trylink: reformat link flags for readability
authorvda <vda@69ca8d6d-28ef-0310-b511-8ec308f3f277>
Tue, 9 Oct 2007 13:49:26 +0000 (13:49 +0000)
committervda <vda@69ca8d6d-28ef-0310-b511-8ec308f3f277>
Tue, 9 Oct 2007 13:49:26 +0000 (13:49 +0000)
trylink: add --sort-section alignment:
    text           data     bss     dec     hex filename
-   6557            428    3260   10245    2805 busybox
+   6555            428    3260   10243    2803 busybox
- 909621           1076   12108  922805   e14b5 libbusybox.so.1.8.0.svn
+ 908868           1050   12016  921934   e114e libbusybox.so.1.8.0.svn

git-svn-id: svn://busybox.net/trunk/busybox@20210 69ca8d6d-28ef-0310-b511-8ec308f3f277

scripts/trylink

index 0829121..cbba900 100755 (executable)
@@ -2,6 +2,42 @@
 
 debug=false
 
+# Linker flags used:
+#
+# Informational:
+# --warn-common
+# -Map $EXE.map
+# --verbose
+#
+# Optimizations:
+# --sort-common                 reduces padding
+# --sort-section alignment      reduces padding
+# --gc-sections                 throws out unused sections,
+#                               does not work for shared libs
+# -O                           Not used, maybe useful?
+#
+# List of files to link:
+# $l_list                       == --start-group -llib1 -llib2 --end-group
+# --start-group $O_FILES $A_FILES --end-group
+# or for shlib:
+# --start-group --whole-archive $A_FILES --no-whole-archive --end-group
+# otherwise we don't pull in all parts of *.a files. Now we pull in too much.
+# FIXME: make it work without --whole-archive, or better, with --gc-sections.
+#
+# Shared library link:
+# -shared                       self-explanatory
+# -fPIC                         position-independent code
+# -Wl,--enable-new-dtags        ?
+# -Wl,-z,combreloc              ?
+# -Wl,-soname="libbusybox.so.$BB_VER"
+# -static                      Not used, but may be useful! manpage:
+#                               "... This option can be used with -shared.
+#                               Doing so means that a shared library
+#                               is being created but that all of the library's
+#                               external references must be resolved by pulling
+#                               in entries from static libraries."
+
+
 try() {
     printf "%s\n" "Output of:" >$EXE.out
     printf "%s\n" "$*" >>$EXE.out
@@ -28,8 +64,10 @@ echo "Trying libraries: $LDLIBS"
 l_list=`echo "$LDLIBS" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
 test "x$l_list" != "x" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
 try $CC $LDFLAGS \
-       -o $EXE -Wl,-Map -Wl,$EXE.map \
-       -Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
+       -o $EXE \
+       -Wl,--sort-common \
+       -Wl,--sort-section -Wl,alignment \
+       -Wl,--gc-sections \
        -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
        $l_list \
 || {
@@ -50,8 +88,10 @@ while test "$LDLIBS"; do
        test "x$l_list" != "x" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
        $debug && echo "Trying -l options: '$l_list'"
        try $CC $LDFLAGS \
-               -o $EXE -Wl,-Map -Wl,$EXE.map \
-               -Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
+               -o $EXE \
+               -Wl,--sort-common \
+               -Wl,--sort-section -Wl,alignment \
+               -Wl,--gc-sections \
                -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
                $l_list
        if test $? = 0; then
@@ -77,10 +117,15 @@ test "x$l_list" != "x" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
 # --verbose gives us gobs of info to stdout (e.g. linker script used)
 if ! test -f busybox_ldscript; then
     try $CC $LDFLAGS \
-           -o $EXE -Wl,-Map -Wl,$EXE.map \
-           -Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
+           -o $EXE \
+           -Wl,--sort-common \
+           -Wl,--sort-section -Wl,alignment \
+           -Wl,--gc-sections \
            -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
-           $l_list -Wl,--verbose \
+           $l_list \
+           -Wl,--warn-common \
+           -Wl,-Map -Wl,$EXE.map \
+           -Wl,--verbose \
     || {
        cat $EXE.out
        exit 1
@@ -92,12 +137,18 @@ else
     #  *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
     #  *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
     # This will eliminate most of the padding (~3kb).
+    # Hmm, "ld --sort-section alignment" should do it too.
     try $CC $LDFLAGS \
-           -o $EXE -Wl,-Map -Wl,$EXE.map \
-           -Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
-           -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
-           $l_list -Wl,--verbose \
+           -o $EXE \
+           -Wl,--sort-common \
+           -Wl,--sort-section -Wl,alignment \
+           -Wl,--gc-sections \
            -Wl,-T -Wl,busybox_ldscript \
+           -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
+           $l_list \
+           -Wl,--warn-common \
+           -Wl,-Map -Wl,$EXE.map \
+           -Wl,--verbose \
     || {
        cat $EXE.out
        exit 1
@@ -118,12 +169,18 @@ if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
 
     EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
     try $CC $LDFLAGS \
-       -o $EXE -Wl,-Map -Wl,$EXE.map \
-       -shared -fPIC -Wl,--enable-new-dtags \
-       -Wl,--start-group -Wl,--whole-archive $A_FILES -Wl,--no-whole-archive -Wl,--end-group \
-       $l_list -Wl,--verbose \
-       -Wl,-soname="libbusybox.so.$BB_VER" \
-       -Wl,-z,combreloc \
+           -o $EXE \
+           -shared -fPIC \
+           -Wl,--enable-new-dtags \
+           -Wl,-z,combreloc \
+           -Wl,-soname="libbusybox.so.$BB_VER" \
+           -Wl,--sort-common \
+           -Wl,--sort-section -Wl,alignment \
+           -Wl,--start-group -Wl,--whole-archive $A_FILES -Wl,--no-whole-archive -Wl,--end-group \
+           $l_list \
+           -Wl,--warn-common \
+           -Wl,-Map -Wl,$EXE.map \
+           -Wl,--verbose \
     || {
        echo "Linking $EXE failed"
        cat $EXE.out
@@ -137,11 +194,15 @@ fi
 if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
     EXE="$sharedlib_dir/busybox_unstripped"
     try $CC $LDFLAGS \
-       -o $EXE -Wl,-Map -Wl,$EXE.map \
-       -Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
-       -Wl,--start-group $O_FILES -Wl,--end-group \
-       -Wl,--verbose \
-       -L"$sharedlib_dir" -lbusybox \
+           -o $EXE \
+           -Wl,--sort-common \
+           -Wl,--sort-section -Wl,alignment \
+           -Wl,--gc-sections \
+           -Wl,--start-group $O_FILES -Wl,--end-group \
+           -L"$sharedlib_dir" -lbusybox \
+           -Wl,--warn-common \
+           -Wl,-Map -Wl,$EXE.map \
+           -Wl,--verbose \
     || {
        echo "Linking $EXE failed"
        cat $EXE.out
@@ -174,9 +235,12 @@ int main(int argc, char **argv)
 
        EXE="$sharedlib_dir/$name"
        try $CC $LDFLAGS "$sharedlib_dir/applet.c" \
-           -o $EXE \
-           -Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
-           -L"$sharedlib_dir" -lbusybox \
+               -o $EXE \
+               -Wl,--sort-common \
+               -Wl,--sort-section -Wl,alignment \
+               -Wl,--gc-sections \
+               -L"$sharedlib_dir" -lbusybox \
+               -Wl,--warn-common \
        || {
            echo "Linking $EXE failed"
            cat $EXE.out