[clang] Enable -fsanitize=thread on Fuchsia.

[charco]

Summary

This CL modifies clang enabling using -fsanitize=thread on fuchsia. The
change doesn't build the runtime for fuchsia, it just enables the
instrumentation to be used.

pair-programmed-with: [e-mail]
Change-Id: I816c4d240d1f15e9eae2803fb8ba3a7bf667ed51

[phosek]

LGTM

[mcgrathr]

I'm not 100% sure we don't need more fiddles in the driver, but we can iterate from here.

[charco]

remove change-id lines.

clang/lib/Driver/ToolChains/CommonArgs.cpp

if (SanArgs.needsUbsanRt() && SanArgs.linkRuntimes()) {
         SharedRuntimes.push_back("ubsan_standalone");
     }
     if (SanArgs.needsScudoRt() && SanArgs.linkRuntimes()) {
       if (SanArgs.requiresMinimalRuntime())
         SharedRuntimes.push_back("scudo_minimal");
       else
         SharedRuntimes.push_back("scudo");
     }
+    if (SanArgs.needsTsanRt() && SanArgs.linkRuntimes())
+      SharedRuntimes.push_back("tsan");
     if (SanArgs.needsHwasanRt() && SanArgs.linkRuntimes())
       SharedRuntimes.push_back("hwasan");
   }
 
   // The stats_client library is also statically linked into DSOs.
   if (SanArgs.needsStatsRt() && SanArgs.linkRuntimes())
     StaticRuntimes.push_back("stats_client");
 
if (SanArgs.needsDfsanRt() && SanArgs.linkRuntimes())
     StaticRuntimes.push_back("dfsan");
   if (SanArgs.needsLsanRt() && SanArgs.linkRuntimes())
     StaticRuntimes.push_back("lsan");
   if (SanArgs.needsMsanRt() && SanArgs.linkRuntimes()) {
     StaticRuntimes.push_back("msan");
     if (SanArgs.linkCXXRuntimes())
       StaticRuntimes.push_back("msan_cxx");
   }
-  if (SanArgs.needsTsanRt() && SanArgs.linkRuntimes()) {
+  if (!SanArgs.needsSharedRt() && SanArgs.needsTsanRt() &&
+      SanArgs.linkRuntimes()) {
     StaticRuntimes.push_back("tsan");
     if (SanArgs.linkCXXRuntimes())
       StaticRuntimes.push_back("tsan_cxx");
   }
   if (!SanArgs.needsSharedRt() && SanArgs.needsUbsanRt() && SanArgs.linkRuntimes()) {
     if (SanArgs.requiresMinimalRuntime()) {
       StaticRuntimes.push_back("ubsan_minimal");
     } else {

clang/lib/Driver/ToolChains/Fuchsia.cpp

else if (Args.hasArg(options::OPT_shared))
     CmdArgs.push_back("-shared");
 
   const SanitizerArgs &SanArgs = ToolChain.getSanitizerArgs();
 
   if (!Args.hasArg(options::OPT_shared)) {
     std::string Dyld = D.DyldPrefix;
     if (SanArgs.needsAsanRt() && SanArgs.needsSharedRt())
       Dyld += "asan/";
+    if (SanArgs.needsTsanRt() && SanArgs.needsSharedRt())
+      Dyld += "tsan/";
     Dyld += "ld.so.1";
     CmdArgs.push_back("-dynamic-linker");
     CmdArgs.push_back(Args.MakeArgString(Dyld));
   }
 
   CmdArgs.push_back("-o");
   CmdArgs.push_back(Output.getFilename());
 
SanitizerMask Fuchsia::getSupportedSanitizers() const {
   Res |= SanitizerKind::Address;
   Res |= SanitizerKind::PointerCompare;
   Res |= SanitizerKind::PointerSubtract;
   Res |= SanitizerKind::Fuzzer;
   Res |= SanitizerKind::FuzzerNoLink;
   Res |= SanitizerKind::Leak;
   Res |= SanitizerKind::SafeStack;
   Res |= SanitizerKind::Scudo;
+  Res |= SanitizerKind::Thread;
   return Res;
 }
 
 SanitizerMask Fuchsia::getDefaultSanitizers() const {
   SanitizerMask Res;
   switch (getTriple().getArch()) {
   case llvm::Triple::aarch64:
     Res |= SanitizerKind::ShadowCallStack;