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

Similar to D116843 for Gnu.cpp

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D119655

(cherry picked from commit d241ce0)

Author: brad0

clang/lib/Driver/ToolChains/NetBSD.cpp

@@ -236,7 +236,8 @@ void netbsd::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)) {
       CmdArgs.push_back(
           Args.MakeArgString(ToolChain.GetFilePath("crt0.o")));
@@ -294,7 +295,8 @@ void netbsd::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
-  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs,
+                   options::OPT_r)) {
     // Use the static OpenMP runtime with -static-openmp
     bool StaticOpenMP = Args.hasArg(options::OPT_static_openmp) &&
                         !Args.hasArg(options::OPT_static);
@@ -330,7 +332,8 @@ void netbsd::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(ToolChain.GetFilePath("crtendS.o")));

clang/test/Driver/netbsd.c

@@ -467,3 +467,11 @@
 // RUN: %clang -target powerpc-unknown-netbsd -### -c %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=POWERPC-SECUREPLT %s
 // POWERPC-SECUREPLT: "-target-feature" "+secure-plt"
+
+// -r suppresses default -l and crt*.o like -nostdlib.
+// RUN: %clang -no-canonical-prefixes -target x86_64-unknown-netbsd -r \
+// RUN: --sysroot=%S/Inputs/basic_netbsd_tree %s -### 2>&1 \
+// RUN: | FileCheck -check-prefix=RELOCATABLE %s
+// RELOCATABLE:     "-r"
+// RELOCATABLE-NOT: "-l
+// RELOCATABLE-NOT: crt{{[^.]+}}.o