https://community.intel.com/t5/Intel-Fortran-Compiler/Different-behaviour-on-code-compiled-with-Qopenmp-option-but/m-p/867129#M71001 Hi,<BR /><BR />I recently upgraded to version 11.1 of the IVF compiler. I noticed that if I compile the same code with and without the /Qopenmp option the results can sometimes be different even if I'm not using any omp directive in the code. I have been assuming that the result would be the same, is that correct?<BR /><BR />In summary, if no omp directives are used, can the /Qopenmp option affect the outcome?<BR /><BR />Thanks,<BR /><BR />Juan<BR /> Wed, 17 Mar 2010 22:29:49 GMT Juan_Senent 2010-03-17T22:29:49Z https://community.intel.com/t5/Intel-Fortran-Compiler/Different-behaviour-on-code-compiled-with-Qopenmp-option-but/m-p/867129#M71001 Hi,<BR /><BR />I recently upgraded to version 11.1 of the IVF compiler. I noticed that if I compile the same code with and without the /Qopenmp option the results can sometimes be different even if I'm not using any omp directive in the code. I have been assuming that the result would be the same, is that correct?<BR /><BR />In summary, if no omp directives are used, can the /Qopenmp option affect the outcome?<BR /><BR />Thanks,<BR /><BR />Juan<BR /> Wed, 17 Mar 2010 22:29:49 GMT https://community.intel.com/t5/Intel-Fortran-Compiler/Different-behaviour-on-code-compiled-with-Qopenmp-option-but/m-p/867129#M71001 Juan_Senent 2010-03-17T22:29:49Z https://community.intel.com/t5/Intel-Fortran-Compiler/Different-behaviour-on-code-compiled-with-Qopenmp-option-but/m-p/867130#M71002 Yes, absolutely. One big difference is that with /Qopenmp, all local variables are allocated on the stack by default, whereas without it, arrays are statically allocated. If your program references uninitialized array elements, you can see a difference. Wed, 17 Mar 2010 23:17:19 GMT https://community.intel.com/t5/Intel-Fortran-Compiler/Different-behaviour-on-code-compiled-with-Qopenmp-option-but/m-p/867130#M71002 Steven_L_Intel1 2010-03-17T23:17:19Z