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configure: speed up flatten_extralibs_wrapper()

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x50 - x200 faster.

Currently configure spends 50-70% of its runtime inside a single
function: flatten_extralibs[_wrapper] - which does string processing.

During its run, nearly 20K command substitutions (subshells) are used,
including its callees unique() and resolve(), which is the reason
for its lengthy run.

This commit avoids all subshells during its execution, speeding it up
by about two orders of magnitude, and reducing the overall configure
runtime by 50-70% .

resolve() is rewritten to avoid subshells, and in unique() and
flatten_extralibs() we "inline" the filter[_out] functionality.

Note that logically, "unique" functionality has more than one possible
output (depending on which of the recurring items is kept). As it
turns out, other parts expect the last recurring item to be kept
(which was the original behavior of uniqie()). This patch preservs
its output order.

Tested-by: Michael Niedermayer <michael@niedermayer.cc>
Tested-by: Helmut K. C. Tessarek <tessarek@evermeet.cx>
Tested-by: Dave Yeo <daveryeo@telus.net>
Tested-by: Reino Wijnsma <rwijnsma@xs4all.nl>
Signed-off-by: James Almer <jamrial@gmail.com>
This commit is contained in:
Avi Halachmi (:avih) 2018-07-30 22:39:15 +03:00 committed by James Almer
parent d91370e0f1
commit 58b81ac621
1 changed files with 33 additions and 13 deletions
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46
configure vendored
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@ -844,22 +844,37 @@ prepend(){
eval "$var=\"$* \$$var\""
}
reverse () {
eval '
reverse_out=
for v in $'$1'; do
reverse_out="$v $reverse_out"
done
'$1'=$reverse_out
'
}
# keeps the last occurence of each non-unique item
unique(){
var=$1
uniq_list=""
for tok in $(eval echo \$$var); do
uniq_list="$(filter_out $tok $uniq_list) $tok"
unique_out=
eval unique_in=\$$1
reverse unique_in
for v in $unique_in; do
# " $unique_out" +space such that every item is surrounded with spaces
case " $unique_out" in *" $v "*) continue; esac # already in list
unique_out="$unique_out$v "
done
eval "$var=\"${uniq_list}\""
reverse unique_out
eval $1=\$unique_out
}
resolve(){
var=$1
tmpvar=
for entry in $(eval echo \$$var); do
tmpvar="$tmpvar $(eval echo \$${entry})"
resolve_out=
eval resolve_in=\$$1
for v in $resolve_in; do
eval 'resolve_out="$resolve_out$'$v' "'
done
eval "$var=\"${tmpvar}\""
eval $1=\$resolve_out
}
add_cppflags(){
@ -6734,14 +6749,19 @@ if test $target_os = "haiku"; then
fi
flatten_extralibs(){
unset nested_entries
nested_entries=
list_name=$1
eval list=\$${1}
for entry in $list; do
entry_copy=$entry
resolve entry_copy
append nested_entries $(filter '*_extralibs' $entry_copy)
flat_entries=$(filter_out '*_extralibs' $entry_copy)
flat_entries=
for e in $entry_copy; do
case $e in
*_extralibs) nested_entries="$nested_entries$e ";;
*) flat_entries="$flat_entries$e ";;
esac
done
eval $entry="\$flat_entries"
done
append $list_name "$nested_entries"