ThinLTO: handles modules with empty summaries

We need to add an entry in the combined-index for modules that have
a hash but otherwise empty summary, this is needed so that we can
get the hash for the module.

Also, if no entry is present in the combined index for a module, we
need to skip it when trying to compute a cache entry.

Differential Revision: https://reviews.llvm.org/D25300

llvm-svn: 283654

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
index f4232dc2f89..8afe13d8e16 100644
--- a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -234,6 +234,10 @@ public:
     if (CachePath.empty())
       return;
 
+    if (!Index.modulePaths().count(ModuleID))
+      // The module does not have an entry, it can't have a hash at all
+      return;
+
     // Compute the unique hash for this entry
     // This is based on the current compiler version, the module itself, the
     // export list, the hash for every single module in the import list, the