[ThinLTO] Move loading of cache entry to client

Summary:
Have the cache pass back the path to the cache entry when it
is ready to be loaded, instead of a buffer.

For gold-plugin we can simply pass this file back to gold directly,
which avoids expensive writing of a separate tmp file. Ensure
the cache entry is not deleted on cleanup by adjusting the setting
of the IsTemporary flags.

Moved the loading of the buffer into llvm-lto2 to maintain current
behavior.

Reviewers: mehdi_amini

Subscribers: llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D23946

llvm-svn: 279883

1 files changed, 2 insertions, 8 deletions

diff --git a/llvm/lib/LTO/Caching.cpp b/llvm/lib/LTO/Caching.cpp
index 118efde6a1f..728e5164dfa 100644
--- a/llvm/lib/LTO/Caching.cpp
+++ b/llvm/lib/LTO/Caching.cpp
@@ -64,14 +64,8 @@ CacheObjectOutput::~CacheObjectOutput() {
       // We commit the tempfile into the cache now, by moving it to EntryPath.
       commitEntry(TempFilename, EntryPath);
   }
-  // Load the entry from the cache now.
-  auto ReloadedBufferOrErr = MemoryBuffer::getFile(EntryPath);
-  if (auto EC = ReloadedBufferOrErr.getError())
-    report_fatal_error(Twine("Can't reload cached file '") + EntryPath + "': " +
-                       EC.message() + "\n");
-
-  // Supply the resulting buffer to the user.
-  AddBuffer(std::move(*ReloadedBufferOrErr));
+  // Supply the cache path to the user.
+  AddBuffer(EntryPath.str());
 }
 
 // Return an allocated stream for the output, or null in case of failure.