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Bug 670659 - Detect GNU ld bug with debugging symbols when using --gc-sections and don't use it then. r=khuey

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This commit is contained in:
Mike Hommey 2011-07-19 08:51:22 +02:00
parent 6bd23f9c3b
commit 84658faf83
1 changed files with 43 additions and 4 deletions
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47
configure.in
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@ -1549,10 +1549,8 @@ if test "$GNU_CC"; then
MKCSHLIB='$(CC) $(CFLAGS) $(DSO_PIC_CFLAGS) $(DSO_LDOPTS) -Wl,-h,$@ -o $@'
DSO_LDOPTS='-shared'
if test "$GCC_USE_GNU_LD"; then
# Don't allow undefined symbols in libraries, and remove dead symbols
DSO_LDOPTS="$DSO_LDOPTS -Wl,-z,defs -Wl,--gc-sections"
CFLAGS="$CFLAGS -ffunction-sections -fdata-sections"
CXXFLAGS="$CXXFLAGS -ffunction-sections -fdata-sections"
# Don't allow undefined symbols in libraries
DSO_LDOPTS="$DSO_LDOPTS -Wl,-z,defs"
fi
WARNINGS_AS_ERRORS='-Werror'
DSO_CFLAGS=''
@ -7298,6 +7296,47 @@ if test -n "$MOZ_DEBUG" -o -n "$MOZ_DEBUG_SYMBOLS"; then
export MOZ_DEBUG_SYMBOLS
fi
dnl ========================================================
dnl = Automatically remove dead symbols
dnl ========================================================
if test "$GNU_CC" -a "$GCC_USE_GNU_LD" -a -n "$MOZ_DEBUG_FLAGS"; then
dnl See bug 670659
AC_CACHE_CHECK([whether removing dead symbols breaks debugging],
GC_SECTIONS_BREAKS_DEBUG_RANGES,
[echo 'int foo() {return 42;}' \
'int bar() {return 1;}' \
'int main() {return foo();}' > conftest.${ac_ext}
if AC_TRY_COMMAND([${CC-cc} -o conftest.${ac_objext} $CFLAGS $MOZ_DEBUG_FLAGS -ffunction-sections conftest.${ac_ext} 1>&2]) &&
AC_TRY_COMMAND([${CC-cc} -o conftest${ac_exeext} $LDFLAGS $MOZ_DEBUG_FLAGS -ffunction-sections -Wl,--gc-sections conftest.${ac_ext} $LIBS 1>&2]) &&
test -s conftest${ac_exeext} -a -s conftest.${ac_objext}; then
dnl objdump -WR would be much simpler, but ancient objdump
dnl doesn't support it.
debug_ranges_lines() {
awk '/^Contents/ { content=0 } /^Contents of the \.debug_ranges/ { content=1 } content { n += 1 } END { print n }'
}
dnl We expect the number of lines after "Contents of the
dnl .debug_ranges" to be the same in the object file and the
dnl linked program. If it's not, then we are hitting the linker
dnl bug.
if test `objdump -W conftest.${ac_objext} 2> /dev/null | debug_ranges_lines` = \
`objdump -W conftest${ac_exeext} 2> /dev/null | debug_ranges_lines`; then
GC_SECTIONS_BREAKS_DEBUG_RANGES=no
else
GC_SECTIONS_BREAKS_DEBUG_RANGES=yes
fi
else
dnl We really don't expect to get here, but just in case
AC_ERROR([couldn't compile a simple C file])
fi
rm -rf conftest*])
if test "$GC_SECTIONS_BREAKS_DEBUG_RANGES" = no; then
DSO_LDOPTS="$DSO_LDOPTS -Wl,--gc-sections"
CFLAGS="$CFLAGS -ffunction-sections -fdata-sections"
CXXFLAGS="$CXXFLAGS -ffunction-sections -fdata-sections"
fi
fi
dnl ========================================================
dnl = Disable any treating of compile warnings as errors
dnl ========================================================