RE: [avr-gcc-list] Re: AVR LLVM backend?

[John Regehr]

> My experience with -fwhole-program -fcombine has been less than stellar. 
> I have seen a 25% code reduction, which is great! But I have also seen 
> up to 25% code *increase*, which is really bad. I would have thought 
> that, at the very least, they would ensure that the code size would not 
> increase. But because of this wide range of results, I can't always rely 
> on those switches, which is a real shame.

I think that ad hoc and embedded-inappropriate inlining heuristics are 
entirely to blame here.  Both llvm and gcc use speed-focused inlining 
where code bloat is an afterthought.  For a target like AVR it won't be 
hard to improve this.

John