ICC has an option that is documented as: auto-p32 Instructs the compiler to analyze the program to determine if there are 64-bit pointers that can be safely sh

ICC has an option that is documented as: auto-p32 Instructs the compiler to analyze the program to determine if there are 64-bit pointers that can be safely shrunk to 32-bit pointers. I don't know how good it is in practice, having never tried it. GCC has -mx32, but that changes ABI completely, you have to recompile everything, and you need a new kernel with another system call table (which your favorite kernel might have disabled).