[clang][Driver] Don't hardcode --as-needed/--no-as-needed on Illumos

[ro]

Summary

ninja check-all currently fails on Illumos:

[84/716] Generating default/Asan-i386-inline-Test
FAILED: projects/compiler-rt/lib/asan/tests/default/Asan-i386-inline-Test
cd /var/llvm/dist-amd64-release/projects/compiler-rt/lib/asan/tests && /var/llvm/dist-amd64-release/./bin/clang ASAN_INST_TEST_OBJECTS.gtest-all.cc.i386-inline.o ASAN_INST_TEST_OBJECTS.asan_globals_test.cpp.i386-inline.o ASAN_INST_TEST_OBJECTS.asan_interface_test.cpp.i386-inline.o ASAN_INST_TEST_OBJECTS.asan_internal_interface_test.cpp.i386-inline.o ASAN_INST_TEST_OBJECTS.asan_test.cpp.i386-inline.o ASAN_INST_TEST_OBJECTS.asan_oob_test.cpp.i386-inline.o ASAN_INST_TEST_OBJECTS.asan_mem_test.cpp.i386-inline.o ASAN_INST_TEST_OBJECTS.asan_str_test.cpp.i386-inline.o ASAN_INST_TEST_OBJECTS.asan_test_main.cpp.i386-inline.o -o /var/llvm/dist-amd64-release/projects/compiler-rt/lib/asan/tests/default/./Asan-i386-inline-Test -g --driver-mode=g++ -fsanitize=address -m32
ld: fatal: unrecognized option '--no-as-needed'
ld: fatal: use the -z help option for usage information
clang-11: error: linker command failed with exit code 1 (use -v to see invocation)

clang unconditionally passes --as-needed/--no-as-needed to the linker. This works
on Solaris 11.[34] which added a couple of option aliases to the native linker to improve
compatibility with GNU ld. Illumos ld didn't do this, so one needs to use the corresponding
native options -z ignore/-z record instead.

Because this works on both Solaris and Illumos, the current patch always passes the
native options on Solaris. This isn't fully correct, however: when using GNU ld on
Solaris (not yet supported; I'm working on that), one still needs --as-needed instead.

I'm hardcoding this decision because a generic detection via a cmake test is hard:
many systems have their own implementation of getDefaultLinker and cmake would
have to duplicate the information encoded there. Besides, it would still break when
-fuse-ld is used.

Tested on amd64-pc-solaris2.11 (Solaris 11.4 and OpenIndiana 2020.04), sparcv9-sun-solaris2.11, and
x86_64-pc-linux-gnu.

[ro]

Ping? It's been two weeks now.

[MaskRay]

#clang does not have many people. You might need to add people explicitly..

clang/lib/Driver/ToolChains/CommonArgs.cpp

633

ignore seems strange. How about start?

634

Can you improve the comment to mention that this is to work around illumnos ld?

636

I'll assume that -zignore has semantics similar to --as-needed.

[ro]

Incorporate review comments: clarify comment and arg name.

[ro]

In D84412#2193600, @MaskRay wrote:

#clang does not have many people. You might need to add people explicitly..

I always found finding reviewers sort of a black art: sometimes the people from the CODE_OWNERS.TXT files work, sometimes people that
recently reviewed changes to the same files are willing to do so again, while at others only repeated nagging works...

clang/lib/Driver/ToolChains/CommonArgs.cpp

633

I'd used ignore based no the description of the option in the ld man page:

-z ignore | record
--as-needed | --no-as-needed

    Ignores, or records, shared object dependencies that are not refer-
    enced as part  of  the  link-edit.  These  options  are  positional

start doesn't tell me much either, so I've gone for as_needed.

634

I hope it's better now. I've removed the GNU ld reference.
You can see my current hack to make clang work with gld on Solaris in D85309.

636

Right: the two are identical semantically.

