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2 points by stefano 4210 days ago | link | parent

A non-optimizing compiler leads easily to a "fast enough" executable. Without optimizations I think the compiled code would be 7x~10x slower than C.

Edit: I've tried the Fibonacci "benchmark" on a simple compiler i'm writing: it takes 0.2 seconds to compile the program and to compute the 32snd Fibonacci's number. On the current Arc interpreter it takes ~5 seconds.



3 points by binx 4210 days ago | link

Your compiler might be much slower if it's with true scheme numbers, + operator as a function(not a primitive operator) and stack overflow checking. These features are currently supported by the arc interpreter on mzscheme.

If you can correctly eliminate function calls on +, your compiler is an optimizing one, not non-optimizing...

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2 points by stefano 4209 days ago | link

I've tried the same example putting a function call and a test around every arithmetic operation, and execution time went from ~0.2s to ~0.26s, not a big difference, although a few optimization will probably be necessary for something more complex than fibonacci's example.

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2 points by binx 4209 days ago | link

Is the function call overhead so small? I didn't realize.^^

But there are other issues: the fib example is not a very good benchmark suit, because in C, general recursion is not a common paradigm. If we compare C loops to Arc tail recursive calls generated by a simple compiler instead of comparing C recursions to Arc recursions, I believe that the difference will be much larger. Because C compiler writers have spent at least 20 years on optimizing loops...

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2 points by stefano 4209 days ago | link

That's absolutely true. Reaching C speed with high level languages such as Lisp it's very very difficult. CMUCL and SBCL reach roughly the speed of C, but they've been developed for a long time. As of loops speed vs. tail recursion speed, the difference shouldn't be too big.

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2 points by binx 4209 days ago | link

Stalin performs as better as C in numerical programs and many other benchmarks. The most exciting thing is that unlike CL, stalin doesn't need type declarations to guide optimizations. It would infer as much type information as possible. The problems is that it compiles too slow and it's not maintained anymore.

Naively implemented tail recursions is still not fast, because many common loop optimizations can't be directly applied to them unless you eliminate the function calls and regard them as true goto's. It's a rough task because the global flow analysis is needed for eliminating as many calls as we can.

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