r338682 | emaste | 2018-09-14 17:15:16 +0200 (Fri, 14 Sep 2018) | 16 lines

lld: add -z interpose support

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

Committed upstream as LLVM r342239.

PR:		230604
Reported by:	jbeich
Reviewed by:	markj
Approved by:	re (kib)
MFC after:	1 week
Relnotes:	Yes
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17172

Index: tools/lld/ELF/Config.h
===================================================================
--- tools/lld/ELF/Config.h	(revision 338681)
+++ tools/lld/ELF/Config.h	(revision 338682)
@@ -156,6 +156,7 @@ struct Configuration {
   bool ZExecstack;
   bool ZHazardplt;
   bool ZIfuncnoplt;
+  bool ZInterpose;
   bool ZNocopyreloc;
   bool ZNodelete;
   bool ZNodlopen;
Index: tools/lld/ELF/Driver.cpp
===================================================================
--- tools/lld/ELF/Driver.cpp	(revision 338681)
+++ tools/lld/ELF/Driver.cpp	(revision 338682)
@@ -670,6 +670,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &
   Config->ZExecstack = hasZOption(Args, "execstack");
   Config->ZHazardplt = hasZOption(Args, "hazardplt");
   Config->ZIfuncnoplt = hasZOption(Args, "ifunc-noplt");
+  Config->ZInterpose = hasZOption(Args, "interpose");
   Config->ZNocopyreloc = hasZOption(Args, "nocopyreloc");
   Config->ZNodelete = hasZOption(Args, "nodelete");
   Config->ZNodlopen = hasZOption(Args, "nodlopen");
Index: tools/lld/ELF/SyntheticSections.cpp
===================================================================
--- tools/lld/ELF/SyntheticSections.cpp	(revision 338681)
+++ tools/lld/ELF/SyntheticSections.cpp	(revision 338682)
@@ -1034,6 +1034,8 @@ template <class ELFT> void DynamicSection<ELFT>::f
   uint32_t DtFlags1 = 0;
   if (Config->Bsymbolic)
     DtFlags |= DF_SYMBOLIC;
+  if (Config->ZInterpose)
+    DtFlags1 |= DF_1_INTERPOSE;
   if (Config->ZNodelete)
     DtFlags1 |= DF_1_NODELETE;
   if (Config->ZNodlopen)