[ELF] - Implement -z nodefaultlib

This is https://bugs.llvm.org//show_bug.cgi?id=38978

Spec says that:
"Objects may be built with the -z nodefaultlib option to
suppress any search of the default locations at runtime.
Use of this option implies that all the dependencies of an
object can be located using its runpaths.
Without this option, which is the most common case, no
matter how you augment the runtime linker's library
search path, its last element is always /usr/lib for 32-bit
objects and /usr/lib/64 for 64-bit objects."

The patch implements this option.

Differential revision: https://reviews.llvm.org/D54577

llvm-svn: 347647

5 files changed, 13 insertions, 5 deletions

diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index c669a04ecf3..37f713f1843 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -189,6 +189,7 @@ struct Configuration {
   bool ZInitfirst;
   bool ZInterpose;
   bool ZKeepTextSectionPrefix;
+  bool ZNodefaultlib;
   bool ZNodelete;
   bool ZNodlopen;
   bool ZNow;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 956f0b37346..37fab4c9642 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -350,8 +350,8 @@ static bool isKnownZFlag(StringRef S) {
          S == "execstack" || S == "global" || S == "hazardplt" ||
          S == "initfirst" || S == "interpose" ||
          S == "keep-text-section-prefix" || S == "lazy" || S == "muldefs" ||
-         S == "nocombreloc" || S == "nocopyreloc" || S == "nodelete" ||
-         S == "nodlopen" || S == "noexecstack" ||
+         S == "nocombreloc" || S == "nocopyreloc" || S == "nodefaultlib" ||
+         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" ||
@@ -876,6 +876,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->ZInterpose = hasZOption(Args, "interpose");
   Config->ZKeepTextSectionPrefix = getZFlag(
       Args, "keep-text-section-prefix", "nokeep-text-section-prefix", false);
+  Config->ZNodefaultlib = hasZOption(Args, "nodefaultlib");
   Config->ZNodelete = hasZOption(Args, "nodelete");
   Config->ZNodlopen = hasZOption(Args, "nodlopen");
   Config->ZNow = getZFlag(Args, "now", "lazy", false);
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index bf62dcd3ada..9f4554e1d63 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -1268,6 +1268,8 @@ template <class ELFT> void DynamicSection<ELFT>::finalizeContents() {
     DtFlags1 |= DF_1_INITFIRST;
   if (Config->ZInterpose)
     DtFlags1 |= DF_1_INTERPOSE;
+  if (Config->ZNodefaultlib)
+    DtFlags1 |= DF_1_NODEFLIB;
   if (Config->ZNodelete)
     DtFlags1 |= DF_1_NODELETE;
   if (Config->ZNodlopen)
diff --git a/lld/docs/ld.lld.1 b/lld/docs/ld.lld.1
index 417706dd0ab..d1ce4a3517f 100644
--- a/lld/docs/ld.lld.1
+++ b/lld/docs/ld.lld.1
@@ -496,6 +496,10 @@ This is a synonym for
 Disable combining and sorting multiple relocation sections.
 .It Cm nocopyreloc
 Disable the creation of copy relocations.
+.It Cm nodefaultlib
+Set the
+.Dv DF_1_NODEFLIB
+flag to indicate that default library search paths should be ignored.
 .It Cm nodelete
 Set the
 .Dv DF_1_NODELETE
diff --git a/lld/test/ELF/dt_flags.s b/lld/test/ELF/dt_flags.s
index 8f84dfca0db..5f6addd0780 100644
--- a/lld/test/ELF/dt_flags.s
+++ b/lld/test/ELF/dt_flags.s
@@ -3,8 +3,8 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
 # RUN: ld.lld -shared %t -o %t.so
 
-# RUN: ld.lld -z global -z initfirst -z interpose -z now -z nodelete \
-# RUN:   -z nodlopen -z origin -Bsymbolic %t %t.so -o %t1
+# RUN: ld.lld -z global -z initfirst -z interpose -z now -z nodefaultlib \
+# RUN:   -z nodelete -z nodlopen -z origin -Bsymbolic %t %t.so -o %t1
 # RUN: llvm-readobj -dynamic-table %t1 | FileCheck -check-prefix=FLAGS %s
 
 # RUN: ld.lld %t %t.so -o %t2
@@ -15,7 +15,7 @@
 
 # FLAGS: DynamicSection [
 # FLAGS:   0x000000000000001E FLAGS ORIGIN SYMBOLIC BIND_NOW
-# FLAGS:   0x000000006FFFFFFB FLAGS_1 NOW GLOBAL NODELETE INITFIRST NOOPEN ORIGIN INTERPOSE
+# FLAGS:   0x000000006FFFFFFB FLAGS_1 NOW GLOBAL NODELETE INITFIRST NOOPEN ORIGIN INTERPOSE NODEFLIB
 # FLAGS: ]
 
 # CHECK: DynamicSection [