[fpc-devel] FPC/Lazarus Rebuild performance

[Jonas Maebe]

On 11 Sep 2010, at 12:23, Martin Schreiber wrote:

> or it isn't true that FPC bottleneck is disk IO. Are we absolutely sure about 
> the bottleneck?

I'm quite certain that there are many reasons that FPC compiles more slowly than Delphi. The bottlenecks probably also vary from platform to platform and from compilation scenario to compilation scenario. I'm quite sure there is not a single thing you can "fix" and suddenly get compilation speeds in the same ballpark as Delphi 7 (how does the compilation speed of current Delphi's compare to Delphi 7 btw? I read that Delphi XE compiles much faster than Delphi 2010 in some cases, but I did not see comparisons to Delphi 7).

One thing that could be done is adding a linear scan register allocator (it would result in slightly worse code than the current register colouring, but it executes more quickly).

Going further, general restructuring of the compiler for compilation speed reasons would only be acceptable if it does not negatively impact the maintainability. There is a reason why we can support 6 architectures and umpteen OSes in the compiler with only a handful of people.


Jonas