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Most programs fits well on <4GB address space but needs to use new features just available on x64 architecture.
Are there compilers/platforms where I can use x64 registers and specific instructions but preserving 32-bits pointers to save memory?
Is it possible do that transparently on legacy code? What switch to do that?
OR
What changes on code is it necessary to get 64-bits features while keep 32-bits pointers?
A simple way to circumvent this is if you’d have only few types for your structures that you are pointing to. Then you could just allocate big arrays for your data and do the indexing with
uint32_t.So a “pointer” in such a model would be just an index in a global array. Usually addressing with that should be efficient enough with a decent compiler, and it would save you some space. You’d loose other things that you might be interested in, dynamic allocation for instance.
Another way to achieve something similar is to encode a pointer with the difference to its actual location. If you can ensure that that difference always fits into 32 bit, you could gain too.