Add a module Hash in the bitcode and the combined index, implementing a kind of "build-id"

This is intended to be used for ThinLTO incremental build.

Differential Revision: http://reviews.llvm.org/D18213

This is a recommit of r265095 after fixing the Windows issues.

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 265111

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/tools/llvm-as/llvm-as.cpp b/llvm/tools/llvm-as/llvm-as.cpp
index 7318bfe341d..7e9500a6672 100644
--- a/llvm/tools/llvm-as/llvm-as.cpp
+++ b/llvm/tools/llvm-as/llvm-as.cpp
@@ -48,6 +48,9 @@ static cl::opt<bool> EmitSummaryIndex("module-summary",
                                       cl::desc("Emit module summary index"),
                                       cl::init(false));
 
+static cl::opt<bool> EmitModuleHash("module-hash", cl::desc("Emit module hash"),
+                                    cl::init(false));
+
 static cl::opt<bool>
 DumpAsm("d", cl::desc("Print assembly as parsed"), cl::Hidden);
 
@@ -82,7 +85,7 @@ static void WriteOutputFile(const Module *M) {
 
   if (Force || !CheckBitcodeOutputToConsole(Out->os(), true))
     WriteBitcodeToFile(M, Out->os(), PreserveBitcodeUseListOrder,
-                       EmitSummaryIndex);
+                       EmitSummaryIndex, EmitModuleHash);
 
   // Declare success.
   Out->keep();