WholeProgramDevirt: Add import/export support for targets without absolute symbol constants.

Not all targets support the use of absolute symbols to export
constants. In particular, ARM has a wide variety of constant encodings
that cannot currently be relocated by linkers. So instead of exporting
the constants using symbols, export them directly in the summary.
The values of the constants are left as zeroes on targets that support
symbolic exports.

This may result in more cache misses when targeting those architectures
as a result of arbitrary changes in constant values, but this seems
somewhat unavoidable for now.

Differential Revision: https://reviews.llvm.org/D37407

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312967 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/LTO/LTO.cpp b/lib/LTO/LTO.cpp
index 6537f4d64d4..a13170cf8ad 100644
--- a/lib/LTO/LTO.cpp
+++ b/lib/LTO/LTO.cpp
@@ -230,6 +230,8 @@ static void computeCacheKey(
           AddUint64(Arg);
         AddUnsigned(ByArg.second.TheKind);
         AddUint64(ByArg.second.Info);
+        AddUnsigned(ByArg.second.Byte);
+        AddUnsigned(ByArg.second.Bit);
       }
     }
   };