fix PR8144, a bug where constant merge would merge globals marked
attribute(used).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113911 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/ConstantMerge.cpp b/lib/Transforms/IPO/ConstantMerge.cpp
index 75282fa..64e8d79 100644
--- a/lib/Transforms/IPO/ConstantMerge.cpp
+++ b/lib/Transforms/IPO/ConstantMerge.cpp
@@ -19,10 +19,12 @@
#define DEBUG_TYPE "constmerge"
#include "llvm/Transforms/IPO.h"
+#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
@@ -46,7 +48,27 @@
ModulePass *llvm::createConstantMergePass() { return new ConstantMerge(); }
+
+
+/// Find values that are marked as llvm.used.
+static void FindUsedValues(GlobalVariable *LLVMUsed,
+ SmallPtrSet<const GlobalValue*, 8> &UsedValues) {
+ if (LLVMUsed == 0) return;
+ ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
+ if (Inits == 0) return;
+
+ for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
+ if (GlobalValue *GV =
+ dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
+ UsedValues.insert(GV);
+}
+
bool ConstantMerge::runOnModule(Module &M) {
+ // Find all the globals that are marked "used". These cannot be merged.
+ SmallPtrSet<const GlobalValue*, 8> UsedGlobals;
+ FindUsedValues(M.getGlobalVariable("llvm.used"), UsedGlobals);
+ FindUsedValues(M.getGlobalVariable("llvm.compiler.used"), UsedGlobals);
+
// Map unique constant/section pairs to globals. We don't want to merge
// globals in different sections.
DenseMap<Constant*, GlobalVariable*> CMap;
@@ -79,9 +101,13 @@
// Only process constants with initializers in the default addres space.
if (!GV->isConstant() ||!GV->hasDefinitiveInitializer() ||
- GV->getType()->getAddressSpace() != 0 || !GV->getSection().empty())
+ GV->getType()->getAddressSpace() != 0 || !GV->getSection().empty() ||
+ // Don't touch values marked with attribute(used).
+ UsedGlobals.count(GV))
continue;
+
+
Constant *Init = GV->getInitializer();
// Check to see if the initializer is already known.