support for 128 bit integer types

[Daniel_D]

Hi,

I need for a project a 128 bit integer data type. As far as I could find out the intel compiler supports __int128 and __uint128. This works fine as long as I do not use %. Here is a complete sample to reproduce the problem:

Environment:

• windows 11, all updates
• intel C++ 2024 latest version

int main()
{
__int128 l_i128Result = 12345678;
l_i128Result %= 13;
}

output:

1>R:\ConsoleApplication1\ConsoleApplication1\ConsoleApplication1.cpp(4,11): : warning : variable 'l_i128Result' set but not used [-Wunused-but-set-variable]
1> 4 | __int128 l_i128Result = 12345678;
1> | ^
1>1 warning generated.
1>ConsoleApplication1.obj : : error LNK2019: unresolved external symbol __modti3 referenced in function main
1>R:\ConsoleApplication1\x64\Debug\ConsoleApplication1.exe : : error LNK1120: 1 unresolved externals
1>Done building project "ConsoleApplication1.vcxproj" -- FAILED.

I could not find out which library I need to add to fix this function call.

Thanks for your help.

[Alex_Y_Intel]

Hi @Daniel_D
What's the command used in this case? 
 

[Daniel_D]

I created a new console project for the intel compiler. Add the lines of code and click on compile. I use the intel project template.

Is it that you are asking or does your question point to something else?

[Alex_Y_Intel]

@Daniel_D it looks like you used Visual Studio instead of Intel oneAPI command prompt?

[Daniel_D]

Yes- all in VS:

Create a new c++ console project. Add the few code lines. Switch to intel compiler and click on compile.

I already found a workaround and use boost:

#include "boost/multiprecision/cpp_int.hpp"
using namespace boost::multiprecision;

it comes with the types I need.

[Theo-at-Stillwater]

Hi Daniel:

boost::multiprecision is an arbitrary precision library that does NOT mimic a fixed-sized type like __int128. So any linear algebra you want to do will not have 'nice' memory layouts because the boost::multiprecision are not byte packed. A number system library that does is Universal (https://github.com/stillwater-sc/universal)

There are custom 128bit integers in the Universal Numbers library 

In Universal you can ask for a specific integer parameterized in size, for example, integer<128>, for a 128-bit integer. Universal allows for parameterization at single bit precision, so if you want a 97 bit integer, you can get one via the declaration: integer<97>.

Universal is a headers-only lib, so all you would need to do is add the include file:

#include <universal/number/integer/integer.hpp> 

and you would be off to the races.

Hope that helps.

Theo

[Alex_Y_Intel]

@Daniel_D I've noticed that this problem happens when you use Visual Studio, but if you Intel oneAPI command prompt then there's no problem. Thus I escalated this issue so our developers can take a look. 

[Bernasek__Franz]

Hi

i have compile this code fragment under Linux ( OpenSUSE Tumbleweed) with the oneAPI 2024 icx

no problems, no compiler error , nothing all works fine

regards

Franz

[Daniel_D]

@Alex_Y_Intel :

Thanks to taking care!

@Bernasek__Franz : 

Will switch to Linux later in the project. At the moment I need windows.

[cw_intel]

Hi,

I tested the code and got the same error with Debug configuration. But with Release configuration, the code could be built successfully. So as a workaround, you can use Release configuration. In the meantime, I will report the issue to our development team to fix it.

Thanks.

[cw_intel]

This issue is related to the option "/Od". In the Debug configuration, the default optimization is "/Od", you can change it to "/O1" or "/O2" or "/O3", then the code can run successfully.

Thanks.

[cw_intel · Accepted solution]

Hi,

This issue is resolved with the clang builtins library. You can build the code with the library clang_rt.builtins-x86_64.lib, for example,

icx-cl.exe /Od ConsoleApplication1.cpp clang_rt.builtins-x86_64.lib

This library was not available in the 2024.0 release, but we have it in the 2024.1 release that become available for download now. Please download the 2024.1 release.

Thanks.

[Daniel_D]

Thanks a lot!