[Darwin][Driver] Don't pass a file as object_path_lto during ThinLTO

[steven_wu]

Summary

After r327851, Driver::GetTemporaryPath will create the file rather than
just create a potientially unqine filename. If clang driver pass the
file as parameter as -object_path_lto, ld64 will pass it back to libLTO
as GeneratedObjectsDirectory, which is going to cause a LLVM ERROR if it
is not a directory.
Now during thinLTO, pass a temp directory path to linker instread.

rdar://problem/47194182

[dexonsmith]

The code looks good. Can you add a test too? Might need to require “shell”.

[steven_wu]

I was planning to add a test but I am not sure how to check the file type of temporary files.

I add a test to check for temp file names because I do create file and directory with different prefix.

[arphaman]

include/clang/Driver/Driver.h

508

Old function name in the comment.

[steven_wu]

Fix the comment

[arphaman]

LGTM

include/clang/Driver/Driver.h

const char *GetNamedOutputPath(Compilation &C, const JobAction &JA,
                                  StringRef NormalizedTriple) const;
 
   /// GetTemporaryPath - Return the pathname of a temporary file to use
   /// as part of compilation; the file will have the given prefix and suffix.
   ///
   /// GCC goes to extra lengths here to be a bit more robust.
   std::string GetTemporaryPath(StringRef Prefix, StringRef Suffix) const;
 
+  /// GetTemporaryPath - Return the pathname of a temporary directory to use
+  /// as part of compilation; the directory will have the given prefix.
+  std::string GetTemporaryDirectory(StringRef Prefix) const;
+
   /// Return the pathname of the pch file in clang-cl mode.
   std::string GetClPchPath(Compilation &C, StringRef BaseName) const;
 
   /// ShouldUseClangCompiler - Should the clang compiler be used to
   /// handle this action.
   bool ShouldUseClangCompiler(const JobAction &JA) const;
 
   /// Returns true if we are performing any kind of LTO.

lib/Driver/Driver.cpp

std::string Driver::GetTemporaryPath(StringRef Prefix, StringRef Suffix) const {
   if (EC) {
     Diag(clang::diag::err_unable_to_make_temp) << EC.message();
     return "";
   }
 
   return Path.str();
 }
 
+std::string Driver::GetTemporaryDirectory(StringRef Prefix) const {
+  SmallString<128> Path;
+  std::error_code EC = llvm::sys::fs::createUniqueDirectory(Prefix, Path);
+  if (EC) {
+    Diag(clang::diag::err_unable_to_make_temp) << EC.message();
+    return "";
+  }
+
+  return Path.str();
+}
+
 std::string Driver::GetClPchPath(Compilation &C, StringRef BaseName) const {
   SmallString<128> Output;
   if (Arg *FpArg = C.getArgs().getLastArg(options::OPT__SLASH_Fp)) {
     // FIXME: If anybody needs it, implement this obscure rule:
     // "If you specify a directory without a file name, the default file name
     // is VCx0.pch., where x is the major version of Visual C++ in use."
     Output = FpArg->getValue();
 

lib/Driver/ToolChains/Darwin.cpp

if (Args.hasArg(options::OPT_rdynamic) && Version[0] >= 137)
     CmdArgs.push_back("-export_dynamic");
 
   // If we are using App Extension restrictions, pass a flag to the linker
   // telling it that the compiled code has been audited.
   if (Args.hasFlag(options::OPT_fapplication_extension,
                    options::OPT_fno_application_extension, false))
     CmdArgs.push_back("-application_extension");
 
-  if (D.isUsingLTO()) {
-    // If we are using LTO, then automatically create a temporary file path for
-    // the linker to use, so that it's lifetime will extend past a possible
-    // dsymutil step.
-    if (Version[0] >= 116 && NeedsTempPath(Inputs)) {
-      const char *TmpPath = C.getArgs().MakeArgString(
-          D.GetTemporaryPath("cc", types::getTypeTempSuffix(types::TY_Object)));
+  if (D.isUsingLTO() && Version[0] >= 116 && NeedsTempPath(Inputs)) {
+    std::string TmpPathName;
+    if (D.getLTOMode() == LTOK_Full) {
+      // If we are using full LTO, then automatically create a temporary file
+      // path for the linker to use, so that it's lifetime will extend past a
+      // possible dsymutil step.
+      TmpPathName =
+          D.GetTemporaryPath("cc", types::getTypeTempSuffix(types::TY_Object));
+    } else if (D.getLTOMode() == LTOK_Thin)
+      // If we are using thin LTO, then create a directory instead.
+      TmpPathName = D.GetTemporaryDirectory("thinlto");
+
+    if (!TmpPathName.empty()) {
+      auto *TmpPath = C.getArgs().MakeArgString(TmpPathName);
       C.addTempFile(TmpPath);
       CmdArgs.push_back("-object_path_lto");
       CmdArgs.push_back(TmpPath);
     }
   }
 
   // Use -lto_library option to specify the libLTO.dylib path. Try to find
   // it in clang installed libraries. ld64 will only look at this argument