Performace problems with gcc 3.0.4

[Dan Nicolaescu]

Joe Buck wrote:

>  > According to [a friend], the following code is about
>  > 50% slower than the version without structs.
>  >  
>  > He was tried the ICC (Intel compiler) and it
>  > generates the same code for the two cases but
>  > gcc does not. He played with all optimization
>  > flags that affect numeric code but to no avail.
>  >  
>  > Does anyone know what might be the problem ?
>     
>  Yes, it's a well-known problem with gcc.  Structs get committed to memory
>  too early.  Some compilers are able to split apart structs and treat their
>  members as independent scalar variables; gcc can only do this for structs
>  or classes with a single member.                                     
   
That is true, but it might not be the problem in this case. 
On SPARC both the assembly generated by gcc-3.0.4 -O2 is identical. 
So you might hit an x86 specific problem...