[Haskell-cafe] Very fast loops. Now!

[Lennart Augustsson]

Yes!  That's the code I like.

On Feb 10, 2007, at 17:46 , Felipe Almeida Lessa wrote:

> On 2/10/07, Rafael Almeida <almeidaraf at gmail.com> wrote:
>> While the haskell program took so long, the C program went really  
>> faster
>> than the haskell version:
>>   $ gcc -O3 -ffast-math -mfpmath=sse -msse2 -std=c99 loop.c -o c_loop
>>   $ time ./c_loop
>>   3.333333
>>
>>   real    0m0.001s
>>   user    0m0.000s
>>   sys     0m0.000s
>>   $ gcc --version
>>   gcc (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
>
> Under gcc (GCC) 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5),
> the following asm code is generated for part of the main function:
>
> mov         dword ptr [esp+4], 0aaaaaaabh
> mov         dword ptr [esp+8], 400aaaaah
> mov         dword ptr [esp], data_804858c
> call        wrapper_8049688_80482b4
>
> where data_804858c is "%f\n" and wrapper_8049688_80482b4 is printf.
> Needless to say that the other argument is exactly the double
> 3.3333333333333335. In the OP's words, "newer gcc's will statically
> compute that loop".
>
> -- 
> Felipe.
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