On 15/07/2020 09:50, Jeroen Ooms wrote:
On Tue, Jul 14, 2020 at 4:22 PM Prof Brian Ripley wrote:
This is a rather technical post about how libraries of compiled code can
be further optimized. LTO generally produces smaller[*] and faster code
(typically by a few percent) at the expense of increased installation
time and is being used for large projects such as browsers and soon for
some Linux distributions.
I have committed a series of enhancements to LTO support in R-devel and
will shortly port the more important of these to R-patched.
Would it be worthwhile looking into this for Windows? We did enable
support for LTO in the rtools40 toolchains*, but those are gcc-8.3.0
and some of the benefits require gcc-9.
*
https://github.com/r-windows/rtools-packages/blob/master/mingw-w64-gcc/PKGBUILD#L166
Way off topic for R-sig-mac, but it is under discussion for Windows once
all the planned LTO changes are in.
A minor point which is relevant here: the recommended gfortran
distribution for macOS (which is from GCC 8.2) contains gcc and g++. So
Mac users could try that to get C/Fortran consistency checks. However,
only much later versions are compatible with Catalina's SDK
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90835), and from trying on
High Sierra it looks like Apple's linker does not understand GCC's LTO
format.
--
Brian D. Ripley, rip...@stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford
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