//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "constmerge"
#include "llvm/Transforms/IPO.h"
+#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
-namespace {
- Statistic NumMerged("constmerge", "Number of global constants merged");
+STATISTIC(NumMerged, "Number of global constants merged");
+namespace {
struct ConstantMerge : public ModulePass {
+ static char ID; // Pass identification, replacement for typeid
+ ConstantMerge() : ModulePass(ID) {}
+
// run - For this pass, process all of the globals in the module,
// eliminating duplicate constants.
//
bool runOnModule(Module &M);
};
-
- RegisterPass<ConstantMerge>X("constmerge","Merge Duplicate Global Constants");
}
+char ConstantMerge::ID = 0;
+INITIALIZE_PASS(ConstantMerge, "constmerge",
+ "Merge Duplicate Global Constants", false, false);
+
ModulePass *llvm::createConstantMergePass() { return new ConstantMerge(); }
bool ConstantMerge::runOnModule(Module &M) {
// Map unique constant/section pairs to globals. We don't want to merge
// globals in different sections.
- std::map<std::pair<Constant*, std::string>, GlobalVariable*> CMap;
+ DenseMap<Constant*, GlobalVariable*> CMap;
// Replacements - This vector contains a list of replacements to perform.
- std::vector<std::pair<GlobalVariable*, GlobalVariable*> > Replacements;
+ SmallVector<std::pair<GlobalVariable*, GlobalVariable*>, 32> Replacements;
bool MadeChange = false;
// because doing so may cause initializers of other globals to be rewritten,
// invalidating the Constant* pointers in CMap.
//
- for (Module::global_iterator GV = M.global_begin(), E = M.global_end();
- GV != E; ++GV)
- // Only process constants with initializers.
- if (GV->isConstant() && GV->hasInitializer()) {
- Constant *Init = GV->getInitializer();
-
- // Check to see if the initializer is already known.
- GlobalVariable *&Slot = CMap[std::make_pair(Init, GV->getSection())];
-
- if (Slot == 0) { // Nope, add it to the map.
- Slot = GV;
- } else if (GV->hasInternalLinkage()) { // Yup, this is a duplicate!
- // Make all uses of the duplicate constant use the canonical version.
- Replacements.push_back(std::make_pair(GV, Slot));
- } else if (GV->hasInternalLinkage()) {
- // Make all uses of the duplicate constant use the canonical version.
- Replacements.push_back(std::make_pair(Slot, GV));
- Slot = GV;
- }
+ for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
+ GVI != E; ) {
+ GlobalVariable *GV = GVI++;
+
+ // If this GV is dead, remove it.
+ GV->removeDeadConstantUsers();
+ if (GV->use_empty() && GV->hasLocalLinkage()) {
+ GV->eraseFromParent();
+ continue;
}
+
+ // Only process constants with initializers in the default addres space.
+ if (!GV->isConstant() ||!GV->hasDefinitiveInitializer() ||
+ GV->getType()->getAddressSpace() != 0 || !GV->getSection().empty())
+ continue;
+
+ Constant *Init = GV->getInitializer();
+
+ // Check to see if the initializer is already known.
+ GlobalVariable *&Slot = CMap[Init];
+
+ if (Slot == 0) { // Nope, add it to the map.
+ Slot = GV;
+ } else if (GV->hasLocalLinkage()) { // Yup, this is a duplicate!
+ // Make all uses of the duplicate constant use the canonical version.
+ Replacements.push_back(std::make_pair(GV, Slot));
+ }
+ }
if (Replacements.empty())
return MadeChange;
// now. This avoid invalidating the pointers in CMap, which are unneeded
// now.
for (unsigned i = 0, e = Replacements.size(); i != e; ++i) {
- // Eliminate any uses of the dead global...
+ // Eliminate any uses of the dead global.
Replacements[i].first->replaceAllUsesWith(Replacements[i].second);
- // Delete the global value from the module...
- M.getGlobalList().erase(Replacements[i].first);
+ // Delete the global value from the module.
+ Replacements[i].first->eraseFromParent();
}
NumMerged += Replacements.size();