How to install Eigen library to IAR c/c++ compiler - c++

Question

is it possible to port Eigen, a C++ template library for linear algebra, to IAR workbench for ARM. I have tried to do this while but am getting following compile errors
Error[Pe337]: linkage specification is incompatible with previous "__nounwind __iar_builtin_get_CONTROL" (declared at line 58 of "C:\Program Files (x86)\IAR Systems\Embedded Workbench 8.3\arm\inc\c\iccarm_builtin.h") C:\Program Files (x86)\IAR Systems\Embedded Workbench 8.3\arm\CMSIS\Core\Include\cmsis_gcc.h 151
This is the entire error I get when I use the preprocessors
__GNUC__
__arm__
if I dont use these preprocessors I get an error from a #error preprocessor
from the Eigen file Macros.h
"error Please tell me what is the equivalent of attribute((aligned(n))) for your compiler"
#if (defined __CUDACC__)
#define EIGEN_ALIGN_TO_BOUNDARY(n) __align__(n)
#elif EIGEN_COMP_GNUC || EIGEN_COMP_PGI || EIGEN_COMP_IBM || EIGEN_COMP_ARM
#define EIGEN_ALIGN_TO_BOUNDARY(n) __attribute__((aligned(n)))
#elif EIGEN_COMP_MSVC
#define EIGEN_ALIGN_TO_BOUNDARY(n) __declspec(align(n))
#elif EIGEN_COMP_SUNCC
// FIXME not sure about this one:
#define EIGEN_ALIGN_TO_BOUNDARY(n) __attribute__((aligned(n)))
#else
//#define EIGEN_ALIGN_TO_BOUNDARY(n) __declspec(align(n))
#error Please tell me what is the equivalent of __attribute__((aligned(n))) for your compiler
#endif
I have it working for visual c++ but not IAR. All includes are added.
These errors change based on the preprocessors I use to try to configure Eigen. Is it possible to use Eigen with IAR?

Answer 1

To add to #chtz answer, here's how I got the EIGEN_ALIGN_TO_BOUNDARY macro to work with IAR, in a way that is consistent with the eigen library:
1: add this to top of Macros.h to identify the IAR ARM compiler
/// \internal EIGEN_COMP_ICCARM set to 1 if the compiler is IAR eWARM
#if defined(__ICCARM__)
#define EIGEN_COMP_ICCARM 1
#else
#define EIGEN_COMP_ICCARM 0
#endif
2: add this case to where EIGEN_ALIGN_TO_BOUNDARY(n) is defined in Macros.h
#elif EIGEN_COMP_ICCARM
#define IAR_STRINGIFY(a) #a
#define IAR_ALIGN_STR(n) IAR_STRINGIFY(data_alignment=n)
#define EIGEN_ALIGN_TO_BOUNDARY(n) _Pragma(IAR_ALIGN_STR(n))
EIGEN_ALIGN_TO_BOUNDARY(n) should now correctly expand to _Pragma("data_alignment=n")

Answer 2

I have now gotten it to build and run. Thank you #chtz for the EIGEN_DONT_ALIGN macro suggestion. This is how I did it. I am unsure however what repercussions this has on the library itself, as in what features this may take away. I did this:
include the directory to where you installed Eigen as the additional includes.
in lines 86, 105, 125, 145 in file DenseStorage.h change the lines
EIGEN_ALIGN_TO_BOUNDARY(8) T array[Size];
to their respective
_Pragma("data_alignment=8") T array[Size];
(pay attention to the number)
in Macros.h , line 665 , comment out the "#error Please tell me what is the"
finally, define the macro EIGEN_DONT_ALIGN in the preprocessor settings.
This is what worked for Eigen 3.3.7