[msan] Handle mixed track-origins and keep-going settings (llvm part).

Before this change, each module defined a weak_odr global __msan_track_origins 
with a value of 1 if origin tracking is enabled, 0 if disabled. If there are 
modules with different values, any of them may win. If 0 wins, and there is at 
least one module with 1, the program will most likely crash.

With this change, __msan_track_origins is only emitted if origin tracking is 
on. Then runtime library detects if there is at least one module with origin 
tracking, and enables runtime support for it.

llvm-svn: 182997

1 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 58108290d8d..a3a688d7c8d 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -366,11 +366,13 @@ bool MemorySanitizer::doInitialization(Module &M) {
   appendToGlobalCtors(M, cast<Function>(M.getOrInsertFunction(
                       "__msan_init", IRB.getVoidTy(), NULL)), 0);
 
-  new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage,
-                     IRB.getInt32(TrackOrigins), "__msan_track_origins");
+  if (TrackOrigins)
+    new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage,
+                       IRB.getInt32(TrackOrigins), "__msan_track_origins");
 
-  new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage,
-                     IRB.getInt32(ClKeepGoing), "__msan_keep_going");
+  if (ClKeepGoing)
+    new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage,
+                       IRB.getInt32(ClKeepGoing), "__msan_keep_going");
 
   return true;
 }