The document discusses the GNU C Compiler (gcc) which is an open source compiler for C and C++. It describes what gcc is, its internals including different stages like preprocessing, compilation and linking. It also covers how to use gcc via various flags, standard paths for headers and libraries, default compiler defines, and related tools like the assembler, linker and archiver.

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gcc & Friends

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What to Expect?
What is 'gcc'?
Internals of 'gcc'
How to use 'gcc'?
Friends of 'gcc'

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What is 'gcc'?
GNU C Compiler
Open Source Compiler for C & C++
Along with standard headers & libraries
Rather a collection of tools
Corresponding to various compiler stages
Various other compilers built using it
Cross Compilers for different architectures

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'gcc': Internals Decoded
Pre
Processor
ICG
(machine
independent)
ICG
(machine
dependent)
Assembler
(as)
Linker
(ld)
.c .i IC(parse trees, ...) .S .o .exe
gcc core
gcc wrapper
gcc -S
gcc -c
gcc
gcc -E

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Using GNU C Compiler
gcc file.c → Creates the executable a.out
gcc file.c -o file
gcc -E file.c → Pre-process only
gcc -S file.c → Generate assembly code
gcc -c file.c → Create object code
gcc -I<hdrs_path> file.c
gcc -L<libs_path> file.c -l<lib>
gcc -D<define> file.c
gcc -On file.c, n = 0, 1, 2, 3, s, fast, g
gcc -M file.c
gcc -MM file.c
gcc -T <linker_script> file.c
gcc -Wl,<linker_option> file.c
... (including many architecture specific flags)

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Default Compiler Defines
Trick to find out (#gcc #define)
gcc -E -dM -xc /dev/null | sort
Also
gcc -E -dM -xc++ /dev/null | sort
gcc -E -dM -xc++ -std=c++0x /dev/null | sort

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Standard Paths
Standard Headers Path: /usr/include/
Standard Libraries Path: /usr/lib/
Library Prefix: lib
Standard Headers
stdio.h, strings.h, math.h, ...
Standard Libraries
libc, libm, …
Where is the code of printf?

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Friends of 'gcc'
Preprocessor: cpp
Assembler: as
Linker: ld
Name Lister: nm
Disassembler: objdump
Archiver: ar
Print strings from files: strings
...

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What all have we learnt?
gcc: GNU C Compiler
Standard Headers & Libraries
Collection of tools
Usage of 'gcc'
Friends of 'gcc'

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Any Queries?

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Advanced Topics
Shared library vs Archive
Linking, Library Function Call, ...
Defining your own headers
Creating a shared library
Creating an archive