segmentation fault with -O3 but not with -ipo

Hi,

     I am struggling with a runtime segmentation fault error and hope that someone may provide useful insight on the issue. I have a code which runs fine with -O1 but crashes with -O2 and -O3 flags. If I add -ipo flag with -O3 or -O2 then the code runs fine again (although with -ipo flags I get some warning messages about unresolved subroutines). When I try to run the code in debugging mode with "-g -traceback -check bounds", it runs without any error, so I don not know what is causing the segmentation fault with -O3 optimization. Additionally, the code is running fine with gcc compiler with -03 flag on. I would greatly appreciate if someone could help me overcome the issue.

Thank you