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gcc & Friends

2. 2© 2010-15 SysPlay Workshops <workshop@sysplay.in>
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What to Expect?
What is 'gcc'?
Internals of 'gcc'
How to use 'gcc'?
Friends of 'gcc'

3. 3© 2010-15 SysPlay Workshops <workshop@sysplay.in>
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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

4. 4© 2010-15 SysPlay Workshops <workshop@sysplay.in>
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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
...

9. 9© 2010-15 SysPlay Workshops <workshop@sysplay.in>
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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?

11. 11© 2010-15 SysPlay Workshops <workshop@sysplay.in>
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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