Use Component in OpenBSD::getCompilerRT to find libraries

[blackgnezdo]

Summary

OpenBSD with this change would use this name for ASan:
/usr/lib/clang/11.1.0/lib/libclang_rt.asan.a

Already submitted to OpenBSD repository then amended
to cover the case of development tree.

[blackgnezdo]

OpenBSD commit: https://github.com/openbsd/src/commit/0b99cc4d5d8311a90145e8f4c6ae23275c275c52

[blackgnezdo]

Addressed the clang-tidy complaint.

[fcambus]

Any update on this?

For info, we started shipping libraries in the OpenBSD base system using this naming scheme for architectures on which we build Clang.

[blackgnezdo]

I reformatted with clang-format to address the lint complaint.

clang/lib/Driver/ToolChains/OpenBSD.cpp

 #include "Arch/Sparc.h"
 #include "CommonArgs.h"
 #include "clang/Config/config.h"
 #include "clang/Driver/Compilation.h"
 #include "clang/Driver/Options.h"
 #include "clang/Driver/SanitizerArgs.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/VirtualFileSystem.h"
 
 using namespace clang::driver;
 using namespace clang::driver::tools;
 using namespace clang::driver::toolchains;
 using namespace clang;
 using namespace llvm::opt;
 
 void openbsd::Assembler::ConstructJob(Compilation &C, const JobAction &JA,
void OpenBSD::AddCXXStdlibLibArgs(const ArgList &Args,
                                   ArgStringList &CmdArgs) const {
   bool Profiling = Args.hasArg(options::OPT_pg);
 
   CmdArgs.push_back(Profiling ? "-lc++_p" : "-lc++");
   CmdArgs.push_back(Profiling ? "-lc++abi_p" : "-lc++abi");
   CmdArgs.push_back(Profiling ? "-lpthread_p" : "-lpthread");
 }
 
-std::string OpenBSD::getCompilerRT(const ArgList &Args,
-                                   StringRef Component,
+std::string OpenBSD::getCompilerRT(const ArgList &Args, StringRef Component,
                                    FileType Type) const {
+  if (Component == "builtins") {
     SmallString<128> Path(getDriver().SysRoot);
     llvm::sys::path::append(Path, "/usr/lib/libcompiler_rt.a");
     return std::string(Path.str());
   }
+  SmallString<128> P(getDriver().ResourceDir);
+  std::string CRTBasename =
+      buildCompilerRTBasename(Args, Component, Type, /*AddArch=*/false);
+  llvm::sys::path::append(P, "lib", CRTBasename);
+  // Checks if this is the base system case which uses a different location.
+  if (getVFS().exists(P))
+    return std::string(P.str());
+  return ToolChain::getCompilerRT(Args, Component, Type);
+}
 
 Tool *OpenBSD::buildAssembler() const {
   return new tools::openbsd::Assembler(*this);
 }
 
 Tool *OpenBSD::buildLinker() const { return new tools::openbsd::Linker(*this); }
 
 bool OpenBSD::HasNativeLLVMSupport() const { return true; }