On Tuesday, 18 August 2015 at 21:43:44 UTC, Walter Bright wrote:
On 8/18/2015 1:33 PM, Jacob Carlborg wrote:
There's profile guided optimization, which LLVM supports.
dmd does have that to some extent. If you run with -profile,
the profiler will emit a trace.def file. This is a script which
can be fed to the linker which controls the layout of functions
in the executable. The layout is organized so that strongly
connected functions reside in the same page, minimizing
swapping and maximizing cache hits.
Unfortunately, nobody makes use of it, which makes me reluctant
to expend further effort on PGO.
http://www.digitalmars.com/ctg/trace.html
I wonder how many people actually use the llvm profile guided
optimizations. I suspect very, very few.
People are lazy and if it takes more than one click people wont
use it. Just like unitesting everyone agrees that its good to
write them but nobody does that. When you put unitesting in
compiler more people are writing tests. PGO is awesome, but it
needs to be made much simpler before people use it everyday.
