http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53570
Bug #: 53570
Summary: Unused symbols are not removed for fully static
targets (avr-gcc)
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: jwa...@gmail.com
Using built-in specs.
COLLECT_GCC=avr-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/avr/4.7.0/lto-wrapper
Target: avr
Configured with: /build/src/gcc-4.7.0/configure --prefix=/usr --libdir=/usr/lib
--libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info
--enable-languages=c,c++ --disable-libssp --disable-nls --target=avr
--with-as=/usr/bin/avr-as --with-ld=/usr/bin/avr-ld --with-gnu-as --with-gnu-ld
Thread model: single
gcc version 4.7.0 (GCC)
This is a problem report for how the linker is not smart enough
to remove unused functions, even with -Os. This makes it very
hard to create libraries of functions where only some functions
may be used in any particular binary. Note: "r" option to ar is
passed in, so the linker should have all the symbol information
it needs to make the determination.
See the attached test program, especially the "lib.cpp" file.
There is nothing in the C++ standard that requires the compiler
or linker to include the not_called symbol, or the
some_large_function symbol, when they are not used. On a small
target like the AVR, including those symbols is too wasteful.
To reproduce:
- untar this archive
- run ./make.sh
- avr-objdump --disassemble main, and find the unused symbols
still included
