47 lines
2.6 KiB
Text
47 lines
2.6 KiB
Text
unusedcode.easy is generated via callcatcher[1] and filtered to remove some
|
|
tricky edge-cases (see Makefile), e.g. anything which could plausibly be
|
|
dlsymed or any symbol defined in an external library bundled into LibreOffice
|
|
which doesn't happen to get used by LibreOffice.
|
|
|
|
unusedcode.easy is generated on an x86_64 --enable-debug --enable-dbgutil
|
|
configuration.
|
|
|
|
Code listed as unused is code that gcc outputs but that nothing calls
|
|
(or takes the address of).
|
|
|
|
a) It's possible that some other platform or configuration uses the code,
|
|
so manual inspection is always required.
|
|
b) At the time of writing the majority of unused code now originates via
|
|
macros, mostly from pre-STL containers, see [2] for killing two birds
|
|
with one stone. These are typically methods of signatures...
|
|
*::Insert
|
|
*::Remove
|
|
*::DeleteAndDestroy
|
|
*::Replace
|
|
c) callcatcher ignores virtuals. But implementations of "pure virtuals"
|
|
are not actually virtual methods. If something is declared pure virtual
|
|
and provides an impl and that base-class impl is not explicitly called
|
|
anywhere, then that impl can go away.
|
|
d) gcc will only emit code for inlines if those inlines are used, so
|
|
sometimes something is listed correctly as unused but some inline
|
|
code takes a pointer or reference to something which cannot be
|
|
instantiated so removal of some method/class fails at build time because
|
|
gcc never emits any code for the unused inline but trips over it at
|
|
compile time after an attempt at removal. i.e. generally the inline method
|
|
can go as well because nothing calls it either, a double win.
|
|
e) if a constructor is listed as unused, and it's the *only* ctor in the class,
|
|
then no object of that class can be constructed, so the whole thing is
|
|
unused, which can lead to a whole cascade of tricky but logical fallout.
|
|
f) if a destructor is listed as unused, and a constructor isn't, then there's
|
|
a leak somewhere, and the destructor most likely *should* be called.
|
|
g) there's more actually unused code then what's listed. The idea is that what's
|
|
listed is definitely unused under the generation configuration, not that
|
|
it's a list of all unused code. If the count of unused easy hits 0 then
|
|
we can have a look at the non-easy and if that hits 0, then strip out
|
|
code from the "release" binaries which only makes sense in debug/dbgutil
|
|
configurations, and then tackle unused virtual method slots :-)
|
|
|
|
Symbols that are known to be false alarms are listed in: unusedcode.exclude
|
|
|
|
[1] http://www.skynet.ie/~caolan/Packages/callcatcher.html
|
|
[2] https://bugs.libreoffice.org/show_bug.cgi?id=38832
|