On 2014/03/31 17:33:38, Fritz wrote:
I agree that passing register size around is not ideal. But I disagree
that
changing that will solve this problem. There is one register file that
is 64
bits. This can be accessed by both 32 bit op codes and 64 bit op codes.
The
register access for those 32 bit operations are going to need to
read/write to
the 64 bit register file because it's shared. So there needs to be some
sort
of
memcpy/type pun to accomplish this. [...]
Nope, that's exactly the fallacy behind all our problems: If you are
*explicit*
about what you're doing, there is *no need at all* to do some funky casts or
memcpy. Making the register size explicit as a template parameter is
achieving
exactly this: The backing store is of course always 64bit, so the 64bit
operations have to do nothing special, while the 32bit operations have to do
some zero/sign-extension. But via template specialization one can easily
make
the distinction a compile-time decision. You can even get away without this
template magic by providing 2 operations Foo32 and Foo64 instead of a
Foo<size>
template, this is essentially the same as using template specialization for
exactly 2 parameter values.
https://codereview.chromium.org/213943002/
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