Bug 1892198 - No longer support linkerscript style for moz_expand_libs r=glandium

@file are supported by gcc since gcc 7 and by clang since clang 3.x,
which removes the need for linker script to list input files.

We cannot directly use @file from the compiler driver (it would expand
to a large number of arguments and hit the linker limit) so pass
-Wl,@FILE instead, which is supported since binutils 2.17.

As a side effect this removes the LTO dependency from the check.

Differential Revision: https://phabricator.services.mozilla.com/D207839

build/autoconf/expandlibs.m4

@@ -14,32 +14,25 @@ dnl ========================================================
 AC_CACHE_CHECK(what kind of list files are supported by the linker,
     moz_cv_expand_libs_list_style,
     [echo "int main() {return 0;}" > conftest.${ac_ext}
-     dnl Because BFD ld doesn't work with LTO + linker scripts, we
-     dnl must pass the LTO CFLAGS to the compile command, and the LTO
-     dnl LDFLAGS to all subsequent link commands.
-     dnl https://sourceware.org/bugzilla/show_bug.cgi?id=23600
-     if AC_TRY_COMMAND(${CC-cc} -o conftest.${OBJ_SUFFIX} -c $MOZ_LTO_CFLAGS $CFLAGS $CPPFLAGS conftest.${ac_ext} 1>&5) && test -s conftest.${OBJ_SUFFIX}; then
-         echo "INPUT(conftest.${OBJ_SUFFIX})" > conftest.list
+     if AC_TRY_COMMAND(${CC-cc} -o conftest.${OBJ_SUFFIX} -c $CFLAGS $CPPFLAGS conftest.${ac_ext} 1>&5) && test -s conftest.${OBJ_SUFFIX}; then
          if test "$CC_TYPE" = "clang-cl"; then
              link="$LINKER -OUT:conftest${ac_exeext}"
          else
              link="${CC-cc} -o conftest${ac_exeext}"
          fi
-         if AC_TRY_COMMAND($link $MOZ_LTO_LDFLAGS $LDFLAGS conftest.list $LIBS 1>&5) && test -s conftest${ac_exeext}; then
-             moz_cv_expand_libs_list_style=linkerscript
+         echo "conftest.${OBJ_SUFFIX}" > conftest.list
+         if AC_TRY_COMMAND($link $LDFLAGS [-Wl,@conftest.list] $LIBS 1>&5) && test -s conftest${ac_exeext}; then
+             moz_cv_expand_libs_list_style=linkerlist
+
+         dnl -filelist is for the OS X linker. We need to try -filelist first
+         dnl because clang understands @file, but may pass an oversized argument
+         dnl list to the linker depending on the contents of @file.
+         elif AC_TRY_COMMAND($link $LDFLAGS [-Wl,-filelist,conftest.list] $LIBS 1>&5) && test -s conftest${ac_exeext}; then
+             moz_cv_expand_libs_list_style=filelist
+         elif AC_TRY_COMMAND($link $LDFLAGS [@conftest.list] $LIBS 1>&5) && test -s conftest${ac_exeext}; then
+             moz_cv_expand_libs_list_style=list
          else
-             echo "conftest.${OBJ_SUFFIX}" > conftest.list
-             dnl -filelist is for the OS X linker.  We need to try -filelist
-             dnl first because clang understands @file, but may pass an
-             dnl oversized argument list to the linker depending on the
-             dnl contents of @file.
-             if AC_TRY_COMMAND($link $MOZ_LTO_LDFLAGS $LDFLAGS [-Wl,-filelist,conftest.list] $LIBS 1>&5) && test -s conftest${ac_exeext}; then
-                 moz_cv_expand_libs_list_style=filelist
-             elif AC_TRY_COMMAND($link $MOZ_LTO_LDFLAGS $LDFLAGS @conftest.list $LIBS 1>&5) && test -s conftest${ac_exeext}; then
-                 moz_cv_expand_libs_list_style=list
-             else
-                 AC_ERROR([Couldn't find one that works])
-             fi
+             AC_ERROR([Couldn't find one that works])
          fi
      else
          dnl We really don't expect to get here, but just in case

python/mozbuild/mozbuild/backend/common.py

@@ -325,15 +325,13 @@ class CommonBackend(BuildBackend):
             list_style = "list"
         list_file_path = mozpath.join(objdir, name)
         objs = [os.path.relpath(o, objdir) for o in objs]
-        if list_style == "linkerscript":
-            ref = list_file_path
-            content = "\n".join('INPUT("%s")' % o for o in objs)
-        elif list_style == "filelist":
+        content = "\n".join(objs)
+        if list_style == "filelist":
             ref = "-Wl,-filelist," + list_file_path
-            content = "\n".join(objs)
+        elif list_style == "linkerlist":
+            ref = "-Wl,@" + list_file_path
         elif list_style == "list":
             ref = "@" + list_file_path
-            content = "\n".join(objs)
         else:
             return None
 

toolkit/library/gen_buildid.py

@@ -18,16 +18,7 @@ from mozbuild.preprocessor import Preprocessor
 
 def main(output, input_file):
     with open(input_file) as fh:
-        if buildconfig.substs["EXPAND_LIBS_LIST_STYLE"] == "linkerscript":
-
-            def cleanup(line):
-                assert line.startswith('INPUT("')
-                assert line.endswith('")')
-                return line[len('INPUT("') : -len('")')]
-
-            objs = [cleanup(l.strip()) for l in fh.readlines()]
-        else:
-            objs = [l.strip() for l in fh.readlines()]
+        objs = [l.strip() for l in fh.readlines()]
 
     pp = Preprocessor()
     pp.out = StringIO()