Hello everyone,
I don't have a question, I merely have a little bash script that can generate some interesting output for those who are curious as to what the different optimization settings do.
Here's the bash script:
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touch optimization_settings.cpp
fn () {
if test -n "$1"; then
g++ "$1" -S -fverbose-asm -o optimization_settings.out optimization_settings.cpp
else
g++ -S -fverbose-asm -o optimization_settings.out optimization_settings.cpp
fi
sed -e 's/\([^#]\) -/\1\
# -/g' optimization_settings.out > "$2"
}
fn "" gcc-default
fn -O gcc-O
fn -O0 gcc-O0
fn -O1 gcc-O1
fn -O2 gcc-O2
fn -O3 gcc-O3
fn -Os gcc-Os
unset -f fn
rm optimization_settings.cpp
rm optimization_settings.out
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The different "gcc-xxxx" files can be diff'd against one another to ascertain the differences between the optimization settings. I strongly suspect that the settings are relative to the platform.
Hope someone finds this useful. And my thanks to the person that mentioned the utility value of the -fverbose-asm flag!
Sincerely,
--Eljay
"Hmmm, so that's the only difference between -O2 and -Os!? Well........."
