support for CMake, so a great number of 3rd party libraries are (very) hard to compile using it.
Anyone knowing if there is any binary compatibility between clang32 and Visual Studio compiler?
There are essentially three different levels of compatibility you need to worry about:
File formats for object code and debug data, which allow you to use clang to build part of your project and Visual C++ cl.exe to build a library and then link them together and debug both.
Ability to write code and structure data that conforms to a portable binary interface, so it can be called across a mix of compilers.
Binary compatibility of the C++ standard library, so that standard library objects can be shared across a mix of compilers.
I can definitely say that (2) is supported and (3) absolutely is not; you can't even share standard library objects between different patchlevels of the same compiler. For (1) I don't know. A common way to bypass the issues with (1) is to build a DLL using each compiler, so they dynamically interface but no static linking nor merging of debug data is necessary.
If your concern is about cmake though, I think your problem is not the compiler (clang is available for Linux and cmake supports it well -- you should find the make scripts are capable of configuring all the compiler options). Whether it can generate project files for C++Builder is a different story, but perhaps you should consider using a different IDE. There are many with clang support, even Microsoft's Visual Studio has some ability to use clang for the compile step, and it's getting better with each release.
I have a C# project, a CLI/C++ project which wraps a C++ project.
I have compiled openCV 3.0.0 and I'm using full static link( *.lib without *.dll files)
since I want to use Intel IPP i want to use the intel Compiler in order to compile the C++ project.
at first I tought I will have problems since the OpenCV libs aren't compiled with the Intel compiler(they are compiled with VS2012 compiler).
So just for trying I switch the toolset flag to Intel Compiler 14.0 and it worked, I can run my app... and use openCV and IPP.
Can you please explain a little bit about why is this possible? is it the same for dynamic loading(*.dll)? or if I use openCV with dynamic loading I will need to compile them with Intel Compiler?
Thanks
Roughly. The compiler used to generate a given machine code does not really matters (except for the quality of the code). What is important is that some conventions are respected : format of object code files, naming external objects and ABI (the way functions are called).
Thinking of using MinGW as an alternative to VC++ on Windows, but am worried about compatibility issues. I am thinking in terms of behaviour, performance on Windows (any chance a MinGW compiled EXE might act up). Also, in terms of calling the Windows API, third-party DLLs, generatic and using compatible static libraries, and other issues encountered with mixing parts of the same application with the two compilers.
First, MinGW is not a compiler, but an environment, it is bundled with gcc.
If you think of using gcc to compile code and have it call the Windows API, it's okay as it's C; but for C++ DLLs generated by MSVC, you might have a harsh wake-up call.
The main issue is that in C++, each compiler has its own name mangling (or more generally ABI) and its own Standard library. You cannot mix two different ABI or two different Standard Libraries. End of the story.
Clang has a specific MSVC compatibility mode, allowing it to accept code that MSVC accepts and to emit code that is binary compatible with code compiled with MSVC. Indeed, it is even officially supported in Visual Studio.
Obviously, you could also simply do the cross-DLL communication in C to circumvent most issues.
EDIT: Kerrek's clarification.
It is possible to compile a large amount of C++ code developed for VC++ with the MinGW toolchain; however, the ease with which you complete this task depends significantly on how C++-standards-compliant the code is.
If the C++ code utilizes VC++ extensions, such as __uuidof, then you will need to rewrite these portions.
You won't be able to compile ATL & MFC code with MinGW because the ATL & MFC headers utilize a number of VC++ extensions and depend on VC++-specific behaviors:
try-except Statements
__uuidof
throw(...)
Calling a function without forward-declaring it.
__declspec(nothrow)
...
You won't be able to use VC++-generated LIB files, so you can't use MinGW's linker, ld, to link static libraries without recompiling the library code as a MinGW A archive.
You can link with closed-source DLLs; however, you will need to export the symbols of the DLL as a DEF file and use dlltool to make the corresponding A archive (similar to the VC++ LIB file for each DLL).
MinGW's inclusion of the w32api project basically means that code using the Windows C API will compile just fine, although some of the newer functions may not be immediately available. For example, a few months ago I was having trouble compiling code that used some of the "secure" functions (the ones with the _s suffix), but I got around this problem by exporting the symbols of the DLL as a DEF, preparing an up-to-date A archive, and writing forward declarations.
In some cases, you will need to adjust the arguments to the MinGW preprocessor, cpp, to make sure that all header files are properly included and that certain macros are predefined correctly.
