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lecture-18 Optimizing Object Oriented languages

# lecture-18 Optimizing Object Oriented languages - in[x ±...

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1 Quick recap of abstract interpretation Approximation Want to show: Cousot and Cousot 77 Cousot and Cousot show that the following conditions are sufficient for proving (1) and (2): (3) (4) (5) Let’s look at the α condition Let’s look at the γ condition Link between local and global

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2 Optimizing OO languages Interproc analysis with data-dependent calls How to break the cycle? Better solution Algorithm
3 Example Example In the context of OO programs Class analysis Intraprocedural class analysis • Domain: Flow functions x := new C in out x := y in out

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4 Flow functions x := new C in out x := y in out out = in[x ° { C }] out = in[x ° in[y]] Flow functions if (x instance of C) in out[0] out[1] T F Flow functions if (x instance of C) in out[0] out[1] out[0] = in[x ° in[x]

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Unformatted text preview: in[x] ± subclasses(C)] T F out[1] = in[x & in[x] – subclasses(C) ] Limitations of intraproc analysis Profile-guided class prediction Specialization 5 Flow insensitive interproc class analysis Example CHA algorithm • Compute applies-to-set: for each method, determine the set of classes the method applies to. • At a message send a.m, take the set of classes inferred for a, and check if this set overlaps with the applies-to sets of all methods that implement m. • If only one set overlaps, then the message send should go to that method. Example Example Improvements 6 Flow-sensitive interproc class analysis Algorithm Problem Partial transfer functions...
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