X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FUnreachableBlockElim.cpp;h=52693f03e82822e6bb9e87b98ef324b3c717ed78;hb=23946fcaaefaf3c1a9d1ef86a3786f622c005f1a;hp=8286239096a072de4502752cb75451f5f125caf6;hpb=bd3ba461eb5578a81ba09ff7bd7eb271d1130196;p=oota-llvm.git

diff --git a/lib/CodeGen/UnreachableBlockElim.cpp b/lib/CodeGen/UnreachableBlockElim.cpp
index 8286239096a..52693f03e82 100644
--- a/lib/CodeGen/UnreachableBlockElim.cpp
+++ b/lib/CodeGen/UnreachableBlockElim.cpp
@@ -26,35 +26,48 @@
 #include "llvm/Function.h"
 #include "llvm/Pass.h"
 #include "llvm/Type.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/ProfileInfo.h"
+#include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineLoopInfo.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 {
-  class VISIBILITY_HIDDEN UnreachableBlockElim : public FunctionPass {
+  class UnreachableBlockElim : public FunctionPass {
     virtual bool runOnFunction(Function &F);
   public:
     static char ID; // Pass identification, replacement for typeid
-    UnreachableBlockElim() : FunctionPass((intptr_t)&ID) {}
+    UnreachableBlockElim() : FunctionPass(ID) {
+      initializeUnreachableBlockElimPass(*PassRegistry::getPassRegistry());
+    }
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.addPreserved<DominatorTree>();
+      AU.addPreserved<ProfileInfo>();
+    }
   };
 }
 char UnreachableBlockElim::ID = 0;
-static RegisterPass<UnreachableBlockElim>
-X("unreachableblockelim", "Remove unreachable blocks from the CFG");
+INITIALIZE_PASS(UnreachableBlockElim, "unreachableblockelim",
+                "Remove unreachable blocks from the CFG", false, false)
 
 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
@@ -74,92 +87,129 @@ bool UnreachableBlockElim::runOnFunction(Function &F) {
     }
 
   // Actually remove the blocks now.
-  for (unsigned i = 0, e = DeadBlocks.size(); i != e; ++i)
+  ProfileInfo *PI = getAnalysisIfAvailable<ProfileInfo>();
+  for (unsigned i = 0, e = DeadBlocks.size(); i != e; ++i) {
+    if (PI) PI->removeBlock(DeadBlocks[i]);
     DeadBlocks[i]->eraseFromParent();
+  }
 
   return DeadBlocks.size();
 }
 
 
 namespace {
-  class VISIBILITY_HIDDEN UnreachableMachineBlockElim : 
-        public MachineFunctionPass {
+  class UnreachableMachineBlockElim : public MachineFunctionPass {
     virtual bool runOnMachineFunction(MachineFunction &F);
-    bool iterateOnFunction(MachineFunction& F);
-    
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+    MachineModuleInfo *MMI;
   public:
     static char ID; // Pass identification, replacement for typeid
-    UnreachableMachineBlockElim() : MachineFunctionPass((intptr_t)&ID) {}
+    UnreachableMachineBlockElim() : MachineFunctionPass(ID) {}
   };
 }
 char UnreachableMachineBlockElim::ID = 0;
 
-static RegisterPass<UnreachableMachineBlockElim>
-Y("unreachable-mbb-elimination",
-  "Remove unreachable machine basic blocks");
+INITIALIZE_PASS(UnreachableMachineBlockElim, "unreachable-mbb-elimination",
+  "Remove unreachable machine basic blocks", false, false)
 
-const PassInfo *const llvm::UnreachableMachineBlockElimID = &Y;
+char &llvm::UnreachableMachineBlockElimID = UnreachableMachineBlockElim::ID;
 
-bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
-  bool changed = true;
-  bool result = false;
-  
-  while (changed) {
-    changed = iterateOnFunction(F);
-    result |= changed;
-  }
-  
-  if (result)
-    F.RenumberBlocks();
-  
-  return result;
+void UnreachableMachineBlockElim::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addPreserved<MachineLoopInfo>();
+  AU.addPreserved<MachineDominatorTree>();
+  MachineFunctionPass::getAnalysisUsage(AU);
 }
 
-bool UnreachableMachineBlockElim::iterateOnFunction(MachineFunction &F) {
-  std::set<MachineBasicBlock*> Reachable;
+bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
+  SmallPtrSet<MachineBasicBlock*, 8> Reachable;
+  bool ModifiedPHI = false;
+
+  MMI = getAnalysisIfAvailable<MachineModuleInfo>();
+  MachineDominatorTree *MDT = getAnalysisIfAvailable<MachineDominatorTree>();
+  MachineLoopInfo *MLI = getAnalysisIfAvailable<MachineLoopInfo>();
 
   // Mark all reachable blocks.
-  for (df_ext_iterator<MachineFunction*> I = df_ext_begin(&F, Reachable),
-         E = df_ext_end(&F, Reachable); I != E; ++I)
+  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)
-    if (!Reachable.count(I)) {
-      MachineBasicBlock *BB = I;
+  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);
-      
+
+      // Update dominator and loop info.
+      if (MLI) MLI->removeBlock(BB);
+      if (MDT && MDT->getNode(BB)) MDT->eraseNode(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) {
+        while (start != succ->end() && start->isPHI()) {
           for (unsigned i = start->getNumOperands() - 1; i >= 2; i-=2)
             if (start->getOperand(i).isMBB() &&
                 start->getOperand(i).getMBB() == BB) {
               start->RemoveOperand(i);
               start->RemoveOperand(i-1);
             }
-          
-          if (start->getNumOperands() == 1) {
-            MachineInstr* phi = start;
-            start++;
-            phi->eraseFromParent();
-          } else
-            start++;
+
+          start++;
         }
-        
+
         BB->removeSuccessor(BB->succ_begin());
       }
     }
+  }
 
   // Actually remove the blocks now.
   for (unsigned i = 0, e = DeadBlocks.size(); i != e; ++i)
     DeadBlocks[i]->eraseFromParent();
 
-  return DeadBlocks.size();
-}
+  // 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->isPHI()) {
+      for (unsigned i = phi->getNumOperands() - 1; i >= 2; i-=2)
+        if (!preds.count(phi->getOperand(i).getMBB())) {
+          phi->RemoveOperand(i);
+          phi->RemoveOperand(i-1);
+          ModifiedPHI = true;
+        }
+
+      if (phi->getNumOperands() == 3) {
+        unsigned Input = phi->getOperand(1).getReg();
+        unsigned Output = phi->getOperand(0).getReg();
+
+        MachineInstr* temp = phi;
+        ++phi;
+        temp->eraseFromParent();
+        ModifiedPHI = true;
+
+        if (Input != Output) {
+          MachineRegisterInfo &MRI = F.getRegInfo();
+          MRI.constrainRegClass(Input, MRI.getRegClass(Output));
+          MRI.replaceRegWith(Output, Input);
+        }
 
+        continue;
+      }
+
+      ++phi;
+    }
+  }
+
+  F.RenumberBlocks();
+
+  return (DeadBlocks.size() || ModifiedPHI);
+}