Makefile Martial Arts Chapter 1: The morning of creation

1. broadlinux
7.2016by quyenlv

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Chapter 1

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Everything was born for a reason
A primitive notion
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Motivation
 So small programs → single and short file
 “Not so small” programs :
 Many lines of code → long file, harder to manage
 Many programmers → can’t modify the same file simultaneously
 Every change requires long compilation
 Solution: divide large programs into smaller, more manageable
pieces with multiple files
 Pros:
 Good division to components
 Easy maintenance of project structure, dependencies and creation
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Original management approach
 Manual with care, must think of everything
 Compiling and linking by hand becomes tedious
 Use shell scripts to comment out some steps to save processing time
 Early automation used simple make.sh and install.sh scripts
 Easily lose track of:
 which files depend on which others
 the exact sequence of operations needed to build program
 which files have been modified recently
 Recompiling everything in sight just to be safe is very wasteful
 Minimum compilation when something is changed
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Repair manual
Repair the
Wheel need
to unplug
the whole car?

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The morning of creation
A primitive notion
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Steve Johnson Stuart Feldman
I wasted a
morning
debugging a
program,
file hadn't been
compiled, cc *.o
was therefore
unaffected
Bell Labs

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I met the same
disaster on a project I
was working on
Need a
tool to
solve it!
♥Make♥
1977
Bell Labs

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make philosophy
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dependency
relationship
target
commandstimestamp
make
Sequence of execution commands
final target
1. Automate the software building
2. Take minimum of effort
Mission

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 A file describes how to generate a particular target file
 Consists a number of rules
 If (target out-of-date with dependencies) then
Execute commands to make target up-to-date
 “Everything is a file”
Makefile
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dependency
relationship
target
commands
target: dependencies
<tab>commands rule

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Makefile in Life
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clothes: shoes wallet mobile t-shirt
look in the mirror
shoes: socks, trousers
make shoes clean
put on shoes
socks:
wash your foot
put on socks
trousers: underpants
put on trousers
underpants:
put on underpants
look in the mirror
wallet, mobile: trousers
put in trouser pockets
t-shirt:
put on t-shirt
walletshoes
trousers
socks underpants
mobile shirt
clothes
<>
$ make clothes
wash your foot
put on socks
put on underpants
look in the mirror
put on trousers
make shoes clean
put on shoes
put wallet in trouser pockets
put mobile in trouser pockets
put on t-shirt

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Learn from Yacc and Lex
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Lexical analyzer
Syntax analyzer
Lex
Yacc
a = b + c * d
id1
=
+
*id2
id3 id4
patterns
grammar
Source code
id1 = id2 + id3 * id4Tokens
Syntax tree
Code generator
load id3
mul id4
add id2
store id1
Generated code
 The basic building blocks of a compiler

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make architecture
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sum (exe)
sum.omain.o
sum.h sum.cmain.c
Makefile
make analyzer
Dependency
Graph
$ make sum
$ gcc –c main.c
$ gcc –c sum.c
$ gcc –o sum main.o sum.o
Build command
Shell commands
# target prerequisite command
# ------------------------------------------------
sum main.o, sum.o gcc –o sum main.o sum.o
main.o main.c, main.h gcc –c main.c
sum.o sum.c, sum.h gcc –c sum.c
Semantic graph
make processor
Makefile
make
1
2
$ com1
$ com2 $ com3
Rule syntax

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New cycle of program development
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think — edit — make — test

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You don’t get everything right at the first time
<tab>

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The worst ever made
 What we see
 What it is
 The interpretation of a makefile can change drastically on the basis
of invisible differences in whitespace.
 “I had a user population of about a dozen, most of them friends, and
I didn’t want to screw up my embedded base. The rest, sadly, is
history.” -- Stuart Feldman --
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The creativity in work
The lesson from make
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18. Stuart Feldman
Google Vice President of Engineering
“
“
Bell Lab, 1977

19. Copyright© 2014 DASAN Networks, Inc.
”It became possible to go home in the evening while
leaving behind long runcoms executing overnight.”
LOUIS POUZIN
1931, France

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Reference
 Make a program for maintaining computer programs
https://www.researchgate.net/publication/220280049_Make-
A_Program_for_Maintaining_Computer_Programs
 The Art of Unix Programming by Eric Steven Raymond
 What’s Wrong With GNU make? http://www.conifersystems.com/whitepapers/gnu-
make/
 Make for data scientists http://blog.kaggle.com/2012/10/15/make-for-data-scientists/
 Introduction to making Makefiles
http://www.jfranken.de/homepages/johannes/vortraege/make_inhalt.en.html
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Thank you!