On Oct 29, 2013 7:36 AM, "Iain Buclaw" <ibuc...@ubuntu.com> wrote: > > > On Oct 29, 2013 7:16 AM, "Joseph Rushton Wakeling" < joseph.wakel...@webdrake.net> wrote: > > > > On 28/10/13 20:02, Iain Buclaw wrote: > >> > >> I don't see it that way. Up until now at least I haven't seen > >> anything they do that wasn't already do-able in GCC. > > > > > > I confess I may be biased here because recently I've been finding that D code compiled with LDC seems to typically run faster than stuff compiled with GDC -- particularly code which makes any kind of serious use of stuff from std.algorithm or any other strongly generic parts of the language. > > > > I can't imagine there are any fundamental frontend glue-code differences that are responsible for that, so I was assuming LLVM had a few areas where its optimizations worked better than the GCC middle/backend for various language constructs. > > > > I did test just now making sure that I used GDC with -march=native just in case that was the issue, but there's still a performance gap. The only other guess I have -- and it's a complete guess -- could it be inline-assembly related, that LDC gains a little here? > > Inline assembler for dynamic array vector operations does improve speed by 20% over the generic loop that GDC uses (for small arrays at least). >
Speaking of arrays, GDC up until recently allocated memory for every single [array, literal] in D code. This would give a noticeable slowdown in such code too. Regards -- Iain Buclaw *(p < e ? p++ : p) = (c & 0x0f) + '0';
