Implement --noinhibit-exec.

Patch by George Rimar!

llvm-svn: 248605

6 files changed, 30 insertions, 3 deletions

diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index 5108a65fc82..b77a2f08671 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -24,6 +24,7 @@ struct Configuration {
   bool DiscardLocals = false;
   bool DiscardNone = false;
   bool ExportDynamic = false;
+  bool NoInhibitExec = false;
 };
 
 extern Configuration *Config;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index deafb6a1b96..307bb08cb68 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -94,6 +94,9 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   if (Args.hasArg(OPT_export_dynamic))
     Config->ExportDynamic = true;
 
+  if (Args.hasArg(OPT_noinhibit_exec))
+    Config->NoInhibitExec = true;
+
   // Create a list of input files.
   std::vector<MemoryBufferRef> Inputs;
 
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 237ca59dd82..4ad9bfc3865 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "InputSection.h"
+#include "Config.h"
 #include "Error.h"
 #include "InputFiles.h"
 #include "OutputSections.h"
diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td
index 897fc157502..5baa58771ec 100644
--- a/lld/ELF/Options.td
+++ b/lld/ELF/Options.td
@@ -28,6 +28,10 @@ def discard_locals : Flag<["-"], "discard-locals">,
 def alias_discard_locals: Flag<["-"], "X">,
      Alias<discard_locals>;
 
+def noinhibit_exec : Flag<["--"], "noinhibit-exec">,
+     HelpText<"Retain the executable output file whenever"
+              " it is still usable">;
+
 def discard_none : Flag<["-"], "discard-none">,
      HelpText<"Keep all symbols in the symbol table">;
 
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 61d72b2734b..464125b9b97 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -281,11 +281,14 @@ static void undefError(const SymbolTable &S, const SymbolBody &Sym) {
     if (&SymE > Syms.begin() && &SymE < Syms.end())
       SymFile = F.get();
   }
+
+  std::string Message = "undefined symbol: " + Sym.getName().str();
   if (SymFile)
-    error(Twine("undefined symbol: ") + Sym.getName() + " in " +
-          SymFile->getName());
+    Message += " in " + SymFile->getName().str();
+  if (Config->NoInhibitExec)
+    warning(Message);
   else
-    error(Twine("undefined symbol: ") + Sym.getName());
+    error(Message);
 }
 
 // Create output section objects and add them to OutputSections.
diff --git a/lld/test/elf2/no-inhibit-exec.s b/lld/test/elf2/no-inhibit-exec.s
new file mode 100644
index 00000000000..272a8d8e3e5
--- /dev/null
+++ b/lld/test/elf2/no-inhibit-exec.s
@@ -0,0 +1,15 @@
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: not lld -flavor gnu2 %t -o %t2
+# RUN: lld -flavor gnu2 %t --noinhibit-exec -o %t2
+# RUN: llvm-objdump -d %t2 | FileCheck %s
+# REQUIRES: x86
+
+# CHECK: Disassembly of section .text:
+# CHECK-NEXT: _start
+# CHECK-NEXT: 11000:   e8 fb ef fe ff   callq   -69637
+
+# next code will not link without noinhibit-exec flag
+# because of undefined symbol _bar
+.globl _start;
+_start:
+  call _bar