X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FScalar%2FDCE.cpp;h=e8a090af40c316f1d3d09b53d00b926f67b633aa;hb=d93e8a06b2ca09ab18f390cd514b7443e2e571f7;hp=ec9a387c18fa92ce05215025de9b3c4f1ba3f2f4;hpb=2ed01d8f0bdb8aa73d893a8beb23b1838422fa32;p=oota-llvm.git

diff --git a/lib/Transforms/Scalar/DCE.cpp b/lib/Transforms/Scalar/DCE.cpp
index ec9a387c18f..e8a090af40c 100644
--- a/lib/Transforms/Scalar/DCE.cpp
+++ b/lib/Transforms/Scalar/DCE.cpp
@@ -1,5 +1,12 @@
 //===- DCE.cpp - Code to perform dead code elimination --------------------===//
 //
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
 // This file implements dead inst elimination and dead code elimination.
 //
 // Dead Inst Elimination performs a single pass over the function removing
@@ -9,108 +16,119 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/Scalar/DCE.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Instruction.h"
+#define DEBUG_TYPE "dce"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/IR/Instruction.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/InstIterator.h"
-#include <set>
+#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/Transforms/Utils/Local.h"
+using namespace llvm;
 
-//===----------------------------------------------------------------------===//
-// DeadInstElimination pass implementation
-//
+STATISTIC(DIEEliminated, "Number of insts removed by DIE pass");
+STATISTIC(DCEEliminated, "Number of insts removed");
 
 namespace {
+  //===--------------------------------------------------------------------===//
+  // DeadInstElimination pass implementation
+  //
   struct DeadInstElimination : public BasicBlockPass {
-    const char *getPassName() const { return "Dead Instruction Elimination"; }
-    
-    virtual bool runOnBasicBlock(BasicBlock *BB) {
-      BasicBlock::InstListType &Vals = BB->getInstList();
+    static char ID; // Pass identification, replacement for typeid
+    DeadInstElimination() : BasicBlockPass(ID) {
+      initializeDeadInstEliminationPass(*PassRegistry::getPassRegistry());
+    }
+    virtual bool runOnBasicBlock(BasicBlock &BB) {
+      TargetLibraryInfo *TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
       bool Changed = false;
-      for (BasicBlock::iterator DI = Vals.begin(); DI != Vals.end(); )
-        if (dceInstruction(Vals, DI))
+      for (BasicBlock::iterator DI = BB.begin(); DI != BB.end(); ) {
+        Instruction *Inst = DI++;
+        if (isInstructionTriviallyDead(Inst, TLI)) {
+          Inst->eraseFromParent();
           Changed = true;
-        else
-          ++DI;
+          ++DIEEliminated;
+        }
+      }
       return Changed;
     }
 
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.preservesCFG();
+      AU.setPreservesCFG();
     }
   };
 }
 
-Pass *createDeadInstEliminationPass() {
+char DeadInstElimination::ID = 0;
+INITIALIZE_PASS(DeadInstElimination, "die",
+                "Dead Instruction Elimination", false, false)
+
+Pass *llvm::createDeadInstEliminationPass() {
   return new DeadInstElimination();
 }
 
 
-
-//===----------------------------------------------------------------------===//
-// DeadCodeElimination pass implementation
-//
-
 namespace {
+  //===--------------------------------------------------------------------===//
+  // DeadCodeElimination pass implementation
+  //
   struct DCE : public FunctionPass {
-    const char *getPassName() const { return "Dead Code Elimination"; }
+    static char ID; // Pass identification, replacement for typeid
+    DCE() : FunctionPass(ID) {
+      initializeDCEPass(*PassRegistry::getPassRegistry());
+    }
 
-    virtual bool runOnFunction(Function *F);
+    virtual bool runOnFunction(Function &F);
 
      virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.preservesCFG();
+      AU.setPreservesCFG();
     }
  };
 }
 
-bool DCE::runOnFunction(Function *F) {
+char DCE::ID = 0;
+INITIALIZE_PASS(DCE, "dce", "Dead Code Elimination", false, false)
+
+bool DCE::runOnFunction(Function &F) {
+  TargetLibraryInfo *TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
+
   // Start out with all of the instructions in the worklist...
-  std::vector<Instruction*> WorkList(inst_begin(F), inst_end(F));
-  std::set<Instruction*> DeadInsts;
-  
+  std::vector<Instruction*> WorkList;
+  for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
+    WorkList.push_back(&*i);
+
   // Loop over the worklist finding instructions that are dead.  If they are
   // dead make them drop all of their uses, making other instructions
   // potentially dead, and work until the worklist is empty.
   //
+  bool MadeChange = false;
   while (!WorkList.empty()) {
     Instruction *I = WorkList.back();
     WorkList.pop_back();
-    
-    if (isInstructionTriviallyDead(I)) {       // If the instruction is dead...
+
+    if (isInstructionTriviallyDead(I, TLI)) { // If the instruction is dead.
       // Loop over all of the values that the instruction uses, if there are
       // instructions being used, add them to the worklist, because they might
       // go dead after this one is removed.
       //
-      for (User::use_iterator UI = I->use_begin(), UE = I->use_end();
-           UI != UE; ++UI)
-        if (Instruction *Used = dyn_cast<Instruction>(*UI))
+      for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI)
+        if (Instruction *Used = dyn_cast<Instruction>(*OI))
           WorkList.push_back(Used);
 
-      // Tell the instruction to let go of all of the values it uses...
-      I->dropAllReferences();
+      // Remove the instruction.
+      I->eraseFromParent();
 
-      // Keep track of this instruction, because we are going to delete it later
-      DeadInsts.insert(I);
-    }
-  }
+      // Remove the instruction from the worklist if it still exists in it.
+      WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
+                     WorkList.end());
 
-  // If we found no dead instructions, we haven't changed the function...
-  if (DeadInsts.empty()) return false;
-
-  // Otherwise, loop over the program, removing and deleting the instructions...
-  for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
-    BasicBlock::InstListType &BBIL = (*I)->getInstList();
-    for (BasicBlock::iterator BI = BBIL.begin(); BI != BBIL.end(); )
-      if (DeadInsts.count(*BI)) {            // Is this instruction dead?
-        delete BBIL.remove(BI);              // Yup, remove and delete inst
-      } else {                               // This instruction is not dead
-        ++BI;                                // Continue on to the next one...
-      }
+      MadeChange = true;
+      ++DCEEliminated;
+    }
   }
-
-  return true;
+  return MadeChange;
 }
 
-Pass *createDeadCodeEliminationPass() {
+FunctionPass *llvm::createDeadCodeEliminationPass() {
   return new DCE();
 }
+