What I recommend is just trying it. You will definitely encounter problems, but you can usually find a solution to each by searching on the Internet or asking someone. If for no other reason, you should try it to learn more about C++, differences between compilers, and what standards-compliant code is.
I know that if I link my c++ program to a dynamic library (DLL) that was built with a different version of Visual Studio, it won't work because of the binary compatibility issue.
(I have experienced this with Boost library and VS 2005 and 2008)
But my question is: is this true for all versions of MSVS? Does this apply to static libraries(LIB) as well? Is this an issue with GCC & Linux as well? and finally how about linking in VS to a DLL built with MinGW?
By the way aside from cross-platform or cross-compiler, why can't two version of the same compiler(VS) be compatibile?
Hi. I know that if I link my c++ program to a dynamic library (DLL) that was built with a different version of Visual Studio, it won't work because of the binary compatibility issue. (I have experienced this with Boost library and VS 2005 and 2008)
I do not remember ever seeing MS changing the ABI, so technically different versions of the compiler will produce the same output (given the same flags (see below)).
Therefore I don't think this is not incompatibilities in Dev Studio but changes in Boost.
Different versions of boost are not backwards compatible (in binary, source they are backward compatible).
But my question is: is this true for all versions of MSVS?
I don't believe there is a problem. Now if you use different flags you can make the object files incompatible. This is why debug/release binaries are built into separate directories and linked against different versions of the standard run-time.
Does this apply to static libraries(LIB) as well?
You must link against the correct static library. But once the static library is in your code it is stuck there all resolved names will not be re-resolved at a later date.
Is this an issue with GCC & Linux as well?
Yes. GCC has broken backwards compatability in the ABI a couple of times (several on purpose (some by mistake)). This is not a real issue as on Linux code is usually distributed as source and you compile it on your platform and it will work.
and finally how about linking in VS to a DLL built with MinGW?
Sorry I don't know.
By the way aside from cross-platform or cross-compiler, why can't two version of the same compiler(VS) be compatibile?
Well fully optimized code objects may be compressed more thus alignment is different. Other compiler flags may affect the way code is generated that is incompatible with other binary objects (changing the way functions are called (all parameters on the stack or some parameters in registers)). Technically only objects compiled with exactly the same flags should be linked together (technically it is a bit looser than that as a lot of flags don't affect the binary compatibility).
Note some libraries are released with multiple versions of the same library that are compiled in different ways. You usually distinguish the library by the extension on the end. At my last job we used the following convention.
libASR.dll // A Sincgle threaded Relase version lib
libASD.dll // A Single threaded Debug version
libAMR.dll // A Multi threaded Release version
libAMD.dll // A Multi threaded Debug version
If properly built, DLLs should be programming-language and version neutral. You can link to DLLs built with VB, C, C++, etc.
You can use dependency walker to examine the exported functions in the dll.
To answer part of your question, GCC/Linux does not have this problem. At least, not as often. libstdc++ and glibc are the standard C++/C libraries on GNU systems, and the authors of those libraries go to efforts to avoid breaking compatibility. glibc is pretty much always backward compatible, but libstdc++ has broken ABI several times in the past and probably will again in the future.
It is very difficult to write stable ABIs in C++ compared to C, because the automatic features in C++ take away some of the control you need to maintain an ABI. Especially once you get into templates and inline functions, where some of the code gets embedded in your application rather than staying contained in the shared library. That means that the object's structure can't ever change without requiring a recompilation of the application.
In practice, it isn't a huge deal on Windows. It would be fantastic if Microsoft just made the MSI installer know how to grab Microsoft-provided DLLs from Windows Update when an app is installed that needs them, but simply adding the redistributable to an InnoSetup-generated installer works well enough.
Due to MSVC10 not allowing the use of inline ASM instructions when targeting x64 architecture, I'm looking for any ways to get around such restrictions. I have learned from googling that writing and compiling separate ASM modules then linking against them and calling them from C++ is one way, however I have no idea how I would do this. Are there any other ways, short of using the compiler intrinsics? Or how does one go about writing/compiling/linking against separate ASM modules in VS2010?
You can use a separate assembler program which will compile complete assembler source files into object files. So long as you follow the correct calling conventions you can provide prototypes for the functions for use in C++ link the C++ and ASM generated object files together.
I use yasm . It uses intel syntax, supports x64 windows and VS2010 integration. It has useful macro and include features. I must confess that I haven't had to use it since VS2008 when integration worked a bit differently, but it is supposed to work well with VS2010.