#define DEBUG_TYPE "globaldce"
#include "llvm/Transforms/IPO.h"
-#include "llvm/Constants.h"
-#include "llvm/Module.h"
-#include "llvm/Pass.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
-#include <set>
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
using namespace llvm;
STATISTIC(NumAliases , "Number of global aliases removed");
namespace {
struct GlobalDCE : public ModulePass {
static char ID; // Pass identification, replacement for typeid
- GlobalDCE() : ModulePass(&ID) {}
+ GlobalDCE() : ModulePass(ID) {
+ initializeGlobalDCEPass(*PassRegistry::getPassRegistry());
+ }
// run - Do the GlobalDCE pass on the specified module, optionally updating
// the specified callgraph to reflect the changes.
bool runOnModule(Module &M);
private:
- std::set<GlobalValue*> AliveGlobals;
+ SmallPtrSet<GlobalValue*, 32> AliveGlobals;
+ SmallPtrSet<Constant *, 8> SeenConstants;
/// GlobalIsNeeded - mark the specific global value as needed, and
/// recursively mark anything that it uses as also needed.
}
char GlobalDCE::ID = 0;
-static RegisterPass<GlobalDCE> X("globaldce", "Dead Global Elimination");
+INITIALIZE_PASS(GlobalDCE, "globaldce",
+ "Dead Global Elimination", false, false)
ModulePass *llvm::createGlobalDCEPass() { return new GlobalDCE(); }
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
Changed |= RemoveUnusedGlobalValue(*I);
// Functions with external linkage are needed if they have a body
- if (!I->hasLocalLinkage() && !I->hasLinkOnceLinkage() &&
+ if (!I->isDiscardableIfUnused() &&
!I->isDeclaration() && !I->hasAvailableExternallyLinkage())
GlobalIsNeeded(I);
}
Changed |= RemoveUnusedGlobalValue(*I);
// Externally visible & appending globals are needed, if they have an
// initializer.
- if (!I->hasLocalLinkage() && !I->hasLinkOnceLinkage() &&
+ if (!I->isDiscardableIfUnused() &&
!I->isDeclaration() && !I->hasAvailableExternallyLinkage())
GlobalIsNeeded(I);
}
I != E; ++I) {
Changed |= RemoveUnusedGlobalValue(*I);
// Externally visible aliases are needed.
- if (!I->hasLocalLinkage() && !I->hasLinkOnceLinkage())
+ if (!I->isDiscardableIfUnused())
GlobalIsNeeded(I);
}
// The first pass is to drop initializers of global variables which are dead.
std::vector<GlobalVariable*> DeadGlobalVars; // Keep track of dead globals
- for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I)
+ for (Module::global_iterator I = M.global_begin(), E = M.global_end();
+ I != E; ++I)
if (!AliveGlobals.count(I)) {
DeadGlobalVars.push_back(I); // Keep track of dead globals
I->setInitializer(0);
// Make sure that all memory is released
AliveGlobals.clear();
+ SeenConstants.clear();
return Changed;
}
/// GlobalIsNeeded - the specific global value as needed, and
/// recursively mark anything that it uses as also needed.
void GlobalDCE::GlobalIsNeeded(GlobalValue *G) {
- std::set<GlobalValue*>::iterator I = AliveGlobals.find(G);
-
// If the global is already in the set, no need to reprocess it.
- if (I != AliveGlobals.end()) return;
-
- // Otherwise insert it now, so we do not infinitely recurse
- AliveGlobals.insert(I, G);
-
+ if (!AliveGlobals.insert(G))
+ return;
+
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(G)) {
// If this is a global variable, we must make sure to add any global values
// referenced by the initializer to the alive set.
// operands. Any operands of these types must be processed to ensure that
// any globals used will be marked as needed.
Function *F = cast<Function>(G);
- // For all basic blocks...
+
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
- // For all instructions...
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
- // For all operands...
for (User::op_iterator U = I->op_begin(), E = I->op_end(); U != E; ++U)
if (GlobalValue *GV = dyn_cast<GlobalValue>(*U))
GlobalIsNeeded(GV);
void GlobalDCE::MarkUsedGlobalsAsNeeded(Constant *C) {
if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
return GlobalIsNeeded(GV);
-
+
// Loop over all of the operands of the constant, adding any globals they
// use to the list of needed globals.
- for (User::op_iterator I = C->op_begin(), E = C->op_end(); I != E; ++I)
- if (Constant *OpC = dyn_cast<Constant>(*I))
- MarkUsedGlobalsAsNeeded(OpC);
+ for (User::op_iterator I = C->op_begin(), E = C->op_end(); I != E; ++I) {
+ // If we've already processed this constant there's no need to do it again.
+ Constant *Op = dyn_cast<Constant>(*I);
+ if (Op && SeenConstants.insert(Op))
+ MarkUsedGlobalsAsNeeded(Op);
+ }
}
// RemoveUnusedGlobalValue - Loop over all of the uses of the specified