[Driver] Support object files in addition to static and shared libraries in compiler-rt

[phosek]

Summary

This change introduces support for object files in addition to static
and shared libraries which were already supported which requires
changing the type of the argument from boolean to an enum.

[echristo]

Is something passing compiler-rt in as a -r link output or something?

[krytarowski]

What's the rationale for this?

[phosek]

This is needed for crtbegin.o/crtend.o, I originally implemented it as part of D28791 but that change is already pretty big so this is an attempt to split independent parts that could land separately into smaller changes.

[krytarowski]

Sorry, but this rather belongs to libc(abi) of Fuchsia. Why to push it into LLVM?

[krytarowski]

I don't know the original rationale of GNU.. but the final result (probably not out of interest of FSF) is that it's a vendor lock of glibc&gcc.

Please implement your crt* in your libc.

[krytarowski]

Adding joerg who raised concerns in the original change and is bypassed with this change.

[phosek]

I'd suggest moving this discussion to D28791 since your comments seem to be more related to the content of that change, not the content of this patch. I'm not trying to bypass the discussion in D28791, I'm just trying to split a rather large patch into smaller more easily reviewable chunks.

[krytarowski]

This patch attempts to add support for .o/object files from compiler-rt and right now there are no users and the only potential ones are crt* according to my guess.

[phosek]

I'd be happy to abandon this change if we decide to not move forward with D28791. I've made that change a parent revision of this change (although they don't necessarily have to land in that order) to make it obvious.

[echristo]

OK, that makes sense. I'm not a huge fan of how this set of code looks, but it also seems unfair to require you to extensively refactor it for this.

Any issues with crtbegin/end and where people believe things should be implemented for any given OS is orthogonal to this.

Thanks!

-eric

[mstorsjo]

clang/lib/Driver/ToolChain.cpp

375

For mingw (Triple.isWindowsGNUEnvironment) the natural extension is .o as well. So maybe check IsITANMSVCWindows instead here?

382

This looks like it's incorrectly rebased across rL343537; the non-mingw case should be .lib, not .dll - that was corrected in that commit.

clang/include/clang/Driver/ToolChain.h

enum RuntimeLibType {
     RLT_Libgcc
   };
 
   enum RTTIMode {
     RM_Enabled,
     RM_Disabled,
   };
 
+  enum FileType { FT_Object, FT_Static, FT_Shared };
+
 private:
   friend class RegisterEffectiveTriple;
 
   const Driver &D;
   llvm::Triple Triple;
   const llvm::opt::ArgList &Args;
 
   // We need to initialize CachedRTTIArg before CachedRTTIMode
public:
   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;
+                                    FileType Type = ToolChain::FT_Static) const;
 
-  const char *getCompilerRTArgString(const llvm::opt::ArgList &Args,
-                                     StringRef Component,
-                                     bool Shared = false) const;
+  const char *
+  getCompilerRTArgString(const llvm::opt::ArgList &Args, StringRef Component,
+                         FileType Type = ToolChain::FT_Static) const;
 
   // Returns <ResourceDir>/lib/<OSName>/<arch>.  This is used by runtimes (such
   // as OpenMP) to find arch-specific libraries.
   std::string getArchSpecificLibPath() const;
 
   // Returns <OSname> part of above.
   StringRef getOSLibName() const;
 

clang/lib/Driver/ToolChain.cpp

if (Triple.isOSUnknown()) {
     llvm::sys::path::append(Path, "lib");
   } else {
     llvm::sys::path::append(Path, "lib", getOSLibName());
   }
   return Path.str();
 }
 
 std::string ToolChain::getCompilerRT(const ArgList &Args, StringRef Component,
-                                     bool Shared) const {
+                                     FileType Type) const {
   const llvm::Triple &TT = getTriple();
   bool IsITANMSVCWindows =
       TT.isWindowsMSVCEnvironment() || TT.isWindowsItaniumEnvironment();
 
-  const char *Prefix = IsITANMSVCWindows ? "" : "lib";
-  const char *Suffix = Shared ? (Triple.isOSWindows() ? ".lib" : ".so")
-                              : (IsITANMSVCWindows ? ".lib" : ".a");
-  if (Shared && Triple.isWindowsGNUEnvironment())
-    Suffix = ".dll.a";
+  const char *Prefix =
+      IsITANMSVCWindows || Type == ToolChain::FT_Object ? "" : "lib";
+  const char *Suffix;
+  switch (Type) {
+  case ToolChain::FT_Object:
+    Suffix = IsITANMSVCWindows ? ".obj" : ".o";
+    break;
+  case ToolChain::FT_Static:
+    Suffix = IsITANMSVCWindows ? ".lib" : ".a";
+    break;
+  case ToolChain::FT_Shared:
+    Suffix = Triple.isOSWindows()
+                 ? (Triple.isWindowsGNUEnvironment() ? ".dll.a" : ".lib")
+                 : ".so";
+    break;
+  }
 
   for (const auto &LibPath : getLibraryPaths()) {
     SmallString<128> P(LibPath);
     llvm::sys::path::append(P, Prefix + Twine("clang_rt.") + Component + Suffix);
     if (getVFS().exists(P))
       return P.str();
   }
 
