1. An Overview to Compiler Design
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2. Outline An Overview of Compiler Structure Front End Middle End
Back End
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3. Reading Slides and Lecture Notes Aho,Lam,Sethi,Ullman:
Chapter 1.4 ~ 1.5
Chapter 2.1 ~ 2.7
Chapter 3.1 ~ 3.5
Chapter 4.1 ~ 4.5
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4. A Review on Compiler Structure/Design
Overall structure
Front-end: lexical and syntax analysis
Middle-end: machine independent code analysis and (scalar, and sometimes loop nest ) optimization
Back-end: Machine dependent code analysis and optimization
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5. Motivation for Compiler optimization
Source Program
COMPILER
Machine Code
Input program example:
int foo( ) {
int x;
return (x + x) ; }
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6. Output Assembly Code (non-optimized)
foo:
sub $sp, $sp, 8
sw $fp, 8($sp)
add $fp, $sp, 8
sw $ra, -4($fp)
add $t0, $a0 $a0
move $v0, $t0
lw $ra, -4($fp)
lw $fp, 0($fp)
add $sp, $sp, 8
jr $ra
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\course\cpeg421-08s\Topic-1a.ppt

7. Output Assembly Code (non-optimized)
foo:
sub $sp, $sp, 8 % Push stack frame
sw $fp, 8($sp) % Save old frame pointer
add $fp, $sp, 8 % Set new frame pointer
sw $ra, -4($fp) % Save return address
add $t0, $a0 $a0 % Addition
move $v0, $t0 % Copy return value
lw $ra, -4($fp) % Restore return address
lw $fp, 0($fp) % Restore frame pointer
add $sp, $sp, 8 % Pop stack frame
jr $ra % Jump to return address
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\course\cpeg421-08s\Topic-1a.ppt

8. Output Assembly Code -- Revisited (non-optimized)
foo:
sub $sp, $sp, 8 % Push stack frame (for what?)
sw $fp, 8($sp) % Save old frame pointer (for what?)
add $fp, $sp, 8 % Set new frame pointer
sw $ra, -4($fp) % Save return address (for what?)
add $t0, $a0, $a0 % Addition
move $v0, $t0 % Copy return value
lw $ra, -4($fp) % Restore return address
lw $fp, 0($fp) % Restore frame pointer
add $sp, $sp, 8 % Pop stack frame
jr $ra % Jump to return address
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\course\cpeg421-08s\Topic-1a.ppt

9. Output Assembly Code (optimized)
foo:
add $v0, $a0, $a0 % Set result
jr $ra % Jump to return address
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\course\cpeg421-08s\Topic-1a.ppt

10. Runtime Memory Organization
frame-1
Entry point
for procedure 1
code for
procedure 1
Space for arguments
(parameters)
frame-2
code area
Space for bookkeeping
Information, including
Return address
code for
procedure 2
frame-3
global/static
area
Entry point for
procedure 2 …
stack
Space in local data …
free space
Space for local
temporaries
code for
procedure n
Runtime
stack
Entry point for
procedure n
A stack frame
heap
Code memory
Address space
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11. Phases of a Compiler Source program Intermediate-code Generator
Lexical Analyzer (Scanner)
Non-optimized Intermediate Code
Tokens
Intermediate-code Optimizer
Syntax Analyzer (Parser)
Optimized Intermediate Code
Parse tree
Target-code Generator/Opt
Semantic Analyzer
Target machine code
Abstract Syntax Tree w/ Attributes
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12. Two models of compiler structures
Low-level Model
Mixed-level Model
String of characters
String of tokens
Parse tree
Abstract Syntax tree
Medium-level intermediate code
Low-level intermediate code
Relocatable object module or
runnable machine code
Lexical
analyzer
Abstract syntax tree
Low-level intermediate code
Relocatable object module or
runnable machine code
String of characters
String of tokens
Parse tree
Lexical
analyzer
Parser
Parser
Semantic
analyzer
Semantic
analyzer
Intermediate-code
generator
Translator
Optimizer
Optimizer
Code generator
Final
assembly
Postpass
optimizer
Two models of compiler structures
(Muchnick, pp. 08)
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13. A Good Compiler Infrastructure Needed – A modern View
Front end
Interprocedural Analysis and Optimization
Good IR
Loop Nest Optimization and Parallelization
Global (Scalar) Optimization
Middle-End
Backend
Code Generation
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