Re: [Haskell-cafe] GHC vs GCC vs JHC
On 29/03/2010, at 02:27, Lennart Augustsson wrote: Does anything change if you swap the first two rhss? No, not as far as I can tell. On Sun, Mar 28, 2010 at 1:28 AM, Roman Leshchinskiy r...@cse.unsw.edu.au wrote: On 28/03/2010, at 09:47, Lennart Augustsson wrote: It's important to switch from mod to rem. This can be done by a simple abstract interpretation. Also, changing the definition of rem from a `rem` b | b == 0 = divZeroError | a == minBound b == (-1) = overflowError | otherwise = a `remInt` b to a `rem` b | b == 0 = divZeroError | b == (-1) a == minBound = overflowError | otherwise = a `remInt` b speeds up the GHC version by about 20%. Figuring out why is left as an exercise to the reader :-) Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
Does anything change if you swap the first two rhss? On Sun, Mar 28, 2010 at 1:28 AM, Roman Leshchinskiy r...@cse.unsw.edu.au wrote: On 28/03/2010, at 09:47, Lennart Augustsson wrote: It's important to switch from mod to rem. This can be done by a simple abstract interpretation. Also, changing the definition of rem from a `rem` b | b == 0 = divZeroError | a == minBound b == (-1) = overflowError | otherwise = a `remInt` b to a `rem` b | b == 0 = divZeroError | b == (-1) a == minBound = overflowError | otherwise = a `remInt` b speeds up the GHC version by about 20%. Figuring out why is left as an exercise to the reader :-) Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
Hi John, Any chance of seeing the benchmark? You're not the only one with an optimising compiler tucked away somewhere :-) I have one benchmark where I outperform GHC by 21 times, although saying it's artificial is a bit of an understatement... Thanks, Neil On Fri, Mar 26, 2010 at 6:27 PM, John Meacham j...@repetae.net wrote: Here are jhc's timings for the same programs on my machine. gcc and ghc both used -O3 and jhc had its full standard optimizations turned on. jhc: ./hs.out 5.12s user 0.07s system 96% cpu 5.380 total gcc: ./a.out 5.58s user 0.00s system 97% cpu 5.710 total ghc: ./try 31.11s user 0.00s system 96% cpu 32.200 total As you can see, jhc shines at this example, actually beating gcc -O3. It isn't too surprising, this is exactly the sort of haskell code that jhc excels at. John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
On Sat, Mar 27, 2010 at 3:25 AM, Neil Mitchell ndmitch...@gmail.com wrote: Hi John, Any chance of seeing the benchmark? You're not the only one with an optimising compiler tucked away somewhere :-) Neil, for some reason John's reply didn't thread with the rest of the thread. Probably because he changed the subject. He was referring to this thread: http://www.haskell.org/pipermail/haskell-cafe/2010-March/075151.html Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
John Meacham wrote: Here are jhc's timings for the same programs on my machine. gcc and ghc both used -O3 and jhc had its full standard optimizations turned on. jhc: ./hs.out 5.12s user 0.07s system 96% cpu 5.380 total gcc: ./a.out 5.58s user 0.00s system 97% cpu 5.710 total ghc: ./try 31.11s user 0.00s system 96% cpu 32.200 total As you can see, jhc shines at this example, actually beating gcc -O3. It isn't too surprising, this is exactly the sort of haskell code that jhc excels at. What's the property of that code which makes jhc excels in it? What makes ghc perform so poorly in comparison? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
It's important to switch from mod to rem. This can be done by a simple abstract interpretation. I'm nore sure if it's jhc or gcc that does this for jhc. -- Lennart On Sat, Mar 27, 2010 at 10:30 PM, Rafael Cunha de Almeida almeida...@gmail.com wrote: John Meacham wrote: Here are jhc's timings for the same programs on my machine. gcc and ghc both used -O3 and jhc had its full standard optimizations turned on. jhc: ./hs.out 5.12s user 0.07s system 96% cpu 5.380 total gcc: ./a.out 5.58s user 0.00s system 97% cpu 5.710 total ghc: ./try 31.11s user 0.00s system 96% cpu 32.200 total As you can see, jhc shines at this example, actually beating gcc -O3. It isn't too surprising, this is exactly the sort of haskell code that jhc excels at. What's the property of that code which makes jhc excels in it? What makes ghc perform so poorly in comparison? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
