[patch 2/9] dynamically sized arrays in genextract

[Zack Weinberg]

On Sat, Jan 07, 2006 at 07:52:15AM +0100, Andreas Jaeger wrote:
> Zack Weinberg <zackw@panix.com> writes:
> 
> > This is one of the most obvious machine dependencies: genextract.c
> > includes insn-config.h so it knows how big to make its arrays.  The
> > patch changes it to use vec.h resizable arrays during the scanning
> > process, then copy to malloc space.
> 
> What kind of performance impact does this - or the complete patch set
> - have on bootstrapping the tree and on compilaton of large files?

There is no measurable difference to the speed of genextract from
this patch.  The overall patchset makes the bootstrap process somewhat
faster (due to the genautomata chainsaw stuff) - should be especially
noticeable in parallel builds which shouldn't serialize on genattrtab
anymore.

Very little changes in code put into the compiler -- a few things
become const when they weren't before, a few arrays of zeroes are
eliminated.  (The big chunks ripped out of insn-attrtab.c are all
code that was #ifdefed out anyway.) I do not expect any measurable
performance difference, but I can say that the scheduler is doing
strictly less work after this patch.

zw