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 "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;

   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 {
-  SmallString<128> Path(getDriver().SysRoot);
-  llvm::sys::path::append(Path, "/usr/lib/libcompiler_rt.a");
-  return std::string(Path.str());
+  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 {