Lennart Augustsson wrote: It's important to switch from mod to rem. This can be done by a simple abstract interpretation. I'm nore sure if it's jhc or gcc that does this for jhc. It's not just adding rem. Ghc still runs much slower using rem. It's only when switching to -fvia-C and using rem that ghc gets close to gcc speed (even though, still slower). Now jhc seems to get it fast right away. What's going on here? Is ghc backend wrose than using gcc as a backend (which is what via-C seems to accomplish)? Are there cases when one way is preferred over the other? What are the tradeoffs here? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
On Sat, Mar 27, 2010 at 07:30:30PM -0300, Rafael Cunha de Almeida wrote: John Meacham wrote: Here are jhc's timings for the same programs on my machine. gcc and ghc both used -O3 and jhc had its full standard optimizations turned on. jhc: ./hs.out 5.12s user 0.07s system 96% cpu 5.380 total gcc: ./a.out 5.58s user 0.00s system 97% cpu 5.710 total ghc: ./try 31.11s user 0.00s system 96% cpu 32.200 total As you can see, jhc shines at this example, actually beating gcc -O3. It isn't too surprising, this is exactly the sort of haskell code that jhc excels at. I have not thoroughly checked it, but I think there are a couple things going on here: jhc is able to determine that all the arguments to the various functions are strict, so it can avoid all heap allocations and evaluations. ghc also benefits from this optimization. jhc sees that all the functions are fully applied to all their arguments, this means that they can always be directly called with optimized calling conventions as they will never have to represent generic 'eval' thunks or partial applications. it sees that all the functions are local to 'main' and not exported, so it can actually translate them to local functions in main in grin, allowing some more useful optimizations. Now the most important one, after optimizing the local functions, jhc sees that they are only called in tail-call position, so jhc is able to turn the function calls into direct jumps, turning them directly into C while/for loops operating fully on automatic variables on the stack. These last two optimizations are enabled by an incredibly useful extension to boquist's GRIN which is to allow a form of local function definitions, which solve a number of issues raised in his paper. Via a series of Grin-Grin transformations I am able to turn these local funciton definitions into direct conditional jumps in the resulting code. (which translate to looping constructs, if's and goto's in C) John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
On 27/03/2010, at 05:27, John Meacham wrote: Here are jhc's timings for the same programs on my machine. gcc and ghc both used -O3 and jhc had its full standard optimizations turned on. jhc: ./hs.out 5.12s user 0.07s system 96% cpu 5.380 total gcc: ./a.out 5.58s user 0.00s system 97% cpu 5.710 total ghc: ./try 31.11s user 0.00s system 96% cpu 32.200 total I really don't understand these GHC numbers. I get about 3s for the C version, about 5s for GHC with rem and about 7.5s for GHC with mod. Is this perhaps on a 64-bit system? What is sizeof(int) in C and sizeOf (undefined :: Int) in Haskell? That said, I suspect the only thing this benchmark really measures is how fast the various compilers can compute i * i + j * j + k * k `mod` 7. Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
On 28/03/2010, at 11:07, John Meacham wrote: I have not thoroughly checked it, but I think there are a couple things going on here: It could also be worthwhile to float out (i*i + j*j) in rangeK instead of computing it in every loop iteration. Neither ghc nor gcc can do this; if jhc can then that might explain the performance difference (although I would expect it to be larger in this case). Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
On 28/03/2010, at 09:47, Lennart Augustsson wrote: It's important to switch from mod to rem. This can be done by a simple abstract interpretation. Also, changing the definition of rem from a `rem` b | b == 0 = divZeroError | a == minBound b == (-1) = overflowError | otherwise = a `remInt` b to a `rem` b | b == 0 = divZeroError | b == (-1) a == minBound = overflowError | otherwise = a `remInt` b speeds up the GHC version by about 20%. Figuring out why is left as an exercise to the reader :-) Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC vs GCC vs JHC
Here are jhc's timings for the same programs on my machine. gcc and ghc both used -O3 and jhc had its full standard optimizations turned on. jhc: ./hs.out 5.12s user 0.07s system 96% cpu 5.380 total gcc: ./a.out 5.58s user 0.00s system 97% cpu 5.710 total ghc: ./try 31.11s user 0.00s system 96% cpu 32.200 total As you can see, jhc shines at this example, actually beating gcc -O3. It isn't too surprising, this is exactly the sort of haskell code that jhc excels at. John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
