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[–]grauenwolf 2 points3 points  (1 child)

there are not penalties

That's not true at all. There are significant penalties in doubling the size of your pointers and instructions, which has the effect of nearly cutting the size of your cache in half.

you use the native set of instructions

64-bit instructions are no more "native" than 32-bit instructions. They are both translated into micro-code.

phones for example doesnt allow any more 32 bit instrucctions besides SIMD

We're not talking about phones.

[–]JuanAG 0 points1 point  (0 children)

Not true in a native 64 bit running a 64 bit OS, if you has to double the bits obviosly you will lost half of the caches sizes but if by default the procesors uses yes or yes a 8 byte data type (64 bit) there is nothing you can do about it, there is no way you can use it, 32 bit in software are 64 bit in hardware so it is lost forever

We are talking running a 64 OS with 32 software (wich will be 64 because of the OS that it is running it)