//===- DCE.cpp - Code to perform dead code elimination --------------------===//
+//
+// 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 implements dead inst elimination and dead code elimination.
//
#include "llvm/Instruction.h"
#include "llvm/Pass.h"
#include "llvm/Support/InstIterator.h"
+#include "Support/Statistic.h"
#include <set>
-//===----------------------------------------------------------------------===//
-// DeadInstElimination pass implementation
-//
-
namespace {
+ Statistic<> DIEEliminated("die", "Number of insts removed");
+ Statistic<> DCEEliminated("dce", "Number of insts removed");
+
+ //===--------------------------------------------------------------------===//
+ // DeadInstElimination pass implementation
+ //
+
struct DeadInstElimination : public BasicBlockPass {
- const char *getPassName() const { return "Dead Instruction Elimination"; }
-
- virtual bool runOnBasicBlock(BasicBlock *BB) {
- BasicBlock::InstListType &Vals = BB->getInstList();
+ virtual bool runOnBasicBlock(BasicBlock &BB) {
bool Changed = false;
- for (BasicBlock::iterator DI = Vals.begin(); DI != Vals.end(); )
- if (dceInstruction(Vals, DI))
+ for (BasicBlock::iterator DI = BB.begin(); DI != BB.end(); )
+ if (dceInstruction(DI)) {
Changed = true;
- else
+ ++DIEEliminated;
+ } else
++DI;
return Changed;
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.preservesCFG();
+ AU.setPreservesCFG();
}
};
+
+ RegisterOpt<DeadInstElimination> X("die", "Dead Instruction Elimination");
}
Pass *createDeadInstEliminationPass() {
namespace {
struct DCE : public FunctionPass {
- const char *getPassName() const { return "Dead Code Elimination"; }
-
- virtual bool runOnFunction(Function *F);
+ virtual bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.preservesCFG();
+ AU.setPreservesCFG();
}
};
+
+ RegisterOpt<DCE> Y("dce", "Dead Code Elimination");
}
-bool DCE::runOnFunction(Function *F) {
+bool DCE::runOnFunction(Function &F) {
// Start out with all of the instructions in the worklist...
std::vector<Instruction*> WorkList(inst_begin(F), inst_end(F));
std::set<Instruction*> DeadInsts;
if (DeadInsts.empty()) return false;
// Otherwise, loop over the program, removing and deleting the instructions...
- for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
- BasicBlock::InstListType &BBIL = (*I)->getInstList();
- for (BasicBlock::iterator BI = BBIL.begin(); BI != BBIL.end(); )
- if (DeadInsts.count(*BI)) { // Is this instruction dead?
- delete BBIL.remove(BI); // Yup, remove and delete inst
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+ for (BasicBlock::iterator BI = I->begin(); BI != I->end(); )
+ if (DeadInsts.count(BI)) { // Is this instruction dead?
+ BI = I->getInstList().erase(BI); // Yup, remove and delete inst
+ ++DCEEliminated;
} else { // This instruction is not dead
++BI; // Continue on to the next one...
}
- }
return true;
}