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Peephole Contest 2008

Peephole Contest 2008. COMP 520. Final Ranking (Total). A-. Submissions. Sound or unsound?. Constant folding iconst_x iconst_y iadd || isub || imul || idiv || irem ---------> ldc x op y. Sound or unsound?. StringBuffer aload x dup ifnull label_1 goto label_2

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Peephole Contest 2008

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  1. Peephole Contest 2008 COMP 520

  2. Final Ranking (Total) A-

  3. Submissions

  4. Sound or unsound? Constant folding iconst_x iconst_y iadd || isub || imul || idiv || irem ---------> ldc x op y

  5. Sound or unsound? StringBuffer aload x dup ifnull label_1 goto label_2 label_1: pop ldc "null" label_2: ------------------------> new j/l/StringBuffer dup invokenonvirtual j/l/StringBuffer/<init>()V aload x invokevirtual j/l/StringBuffer/append(Lj/l/String;)Lj/l/StringBuffer; invokevirtual j/l/StringBuffer/toString()Lj/l/String;

  6. Sound or unsound? StringBuffer invokevirtual j/l/String/concat(Lj/l/String;)Lj/l/String; dup ifnonnull lbl1 pop ldc "null" label lbl1 ---------> invokevirtual j/l/String/concat(Lj/l/String;)Lj/l/String;

  7. Sound or unsound? Dead code elimination

  8. Rules to keep in mind • Ok to assume “sensible code”, i.e. verifyable code • Should not assume certain code-generation scheme • Why? Times change, and code generation schemes, too!

  9. Results Tatatataaaaa….

  10. 2004 Benchmarks Group 5 javac Group 1 Group 4 A+ A-

  11. 2007 Benchmarks javac Group 5 Group 4 Group 1 A+ A-

  12. 2008 Benchmarks Group 5 javac Group 1 A+ Group 2 A-

  13. Most gain for the pain Group 4 Group 3 Group 2

  14. Final Ranking (Total) Group 5 javac Group 1 Group 4 A+ A-

  15. COMP 520 PRESENTS Winners of the Peephole Contestof the Year 2008 GROUP 5 NingJia Alexis Malozemoff Wei Wu November 21st, 2008 Eric Bodden & ReehanShaikh

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