#include "llvm/Transforms/Scalar.h"
#include "llvm/BasicBlock.h"
#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Pass.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/InstIterator.h"
-#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
using namespace llvm;
namespace {
struct VISIBILITY_HIDDEN ADCE : public FunctionPass {
static char ID; // Pass identification, replacement for typeid
- ADCE() : FunctionPass((intptr_t)&ID) {}
-
- DenseSet<Instruction*> alive;
- SmallVector<Instruction*, 1024> worklist;
-
- DenseSet<BasicBlock*> reachable;
- SmallVector<BasicBlock*, 1024> unreachable;
+ ADCE() : FunctionPass(&ID) {}
virtual bool runOnFunction(Function& F);
static RegisterPass<ADCE> X("adce", "Aggressive Dead Code Elimination");
bool ADCE::runOnFunction(Function& F) {
- alive.clear();
- worklist.clear();
- reachable.clear();
- unreachable.clear();
-
- // First, collect the set of reachable blocks ...
- for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
- DE = df_end(&F.getEntryBlock()); DI != DE; ++DI)
- reachable.insert(*DI);
-
- // ... and then invert it into the list of unreachable ones. These
- // blocks will be removed from the function.
- for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
- if (!reachable.count(FI))
- unreachable.push_back(FI);
-
- // Prepare to remove blocks by removing the PHI node entries for those blocks
- // in their successors, and remove them from reference counting.
- for (SmallVector<BasicBlock*, 1024>::iterator UI = unreachable.begin(),
- UE = unreachable.end(); UI != UE; ++UI) {
- BasicBlock* BB = *UI;
- for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
- SI != SE; ++SI) {
- BasicBlock* succ = *SI;
- BasicBlock::iterator succ_inst = succ->begin();
- while (PHINode* P = dyn_cast<PHINode>(succ_inst)) {
- P->removeIncomingValue(BB);
- ++succ_inst;
- }
- }
-
- BB->dropAllReferences();
- }
-
- // Finally, erase the unreachable blocks.
- for (SmallVector<BasicBlock*, 1024>::iterator UI = unreachable.begin(),
- UE = unreachable.end(); UI != UE; ++UI)
- (*UI)->eraseFromParent();
+ SmallPtrSet<Instruction*, 128> alive;
+ 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()) ||
- I->mayWriteToMemory()) {
+ isa<DbgInfoIntrinsic>(I.getInstructionIterator()) ||
+ I->mayHaveSideEffects()) {
alive.insert(I.getInstructionIterator());
worklist.push_back(I.getInstructionIterator());
}
NumRemoved++;
(*I)->eraseFromParent();
}
-
+
return !worklist.empty();
}