1. A Java Compiler Overview

2. October 21, 2003Shane A. Brewer2 Who Am I? Shane A. Brewer brewer@cs.ualberta.ca http://www.cs.ualberta.ca/~brewer Masters Graduate Student Supervisor: Dr. Nelson Amaral Research: Using Method Specialization In Java Virtual Machines for Method Devirtualization Member of the U of A Swim Team NOTE: Presentation Slides will be made available via my web site.

3. October 21, 2003Shane A. Brewer3 This Lecture… Will give an overview of the Java Environment. Discuss the differences in how compiler optimizations are applied compared with other languages (C, C++, etc) Will give an overview of a toolset developed specifically for Java (Soot)

4. October 21, 2003Shane A. Brewer4 Outline A Brief Java Overview Java Bytecode, Class files, and Bytecode Compilers Java Virtual Machines and Compilation Techniques Soot Overview Soot Intermediate Representations Soot Optimizations and Performance Soot Eclipse Plugin Demonstration

5. October 21, 2003Shane A. Brewer5 Java History First release of Java in 1996 by Sun Microsystems The Java Language Specification by James Gosling published in 1996 The Java Virtual Machine Specification by Tim Lindholm and Frank Yelle published in 1996 Is now one of the most popular programming languages, especially in enterprise development. Java 1.5 to be released late 2003 and will include: Auto Boxing/Unboxing Enhanced For loops Generics (Templates) Enumerations

6. October 21, 2003Shane A. Brewer6 Java Overview Is an object-oriented language that is executed on a virtual machine Originally designed for Internet-based usage Combines procedural and object-oriented features Combines primitive data types and objects Originally designed to be very portable Strongly Typed Supports Dynamic Class Loading Built-in support for multi-threading

7. October 21, 2003Shane A. Brewer7 Java Environment [6]

8. October 21, 2003Shane A. Brewer8 Java Overview Continued Java Source Files Java Classfiles int d = 2 + 3; object.foo(); Java Bytecode Compiler i_const2 i_const3 iadd invokevirtual #40 Java Virtual Machine i0 := 2; i1 := 3; i2 := i0 + i2; java.lang.Object.foo(); lw $s1, 100($s2) add $s1, $s2, $s3 Compiler Intermediate Representation Executable Machine Code

9. October 21, 2003Shane A. Brewer9 The Java Platform [6]

10. October 21, 2003Shane A. Brewer10 A Java Program public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly } // End class javaTest class javaTest { public static void main(String[] args) { int x = stepPoly(6); System.out.println(x); } // End method main

11. October 21, 2003Shane A. Brewer11 Dynamic Class Loading Allows a new class to be loaded into the class hierarchy at any point in execution 2 Ways This Is Done In Java Class.forName() method gets the runtime class descriptor Class toRun = Class.forName(args[0]); User-defined Class Loaders allows a user to load classes in custom ways (across a network, local, etc) Good for program design Lazy class loading Dynamic installation of software Bad for optimization

12. October 21, 2003Shane A. Brewer12 Dynamic Class Loading Example Class A { public void func() { foo(); bar(); } public void foo() {} public void bar() {} } // End Class A Class B extends A { … } // End Class B Can we make these Method calls static?

13. October 21, 2003Shane A. Brewer13 Dynamic Class Loading Example Class A { public void func() { A.foo(); A.bar(); } public void foo() {} public void bar() {} } // End Class A Class B extends A { … } // End Class B Can we make these Method calls static?

14. October 21, 2003Shane A. Brewer14 Dynamic Class Loading Example Class A { public void func() { A.foo(); A.bar(); public void foo() {} public void bar() {} } } // End Class A Class B extends A { … } // End Class B Class C extends B { public void foo() {} public void bar() {} } // End Class C No! A class of type C can be loaded at any point in program execution. Consider an object objC of type C. A method call objC.func() would result in A.foo() and A.bar() incorrectly being called. WRONG!!!

