[PATCH] D53796: [libcxx] Use AS_NEEDED command for linker script inputs

[Petr Hosek via Phabricator]

phosek created this revision.
phosek added reviewers: EricWF, ldionne, mclow.lists.
Herald added subscribers: libcxx-commits, christof.

This ensures that ELF shared libraries are only added when they are
actually needed, so when using C++ driver for linking, ELF outputs
that don't use any C++ standard library symbols won't end up with
unnecessary DT_NEEDED entries in the dynamic section.


Repository:
  rCXX libc++

https://reviews.llvm.org/D53796

Files:
  libcxx/utils/gen_link_script.py


Index: libcxx/utils/gen_link_script.py
===================================================================
--- libcxx/utils/gen_link_script.py
+++ libcxx/utils/gen_link_script.py
@@ -70,7 +70,7 @@
 
     # Generate the linker script contents and print the script and destination
     # information.
-    contents = "INPUT(%s %s)" % (linked_libcxx, ' '.join(public_libs))
+    contents = "INPUT(AS_NEEDED(%s %s))" % (linked_libcxx, ' '.join(public_libs))
     print("GENERATING SCRIPT: '%s' as file %s" % (contents, symlink_file))
 
     # Remove the existing libc++ symlink and replace it with the script.


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