Author: resistor
Date: Mon Jul 23 19:08:38 2007
New Revision: 40456
URL: http://llvm.org/viewvc/llvm-project?rev=40456&view=rev
Log:
Rename FastDLE as RedundantLoadElimination.
Added:
llvm/trunk/lib/Transforms/Scalar/RedundantLoadElimination.cpp
- copied unchanged from r40448,
llvm/trunk/lib/Transforms/Scalar/FastDLE.cpp
Removed:
llvm/trunk/lib/Transforms/Scalar/FastDLE.cpp
Removed: llvm/trunk/lib/Transforms/Scalar/FastDLE.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/FastDLE.cpp?rev=40455&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/FastDLE.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/FastDLE.cpp (removed)
@@ -1,134 +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 "fdle"
-#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 FDLE : public FunctionPass {
- static char ID; // Pass identification, replacement for typeid
- FDLE() : 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 FDLE::ID = 0;
- RegisterPass<FDLE> X("fdle", "Fast Dead Load Elimination");
-}
-
-FunctionPass *llvm::createFastDeadLoadEliminationPass() { return new FDLE(); }
-
-bool FDLE::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;
-}
-
-
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