15. October 21, 2003Shane A. Brewer15 Differences Between C++ and Java Java is run by a virtual machine Java does not contain pointers (YAY!) Java does not support generics (Will be supported in version 1.5) Java does not contain a preprocessor Java only allows single inheritance. Interfaces can be used to remedy this. Java contains built-in multi-threaded tools.

16. October 21, 2003Shane A. Brewer16 Problems With Java Relatively Slow execution? Compilation done at run-time Run-time exception checking Optimizations have to deal with dynamic class loading Slow execution can be offset by spending time optimizing “hot” portions of code Not pure object-oriented No Generics (Version 1.5) Everything is a reference No const method arguments

17. October 21, 2003Shane A. Brewer17 Outline A Brief Java Overview Java Bytecode, Class files, and Bytecode Compilers Java Virtual Machines and Compilation Techniques Soot Overview Soot Intermediate Representations Soot Optimizations and Performance Soot Eclipse Plugin Demonstration

18. October 21, 2003Shane A. Brewer18 The Java Bytecode Compiler Converts Java source code to Java bytecode and into Class files Can be thought of a the “front end” of a traditional compiler Can perform a limited set of optimizations Optimizations are harder to perform because: Some bytecode instructions are high-level Dynamic class loading Examples: Sun Microsystems: javac IBM: Jikes

19. October 21, 2003Shane A. Brewer19 Java Bytecodes Defined by the Java Virtual Machine Instruction Set. Are stack based Keeps the instruction set compact Facilitates implementation on architectures with few or irregular registers. Most of the operators are typed iadd (Adds 2 integers together) Some operators are not typed dup (Duplicates the top value on the stack)

20. October 21, 2003Shane A. Brewer20 The Class file Are not limited to the Java programming language Is a file containing : Java bytecodes a definition of a single class or interface Contains everything a JVM needs to know about the particular class or interface. Are strictly defined so JVM know what to expect Are variable length Contains 3 major parts: Identification Constant Pool Detailed Information

21. October 21, 2003Shane A. Brewer21

22. October 21, 2003Shane A. Brewer22 A Java Program public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static void main(String[] args) { int x = stepPoly(6); System.out.println(x); } // End method main

23. October 21, 2003Shane A. Brewer23 Java Bytecode public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn To obtain a listing of the bytecode from a classfile, use the command: javap –c

24. October 21, 2003Shane A. Brewer24 Java Bytecode public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn -Pushes an integer located at local variable index 0 on the stack (the first parameter to the method “x”) -Sees if x (position 14 in the constant pool) is greater than 0

25. October 21, 2003Shane A. Brewer25 Java Bytecode public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn -Pushes the receiver object System.out on to the stack. -Pushes the parameter to the method (String “Bad Argument) on the stack -Invokes the virtual method

26. October 21, 2003Shane A. Brewer26 Java Bytecode public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn -Pushes literal -1 on the stack -Returns from the function with an integer

27. October 21, 2003Shane A. Brewer27 Java Bytecode public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn -Pushes integer from local variable at index 0 (first parameter to the method) -Pushes the constant 5 on the stack -Compares the 2 values on the stack and jumps to line 23 if x is greater than 5.

28. October 21, 2003Shane A. Brewer28 Java Bytecode public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn -Load x on the stack (twice) -Execute an integer multiplication and push the result on the stack -Return the result

29. October 21, 2003Shane A. Brewer29 Java Bytecode public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn -Push x on the stack -Push 5 on the stack -Multiply the values and push the result on the stack -Push 16 on the stack -Add the values and push the result -Return the integer on the stack

30. October 21, 2003Shane A. Brewer30 Outline A Brief Java Overview Java Bytecode, Class files, and Bytecode Compilers Java Virtual Machines and Compilation Techniques Soot Overview Soot Intermediate Representations Soot Optimizations and Performance Soot Eclipse Plugin Demonstration

31. October 21, 2003Shane A. Brewer31 The Java Virtual Machine Is an abstract computing machine Only takes class files as input Executes the corresponding bytecodes on the computer architecture Techniques are left up to the VM implementer: Compilation Optimization Memory Management Object Layout Examples: Sun Microsystems: Hot Spot IBM: Jikes RVM Blackdown: Blackdown VM (Linux)

