//
// 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 is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#include "llvm/Function.h"
#include "llvm/Pass.h"
#include "llvm/Type.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
using namespace llvm;
namespace {
virtual bool runOnFunction(Function &F);
public:
static char ID; // Pass identification, replacement for typeid
- UnreachableBlockElim() : FunctionPass((intptr_t)&ID) {}
+ UnreachableBlockElim() : FunctionPass(&ID) {}
};
- char UnreachableBlockElim::ID = 0;
- RegisterPass<UnreachableBlockElim>
- X("unreachableblockelim", "Remove unreachable blocks from the CFG");
}
+char UnreachableBlockElim::ID = 0;
+static RegisterPass<UnreachableBlockElim>
+X("unreachableblockelim", "Remove unreachable blocks from the CFG");
FunctionPass *llvm::createUnreachableBlockEliminationPass() {
return new UnreachableBlockElim();
}
bool UnreachableBlockElim::runOnFunction(Function &F) {
- std::set<BasicBlock*> Reachable;
+ SmallPtrSet<BasicBlock*, 8> Reachable;
// Mark all reachable blocks.
- for (df_ext_iterator<Function*> I = df_ext_begin(&F, Reachable),
- E = df_ext_end(&F, Reachable); I != E; ++I)
+ for (df_ext_iterator<Function*, SmallPtrSet<BasicBlock*, 8> > I =
+ df_ext_begin(&F, Reachable), E = df_ext_end(&F, Reachable); I != E; ++I)
/* Mark all reachable blocks */;
// Loop over all dead blocks, remembering them and deleting all instructions
BB->dropAllReferences();
}
- if (DeadBlocks.empty()) return false;
+ // Actually remove the blocks now.
+ for (unsigned i = 0, e = DeadBlocks.size(); i != e; ++i)
+ DeadBlocks[i]->eraseFromParent();
+
+ return DeadBlocks.size();
+}
+
+
+namespace {
+ class VISIBILITY_HIDDEN UnreachableMachineBlockElim :
+ public MachineFunctionPass {
+ virtual bool runOnMachineFunction(MachineFunction &F);
+
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ UnreachableMachineBlockElim() : MachineFunctionPass(&ID) {}
+ };
+}
+char UnreachableMachineBlockElim::ID = 0;
+
+static RegisterPass<UnreachableMachineBlockElim>
+Y("unreachable-mbb-elimination",
+ "Remove unreachable machine basic blocks");
+
+const PassInfo *const llvm::UnreachableMachineBlockElimID = &Y;
+
+bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
+ SmallPtrSet<MachineBasicBlock*, 8> Reachable;
+
+ // Mark all reachable blocks.
+ for (df_ext_iterator<MachineFunction*, SmallPtrSet<MachineBasicBlock*, 8> >
+ I = df_ext_begin(&F, Reachable), E = df_ext_end(&F, Reachable);
+ I != E; ++I)
+ /* Mark all reachable blocks */;
+
+ // Loop over all dead blocks, remembering them and deleting all instructions
+ // in them.
+ std::vector<MachineBasicBlock*> DeadBlocks;
+ for (MachineFunction::iterator I = F.begin(), E = F.end(); I != E; ++I) {
+ MachineBasicBlock *BB = I;
+
+ // Test for deadness.
+ if (!Reachable.count(BB)) {
+ DeadBlocks.push_back(BB);
+
+ while (BB->succ_begin() != BB->succ_end()) {
+ MachineBasicBlock* succ = *BB->succ_begin();
+
+ MachineBasicBlock::iterator start = succ->begin();
+ while (start != succ->end() &&
+ start->getOpcode() == TargetInstrInfo::PHI) {
+ for (unsigned i = start->getNumOperands() - 1; i >= 2; i-=2)
+ if (start->getOperand(i).isMachineBasicBlock() &&
+ start->getOperand(i).getMBB() == BB) {
+ start->RemoveOperand(i);
+ start->RemoveOperand(i-1);
+ }
+
+ start++;
+ }
+
+ BB->removeSuccessor(BB->succ_begin());
+ }
+ }
+ }
// Actually remove the blocks now.
for (unsigned i = 0, e = DeadBlocks.size(); i != e; ++i)
- F.getBasicBlockList().erase(DeadBlocks[i]);
+ DeadBlocks[i]->eraseFromParent();
+
+ // Cleanup PHI nodes.
+ for (MachineFunction::iterator I = F.begin(), E = F.end(); I != E; ++I) {
+ MachineBasicBlock *BB = I;
+ // Prune unneeded PHI entries.
+ SmallPtrSet<MachineBasicBlock*, 8> preds(BB->pred_begin(),
+ BB->pred_end());
+ MachineBasicBlock::iterator phi = BB->begin();
+ while (phi != BB->end() &&
+ phi->getOpcode() == TargetInstrInfo::PHI) {
+ for (unsigned i = phi->getNumOperands() - 1; i >= 2; i-=2)
+ if (!preds.count(phi->getOperand(i).getMBB())) {
+ phi->RemoveOperand(i);
+ phi->RemoveOperand(i-1);
+ }
+
+ if (phi->getNumOperands() == 3) {
+ unsigned Input = phi->getOperand(1).getReg();
+ unsigned Output = phi->getOperand(0).getReg();
- return true;
+ MachineInstr* temp = phi;
+ ++phi;
+ temp->eraseFromParent();
+
+ if (Input != Output)
+ F.getRegInfo().replaceRegWith(Output, Input);
+
+ continue;
+ }
+
+ ++phi;
+ }
+ }
+
+ F.RenumberBlocks();
+
+ return DeadBlocks.size();
}
+