Re: Emacs 28.1 built with x32 ABI outperforms x86-64

[Sven Hartrumpf]

Hello.

Emanuel wrote, 2022-04-08 19:17:
> Sven wrote:
> Yes, can you post the script (or function) that carried out
> the experiment?

Sure, see below.

Some notes:

- gccx32 is a tiny script that calls gcc in x32 mode
  (just passing CFLAGS to configure does not work as expected), containing:
 gcc-11 -mx32 -I/usr/local/include/x86_64-linux-gnux32 
-I/usr/x86_64-linux-gnux32/include "$@"

- dropcaches-root is s tool that avoids filesystem cache effects, simlar to a:
  echo 3 > /proc/sys/vm/drop_caches

- I call the script emacs.install as follows:
    emacs.install x86-64 |& tee emacs.64
    emacs.install x32 |& tee emacs.x32
  To test the second line, you will need all the x32 builds that I mentioned in 
my first mail.

--- emacs.install

#!/bin/bash
set -e -u -x

ABI=$1
tar xf emacs-28.1.tar.gz
cd emacs-28.1
if [ "$ABI" == "x32" ] ; then
  CC=gccx32 ./configure --prefix=/usr/local --bindir=/usr/local/binx32 
--includedir=/usr/local/includex32 --libdir=/usr/local/libx32 --with-sound=no 
--without-dbus --without-x
else # normal 64 bit
  CC=gcc-11 ./configure --prefix=/usr/local --bindir=/usr/local/bin64 
--libdir=/usr/local/lib64 --with-sound=no --without-dbus --without-x
fi
make -j4
strip src/emacs
dropcaches-root
date -Is
make check
find lisp -name '*.elc' | grep -v -e '/c-by.elc$' -e 'bindat.elc' | xargs rm # 
grep to avoid 2 files where compilation fails with max-lisp-eval-depth error
date -Is
make
date -Is

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