32. October 21, 2003Shane A. Brewer32 Bytecode Translation Methods Interpreted Stack based Done one bytecode at a time SLOW! Just-In-Time (JIT) Bytecodes are compiled to native machine instructions when they are executed. Compilation only done once Optimizations can take advantage of run-time profiling Optimizations must be done during execution, making high cost optimizations unattractive

33. October 21, 2003Shane A. Brewer33 Bytecode Translation Methods Continued Adaptive Just-In-Time Similar to JIT compilers Performs dynamic analysis to determine “hot” portions of code and perform higher levels of optimization Can also use analysis to determine which optimizations will obtain the greatest speedup Compilation can be done multiple times Ahead-of-time (Way-Ahead-of-Time) Compilation to native machine code is done by the bytecode compiler, just like C++ Allows high cost optimizations to be performed Portability is lost Dynamic Class Loading is not permitted

34. October 21, 2003Shane A. Brewer34 Stack-based Interpretation Local Variables Array 6 Stack public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Entering method stepPoly from call site: int x = stepPoly(6);

35. October 21, 2003Shane A. Brewer35 Stack-based Interpretation Local Variables Array 6 Stack 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pushes the integer located at index 0 in the local variable array on the stack

36. October 21, 2003Shane A. Brewer36 Stack-based Interpretation Local Variables Array 6 Stack 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pops the stack and determines if the value is greater than or equal to 0. If true, jump to the index in the byte array.

37. October 21, 2003Shane A. Brewer37 Stack-based Interpretation Local Variables Array 6 Stack 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pops the stack and determines if the value is greater than or equal to 0. If true, jump to the index in the byte array. 6 < 0?

38. October 21, 2003Shane A. Brewer38 Stack-based Interpretation Local Variables Array 6 Stack public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pops the stack and determines if the value is greater than or equal to 0. If true, jump to the index in the byte array.

39. October 21, 2003Shane A. Brewer39 Stack-based Interpretation Local Variables Array 6 Stack 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pushes the integer located at index 0 in the local variable array on the stack

40. October 21, 2003Shane A. Brewer40 Stack-based Interpretation Local Variables Array 6 Stack 5 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pushes the integer constant 5 on the stack

41. October 21, 2003Shane A. Brewer41 Stack-based Interpretation Local Variables Array 6 Stack 5 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn The top 2 values on the stack are popped and compared. If value 1 is greater than value 2, control transfers to the specified index in the byte array.

42. October 21, 2003Shane A. Brewer42 Stack-based Interpretation Local Variables Array 6 Stack 5 (Value 2) 6 (Value 1) public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn The top 2 values on the stack are popped and compared. If value 1 is greater than value 2, control transfers to the specified index in the byte array. Is 6 < 5?

43. October 21, 2003Shane A. Brewer43 Stack-based Interpretation Local Variables Array 6 Stack public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn The top 2 values on the stack are popped and compared. If value 1 is greater than value 2, control transfers to the specified index in the byte array. Is 6 < 5?

44. October 21, 2003Shane A. Brewer44 Stack-based Interpretation Local Variables Array 6 Stack 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pushes the integer located at index 0 in the local variable array on the stack

45. October 21, 2003Shane A. Brewer45 Stack-based Interpretation Local Variables Array 6 Stack 5 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pushes the integer constant 5 on the stack

46. October 21, 2003Shane A. Brewer46 Stack-based Interpretation Local Variables Array 6 Stack 5 6 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pop the top 2 values off of the stack. Multiply them together and push the result on the stack

47. October 21, 2003Shane A. Brewer47 Stack-based Interpretation Local Variables Array 6 Stack public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pop the top 2 values off of the stack. Multiply them together and push the result on the stack 5 * 6 = 30

48. October 21, 2003Shane A. Brewer48 Stack-based Interpretation Local Variables Array 6 Stack 30 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pop the top 2 values off of the stack. Multiply them together and push the result on the stack 5 * 6 = 30

49. October 21, 2003Shane A. Brewer49 Stack-based Interpretation Local Variables Array 6 Stack 30 16 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Push the immediate byte (an integer) on to the stack.