   StringRef Arch = getArchNameForCompilerRTLib(*this, Args);
   const char *Env = TT.isAndroid() ? "-android" : "";
   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 {
-  return Args.MakeArgString(getCompilerRT(Args, Component, Shared));
+                                              FileType Type) const {
+  return Args.MakeArgString(getCompilerRT(Args, Component, Type));
 }
 
 std::string ToolChain::getArchSpecificLibPath() const {
   SmallString<128> Path(getDriver().ResourceDir);
   llvm::sys::path::append(Path, "lib", getOSLibName(),
                           llvm::Triple::getArchTypeName(getArch()));
   return Path.str();
 }

clang/lib/Driver/ToolChains/CommonArgs.cpp

 }
 
 static void addSanitizerRuntime(const ToolChain &TC, const ArgList &Args,
                                 ArgStringList &CmdArgs, StringRef Sanitizer,
                                 bool IsShared, bool IsWhole) {
   // Wrap any static runtimes that must be forced into executable in
   // whole-archive.
   if (IsWhole) CmdArgs.push_back("--whole-archive");
-  CmdArgs.push_back(TC.getCompilerRTArgString(Args, Sanitizer, IsShared));
+  CmdArgs.push_back(TC.getCompilerRTArgString(
+      Args, Sanitizer, IsShared ? ToolChain::FT_Shared : ToolChain::FT_Static));
   if (IsWhole) CmdArgs.push_back("--no-whole-archive");
 
   if (IsShared) {
     addArchSpecificRPath(TC, Args, CmdArgs);
   }
 }
 
 // Tries to use a file with the list of dynamic symbols that need to be exported

clang/lib/Driver/ToolChains/MinGW.cpp

if (!Args.hasArg(options::OPT_nodefaultlibs)) {
       if (Args.hasArg(options::OPT_pg))
         CmdArgs.push_back("-lgmon");
 
       if (Args.hasArg(options::OPT_pthread))
         CmdArgs.push_back("-lpthread");
 
       if (Sanitize.needsAsanRt()) {
         // MinGW always links against a shared MSVCRT.
-        CmdArgs.push_back(
-            TC.getCompilerRTArgString(Args, "asan_dynamic", true));
+        CmdArgs.push_back(TC.getCompilerRTArgString(Args, "asan_dynamic",
+                                                    ToolChain::FT_Shared));
         CmdArgs.push_back(
             TC.getCompilerRTArgString(Args, "asan_dynamic_runtime_thunk"));
         CmdArgs.push_back(Args.MakeArgString("--require-defined"));
         CmdArgs.push_back(Args.MakeArgString(TC.getArch() == llvm::Triple::x86
                                                  ? "___asan_seh_interceptor"
                                                  : "__asan_seh_interceptor"));
         // Make sure the linker consider all object files from the dynamic
         // runtime thunk.

clang/lib/Driver/ToolChains/MipsLinux.h

public:
 
   void addLibCxxIncludePaths(
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
 
   void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
                            llvm::opt::ArgStringList &CmdArgs) const override;
 
-  std::string getCompilerRT(const llvm::opt::ArgList &Args, StringRef Component,
-                            bool Shared = false) const override;
+  std::string
+  getCompilerRT(const llvm::opt::ArgList &Args, StringRef Component,
+                FileType Type = ToolChain::FT_Static) const override;
 
   std::string computeSysRoot() const override;
 
   RuntimeLibType GetDefaultRuntimeLibType() const override {
     return GCCInstallation.isValid() ? RuntimeLibType::RLT_Libgcc
                                      : RuntimeLibType::RLT_CompilerRT;
   }
 

clang/lib/Driver/ToolChains/MipsLinux.cpp

void MipsLLVMToolChain::AddCXXStdlibLibArgs(const ArgList &Args,
 
   CmdArgs.push_back("-lc++");
   CmdArgs.push_back("-lc++abi");
   CmdArgs.push_back("-lunwind");
 }
 
 std::string MipsLLVMToolChain::getCompilerRT(const ArgList &Args,
                                              StringRef Component,
-                                             bool Shared) const {
+                                             FileType Type) const {
   SmallString<128> Path(getDriver().ResourceDir);
   llvm::sys::path::append(Path, SelectedMultilib.osSuffix(), "lib" + LibSuffix,
                           getOS());
-  llvm::sys::path::append(Path, Twine("libclang_rt." + Component + "-" +
-                                      "mips" + (Shared ? ".so" : ".a")));
+  const char *Suffix;
+  switch (Type) {
+  case ToolChain::FT_Object:
+    Suffix = ".o";
+    break;
+  case ToolChain::FT_Static:
+    Suffix = ".a";
+    break;
+  case ToolChain::FT_Shared:
+    Suffix = ".so";
+    break;
+  }
+  llvm::sys::path::append(
+      Path, Twine("libclang_rt." + Component + "-" + "mips" + Suffix));
   return Path.str();
 }