[ThinLTO] Add an API to trigger file-based API for returning objects to the linker

Summary:
The motivation is to support better the -object_path_lto option on
Darwin. The linker needs to write down the generate object files on
disk for later use by lldb or dsymutil (debug info are not present
in the final binary). We're moving this into libLTO so that we can
be smarter when a cache is enabled and hard-link when possible
instead of duplicating the files.

Reviewers: tejohnson, deadalnix, pcc

Subscribers: dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D27507

llvm-svn: 289631

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
index 3812c5fb5de..e0b11aaff00 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -285,6 +285,19 @@ std::error_code create_link(const Twine &to, const Twine &from) {
   return std::error_code();
 }
 
+std::error_code create_hard_link(const Twine &to, const Twine &from) {
+  // Get arguments.
+  SmallString<128> from_storage;
+  SmallString<128> to_storage;
+  StringRef f = from.toNullTerminatedStringRef(from_storage);
+  StringRef t = to.toNullTerminatedStringRef(to_storage);
+
+  if (::link(t.begin(), f.begin()) == -1)
+    return std::error_code(errno, std::generic_category());
+
+  return std::error_code();
+}
+
 std::error_code remove(const Twine &path, bool IgnoreNonExisting) {
   SmallString<128> path_storage;
   StringRef p = path.toNullTerminatedStringRef(path_storage);