[Driver] Search compiler-rt paths in -print-file-name=

[phosek]

Summary

This makes it possible to print the name of compiler-rt libraries
by using simply clang -print-file-name=libclang_rt.${runtime}-${arch}.so
same as other libraries, without having to know the details of the
resource directory organization.

[mcgrathr]

LGTM. Perhaps there should be a test.

[ldionne]

cfe/trunk/include/clang/Driver/ToolChain.h

312

By introducing a second way of getting the path to compiler-rt, this created inconsistencies where some platforms that implement getCompilerRT(...) now won't return the right value for getCompilerRTPath().

Is this the intent: getCompilerRT() == append(getCompilerRTPath(), basename(getCompilerRT(...))? If so, I think it would make sense to refactor this a bit so that we have:

getCompilerRTDir(); // What's currently called getCompilerRTPath(). This would be overriden by toolchains.
getCompilerRTBasename(args...); // Exists currently, but we would override this in the toolchains instead of having a default implementation.
getCompilerRT(args...); // This would basically do append(getCompilerRTDir(), getCompilerRTBasename(args...))

WDYT?

cfe/trunk/include/clang/Driver/ToolChain.h

public:
   virtual RuntimeLibType GetDefaultRuntimeLibType() const {
     return ToolChain::RLT_Libgcc;
   }
 
   virtual CXXStdlibType GetDefaultCXXStdlibType() const {
     return ToolChain::CST_Libstdcxx;
   }
 
+  virtual std::string getCompilerRTPath() const;
+
   virtual std::string getCompilerRT(const llvm::opt::ArgList &Args,
                                     StringRef Component,
                                     bool Shared = false) const;
 
   const char *getCompilerRTArgString(const llvm::opt::ArgList &Args,
                                      StringRef Component,
                                      bool Shared = false) const;
 

cfe/trunk/lib/Driver/Driver.cpp

for (const std::string &Dir : PrefixDirs) {
     if (Dir.empty())
       continue;
     SmallString<128> P(Dir[0] == '=' ? SysRoot + Dir.substr(1) : Dir);
     llvm::sys::path::append(P, Name);
     if (llvm::sys::fs::exists(Twine(P)))
       return P.str();
   }
 
-  SmallString<128> P(ResourceDir);
+  SmallString<128> R(ResourceDir);
+  llvm::sys::path::append(R, Name);
+  if (llvm::sys::fs::exists(Twine(R)))
+    return R.str();
+
+  SmallString<128> P(TC.getCompilerRTPath());
   llvm::sys::path::append(P, Name);
   if (llvm::sys::fs::exists(Twine(P)))
     return P.str();
 
   for (const std::string &Dir : TC.getFilePaths()) {
     if (Dir.empty())
       continue;
     SmallString<128> P(Dir[0] == '=' ? SysRoot + Dir.substr(1) : Dir);

cfe/trunk/lib/Driver/ToolChain.cpp

static StringRef getArchNameForCompilerRTLib(const ToolChain &TC,
   if (TC.getArch() == llvm::Triple::arm || TC.getArch() == llvm::Triple::armeb)
     return (arm::getARMFloatABI(TC, Args) == arm::FloatABI::Hard && !IsWindows)
                ? "armhf"
                : "arm";
 
   return TC.getArchName();
 }
 
+std::string ToolChain::getCompilerRTPath() const {
+  SmallString<128> Path(getDriver().ResourceDir);
+  StringRef OSLibName = Triple.isOSFreeBSD() ? "freebsd" : getOS();
+  llvm::sys::path::append(Path, "lib", OSLibName);
+  return Path.str();
+}
+
 std::string ToolChain::getCompilerRT(const ArgList &Args, StringRef Component,
                                      bool Shared) const {
   const llvm::Triple &TT = getTriple();
   const char *Env = TT.isAndroid() ? "-android" : "";
   bool IsITANMSVCWindows =
       TT.isWindowsMSVCEnvironment() || TT.isWindowsItaniumEnvironment();
 
   StringRef Arch = getArchNameForCompilerRTLib(*this, Args);
   const char *Prefix = IsITANMSVCWindows ? "" : "lib";
   const char *Suffix = Shared ? (Triple.isOSWindows() ? ".dll" : ".so")
                               : (IsITANMSVCWindows ? ".lib" : ".a");
 
-  SmallString<128> Path(getDriver().ResourceDir);
-  StringRef OSLibName = Triple.isOSFreeBSD() ? "freebsd" : getOS();
-  llvm::sys::path::append(Path, "lib", OSLibName);
+  SmallString<128> Path(getCompilerRTPath());
   llvm::sys::path::append(Path, Prefix + Twine("clang_rt.") + Component + "-" +
                                     Arch + Env + Suffix);
   return Path.str();
 }
 
 const char *ToolChain::getCompilerRTArgString(const llvm::opt::ArgList &Args,
                                               StringRef Component,
                                               bool Shared) const {