Compiler

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Compiler

• Chang Chi-Chung
• 2008.02.26

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Textbook

• Compilers Principles, Techniques, and Tools,
  2/E.
• Alfred V. Aho, Columbia University
• Monica S. Lam, Stanford University
• Ravi Sethi, Avaya Labs
• Jeffrey D. Ullman, Stanford University
• Free books
• http//freecomputerbooks.com

Dragon
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Score

• Midterm Examination 20
• Final Examination 25
• Quizz(2) 30
• Project 10
• Homework 10
• Participation 5

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Objectives

• ??????????
• Know how to use compiler construction tools, such
  as generators of scanners and parsers
• Be able to define LL(1), LR(1), and LALR(1)
  grammars
• Be familiar with compiler analysis and
  optimization techniques
• ??????????

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History

• Early 1950s
• Mnemonic assembly languages.
• Macro instructions were added later.
• In the latter half of the 1950
• Fortran scientific computation.
• To take 18 man-years
• Cobol business data processing.
• Lisp symbolic computation.

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History - Grace Hooper
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(No Transcript)
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Programming Languages
???? none
???? machine independent
???? machine dependent
Chinese English German
????
????
C?C?Java
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Introduction to Compilers(1)
Compiler
Source Program
Target Program

• Source program must be equivalent to target
  program.
• Definitions
• Recognizer
• Translator

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Introduction to Compilers(2)

• Translator
• from one format to another
• query interpreter
• text formatter
• silicon compiler
• infix notation ? postfix notation
• 3 5 - 6 6 gt 3 5 6 6 -
• pretty printers
• Computational theory
• power of certain machines
• the set of languages that can be recognized by
  this machine
• Grammar
• definition of this machine

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Impacts on Compilers

• Programming languages
• Machine architecture
• Language theory
• Algorithms and data structures
• Software engineering

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Use the Compiler Techniques

• Programming Languages (C?C)
• Scripts (Javascript?bash)
• Editors (syntax highlighting)
• Pretty printers (e.g. Doxygen)
• Static checkers (e.g. Lint and Splint)
• Interpreters
• Text formatters (e.g. TeX and LaTeX)
• Silicon compilers (e.g. VHDL)
• Query interpreters/compilers (Databases)

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Compilers ???

• Compilation
• Translation of a program written in a source
  language into a semantically equivalent program
  written in a target language

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Interpreters ???

• Interpretation
• Performing the operations implied by the source
  program

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Hybrid
Source Program
Translator
Virtual Machine
intermediate program
input
output
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Compiler vs. Interpreter

• ?????????

Compiler Interpreter
???? 1 More
?? ?? ??


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A Language-Processing System
source program
Preprocessor
Try for example gcc -v myprog.c
modified source program
Compiler
target assembly program
Assembler
relocatable machine code
library files relocatable object files
Linker/Loader
target machine code
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character stream
Phases of a Compiler
Lexical Analyzer
token stream
Syntax Analyzer
syntax tree
Semantic Analyzer
syntax tree
Symbol Table
Intermediate Code Generator
intermediate representation
Machine-Independent Code Optimizer
intermediate representation
Code Generator
target-machine code
Machine-Dependent Code Optimizer
target-machine code
target-machine code
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character stream
position initial rate 60
Lexical Analyzer
ltid,1gt ltgt ltid,2gt ltgt ltid,3gt ltgt lt60gt
Syntax Analyzer
Semantic Analyzer
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Intermediate Code Generator
t1 inttofloat(60) t2 id3 t1 t3 id2
t2 id1 t3
Machine-Independent Code Optimizer
t1 id3 60.0 id1 id2 t1
Code Generator
1 position
2 initial
3 rate

LDF R2, id3 MULF R2, R2, 60.0 LDF R1, id2 ADDF
R1, R1, R2 STF id1, R1
SYMBOL TABLE
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The Grouping of Phases

• Compiler front and back ends
• Front end analysis (machine independent)
• Back end synthesis (machine dependent)
• Compiler passes
• A collection of phases is done only once (single
  pass) or multiple times (multi pass)
• Single pass usually requires everything to be
  defined before being used in source program
• Multi pass compiler may have to keep entire
  program representation in memory

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The Analysis-Synthesis Model of Compilation

• There are two parts to compilation
• Analysis determines the operations implied by the
  source program which are recorded in a tree
  structure
• Synthesis takes the tree structure and translates
  the operations therein into the target program

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Compiler-Construction Tools

• Software development tools are available to
  implement one or more compiler phases
• Scanner generators
• Parser generators
• Syntax-directed translation engines
• Automatic code generators
• Data-flow engines

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Programming Language Basic(1)

• Static vs. Dynamic
• Compile Time vs. Run Time
• Examples
• scope of declarations
• memory location of variables
• Environments and States

environment
state
locations (variables)
names
values
According to the scope rules of a language
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Programming Language Basic(2)

• Static Scope and Block Structure
• C/C uses
• Pascal uses begin, end
• Explicit Access Control
• C, C, Java provide public, protected, private
• Dynamic Scope
• Parameter Passing Mechanisms
• caller and callee
• actual parameters and formal parameters.
• call by value
• call by reference (call by address)
• call by name
• Aliasing

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An Example
procedure SUB(i,j) begin ii1 print(x)
iij print(i) end

• program TEST
• beginx1y2SUB(x,xy)print(x)
• end

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Results

• Answer
• Call-by-reference 2,5,5
• Call-by-value 1,5,1
• Call-by-name 2,6,6
• Call-by-value and copy-restore 1,5,5