Question

I have a VC++ project (2005) that generates both 32-bit and 64-bit dlls. The 32-bit dll is 1044 KB whereas the 64-bit version is 1620 KB. I’m curious why the size is so large. Is it just because of the larger address size, or is there a compiler option that I’m missing?

Answer 1

Maybe your code contains a lot of pointers.

The Free Lunch Is Over

….

(Aside:
Here’s an anecdote to demonstrate
“space is speed” that recently hit my
compiler team. The compiler uses the
same source base for the 32-bit and
64-bit compilers; the code is just
compiled as either a 32-bit process or
a 64-bit one. The 64-bit compiler
gained a great deal of baseline
performance by running on a 64-bit
CPU, principally because the 64-bit
CPU had many more registers to work
with and had other code performance
features. All well and good. But what
about data? Going to 64 bits didn’t
change the size of most of the data in
memory, except that of course pointers
in particular were now twice the size
they were before. As it happens, our
compiler uses pointers much more
heavily in its internal data
structures than most other kinds of
applications ever would. Because
pointers were now 8 bytes instead of 4
bytes, a pure data size increase, we
saw a significant increase in the
64-bit compiler’s working set. That
bigger working set caused a
performance penalty that almost
exactly offset the code execution
performance increase we’d gained from
going to the faster processor with
more registers. As of this writing,
the 64-bit compiler runs at the same
speed as the 32-bit compiler, even
though the source base is the same for
both and the 64-bit processor offers
better raw processing throughput.
Space is speed.)