.. -*- coding: utf-8; -*-

=====

 GCC

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.. contents::

   :local:

Remove dead code

================

::

  STRIP_DEAD_CODE = -Wl,-static -fvtable-gc -fdata-sections -ffunction-sections -Wl,--gc-sections -Wl,-s

``-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.)

Map file

========

::

  $ ld -Map=file.map <opts> <files>

or::

  $ gcc -Wl,-Map=file.map <opts> <files>

Predefined macros

=================

::

  $ gcc -arch ppc -dM -E - < /dev/null | sort

Default search path

===================

::

  $ echo | gcc -v -x c -E -

  $ gcc -print-search-dirs

  install: ...

  programs: ...

  libraries: ...

Use ``-###`` in actual invoking::

  $ gcc -### -o foo foo.c

  $ ld --verbose | grep SEARCH_DIR

``LIBRARY_PATH`` and ``LD_LIBRARY_PATH``::

  $ cpp -Wp,-v

  $ cpp -Wp,-lang-c++,-v

  $ cpp -x c++ -Wp,-v