50. October 21, 2003Shane A. Brewer50 Stack-based Interpretation Local Variables Array 6 Stack 30 16 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pop the top 2 values from the stack, add them together, and push the result on the stack.

51. October 21, 2003Shane A. Brewer51 Stack-based Interpretation Local Variables Array 6 Stack public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pop the top 2 values from the stack, add them together, and push the result on the stack. 30 + 16 = 46

52. October 21, 2003Shane A. Brewer52 Stack-based Interpretation Local Variables Array 6 Stack 46 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pop the top 2 values from the stack, add them together, and push the result on the stack. 30 + 16 = 46

53. October 21, 2003Shane A. Brewer53 Stack-based Interpretation Local Variables Array 6 Stack 46 public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Pop the top value from the stack from this method frame, and push the value on to the stack of the caller method’s stack. Any other values on the stack are discarded.

54. October 21, 2003Shane A. Brewer54 Outline A Brief Java Overview Java Bytecode, Class files, and Bytecode Compilers Java Virtual Machines and Compilation Techniques Soot Overview Soot Intermediate Representations Soot Optimizations and Performance Soot Eclipse Plugin Demonstration

55. October 21, 2003Shane A. Brewer55 What Is Soot? A Java bytecode compiler written in Java Includes decompilation and visualization Used to analyze and transform Java bytecode Comes as a command line tool or Eclipse plugin Output is an optimized class file

56. October 21, 2003Shane A. Brewer56

57. October 21, 2003Shane A. Brewer57 Outline A Brief Java Overview Java Bytecode, Class files, and Bytecode Compilers Java Virtual Machines and Compilation Techniques Soot Overview Soot Intermediate Representations Soot Optimizations and Performance Soot Eclipse Plugin Demonstration

58. October 21, 2003Shane A. Brewer58 Soot Intermediate Representations (IRs) Baf: A stack representation without the complexities of Java bytecode. Jimple: A typed, 3-address code representation of Java bytecode (Java Simple) Shrimple: An SSA-version of Jimple Grimp: Like Jimple, but with aggregated expressions. Dava: A structured representation suitable for Decompiling Java

59. October 21, 2003Shane A. Brewer59 Soot Intermediate Representations

60. October 21, 2003Shane A. Brewer60 Baf: In Depth Analysis and transformations on Java bytecode is problematic for 2 reasons: Encoding Issues Untyped Bytecodes A stack based representation Easier to manipulate as it is fully typed

61. October 21, 2003Shane A. Brewer61 Previous Example public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static void main(String[] args) { int x = stepPoly(6); System.out.println(x); } // End method main Refer back to our Java example

62. October 21, 2003Shane A. Brewer62 Previous Example public static int stepPoly(int x) { if(x < 0) { System.out.println("Bad Argument"); return -1; } else if (x <= 5) { return x * x; } else { return x * 5 + 16; } // End if-else } // End method stepPoly public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn Java method with corresponding bytecode

63. October 21, 2003Shane A. Brewer63 Bytecode and Corresponding Baf public static int stepPoly(int); Code: 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn public static int stepPoly(int) { word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke ; push -1; return.i; label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i; }

64. October 21, 2003Shane A. Brewer64 Bytecode and Corresponding Baf: Broken Up 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke <java.io.PrintStream: void println(java.lang.String)>; push -1; return.i; The baf file starts off with variable declarations. A prefix of “r” refers to a general purpose variable while an “i” refers a variable that stores an integer.

65. October 21, 2003Shane A. Brewer65 Bytecode and Corresponding Baf: Broken Up 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke <java.io.PrintStream: void println(java.lang.String)>; push -1; return.i; -The first instruction takes the first parameter to the method and stores it in variable i0. -The second instruction loads in the value of variable i0 and push it on the stack.

