使用GCC/GNU-ld删除dead code

[url]
https://gcc.gnu.org/ml/gcc-help/2003-08/msg00128.html
https://embeddedfreak.wordpress.com/2009/02/10/removing-unused-functionsdead-codes-with-gccgnu-ld/
[/url]


[quote]
Hi Dr. Rupp,

I was just looking into this very thing!

Do this in your Makefile...
--------8<--------
DEADCODESTRIP := -Wl,-static -fvtable-gc -fdata-sections -ffunction-sections -Wl,--gc-sections -Wl,-s

foo : foo.c
g++ $(DEADCODESTRIP) $< -o $@
--------8<--------

Step by step...

-Wl,-static
Link against static libraries. Required for dead-code elimination.

-fvtable-gc
C++ virtual method table instrumented with garbage collection information for the linker.

-fdata-sections
Keeps data in separate data sections, so they can be discarded if unused.

-ffunction-sections
Keeps funcitons in separate data sections, so they can be discarded if unused.

-Wl,--gc-sections
Tell the linker to garbage collect and discard unused sections.

-s
Strip the debug information, so as to make the code as small as possible. (I presume that you'd want to do this in a dead-code removal build.)

The requirement to link against the static libraries was surprising to me. But there you go.

HTH,
[/quote]