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[CLJS-773] Use unchecked-*-int functions for real 32-bit math Created: 26/Feb/14  Updated: 02/Dec/14

Status: Open
Project: ClojureScript
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Francis Avila Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: numerics
Environment:

r2173



 Description   

Currently the unchecked-* functions and macros simply alias the primitive js operators. It would be nice if the unchecked-*-int family of functions and macros implemented C/Java-like signed int operations with silent overflows (just like in Clojure) using asm.js coersion idioms. This should also allow us to share such code between clojure and clojurescript without worrying about their different numerics.

A use case is that porting hash algorithms from java to clojurescript is trickier and more verbose than it needs to be.



 Comments   
Comment by David Nolen [ 08/May/14 6:43 PM ]

This sounds interesting, would like to see more thoughts on approach, benchmarks etc.

Comment by David Nolen [ 02/Dec/14 5:46 AM ]

Bump, this enhancements sound simple & fine.

Comment by Francis Avila [ 02/Dec/14 1:26 PM ]

I'll have time to do this in about a week. The implementation is straightforward (basically use xor 0 everywhere). The goal is correctness, but I expect performance to be as good as or better than it is now on most platforms. I'm not sure if advanced mode will drop intermediate truncations or what impact this has on performance.

Some higher-level numeric analysis using the asm.js type system is possible but I doubt it's worth it.

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