Fix PR3667

[oota-llvm.git] / lib / CodeGen / UnreachableBlockElim.cpp

diff --git a/lib/CodeGen/UnreachableBlockElim.cpp b/lib/CodeGen/UnreachableBlockElim.cpp
index ca682fd65a0a7d53c66e87512d3d199cad55ce4b..c3b213cebe9543a95020d13b26a95c215e91661d 100644 (file)
--- a/lib/CodeGen/UnreachableBlockElim.cpp
+++ b/lib/CodeGen/UnreachableBlockElim.cpp
@@ -27,11 +27,13 @@
 #include "llvm/Pass.h"
 #include "llvm/Type.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineModuleInfo.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 {
@@ -39,7 +41,7 @@ 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;
@@ -51,11 +53,11 @@ FunctionPass *llvm::createUnreachableBlockEliminationPass() {
 }
 
 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
@@ -83,13 +85,13 @@ bool UnreachableBlockElim::runOnFunction(Function &F) {
 
 
 namespace {
-  class VISIBILITY_HIDDEN UnreachableMachineBlockElim : 
+  class VISIBILITY_HIDDEN UnreachableMachineBlockElim :
         public MachineFunctionPass {
     virtual bool runOnMachineFunction(MachineFunction &F);
-    
+    MachineModuleInfo *MMI;
   public:
     static char ID; // Pass identification, replacement for typeid
-    UnreachableMachineBlockElim() : MachineFunctionPass((intptr_t)&ID) {}
+    UnreachableMachineBlockElim() : MachineFunctionPass(&ID) {}
   };
 }
 char UnreachableMachineBlockElim::ID = 0;
@@ -101,24 +103,29 @@ Y("unreachable-mbb-elimination",
 const PassInfo *const llvm::UnreachableMachineBlockElimID = &Y;
 
 bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
-  std::set<MachineBasicBlock*> Reachable;
+  SmallPtrSet<MachineBasicBlock*, 8> Reachable;
+
+  MMI = getAnalysisIfAvailable<MachineModuleInfo>();
 
   // 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);
-      
+
       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) {
@@ -128,30 +135,65 @@ bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
               start->RemoveOperand(i);
               start->RemoveOperand(i-1);
             }
-          
-          if (start->getNumOperands() == 3) {
-            MachineInstr* phi = start;
-            unsigned Input = phi->getOperand(1).getReg();
-            unsigned Output = phi->getOperand(0).getReg();
-            
-            start++;
-            phi->eraseFromParent();
-            
-            F.getRegInfo().replaceRegWith(Output, Input);
-          } 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();
+  for (unsigned i = 0, e = DeadBlocks.size(); i != e; ++i) {
+    MachineBasicBlock *MBB = DeadBlocks[i];
+    // If there are any labels in the basic block, unregister them from
+    // MachineModuleInfo.
+    if (MMI && !MBB->empty()) {
+      for (MachineBasicBlock::iterator I = MBB->begin(),
+             E = MBB->end(); I != E; ++I) {
+        if (I->isLabel())
+          // The label ID # is always operand #0, an immediate.
+          MMI->InvalidateLabel(I->getOperand(0).getImm());
+      }
+    }
+    MBB->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();
+
+        MachineInstr* temp = phi;
+        ++phi;
+        temp->eraseFromParent();
+
+        if (Input != Output)
+          F.getRegInfo().replaceRegWith(Output, Input);
+
+        continue;
+      }
+
+      ++phi;
+    }
+  }
 
   F.RenumberBlocks();
 
   return DeadBlocks.size();
 }
-