On 1/31/13 11:21 AM, L. David Baron wrote:
On Thu, Jan 31, 2013 at 1:31 PM, L. David Baron <dba...@dbaron.org> wrote:
Is it possible we might be able to make MOZ_LIKELY and MOZ_UNLIKELY
meaningful on Windows (they currently only do anything on gcc or
clang builds)? If we did, might that get back some of the gain from
turning off PGO?
Patrick McManus benchmarked the benefit of gcc's likely/unlikely macros
on the Linux kernel (where they are very commonly used). He found _no_
measurable differences after redefining likely/unlikely to nops.
Patrick ran his tests in 2008, so perhaps the results would different
with a recent version of gcc. I would also be interested is seeing test
results when reversing the macros' definitions (#define likely <->
unlikely). :)
http://bitsup.blogspot.com/2008/04/measuring-performance-of-linux-kernel.html
chris
_______________________________________________
dev-platform mailing list
dev-platform@lists.mozilla.org
https://lists.mozilla.org/listinfo/dev-platform
