unresolved external symbol __libm_sse2 and _iob

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January 5, 2010 11:00 PM PST


Symptom(s):

When linking with the static threaded version of IPP libraries, e.g ippiemergedem64t.lib ippimergedem64_t.lib, you may receive the following error:

ippimergedem64t_t.lib(piwarp_split_mx_ippiGetRotateShift.obj) : error LNK2019: unresolved external symbol __libm_sse2_sincos referenced in function mx_ippixxx

Cause:

The symbol is defined in the Intel Math library libm*.lib provided by Intel® C++ Compiler. The Math library contains highly optimized mathematical functions, such as sin(), cos(). Some IPP functions depend on them.

Library Option Description
libm.lib Default static math library.
libmmt.lib /MT Multi-threaded static math library.
libmmd.lib /MD Dynamically linked math library.
libmmdd.lib /MDd Dynamically linked debug math library.
libmmds.lib Static version compiled with /MD option.

Solution:

Link the libmmt.lib in your application.

IPP bundles the library libmmt.lib/libm.lib in directory lib, by default they are in C:\Program Files\Intel\IPP\6.0.0.xx\[em64t|ia32]\lib.

Please note, we assume that the applicatoin is built with /MT option here.  The Intel math library linked to an application depends on the compilation or linkage options specified. Refer to the above table.

Troubleshooting
After linking libmmt.lib, a sequential error may appear:

libmmt.lib(libm_error.obj) : error LNK2019: unresolved external symbol _iob referenced in function write_message 

The symbol _iob is defined in the MSVC static C run-time library libcmt.lib.  When using IPP static threaded library in MSVC, we assume that the application is built with the /MT option, thus link libcmt.lib automatically.  
 
But one application or its parts may have been built with the /MD option, which will link MSVC dynamic C run-time library MSVCRT*.dll,which does not have the symbol defined. In this case, please link libmmds.lib instead.

libmmds.lib -  Static math library version compiled with /MD option, which is provided by Intel Compiler.

Notes:
Both Intel Profession Compiler and Intel Parallel Composer include IPP library and the Intel Math Libraries. You may find them in their install directory.  


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This article applies to: Intel® Integrated Performance Primitives Knowledge Base,   Intel® Parallel Composer Knowledge Base