Revert r215343.

This was contentious and needs invesigation.

llvm-svn: 218971

1 files changed, 1 insertions, 25 deletions

diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index 961fb0f7aef..414aaab265a 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -545,31 +545,7 @@ bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) {
   // cache needs updating, i.e. if we have solve a new value or not.
   OverDefinedCacheUpdater ODCacheUpdater(Val, BB, BBLV, this);
 
-  // Once this BB is encountered, Val's value for this BB will not be Undefined
-  // any longer. When we encounter this BB again, if Val's value is Overdefined,
-  // we need to compute its value again.
-  // 
-  // For example, considering this control flow,
-  //   BB1->BB2, BB1->BB3, BB2->BB3, BB2->BB4
-  //
-  // Suppose we have "icmp slt %v, 0" in BB1, and "icmp sgt %v, 0" in BB3. At
-  // the very beginning, when analyzing edge BB2->BB3, we don't know %v's value
-  // in BB2, and the data flow algorithm tries to compute BB2's predecessors, so
-  // then we know %v has negative value on edge BB1->BB2. And then we return to
-  // check BB2 again, and at this moment BB2 has Overdefined value for %v in
-  // BB2. So we should have to follow data flow propagation algorithm to get the
-  // value on edge BB1->BB2 propagated to BB2, and finally %v on BB2 has a
-  // constant range describing a negative value.
-  //
-  // In the mean time, limit the number of additional lowering lattice value to
-  // avoid unjustified memory grows.
-
-  if (LoweringOverdefinedTimes.count(BB) == 0)
-    LoweringOverdefinedTimes.insert(std::make_pair(BB, 0));
-  if ((!BBLV.isUndefined() && !BBLV.isOverdefined()) ||
-      (BBLV.isOverdefined() &&
-       (LoweringOverdefinedTimes[BB] > OverdefinedThreshold ||
-        LoweringOverdefinedTimes.size() > OverdefinedBBThreshold))) {
+  if (!BBLV.isUndefined()) {
     DEBUG(dbgs() << "  reuse BB '" << BB->getName() << "' val=" << BBLV <<'\n');
     
     // Since we're reusing a cached value here, we don't need to update the