#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/Target/TargetData.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Constants.h"
+#include "llvm/DataLayout.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
using namespace llvm;
STATISTIC(NumMerged, "Number of global constants merged");
// alignment to a concrete value.
unsigned getAlignment(GlobalVariable *GV) const;
- const TargetData *TD;
+ const DataLayout *TD;
};
}
}
bool ConstantMerge::runOnModule(Module &M) {
- TD = getAnalysisIfAvailable<TargetData>();
+ TD = getAnalysisIfAvailable<DataLayout>();
// Find all the globals that are marked "used". These cannot be merged.
SmallPtrSet<const GlobalValue*, 8> UsedGlobals;
// Map unique <constants, has-unknown-alignment> pairs to globals. We don't
// want to merge globals of unknown alignment with those of explicit
- // alignment. If we have TargetData, we always know the alignment.
+ // alignment. If we have DataLayout, we always know the alignment.
DenseMap<PointerIntPair<Constant*, 1, bool>, GlobalVariable*> CMap;
// Replacements - This vector contains a list of replacements to perform.
UsedGlobals.count(GV))
continue;
+ // This transformation is legal for weak ODR globals in the sense it
+ // doesn't change semantics, but we really don't want to perform it
+ // anyway; it's likely to pessimize code generation, and some tools
+ // (like the Darwin linker in cases involving CFString) don't expect it.
+ if (GV->isWeakForLinker())
+ continue;
+
Constant *Init = GV->getInitializer();
// Check to see if the initializer is already known.
PointerIntPair<Constant*, 1, bool> Pair(Init, hasKnownAlignment(GV));
GlobalVariable *&Slot = CMap[Pair];
- // If this is the first constant we find or if the old on is local,
- // replace with the current one. It the current is externally visible
+ // If this is the first constant we find or if the old one is local,
+ // replace with the current one. If the current is externally visible
// it cannot be replace, but can be the canonical constant we merge with.
- if (Slot == 0 || IsBetterCannonical(*GV, *Slot)) {
+ if (Slot == 0 || IsBetterCannonical(*GV, *Slot))
Slot = GV;
- }
}
// Second: identify all globals that can be merged together, filling in