In the Vivado 2014.4 IDE there is a Simulation Setting to specify whether a 64-bit or 32-bit 3rd Party Simulator is going to be used.
Starting in 2015.1, the IDE option is gone. How do I specify a 32-bit vs a 64-bit 3rd Party Simulator?
Starting in 2015.1 the IDE option was removed and replaced with a universal property for ALL 3rd Party Simulators. The default behavior for Vivado is to use a 64-bit Simulator.
To specify the use of a 32-bit Simulator, use the following set_property command:
set_property 32bit 1 [current_fileset -simset]