Prep for merging 3.4: Undo changes from 3.3 branch

lib/Transforms/Scalar/CodeGenPrepare.cpp

Index: lib/Transforms/Scalar/CodeGenPrepare.cpp
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index f0d29c88a82ea91613e7d620b73a9010b6abeb8f..615c5174492616885ecc75d5f5b9634707f67e36 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -18,7 +18,6 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/ValueMap.h"
 #include "llvm/Analysis/DominatorInternals.h"
 #include "llvm/Analysis/Dominators.h"
 #include "llvm/Analysis/InstructionSimplify.h"
@@ -89,7 +88,7 @@ namespace {
     /// Keeps track of non-local addresses that have been sunk into a block.
     /// This allows us to avoid inserting duplicate code for blocks with
     /// multiple load/stores of the same address.
-    ValueMap<Value*, Value*> SunkAddrs;
+    DenseMap<Value*, Value*> SunkAddrs;
 
     /// ModifiedDT - If CFG is modified in anyway, dominator tree may need to
     /// be updated.
@@ -1654,6 +1653,10 @@ bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
       // start of the block.
       CurInstIterator = BB->begin();
       SunkAddrs.clear();
+    } else {
+      // This address is now available for reassignment, so erase the table
+      // entry; we don't want to match some completely different instruction.
+      SunkAddrs[Addr] = 0;
     }
   }
   ++NumMemoryInsts;