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

[brad]

Summary

Similar to D116843 for Gnu.cpp

[joerg]

I'm ambivalent about this change. To me, it falls into the category of "stop passing random ld options to the compiler driver".

[MaskRay]

In D119655#3318003, @joerg wrote:

I'm ambivalent about this change. To me, it falls into the category of "stop passing random ld options to the compiler driver".

It's not only about options, but also some crt files. Very few projects assume the behavior and for the few, not implying -nostdlib for -r will cause them some portability inconvenience.
Well, you maintain the NetBSD part and can certainly disagree :)

[joerg]

Well, it doesn't work with GCC either, that's why I don't care much about this change. It just attempts to legalize a user bug (using a linker option directly as a compiler flag). But I don't care enough to object either.

[MaskRay]

In D119655#3318586, @joerg wrote:

Well, it doesn't work with GCC either, that's why I don't care much about this change. It just attempts to legalize a user bug (using a linker option directly as a compiler flag). But I don't care enough to object either.

-r is different from -Wl,-r.
GCC is free to assign specific semantics to -r, like -no-pie, -pie, -shared, to alter crt files and -l libraries a bit.

[uabelho]

clang/test/Driver/netbsd.c

477

Hi,

I see this CHECK-NOT fail every now and then due to bad luck:

13:48:46 /repo/bbiswjenk/fem2s10-eiffel176/workspace/llvm/llvm-main-gcc/clang/test/Driver/netbsd.c:477:21: error: RELOCATABLE-NOT: excluded string found in input
13:48:46 // RELOCATABLE-NOT: crt{{[^.]+}}.o
13:48:46 ^
13:48:46 <stdin>:6:286: note: found here
13:48:46 "/proj/bbi_twh/wh_bbi/x86_64-Linux2/bbigcc/1.9.3.0/crosscompiler/bin/ld" "--sysroot=/repo/bbiswjenk/fem2s10-eiffel176/workspace/llvm/llvm-main-gcc/clang/test/Driver/Inputs/basic_netbsd_tree" "--eh-frame-hdr" "-dynamic-linker" "/libexec/ld.elf_so" "-o" "a.out" "-r" "-r" "/tmp/lit-tmp-crtcq7cs/netbsd-94b421.o"
13:48:46 ^~~~~~~~~~~~~~~~~~~~~~~~

Same thing with

13:59:16 Failed Tests (5):
13:59:16 Clang :: Driver/freebsd.c
13:59:16 Clang :: Driver/fuchsia.c
13:59:16 Clang :: Driver/linux-cross.cpp
13:59:16 Clang :: Driver/netbsd.c
13:59:16 Clang :: Driver/openbsd.c

Perhaps the CHECK-NOT can be made stricter to avoid these matches due to bad luck?

clang/lib/Driver/ToolChains/NetBSD.cpp

void netbsd::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   if (Output.isFilename()) {
     CmdArgs.push_back("-o");
     CmdArgs.push_back(Output.getFilename());
   } else {
     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")));
     }
     CmdArgs.push_back(
         Args.MakeArgString(ToolChain.GetFilePath("crti.o")));
     if (Args.hasArg(options::OPT_shared) || Args.hasArg(options::OPT_pie)) {
       CmdArgs.push_back(
if (OsVersion >= VersionTuple(7) || OsVersion.getMajor() == 0) {
     case llvm::Triple::x86_64:
       useLibgcc = false;
       break;
     default:
       break;
     }
   }
 
-  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);
     addOpenMPRuntime(CmdArgs, ToolChain, Args, StaticOpenMP);
 
     if (D.CCCIsCXX()) {
       if (ToolChain.ShouldLinkCXXStdlib(Args))
         ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
if (useLibgcc) {
         CmdArgs.push_back("-lgcc");
         CmdArgs.push_back("--as-needed");
         CmdArgs.push_back("-lgcc_s");
         CmdArgs.push_back("--no-as-needed");
       }
     }
   }
 
-  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")));
     else
       CmdArgs.push_back(
           Args.MakeArgString(ToolChain.GetFilePath("crtend.o")));
     CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crtn.o")));
   }

clang/test/Driver/netbsd.c

 // PTHREAD-NOT: _POSIX_THREADS
 // PTHREAD:     _REENTRANT
 // PTHREAD-NOT: _POSIX_THREADS
 
 // Check PowerPC for Secure PLT
 // 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