[MaskRay]

LGTM.

clang/lib/Driver/ToolChains/CommonArgs.cpp

static bool addSanitizerDynamicList(const ToolChain &TC, const ArgList &Args,
   SmallString<128> SanRT(TC.getCompilerRT(Args, Sanitizer));
   if (llvm::sys::fs::exists(SanRT + ".syms")) {
     CmdArgs.push_back(Args.MakeArgString("--dynamic-list=" + SanRT + ".syms"));
     return true;
   }
   return false;
 }
 
+static const char *getAsNeededOption(const ToolChain &TC, bool as_needed) {
+  // While the Solaris 11.2 ld added --as-needed/--no-as-needed as aliases
+  // for the native forms -z ignore/-z record, they are missing in Illumos,
+  // so always use the native form.
+  if (TC.getTriple().isOSSolaris())
+    return as_needed ? "-zignore" : "-zrecord";
+  else
+    return as_needed ? "--as-needed" : "--no-as-needed";
+}
+
 void tools::linkSanitizerRuntimeDeps(const ToolChain &TC,
                                      ArgStringList &CmdArgs) {
   // Fuchsia never needs these.  Any sanitizer runtimes with system
   // dependencies use the `.deplibs` feature instead.
   if (TC.getTriple().isOSFuchsia())
     return;
 
   // Force linking against the system libraries sanitizers depends on
   // (see PR15823 why this is necessary).
-  CmdArgs.push_back("--no-as-needed");
+  CmdArgs.push_back(getAsNeededOption(TC, false));
   // There's no libpthread or librt on RTEMS & Android.
   if (TC.getTriple().getOS() != llvm::Triple::RTEMS &&
       !TC.getTriple().isAndroid()) {
     CmdArgs.push_back("-lpthread");
     if (!TC.getTriple().isOSOpenBSD())
       CmdArgs.push_back("-lrt");
   }
   CmdArgs.push_back("-lm");
if (TC.getXRayArgs().needsXRayRt()) {
     CmdArgs.push_back("-no-whole-archive");
     return true;
   }
 
   return false;
 }
 
 void tools::linkXRayRuntimeDeps(const ToolChain &TC, ArgStringList &CmdArgs) {
-  CmdArgs.push_back("--no-as-needed");
+  CmdArgs.push_back(getAsNeededOption(TC, false));
   CmdArgs.push_back("-lpthread");
   if (!TC.getTriple().isOSOpenBSD())
     CmdArgs.push_back("-lrt");
   CmdArgs.push_back("-lm");
 
   if (!TC.getTriple().isOSFreeBSD() &&
       !TC.getTriple().isOSNetBSD() &&
       !TC.getTriple().isOSOpenBSD())
if (TC.getTriple().isAndroid() || TC.getTriple().isOSIAMCU() ||
       TC.getTriple().isOSBinFormatWasm() ||
       UNW == ToolChain::UNW_None)
     return;
 
   LibGccType LGT = getLibGccType(D, Args);
   bool AsNeeded = LGT == LibGccType::UnspecifiedLibGcc &&
                   !TC.getTriple().isAndroid() && !TC.getTriple().isOSCygMing();
   if (AsNeeded)
-    CmdArgs.push_back("--as-needed");
+    CmdArgs.push_back(getAsNeededOption(TC, true));
 
   switch (UNW) {
   case ToolChain::UNW_None:
     return;
   case ToolChain::UNW_Libgcc: {
     if (LGT == LibGccType::StaticLibGcc)
       CmdArgs.push_back("-lgcc_eh");
     else
else if (TC.getTriple().isOSCygMing()) {
         // depending on what's available, and depending on the -static flag
         CmdArgs.push_back("-lunwind");
     } else
       CmdArgs.push_back("-l:libunwind.so");
     break;
   }
 
   if (AsNeeded)
-    CmdArgs.push_back("--no-as-needed");
+    CmdArgs.push_back(getAsNeededOption(TC, false));
 }
 
 static void AddLibgcc(const ToolChain &TC, const Driver &D,
                       ArgStringList &CmdArgs, const ArgList &Args) {
   LibGccType LGT = getLibGccType(D, Args);
   if (LGT != LibGccType::SharedLibGcc)
     CmdArgs.push_back("-lgcc");
   AddUnwindLibrary(TC, D, CmdArgs, Args);