From 86f91e17576ff56d7e377b014386e77162354dd6 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Fri, 14 Sep 2007 22:33:52 +0000
Subject: [PATCH] Remove RLE.  It is subsumed by GVN.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41968 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../Scalar/RedundantLoadElimination.cpp       | 135 ------------------
 1 file changed, 135 deletions(-)
 delete mode 100644 lib/Transforms/Scalar/RedundantLoadElimination.cpp

diff --git a/lib/Transforms/Scalar/RedundantLoadElimination.cpp b/lib/Transforms/Scalar/RedundantLoadElimination.cpp
deleted file mode 100644
index 3b719df4f6e..00000000000
--- a/lib/Transforms/Scalar/RedundantLoadElimination.cpp
+++ /dev/null
@@ -1,135 +0,0 @@
-//===- FastDLE.cpp - Fast Dead Load Elimination ---------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file was developed by Owen Anderson and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements a trivial dead load elimination that only considers
-// basic-block local redundant load.
-//
-// FIXME: This should eventually be extended to be a post-dominator tree
-// traversal.  Doing so would be pretty trivial.
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "rle"
-#include "llvm/Transforms/Scalar.h"
-#include "llvm/Function.h"
-#include "llvm/Instructions.h"
-#include "llvm/Pass.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/MemoryDependenceAnalysis.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Support/Compiler.h"
-using namespace llvm;
-
-STATISTIC(NumFastLoads, "Number of loads deleted");
-
-namespace {
-  struct VISIBILITY_HIDDEN RLE : public FunctionPass {
-    static char ID; // Pass identification, replacement for typeid
-    RLE() : FunctionPass((intptr_t)&ID) {}
-
-    virtual bool runOnFunction(Function &F) {
-      bool Changed = false;
-      for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
-        Changed |= runOnBasicBlock(*I);
-      return Changed;
-    }
-
-    bool runOnBasicBlock(BasicBlock &BB);
-
-    // getAnalysisUsage - We require post dominance frontiers (aka Control
-    // Dependence Graph)
-    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.setPreservesCFG();
-      AU.addRequired<MemoryDependenceAnalysis>();
-      AU.addPreserved<MemoryDependenceAnalysis>();
-    }
-  };
-  char RLE::ID = 0;
-  RegisterPass<RLE> X("rle", "Redundant Load Elimination");
-}
-
-FunctionPass *llvm::createRedundantLoadEliminationPass() { return new RLE(); }
-
-bool RLE::runOnBasicBlock(BasicBlock &BB) {
-  MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
-  
-  // Record the last-seen load from this pointer
-  DenseMap<Value*, LoadInst*> lastLoad;
-  
-  bool MadeChange = false;
-  
-  // Do a top-down walk on the BB
-  for (BasicBlock::iterator BBI = BB.begin(), BBE = BB.end(); 
-       BBI != BBE; ++BBI) {
-    // If we find a store or a free...
-    if (LoadInst* L = dyn_cast<LoadInst>(BBI)) {
-      // We can't delete volatile loads
-      if (L->isVolatile()) {
-        lastLoad[L->getPointerOperand()] = L;
-        continue;
-      }
-      
-      Value* pointer = L->getPointerOperand();
-      LoadInst*& last = lastLoad[pointer];
-      
-      // ... to a pointer that has been loaded from before...
-      Instruction* dep = MD.getDependency(BBI);
-      bool deletedLoad = false;
-      
-      while (dep != MemoryDependenceAnalysis::None &&
-             dep != MemoryDependenceAnalysis::NonLocal &&
-             (isa<LoadInst>(dep) || isa<StoreInst>(dep))) {
-        // ... that depends on a store ...
-        if (StoreInst* S = dyn_cast<StoreInst>(dep)) {
-          if (S->getPointerOperand() == pointer) {
-            // Remove it!
-            MD.removeInstruction(BBI);
-            
-            BBI--;
-            L->replaceAllUsesWith(S->getOperand(0));
-            L->eraseFromParent();
-            NumFastLoads++;
-            deletedLoad = true;
-            MadeChange = true;
-          }
-          
-          // Whether we removed it or not, we can't
-          // go any further
-          break;
-        } else if (!last) {
-          // If we don't depend on a store, and we haven't
-          // been loaded before, bail.
-          break;
-        } else if (dep == last) {
-          // Remove it!
-          MD.removeInstruction(BBI);
-          
-          BBI--;
-          L->replaceAllUsesWith(last);
-          L->eraseFromParent();
-          deletedLoad = true;
-          NumFastLoads++;
-          MadeChange = true;
-            
-          break;
-        } else {
-          dep = MD.getDependency(BBI, dep);
-        }
-      }
-      
-      if (!deletedLoad)
-        last = L;
-    }
-  }
-  
-  return MadeChange;
-}
-
-