I learnt from the good people on this list that usage of:
-fdata-sections -ffunction-sections -Wl,--gc-sections
will ensure that only those sections of object modules get linked to the
target which are actually used in the target.
Recently I was musing on whether I can use this when I recompile the Qt
4 libraries for static linking. But the thing is that the Qt libraries
are already very optimized in this aspect -- in that there is a separate
source file per class and consequently a separate object file per class.
However I was wondering whether even then I could do my
hyper-optimization because I will be using only a small number of
functions in each class. It is highly unlikely that I (or anyone else)
is going to use all member functions of a class.
Then I thought how I could possibly prevent linking a function which was
part of a class definition. To my understanding at runtime whenever a
class is loaded into memory (I'm not talking about the individual
instances) its members including functions are all loaded into memory.
If a particular function is not present for loading, wouldn't that be a
fatal error?
So the long and short of it is, are these options useful to filter out
unused class members or not?
Thanks as always,
Shriramana Sharma.
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