[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, 3 insertions, 4 deletions

diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
index 9a6fe270179..9c2280eb010 100644
--- a/llvm/tools/gold/gold-plugin.cpp
+++ b/llvm/tools/gold/gold-plugin.cpp
@@ -802,14 +802,13 @@ static ld_plugin_status allSymbolsReadHook() {
     auto &OutputName = Filenames[Task];
     getOutputFileName(Filename, /*TempOutFile=*/!SaveTemps, OutputName,
                       MaxTasks > 1 ? Task : -1);
-    IsTemporary[Task] = !SaveTemps;
+    IsTemporary[Task] = !SaveTemps && options::cache_dir.empty();
     if (options::cache_dir.empty())
       return llvm::make_unique<LTOOutput>(OutputName);
 
     return llvm::make_unique<CacheObjectOutput>(
-        options::cache_dir, [OutputName](std::unique_ptr<MemoryBuffer> Buffer) {
-          *LTOOutput(OutputName).getStream() << Buffer->getBuffer();
-        });
+        options::cache_dir,
+        [&OutputName](std::string EntryPath) { OutputName = EntryPath; });
   };
 
   check(Lto->run(AddOutput));