66. October 21, 2003Shane A. Brewer66 Bytecode and Corresponding Baf: Broken Up 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke <java.io.PrintStream: void println(java.lang.String)>; push -1; return.i; -Here, the if-greater-than-or-equal is replaced by a label, rather than an index into the bytecode array. Note that the label is not shown in this snippet.

67. October 21, 2003Shane A. Brewer67 Bytecode and Corresponding Baf: Broken Up 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke <java.io.PrintStream: void println(java.lang.String)>; push -1; return.i; -The first instruction obtains the receiver object of the static method “java.io.PrintStream.println”. Here, the receiver object is the class “java.lang.System.out” where the type of “out” is “java.io.PrintStream”. -The second instruction pushes the first argument to the method on the stack. In this case it is the string “Bad Argument”. -The last instruction invokes the virtual method “java.io.PrintStream” with a return value of void, and a single argument of type “java.lang.String”

68. October 21, 2003Shane A. Brewer68 Bytecode and Corresponding Baf: Broken Up 0:iload_0 1:ifge14 4:getstatic#25; //Field java/lang/System.out: Ljava/io/PrintStream; 7:ldc#37; //String Bad Argument 9:invokevirtual#40; //Method java/io/PrintStream.println: (Ljava/lang/String;)V 12:iconst_m1 13:ireturn word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke <java.io.PrintStream: void println(java.lang.String)>; push -1; return.i; -The constant -1 is pushed on to the stack -The method exits, returning a integer located on the top of the stack

69. October 21, 2003Shane A. Brewer69 Bytecode and Corresponding Baf -Targets of gotos are specifically labeled in Baf 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i;

70. October 21, 2003Shane A. Brewer70 Bytecode and Corresponding Baf -An integer (The first argument to the method) is pushed on the stack. Remember that we stored the first argument into variable i0 in the previous snippet. -The constant 5 is pushed on the stack -A comparison of the top 2 values on the stack are compared. Note the difference between the target of the gotos if the test succeeds. 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i;

71. October 21, 2003Shane A. Brewer71 Bytecode and Corresponding Baf 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i; -The first argument is pushed on to the stack twice (not much difference) -Integer multiplication is performed -The top value on the stack (an integer) is returned

72. October 21, 2003Shane A. Brewer72 Bytecode and Corresponding Baf 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i; -Argument is loaded again -The constant 5 is pushed on the stack -Integer multiplication is done. Result is pushed on the stack

73. October 21, 2003Shane A. Brewer73 Bytecode and Corresponding Baf 14:iload_0 15:iconst_5 16:if_icmpgt23 19:iload_0 20:iload_0 21:imul 22:ireturn 23:iload_0 24:iconst_5 25:imul 26:bipush16 28:iadd 29:ireturn label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i; -The constant 16 is pushed on the stack -Integer addition is performed on the top 2 values on the stack -The method returns the top value on the stack (An integer)

74. October 21, 2003Shane A. Brewer74 Jimple: In Depth Optimizing stack code is awkward Expression are not explicit; An instruction may have it’s operands separated by an arbitrary number of stack instructions Stack is untyped by nature Jimple is a 3-address code representation of bytecode Typed Is ideal for performing optimizations and analysis Operators are untyped Local variables are given explicit primitive, class, or interface types

75. October 21, 2003Shane A. Brewer75 Baf and Corresponding Jimple public static int stepPoly(int) { word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke ; push -1; return.i; label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i; } public static int stepPoly(int) { int i0, $i1, $i2, $i3; java.io.PrintStream $r0; i0 := @parameter0: int; if i0 >= 0 goto label0; $r0 = ; virtualinvoke $r0.<java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; label0: if i0 > 5 goto label1; $i1 = i0 * i0; return $i1; label1: $i2 = i0 * 5; $i3 = $i2 + 16; return $i3; }

