This is popular with dependency injection frameworks, and is even harder to reason about in the face of deserialisation or dynamic module loading. WriteLine "Dead code! Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Question feed. If YourVendor. This technique is common in debugging to optionally activate blocks of code; using an optimizer with dead code elimination eliminates the need for using a preprocessor to perform the same task. Categories : Compiler optimizations. How should this be implemented?
PDF | A new aggressive algorithm for the elimination of par- tially dead code is problems there is a significant difference here: partial dead code elimination. problem of dead code elimination, our method ma k es the fl ow information about. In the rest of the examples, we will stic k to this convention of using ε´ for. In compiler theory, dead code elimination is a compiler optimization to remove code which does not affect the program results.
This isn't a tractable problem.
Global value numbering Sparse conditional constant propagation. I am not actually feeding the dead-code detector's source code to itself, but the source code of the program that uses it. Furthermore, given the function returns a static value 96it may be simplified to the value it returns this simplification is called constant folding.
For example, a software may be configurable to include or exclude certain features depending on user preference, making certain sections of code seemingly dead in particular scenarios. I consider the preprocessor to be part of the compiler, though I know it technically isn't.
Dead code elimination example problems
|Kenneth It could, possibly, maybe, but it doesn't.
CiaPan CiaPan 6, 2 2 gold badges 15 15 silver badges 29 29 bronze badges. Can you prove that actnumber will never be 2 so that Action2 is never called?
The compiler will always lack some context information.
Dead Code Elimination for Beginners
In the example below, the value assigned to i is never used, and the dead store can be eliminated. Below is the code fragment after dead code elimination.
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Furthermore, b is declared as a local variable inside fooso its value cannot be used outside foo. If the procedure had a more complex control flowsuch as a label after the return statement and a goto elsewhere in the procedure, then a feasible execution path might exist to the assignment to b. Featured on Meta.
Dead Code Elimination can be a valid optimization, but it's easy for naive For example if you change this comparison inside math-cordic: Additionally, there are a bunch of other problems with the Dead Code Elimination.
We address the problem of formally proving the correct- ness of dead code elimination (DCE) on static single as- signment (SSA) intermediate a DCE algorithm within the theorem prover Isabelle/HOL which eliminates all variables that have.
University of CincinnatiEngineering: Computer Engineering. Taemyr Then it wouldn't be known to be unconditionally dead, now would it? If you can analyse the callers of the function, then you may be able to, yes.
Why can't dead code detection be fully solved by a compiler Stack Overflow
There is value in allowing a compiler to defer slow calculations whose results may or may not be used until the point where their results would actually be needed; this optimization could in some cases be useful even if the compiler can't prove the calculations terminate.
It's a problem that can't be brute-forced anyway. When the code is compiled, all the compiler knows is that a certain string value is being passed to that method. ArtOfWarfare we're not talking about how it could be done.