From 31d3137c01795c941ec9efd41994d28e068cf873 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sat, 10 Oct 2009 23:04:12 +0000
Subject: [PATCH] remove dead code

llvm-svn: 83742
---
 lib/Transforms/Scalar/GVN.cpp | 65 -----------------------------------
 1 file changed, 65 deletions(-)

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index bd5b02895ec..125793bab63 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -735,7 +735,6 @@ namespace {
     Value *CollapsePhi(PHINode* p);
     bool performPRE(Function& F);
     Value *lookupNumber(BasicBlock *BB, uint32_t num);
-    Value *AttemptRedundancyElimination(Instruction *orig, unsigned valno);
     void cleanupGlobalSets();
     void verifyRemoved(const Instruction *I) const;
   };
@@ -1729,59 +1728,6 @@ Value *GVN::lookupNumber(BasicBlock *BB, uint32_t num) {
   return 0;
 }
 
-/// AttemptRedundancyElimination - If the "fast path" of redundancy elimination
-/// by inheritance from the dominator fails, see if we can perform phi
-/// construction to eliminate the redundancy.
-Value *GVN::AttemptRedundancyElimination(Instruction *orig, unsigned valno) {
-  BasicBlock *BaseBlock = orig->getParent();
-
-  SmallPtrSet<BasicBlock*, 4> Visited;
-  SmallVector<BasicBlock*, 8> Stack;
-  Stack.push_back(BaseBlock);
-
-  DenseMap<BasicBlock*, Value*> Results;
-
-  // Walk backwards through our predecessors, looking for instances of the
-  // value number we're looking for.  Instances are recorded in the Results
-  // map, which is then used to perform phi construction.
-  while (!Stack.empty()) {
-    BasicBlock *Current = Stack.back();
-    Stack.pop_back();
-
-    // If we've walked all the way to a proper dominator, then give up. Cases
-    // where the instance is in the dominator will have been caught by the fast
-    // path, and any cases that require phi construction further than this are
-    // probably not worth it anyways.  Note that this is a SIGNIFICANT compile
-    // time improvement.
-    if (DT->properlyDominates(Current, orig->getParent())) return 0;
-
-    DenseMap<BasicBlock*, ValueNumberScope*>::iterator LA =
-                                                       localAvail.find(Current);
-    if (LA == localAvail.end()) return 0;
-    DenseMap<uint32_t, Value*>::iterator V = LA->second->table.find(valno);
-
-    if (V != LA->second->table.end()) {
-      // Found an instance, record it.
-      Results.insert(std::make_pair(Current, V->second));
-      continue;
-    }
-
-    // If we reach the beginning of the function, then give up.
-    if (pred_begin(Current) == pred_end(Current))
-      return 0;
-
-    for (pred_iterator PI = pred_begin(Current), PE = pred_end(Current);
-         PI != PE; ++PI)
-      if (Visited.insert(*PI))
-        Stack.push_back(*PI);
-  }
-
-  // If we didn't find instances, give up.  Otherwise, perform phi construction.
-  if (Results.size() == 0)
-    return 0;
-  
-  return GetValueForBlock(BaseBlock, orig, Results, true);
-}
 
 /// processInstruction - When calculating availability, handle an instruction
 /// by inserting it into the appropriate sets
@@ -1865,17 +1811,6 @@ bool GVN::processInstruction(Instruction *I,
     toErase.push_back(I);
     return true;
 
-#if 0
-  // Perform slow-pathvalue-number based elimination with phi construction.
-  } else if (Value *repl = AttemptRedundancyElimination(I, Num)) {
-    // Remove it!
-    VN.erase(I);
-    I->replaceAllUsesWith(repl);
-    if (isa<PointerType>(repl->getType()))
-      MD->invalidateCachedPointerInfo(repl);
-    toErase.push_back(I);
-    return true;
-#endif
   } else {
     localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
   }