[Driver][DragonFly] -r: imply -nostdlib like GCC

Similar to D116843 for Gnu.cpp

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D119656

(cherry picked from commit cbd9d13)

Author: brad0

clang/lib/Driver/ToolChains/DragonFly.cpp

@@ -91,7 +91,8 @@ void dragonfly::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     assert(Output.isNothing() && "Invalid output.");
   }
 
-  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles)) {
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles,
+                   options::OPT_r)) {
     if (!Args.hasArg(options::OPT_shared)) {
       if (Args.hasArg(options::OPT_pg))
         CmdArgs.push_back(
@@ -119,7 +120,8 @@ void dragonfly::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs, JA);
 
-  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs,
+                   options::OPT_r)) {
     CmdArgs.push_back("-L/usr/lib/gcc80");
 
     if (!Args.hasArg(options::OPT_static)) {
@@ -158,7 +160,8 @@ void dragonfly::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
-  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles)) {
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles,
+                   options::OPT_r)) {
     if (Args.hasArg(options::OPT_shared) || Args.hasArg(options::OPT_pie))
       CmdArgs.push_back(
           Args.MakeArgString(getToolChain().GetFilePath("crtendS.o")));

clang/test/Driver/dragonfly.c

@@ -4,4 +4,9 @@
 // CHECK: clang{{.*}}" "-cc1" "-triple" "x86_64-pc-dragonfly"
 // CHECK: ld{{.*}}" "--eh-frame-hdr" "-dynamic-linker" "/usr/libexec/ld-elf.so.{{.*}}" "--hash-style=gnu" "--enable-new-dtags" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbegin.o" "{{.*}}.o" "-L{{.*}}gcc{{.*}}" "-rpath" "{{.*}}gcc{{.*}}" "-lc" "-lgcc" "{{.*}}crtend.o" "{{.*}}crtn.o"
 
-
+// -r suppresses default -l and crt*.o like -nostdlib.
+// RUN: %clang -### %s --target=x86_64-pc-dragonfly -r \
+// RUN:   2>&1 | FileCheck %s --check-prefix=RELOCATABLE
+// RELOCATABLE:     "-r"
+// RELOCATABLE-NOT: "-l
+// RELOCATABLE-NOT: {{.*}}crt{{[^.]+}}.o