[XRay][Driver] Do not link in XRay runtime in shared libs

[dberris]

Summary

This change ensures that we don't link in the XRay runtime when building
shared libraries with clang. This doesn't prevent us from building
shared libraris tht have XRay instrumentation sleds, but it does prevent
us from linking in the static XRay runtime into a shared library.

The XRay runtime currently doesn't support dynamic registration of
instrumentation sleds in shared objects, which we'll start enabling in
the future. That work has to happen in the back-end and in the runtime.

[rnk]

Looks good

[dberris]

• fixup: limit tests to run on supported platforms and oses

[dberris]

• fixup: use supported target list in test from clang implementation

[dberris]

Already landed; manually closing.

lib/Driver/ToolChains/Gnu.cpp

 
 void tools::gcc::Linker::RenderExtraToolArgs(const JobAction &JA,
                                              ArgStringList &CmdArgs) const {
   // The types are (hopefully) good enough.
 }
 
 static bool addXRayRuntime(const ToolChain &TC, const ArgList &Args,
                            ArgStringList &CmdArgs) {
+  // Do not add the XRay runtime to shared libraries.
+  if (Args.hasArg(options::OPT_shared))
+    return false;
+
   if (Args.hasFlag(options::OPT_fxray_instrument,
                    options::OPT_fnoxray_instrument, false)) {
     CmdArgs.push_back("-whole-archive");
     CmdArgs.push_back(TC.getCompilerRTArgString(Args, "xray", false));
     CmdArgs.push_back("-no-whole-archive");
     return true;
   }
+
   return false;
 }
 
 static void linkXRayRuntimeDeps(const ToolChain &TC, const ArgList &Args,
                                 ArgStringList &CmdArgs) {
   CmdArgs.push_back("--no-as-needed");
   CmdArgs.push_back("-lpthread");
   CmdArgs.push_back("-lrt");

test/Driver/XRay/lit.local.cfg

 target_triple_components = config.target_triple.split('-')
 config.available_features.update(target_triple_components)
+
+# Only run the tests in platforms where XRay instrumentation is supported.
+supported_targets = [
+    'amd64', 'x86_64', 'x86_64h', 'arm', 'aarch64', 'arm64', 'powerpc64le',
+    'mips', 'mipsel', 'mips64', 'mips64el'
+]
+
+# Only on platforms we support.
+supported_oses = [
+    'linux'
+]
+
+triple_set = set(target_triple_components)
+if len(triple_set.intersection(supported_targets)) == 0:
+  config.unsupported = True
+
+# Do not run for 'android' despite being linux.
+if len(triple_set.intersection(supported_oses)) == 0 or 'android' in triple_set:
+  config.unsupported = True

test/Driver/XRay/xray-shared-noxray.cpp

+// RUN: %clangxx -shared -fPIC -o /dev/null -v -fxray-instrument %s 2>&1 | \
+// RUN:     FileCheck %s --check-prefix=SHARED
+// RUN: %clangxx -static -o /dev/null -v -fxray-instrument %s 2>&1 -DMAIN | \
+// RUN:     FileCheck %s --check-prefix=STATIC
+// RUN: %clangxx -static -fPIE -o /dev/null -v -fxray-instrument %s 2>&1 \
+// RUN:     -DMAIN | FileCheck %s --check-prefix=STATIC
+//
+// SHARED-NOT: {{clang_rt\.xray-}}
+// STATIC: {{clang_rt\.xray-}}
+//
+// REQUIRES: linux
+int foo() { return 42; }
+
+#ifdef MAIN
+int main() { return foo(); }
+#endif