76. October 21, 2003Shane A. Brewer76 Baf and Corresponding Jimple word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke <java.io.PrintStream: void println(java.lang.String)>; push -1; return.i; int i0, $i1, $i2, $i3; java.io.PrintStream $r0; i0 := @parameter0: int; if i0 >= 0 goto label0; $r0 = ; virtualinvoke $r0.<java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; -Variable declarations come first. In Jimple, variables prefixed with a “$” refer to a stack position. -Variables i0, $i1, $i2, $i3 are typed as integers. -Variable $r0 is typed as java.io.PrintStream

77. October 21, 2003Shane A. Brewer77 Baf and Corresponding Jimple word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke <java.io.PrintStream: void println(java.lang.String)>; push -1; return.i; int i0, $i1, $i2, $i3; java.io.PrintStream $r0; i0 := @parameter0: int; if i0 >= 0 goto label0; $r0 = ; virtualinvoke $r0.<java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; -Variable i0 gets the value of the first parameter to the method. -The if check is reduced to a single instruction, compared with 2 stack-based instructions. Goto and labels remain the same.

78. October 21, 2003Shane A. Brewer78 Baf and Corresponding Jimple word i0; i0 := @parameter0: int; load.i i0; ifge label0; staticget ; push "Bad Arugument"; virtualinvoke <java.io.PrintStream: void println(java.lang.String)>; push -1; return.i; int i0, $i1, $i2, $i3; java.io.PrintStream $r0; i0 := @parameter0: int; if i0 >= 0 goto label0; $r0 = ; virtualinvoke $r0.<java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; -The receiver of the method call “java.io.PrintStream” is stored in variable $r0. Note that in Baf, this was a stack position. -The virtual method “println” is invoked on the object stored in $r0. -The constant -1 is returned from the method.

79. October 21, 2003Shane A. Brewer79 Baf and Corresponding Jimple label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i; } label0: if i0 > 5 goto label1; $i1 = i0 * i0; return $i1; label1: $i2 = i0 * 5; $i3 = $i2 + 16; return $i3; -The if statement is reduced from 3 Baf instructions to 1 Jimple instruction.

80. October 21, 2003Shane A. Brewer80 Baf and Corresponding Jimple label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i; } label0: if i0 > 5 goto label1; $i1 = i0 * i0; return $i1; label1: $i2 = i0 * 5; $i3 = $i2 + 16; return $i3; -The multiplication operation is no longer typed in Jimple. -The variable $i1 refers to the result of the multiplication operation that was a stack position.

81. October 21, 2003Shane A. Brewer81 Baf and Corresponding Jimple label0: load.i i0; push 5; ifcmpgt.i label1; load.i i0; mul.i; return.i; label1: load.i i0; push 5; mul.i; push 16; add.i; return.i; } label0: if i0 > 5 goto label1; $i1 = i0 * i0; return $i1; label1: $i2 = i0 * 5; $i3 = $i2 + 16; return $i3; -The results of the multiplication and addition operations are stored in the $i2 and $i3 variables. These are stack positions in Baf.

82. October 21, 2003Shane A. Brewer82 Grimp: In Depth 3 address code is sometimes harder to deal with than complex structures. Generating stack code is simpler with large expressions. Grimp is an unstructured representation which allows trees to be constructed for expressions. Easy to read Used for the foundation of a decompiler. Similar to the original Java code.

83. October 21, 2003Shane A. Brewer83 Jimple and Corresponding Grimp public static int stepPoly(int) { int i0, $i1, $i2, $i3; java.io.PrintStream $r0; i0 := @parameter0: int; if i0 >= 0 goto label0; $r0 = ; virtualinvoke $r0.<java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; label0: if i0 > 5 goto label1; $i1 = i0 * i0; return $i1; label1: $i2 = i0 * 5; $i3 = $i2 + 16; return $i3; } public static int stepPoly(int) { int i0; i0 := @parameter0: int; if i0 >= 0 goto label0;. <java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; label0: if i0 > 5 goto label1; return i0 * i0; label1: return i0 * 5 + 16; }

84. October 21, 2003Shane A. Brewer84 Jimple and Corresponding Grimp int i0, $i1, $i2, $i3; java.io.PrintStream $r0; i0 := @parameter0: int; if i0 >= 0 goto label0; $r0 = ; virtualinvoke $r0.<java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; int i0; i0 := @parameter0: int; if i0 >= 0 goto label0;. <java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; -Only one variable is needed as the operations are aggregated together.

