[XRay][clang] Allow clang to build XRay instrumented binaries in OpenBSD

Summary:
This patch was originally reviewed in D45126. It enables clang to add
the XRay runtime and the link-time dependencies for XRay instrumentation
in OpenBSD.

Landing for devnexen.

Reviewers: brad, dberris

Subscribers: dberris, krytarowski, cfe-commits

Author: devnexen

Differential Revision: https://reviews.llvm.org/D45126

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@329183 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Driver/ToolChains/OpenBSD.cpp

@@ -22,6 +22,29 @@ using namespace clang::driver::toolchains;
 using namespace clang;
 using namespace llvm::opt;
 
+static bool addXRayRuntime(const ToolChain &TC, const ArgList &Args,
+                           ArgStringList &CmdArgs) {
+  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("-lm");
+  CmdArgs.push_back("-lpthread");
+}
+
 void openbsd::Assembler::ConstructJob(Compilation &C, const JobAction &JA,
                                       const InputInfo &Output,
                                       const InputInfoList &Inputs,
@@ -180,6 +203,7 @@ void openbsd::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                             options::OPT_Z_Flag, options::OPT_r});
 
   bool NeedsSanitizerDeps = addSanitizerRuntimes(ToolChain, Args, CmdArgs);
+  bool NeedsXRayDeps = addXRayRuntime(ToolChain, Args, CmdArgs);
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs, JA);
 
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
@@ -195,6 +219,10 @@ void openbsd::Linker::ConstructJob(Compilation &C, const JobAction &JA,
       CmdArgs.push_back(ToolChain.getCompilerRTArgString(Args, "builtins", false));
       linkSanitizerRuntimeDeps(ToolChain, CmdArgs);
     }
+    if (NeedsXRayDeps) {
+      CmdArgs.push_back(ToolChain.getCompilerRTArgString(Args, "builtins", false));
+      linkXRayRuntimeDeps(ToolChain, Args, CmdArgs);
+    }
     // FIXME: For some reason GCC passes -lgcc before adding
     // the default system libraries. Just mimic this for now.
     CmdArgs.push_back("-lgcc");

lib/Driver/XRayArgs.cpp

@@ -49,7 +49,8 @@ XRayArgs::XRayArgs(const ToolChain &TC, const ArgList &Args) {
         D.Diag(diag::err_drv_clang_unsupported)
             << (std::string(XRayInstrumentOption) + " on " + Triple.str());
       }
-    } else if (Triple.getOS() == llvm::Triple::FreeBSD) {
+    } else if (Triple.getOS() == llvm::Triple::FreeBSD ||
+               Triple.getOS() == llvm::Triple::OpenBSD) {
         if (Triple.getArch() != llvm::Triple::x86_64) {
           D.Diag(diag::err_drv_clang_unsupported)
               << (std::string(XRayInstrumentOption) + " on " + Triple.str());