busybox/scripts/generate_BUFSIZ.sh
Denys Vlasenko 93e1aaa1c7 libbb: constify *bb_common_bufsiz1 (if it is compiled to be a pointer)
This lets gcc optimize much better:

   text	   data	    bss	    dec	    hex	filename
 922846	    910	  13056	 936812	  e4b6c	busybox_unstripped.nonconst
 920255	    910	  13056	 934221	  e414d	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2016-04-21 21:47:45 +02:00

118 lines
3.3 KiB
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#!/bin/sh
# Called from top-level directory a-la
#
# scripts/generate_BUFSIZ.sh include/common_bufsiz.h
. ./.config || exit 1
debug=false
common_bufsiz_h=$1
test x"$NM" = x"" && NM="${CONFIG_CROSS_COMPILER_PREFIX}nm"
test x"$CC" = x"" && CC="${CONFIG_CROSS_COMPILER_PREFIX}gcc"
regenerate() {
cat >"$1.$$"
test -f "$1" && diff "$1.$$" "$1" >/dev/null && rm "$1.$$" && return
mv "$1.$$" "$1"
}
generate_std_and_exit() {
$debug && echo "Default: bb_common_bufsiz1[] in bss"
{
echo "enum { COMMON_BUFSIZE = 1024 };"
echo "extern char bb_common_bufsiz1[];"
echo "#define setup_common_bufsiz() ((void)0)"
} | regenerate "$common_bufsiz_h"
exit 0
}
# User does not want any funky stuff?
test x"$CONFIG_FEATURE_USE_BSS_TAIL" = x"y" || generate_std_and_exit
test -f busybox_unstripped || {
# We did not try anything yet
$debug && echo "Will try to fit bb_common_bufsiz1[] into _end[]"
{
echo "enum { COMMON_BUFSIZE = 1024 };"
echo "extern char _end[]; /* linker-provided label */"
echo "#define bb_common_bufsiz1 _end"
echo "#define setup_common_bufsiz() ((void)0)"
} | regenerate "$common_bufsiz_h"
echo 1024 >"$common_bufsiz_h.BUFSIZE"
exit 0
}
# Get _end address
END=`$NM busybox_unstripped | grep ' . _end$'| cut -d' ' -f1`
test x"$END" = x"" && generate_std_and_exit
$debug && echo "END:0x$END $((0x$END))"
END=$((0x$END))
# Get PAGE_SIZE
echo "\
#include <sys/user.h>
#if defined(PAGE_SIZE) && PAGE_SIZE > 0
char page_size[PAGE_SIZE];
#else
char page_size[1];
#endif
" >page_size_$$.c
$CC -c "page_size_$$.c" || generate_std_and_exit
PAGE_SIZE=`$NM --size-sort "page_size_$$.o" | cut -d' ' -f1`
rm "page_size_$$.c" "page_size_$$.o"
test x"$PAGE_SIZE" = x"" && generate_std_and_exit
$debug && echo "PAGE_SIZE:0x$PAGE_SIZE $((0x$PAGE_SIZE))"
PAGE_SIZE=$((0x$PAGE_SIZE))
test $PAGE_SIZE -lt 1024 && generate_std_and_exit
# How much space between _end[] and next page?
PAGE_MASK=$((PAGE_SIZE-1))
REM=$(( (-END) & PAGE_MASK ))
$debug && echo "REM:$REM"
if test $REM -lt 1024; then
# _end[] has no enough space for bb_common_bufsiz1[],
# users will need to malloc it.
{
echo "enum { COMMON_BUFSIZE = 1024 };"
echo "extern char *const bb_common_bufsiz1;"
echo "void setup_common_bufsiz(void);"
} | regenerate "$common_bufsiz_h"
# Check that we aren't left with a buggy binary:
if test -f "$common_bufsiz_h.BUFSIZE"; then
rm "$common_bufsiz_h.BUFSIZE"
echo "Warning! Space in _end[] is too small ($REM bytes)!"
echo "Rerun make to build a binary which doesn't use it!"
exit 1
fi
echo "COMMON_BUFSIZE = 1024 bytes, the buffer will be malloced"
exit 0
fi
# _end[] has REM bytes for bb_common_bufsiz1[]
OLD=1024
test -f "$common_bufsiz_h.BUFSIZE" && OLD=`cat "$common_bufsiz_h.BUFSIZE"`
$debug && echo "OLD:$OLD"
{
echo "enum { COMMON_BUFSIZE = $REM };"
echo "extern char _end[]; /* linker-provided label */"
echo "#define bb_common_bufsiz1 _end"
echo "#define setup_common_bufsiz() ((void)0)"
} | regenerate "$common_bufsiz_h"
echo $REM >"$common_bufsiz_h.BUFSIZE"
# Check that code did not grow too much and thus _end[] did not shrink:
if test $OLD -gt $REM; then
echo "Warning! Space in _end[] has decreased from $OLD to $REM bytes!"
echo "Rerun make!"
exit 1
fi
if test $OLD != $REM; then
echo "Space in _end[] is $REM bytes. Rerun make to use larger COMMON_BUFSIZE."
else
echo "COMMON_BUFSIZE = $REM bytes"
fi