STATISTIC(NumRemoved, "Number of instructions removed");
namespace {
- struct ADCE : public FunctionPass {
- static char ID; // Pass identification, replacement for typeid
- ADCE() : FunctionPass(ID) {
- initializeADCEPass(*PassRegistry::getPassRegistry());
- }
-
- bool runOnFunction(Function& F) override;
+struct ADCE : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ ADCE() : FunctionPass(ID) {
+ initializeADCEPass(*PassRegistry::getPassRegistry());
+ }
- void getAnalysisUsage(AnalysisUsage& AU) const override {
- AU.setPreservesCFG();
- }
+ bool runOnFunction(Function& F) override;
- };
+ void getAnalysisUsage(AnalysisUsage& AU) const override {
+ AU.setPreservesCFG();
+ }
+};
}
char ADCE::ID = 0;
SmallVector<Instruction*, 128> Worklist;
// Collect the set of "root" instructions that are known live.
- for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
- if (isa<TerminatorInst>(I.getInstructionIterator()) ||
- isa<DbgInfoIntrinsic>(I.getInstructionIterator()) ||
- isa<LandingPadInst>(I.getInstructionIterator()) ||
- I->mayHaveSideEffects()) {
- Alive.insert(I.getInstructionIterator());
- Worklist.push_back(I.getInstructionIterator());
+ for (Instruction &I : inst_range(F)) {
+ if (isa<TerminatorInst>(I) || isa<DbgInfoIntrinsic>(I) ||
+ isa<LandingPadInst>(I) || I.mayHaveSideEffects()) {
+ Alive.insert(&I);
+ Worklist.push_back(&I);
}
+ }
// Propagate liveness backwards to operands.
while (!Worklist.empty()) {
- Instruction* Curr = Worklist.pop_back_val();
- for (Instruction::op_iterator OI = Curr->op_begin(), OE = Curr->op_end();
- OI != OE; ++OI)
- if (Instruction* Inst = dyn_cast<Instruction>(OI))
+ Instruction *Curr = Worklist.pop_back_val();
+ for (Use &OI : Curr->operands()) {
+ if (Instruction *Inst = dyn_cast<Instruction>(OI))
if (Alive.insert(Inst).second)
Worklist.push_back(Inst);
+ }
}
// The inverse of the live set is the dead set. These are those instructions
// which have no side effects and do not influence the control flow or return
// value of the function, and may therefore be deleted safely.
// NOTE: We reuse the Worklist vector here for memory efficiency.
- for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
- if (!Alive.count(I.getInstructionIterator())) {
- Worklist.push_back(I.getInstructionIterator());
- I->dropAllReferences();
+ for (Instruction &I : inst_range(F)) {
+ if (!Alive.count(&I)) {
+ Worklist.push_back(&I);
+ I.dropAllReferences();
}
+ }
- for (SmallVectorImpl<Instruction *>::iterator I = Worklist.begin(),
- E = Worklist.end(); I != E; ++I) {
+ for (Instruction *&I : Worklist) {
++NumRemoved;
- (*I)->eraseFromParent();
+ I->eraseFromParent();
}
return !Worklist.empty();