//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar/DCE.h"
-#include "llvm/Instruction.h"
#include "llvm/Type.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/Writer.h"
#define DEBUG_ADCE 1
+namespace {
+
//===----------------------------------------------------------------------===//
// ADCE Class
//
// This class does all of the work of Agressive Dead Code Elimination.
// It's public interface consists of a constructor and a doADCE() method.
//
-class ADCE {
- Function *M; // The function that we are working on
+class ADCE : public FunctionPass {
+ Function *Func; // The function that we are working on
std::vector<Instruction*> WorkList; // Instructions that just became live
std::set<Instruction*> LiveSet; // The set of live instructions
bool MadeChanges;
// The public interface for this class
//
public:
- // ADCE Ctor - Save the function to operate on...
- inline ADCE(Function *f) : M(f), MadeChanges(false) {}
+ const char *getPassName() const { return "Aggressive Dead Code Elimination"; }
+
+ // doADCE - Execute the Agressive Dead Code Elimination Algorithm
+ //
+ virtual bool runOnFunction(Function *F) {
+ Func = F; MadeChanges = false;
+ doADCE(getAnalysis<DominanceFrontier>(DominanceFrontier::PostDomID));
+ assert(WorkList.empty());
+ LiveSet.clear();
+ return MadeChanges;
+ }
+ // getAnalysisUsage - We require post dominance frontiers (aka Control
+ // Dependence Graph)
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired(DominanceFrontier::PostDomID);
+ }
- // doADCE() - Run the Agressive Dead Code Elimination algorithm, returning
- // true if the function was modified.
- bool doADCE(DominanceFrontier &CDG);
//===--------------------------------------------------------------------===//
// The implementation of this class
//
private:
+ // doADCE() - Run the Agressive Dead Code Elimination algorithm, returning
+ // true if the function was modified.
+ //
+ void doADCE(DominanceFrontier &CDG);
+
inline void markInstructionLive(Instruction *I) {
if (LiveSet.count(I)) return;
#ifdef DEBUG_ADCE
const std::set<BasicBlock*> &AliveBlocks);
};
+} // End of anonymous namespace
+
+Pass *createAgressiveDCEPass() {
+ return new ADCE();
+}
// doADCE() - Run the Agressive Dead Code Elimination algorithm, returning
// true if the function was modified.
//
-bool ADCE::doADCE(DominanceFrontier &CDG) {
+void ADCE::doADCE(DominanceFrontier &CDG) {
#ifdef DEBUG_ADCE
- cerr << "Function: " << M;
+ cerr << "Function: " << Func;
#endif
// Iterate over all of the instructions in the function, eliminating trivially
// instructions live in basic blocks that are unreachable. These blocks will
// be eliminated later, along with the instructions inside.
//
- for (df_iterator<Function*> BBI = df_begin(M),
- BBE = df_end(M);
+ for (df_iterator<Function*> BBI = df_begin(Func), BBE = df_end(Func);
BBI != BBE; ++BBI) {
BasicBlock *BB = *BBI;
for (BasicBlock::iterator II = BB->begin(), EI = BB->end(); II != EI; ) {
#ifdef DEBUG_ADCE
cerr << "Current Function: X = Live\n";
- for (Function::iterator I = M->begin(), E = M->end(); I != E; ++I)
+ for (Function::iterator I = Func->begin(), E = Func->end(); I != E; ++I)
for (BasicBlock::iterator BI = (*I)->begin(), BE = (*I)->end();
BI != BE; ++BI) {
if (LiveSet.count(*BI)) cerr << "X ";
// order, patching up references to dead blocks...
//
std::set<BasicBlock*> VisitedBlocks;
- BasicBlock *EntryBlock = fixupCFG(M->front(), VisitedBlocks, AliveBlocks);
- if (EntryBlock && EntryBlock != M->front()) {
+ BasicBlock *EntryBlock = fixupCFG(Func->front(), VisitedBlocks, AliveBlocks);
+ if (EntryBlock && EntryBlock != Func->front()) {
if (isa<PHINode>(EntryBlock->front())) {
// Cannot make the first block be a block with a PHI node in it! Instead,
// strip the first basic block of the function to contain no instructions,
// then add a simple branch to the "real" entry node...
//
- BasicBlock *E = M->front();
+ BasicBlock *E = Func->front();
if (!isa<TerminatorInst>(E->front()) || // Check for an actual change...
cast<TerminatorInst>(E->front())->getNumSuccessors() != 1 ||
cast<TerminatorInst>(E->front())->getSuccessor(0) != EntryBlock) {
} else {
// We need to move the new entry block to be the first bb of the function
- Function::iterator EBI = find(M->begin(), M->end(), EntryBlock);
- std::swap(*EBI, *M->begin()); // Exchange old location with start of fn
+ Function::iterator EBI = find(Func->begin(), Func->end(), EntryBlock);
+ std::swap(*EBI, *Func->begin()); // Exchange old location with start of fn
MadeChanges = true;
}
}
// Now go through and tell dead blocks to drop all of their references so they
// can be safely deleted.
//
- for (Function::iterator BI = M->begin(), BE = M->end(); BI != BE; ++BI) {
+ for (Function::iterator BI = Func->begin(), BE = Func->end(); BI != BE; ++BI){
BasicBlock *BB = *BI;
if (!AliveBlocks.count(BB)) {
BB->dropAllReferences();
// now because we know that there are no references to dead blocks (because
// they have dropped all of their references...
//
- for (Function::iterator BI = M->begin(); BI != M->end();) {
+ for (Function::iterator BI = Func->begin(); BI != Func->end();) {
if (!AliveBlocks.count(*BI)) {
- delete M->getBasicBlocks().remove(BI);
+ delete Func->getBasicBlocks().remove(BI);
MadeChanges = true;
continue; // Don't increment iterator
}
++BI; // Increment iterator...
}
-
- return MadeChanges;
}
}
}
-namespace {
- struct AgressiveDCE : public FunctionPass {
- const char *getPassName() const {return "Aggressive Dead Code Elimination";}
-
- // doADCE - Execute the Agressive Dead Code Elimination Algorithm
- //
- virtual bool runOnFunction(Function *F) {
- return ADCE(F).doADCE(
- getAnalysis<DominanceFrontier>(DominanceFrontier::PostDomID));
- }
- // getAnalysisUsage - We require post dominance frontiers (aka Control
- // Dependence Graph)
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired(DominanceFrontier::PostDomID);
- }
- };
-}
-
-Pass *createAgressiveDCEPass() {
- return new AgressiveDCE();
-}
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