knknkn1162 / advancedgcc

GCC advance topics

AdvanceGCC

This is the collection of confusing but common tips in C-lang, gcc, make and ld.

Preparations && Build

# version: 9.2.0
docker run -it -v $(pwd):/home/me -w /home/me --rm gcc
# inside docker
make
# When you run all sample programs..
make run

If you want to erase this, make clean.

tips

ar

stdin_compile

• .ONESHELL .. This enables here document in Makefile.

• gcc compile from stdin .. see https://www15.big.or.jp/~yamamori/sun/gcc/stdin.html.

Makefile

Reference

• https://qiita.com/knknkn1162/items/c67ae7c2ef71a713adf8 : How to use readelf, hexdump and ld
• https://ftp.gnu.org/old-gnu/Manuals/make-3.79.1/html_chapter/make_10.html : implicit rule(official)
• https://goth-wrist-cut.hatenadiary.org/entry/20080317/1205769293 : examples of patsubst, foreach and shell

Implicit rules

For more details, see the link:

• $(CC) -c $(CPPFLAGS) $(CFLAGS) in C -> object file

• $(CXX) -c $(CPPFLAGS) $(CXXFLAGS) in C++ -> object file

• $(CC) $(LDFLAGS) $(TARGET_ARCH) $^ $(LOADLIBES) -o $@ in C -> exec file

• $(AS) $(ASFLAGS) in asm

• $(CC) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS) -o $@ in linker. The ar directory uses implicit rule on link

PHONY

# Makefile
compile_switch:
	make -C compile_switch

make compile_switch
make: 'compile_switch' is up to date.

This is because compile_switch directory has been already created before make compile_swtich.

To avoid this, write .PHONY compile_switch and you can fully compile this.

Misc

• If docker container was freezed, type Ctrl-C.