85. October 21, 2003Shane A. Brewer85 Jimple and Corresponding Grimp int i0, $i1, $i2, $i3; java.io.PrintStream $r0; i0 := @parameter0: int; if i0 >= 0 goto label0; $r0 = ; virtualinvoke $r0.<java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; int i0; i0 := @parameter0: int; if i0 >= 0 goto label0;. <java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; -These instructions stay the same.

86. October 21, 2003Shane A. Brewer86 Jimple and Corresponding Grimp int i0, $i1, $i2, $i3; java.io.PrintStream $r0; i0 := @parameter0: int; if i0 >= 0 goto label0; $r0 = ; virtualinvoke $r0.<java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; int i0; i0 := @parameter0: int; if i0 >= 0 goto label0;. <java.io.PrintStream: void println(java.lang.String)>("Bad Arugument"); return -1; -The receiver object “java.lang.System.out” is hard coded in the method call instruction along with the argument.

87. October 21, 2003Shane A. Brewer87 Jimple and Corresponding Grimp label0: if i0 > 5 goto label1; $i1 = i0 * i0; return $i1; label1: $i2 = i0 * 5; $i3 = $i2 + 16; return $i3; label0: if i0 > 5 goto label1; return i0 * i0; label1: return i0 * 5 + 16; -Instructions are aggregated together into a single instruction.

88. October 21, 2003Shane A. Brewer88 Outline A Brief Java Overview Java Bytecode, Class files, and Bytecode Compilers Java Virtual Machines and Compilation Techniques Soot Overview Soot Intermediate Representations Soot Optimizations and Performance Soot Eclipse Plugin Demonstration

89. October 21, 2003Shane A. Brewer89 Soot Optimizations Common Subexpression Elimination Busy Code Motion Lazy Code Motion Copy Propagation Constant Propagation Dead Assignment Elimination Unreachable Code Elimination Unconditional Branch Folding

90. October 21, 2003Shane A. Brewer90 Soot Perfomance Changing bytecode to Baf, then Jimple, the Grimp, and then back to Bytecode with no optimizations reduces performance by only 2%. With whole program optimizations turned on, speedups of 21% were found for SPECjvm98. Using the attributes extension, programs exhibited speedups of approximately 8% (Some with slowdown)

91. October 21, 2003Shane A. Brewer91 Summary Java offers new challenges for compilers at both the classfile level and the virtual machine level. Soot offers a set of tools to optimize classfiles. Will Java become faster than other languages? (C, C++, etc)

92. October 21, 2003Shane A. Brewer92 References 1. http://www.sable.mcgill.ca/soot http://www.sable.mcgill.ca/soot 2. http://www.eclipse.org http://www.eclipse.org 3. P. Pominville, F. Qian, R. Vallee-Rai, L. Hendren, and C. Verbrugge, “A Gramework For Optimizing Java Using Attributes”, Lecture Notes In Computer Science, 2001. 4. R. Vallee-Rai, P. Co, E. Gagnon, L. Hendren, P. Lam, and V. Sundaresan, “Soot – A Java Bytecode Optimization Framework”, Proceedings of CASCON '99, 1999. 5. R. Vallee-Rai, E. Gagnon, L. Hendren, P. Lam, P. Pominville, and V. Sundaresan, “Optimizing Java Bytecode Using The Soot Gramework: Is It Feasible?”, Computational Complexity, 2000. 6. Bill Venners, “Inside the Java 2 Virtual Machine”, McGraw-Hill Osborne Media, 2000.

93. October 21, 2003Shane A. Brewer93 Outline A Brief Java Overview Java Bytecode, Class files, and Bytecode Compilers Java Virtual Machines and Compilation Techniques Soot Overview Soot Intermediate Representations Soot Optimizations and Performance Soot Eclipse Plugin Demonstration