When computing the value on an edge, in certain cases LVI would fail to compute the...

in the predecessor block, leading to an incorrect conclusion for the edge value.  Found by inspection.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122908 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/LazyValueInfo.cpp b/lib/Analysis/LazyValueInfo.cpp
index 38355edb83dda8931e3d87c5b6bf55498bce23d7..17348cd028ea21a488e02d0656537aed683b0db8 100644 (file)
--- a/lib/Analysis/LazyValueInfo.cpp
+++ b/lib/Analysis/LazyValueInfo.cpp
@@ -817,6 +817,11 @@ bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom,
           if (!isTrueDest) TrueValues = TrueValues.inverse();
           
           // Figure out the possible values of the query BEFORE this branch.  
+          if (!hasBlockValue(Val, BBFrom)) {
+            block_value_stack.push(std::make_pair(BBFrom, Val));
+            return false;
+          }
+          
           LVILatticeVal InBlock = getBlockValue(Val, BBFrom);
           if (!InBlock.isConstantRange()) {
             Result = LVILatticeVal::getRange(TrueValues);