move some functions, add a comment.

[oota-llvm.git] / lib / Transforms / Scalar / DCE.cpp

diff --git a/lib/Transforms/Scalar/DCE.cpp b/lib/Transforms/Scalar/DCE.cpp
index 998d87cf1b67a0640a7ce0eff3ac2c295387e115..39940c35da5d5f076857ec31822b62b2dcaf292b 100644 (file)
--- a/lib/Transforms/Scalar/DCE.cpp
+++ b/lib/Transforms/Scalar/DCE.cpp
@@ -2,8 +2,8 @@
 //
 //                     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.
 //
 //===----------------------------------------------------------------------===//
 //
@@ -21,7 +21,6 @@
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Instruction.h"
 #include "llvm/Pass.h"
-#include "llvm/Support/Compiler.h"
 #include "llvm/Support/InstIterator.h"
 #include "llvm/ADT/Statistic.h"
 #include <set>
@@ -34,15 +33,19 @@ namespace {
   //===--------------------------------------------------------------------===//
   // DeadInstElimination pass implementation
   //
-  struct VISIBILITY_HIDDEN DeadInstElimination : public BasicBlockPass {
+  struct DeadInstElimination : public BasicBlockPass {
+    static char ID; // Pass identification, replacement for typeid
+    DeadInstElimination() : BasicBlockPass(&ID) {}
     virtual bool runOnBasicBlock(BasicBlock &BB) {
       bool Changed = false;
-      for (BasicBlock::iterator DI = BB.begin(); DI != BB.end(); )
-        if (dceInstruction(DI)) {
+      for (BasicBlock::iterator DI = BB.begin(); DI != BB.end(); ) {
+        Instruction *Inst = DI++;
+        if (isInstructionTriviallyDead(Inst)) {
+          Inst->eraseFromParent();
           Changed = true;
           ++DIEEliminated;
-        } else
-          ++DI;
+        }
+      }
       return Changed;
     }
 
@@ -50,10 +53,12 @@ namespace {
       AU.setPreservesCFG();
     }
   };
-
-  RegisterPass<DeadInstElimination> X("die", "Dead Instruction Elimination");
 }
 
+char DeadInstElimination::ID = 0;
+static RegisterPass<DeadInstElimination>
+X("die", "Dead Instruction Elimination");
+
 Pass *llvm::createDeadInstEliminationPass() {
   return new DeadInstElimination();
 }
@@ -64,16 +69,20 @@ namespace {
   // DeadCodeElimination pass implementation
   //
   struct DCE : public FunctionPass {
+    static char ID; // Pass identification, replacement for typeid
+    DCE() : FunctionPass(&ID) {}
+
     virtual bool runOnFunction(Function &F);
 
      virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.setPreservesCFG();
     }
  };
-
-  RegisterPass<DCE> Y("dce", "Dead Code Elimination");
 }
 
+char DCE::ID = 0;
+static RegisterPass<DCE> Y("dce", "Dead Code Elimination");
+
 bool DCE::runOnFunction(Function &F) {
   // Start out with all of the instructions in the worklist...
   std::vector<Instruction*> WorkList;
@@ -102,13 +111,13 @@ bool DCE::runOnFunction(Function &F) {
       I->eraseFromParent();
 
       // Remove the instruction from the worklist if it still exists in it.
-      for (std::vector<Instruction*>::iterator WI = WorkList.begin(),
-             E = WorkList.end(); WI != E; ++WI)
-        if (*WI == I) {
-          WorkList.erase(WI);
-          --E;
-          --WI;
-        }
+      for (std::vector<Instruction*>::iterator WI = WorkList.begin();
+           WI != WorkList.end(); ) {
+        if (*WI == I)
+          WI = WorkList.erase(WI);
+        else
+          ++WI;
+      }
 
       MadeChange = true;
       ++DCEEliminated;