Add -disable-global-ctor-const-promotion flag.

Add a flag to disable the promotion of the global constant
with constructors.

Change-Id: Ib21dc56edaea5a0eae76e9643cc0338bd187391f

1 files changed, 12 insertions, 4 deletions

diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 1522aa408b6..36d70f5e9c2 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -28,6 +28,7 @@
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Support/CallSite.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/GetElementPtrTypeIterator.h"
@@ -58,6 +59,12 @@ STATISTIC(NumAliasesResolved, "Number of global aliases resolved");
 STATISTIC(NumAliasesRemoved, "Number of global aliases eliminated");
 STATISTIC(NumCXXDtorsRemoved, "Number of global C++ destructors removed");
 
+static cl::opt<bool> DisableGlobalCtorConstPromotion(
+  "disable-global-ctor-const-promotion",
+  cl::desc("Disable constant promotion of global constants with constructors."),
+  cl::init(false),
+  cl::Hidden);
+
 namespace {
   struct GlobalStatus;
   struct GlobalOpt : public ModulePass {
@@ -2703,10 +2710,11 @@ static bool EvaluateStaticConstructor(Function *F, const TargetData *TD,
            Eval.getMutatedMemory().begin(), E = Eval.getMutatedMemory().end();
 	 I != E; ++I)
       CommitValueTo(I->second, I->first);
-    for (SmallPtrSet<GlobalVariable*, 8>::const_iterator I =
-           Eval.getInvariants().begin(), E = Eval.getInvariants().end();
-         I != E; ++I)
-      (*I)->setConstant(true);
+    if (!DisableGlobalCtorConstPromotion)
+      for (SmallPtrSet<GlobalVariable*, 8>::const_iterator I =
+             Eval.getInvariants().begin(), E = Eval.getInvariants().end();
+           I != E; ++I)
+        (*I)->setConstant(true);
   }
 
   return EvalSuccess;