On Thu, Feb 01, 2007 at 11:20:16PM +0300, Alexei Alexandrov wrote: > Hi Bram et al., > > I'm doing some performance investigations of Vim code trying to understand > whether there are any possibilities to improve it. > Currently I've made the following observations (all investigations are done > on Windows): > > Redundant work is done during regexp operations in syntax highlighting. On > some files it is very noticable. The stack of the hotspot is ... > > syn_current_attr > syn_regexec > vim_regexec_multi > vim_regexec_both > > regtry > regmatch > ga_grow > alloc_clear > memset. So alloc_clear spends > quite a few clockticks in lalloc() and memset(). > The reason for this is pessimistically big grow size for regset growing array: > > ga_init2(®stack, 1, 10000); > > This is not very good: many regexp operations don't go deep - non-match is > detected very quickly. But even one element on the stack will lead to > allocating at least 10000 bytes (which should be fast with good CRT memory > allocator) and (worse) initializing these 10000 bytes with zeros (won't be > that fast).
I am not sure if this is really relevant to vim, because I don't have a clue which regexp matching algorithm it is using, but you might want to look into this article, when it comes to regexp speed: http://swtch.com/~rsc/regexp/regexp1.html regards, Martin
