GCC is 7 times slower than Intel? How to optimize? Need help!!

[Andrew Haley]

John Fine wrote:
> Andrew Haley wrote:
>> jackfrost wrote:
>>  
>>> Ian Lance Taylor-3 wrote:
>>>    
>>>> Try -ffast-math.  I think it's the default for icc when optimizing.
>>>>       
>>> I've tried  -ffast-math with the same result.
>>>     
>>
>> You're going to have to look at the generated assembler code.
>>
>>   
> 
> The generated assembler code wouldn't tell you anything.
> 
> Almost all the CPU time is spent inside the exp() function.

We haven't yet determined that.

> I'm confident neither gcc nor Intel10 is inlining the exp() function,

Why are you confident of that?  With -ffast-math -O2 that is precisely what
gcc will do.  That's why Ian suggested it.

Andrew.