lld: add -z interpose support

-z interpose sets the DF_1_INTERPOSE flag, marking the object as an
interposer.

Via FreeBSD PR 230604, linking Valgrind with lld failed.

Differential Revision:	https://reviews.llvm.org/D52094

llvm-svn: 342239

1 files changed, 5 insertions, 3 deletions

diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 49ad1b30603..f7abcfe0fd4 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -341,9 +341,10 @@ static bool getZFlag(opt::InputArgList &Args, StringRef K1, StringRef K2,
 static bool isKnown(StringRef S) {
   return S == "combreloc" || S == "copyreloc" || S == "defs" ||
          S == "execstack" || S == "global" || S == "hazardplt" ||
-         S == "initfirst" || S == "keep-text-section-prefix" || S == "lazy" ||
-         S == "muldefs" || S == "nocombreloc" || S == "nocopyreloc" ||
-         S == "nodelete" || S == "nodlopen" || S == "noexecstack" ||
+         S == "initfirst" || S == "interpose" ||
+         S == "keep-text-section-prefix" || S == "lazy" || S == "muldefs" ||
+         S == "nocombreloc" || S == "nocopyreloc" || S == "nodelete" ||
+         S == "nodlopen" || S == "noexecstack" ||
          S == "nokeep-text-section-prefix" || S == "norelro" || S == "notext" ||
          S == "now" || S == "origin" || S == "relro" || S == "retpolineplt" ||
          S == "rodynamic" || S == "text" || S == "wxneeded" ||
@@ -836,6 +837,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->ZGlobal = hasZOption(Args, "global");
   Config->ZHazardplt = hasZOption(Args, "hazardplt");
   Config->ZInitfirst = hasZOption(Args, "initfirst");
+  Config->ZInterpose = hasZOption(Args, "interpose");
   Config->ZKeepTextSectionPrefix = getZFlag(
       Args, "keep-text-section-prefix", "nokeep-text-section-prefix", false);
   Config->ZNodelete = hasZOption(Args, "nodelete");