hush/scripts/trylink
Denis Vlasenko 6ca409e0e4 trylink: produce even more info about final link stage
trylink: explain how to modify link and drastically decrease amount
  of padding (unfortunately, needs hand editing ATM).
*: add ALIGN1 / ALIGN2 to global strings and arrays of bytes and shorts

size saving: 0.5k
2007-08-12 20:58:27 +00:00

80 lines
2.9 KiB
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Executable File

#!/bin/sh
debug=false
try() {
added="$1"
shift
$debug && echo "Trying: $* $added"
"$@" $added 2>busybox_ld.err
}
# Sanitize lib list (dups, extra spaces etc)
#echo "BBOX_LIB_LIST=$BBOX_LIB_LIST"
BBOX_LIB_LIST=`echo "$BBOX_LIB_LIST" | xargs -n1 | sort | uniq | xargs`
# First link with all libs. If it fails, bail out
l_list=`echo "$BBOX_LIB_LIST" | sed -e 's/ / -l/g' -e 's/^/-l/'`
echo "Trying libraries: $BBOX_LIB_LIST"
try "-Wl,--start-group $l_list -Wl,--end-group" "$@" \
|| {
echo "Failed: $* -Wl,--start-group $l_list -Wl,--end-group"
cat busybox_ld.err
exit 1
}
#### Hack disabled: conflicts with ld --verbose flag in last link phase
##### Hack: we are not supposed to know executable name,
##### but this hack cuts down link time
####mv busybox_unstripped busybox_unstripped.tmp
####mv busybox.map busybox.map.tmp
# Now try to remove each lib and build without it.
# Stop when no lib can be removed.
####ever_discarded=false
while test "$BBOX_LIB_LIST"; do
$debug && echo "Trying libraries: $BBOX_LIB_LIST"
all_needed=true
for one in $BBOX_LIB_LIST; do
without_one=`echo " $BBOX_LIB_LIST " | sed "s/ $one / /g" | xargs`
l_list=`echo "$without_one" | sed -e 's/ / -l/g' -e 's/^/-l/'`
$debug && echo "Trying -l options: $l_list"
if try "-Wl,--start-group $l_list -Wl,--end-group" "$@"; then
echo "Library $one is not needed"
BBOX_LIB_LIST="$without_one"
all_needed=false
#### ever_discarded=true
else
echo "Library $one is needed"
fi
done
# All libs were needed, can't remove any
$all_needed && break
# If there is no space char, the list has just one lib.
# I'm not sure that in this case lib really is 100% needed.
# Let's try linking without it anyway... thus commented out.
#{ echo "$BBOX_LIB_LIST" | grep -q ' '; } || break
done
####mv busybox_unstripped.tmp busybox_unstripped
####mv busybox.map.tmp busybox.map
####$ever_discarded && {
# Make the binary with final, minimal list of libs
echo "Final link with: $BBOX_LIB_LIST"
l_list=`echo "$BBOX_LIB_LIST" | sed -e 's/ / -l/g' -e 's/^/-l/'`
# --verbose gives us gobs of info to stdout (e.g. linker script used)
try "-Wl,--start-group $l_list -Wl,--end-group -Wl,--verbose" "$@" >busybox_ld.out ####|| exit 1
#
# Add SORT_BY_ALIGNMENT to linker script (found in busybox_ld.out):
# .rodata : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
# *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
# *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
# This will eliminate most of the data padding. Use linker script
# by commenting "try" above and uncommenting this one (tested on i386):
#try "-Wl,--start-group $l_list -Wl,--end-group -Wl,--verbose -Wl,-T -Wl,busybox_ldscript" "$@" >busybox_ld.out
#
####}
####rm busybox_ld.err
####exit 0 # Ensure "success" exit code