For better or worse, load from i1 is assumed to be zero extended. Do not
form a load from i1 from larger loads that may not be zext'd.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31933 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 4499069..99de15c 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2192,7 +2192,12 @@
return N0.getOperand(0);
}
// fold (truncate (load x)) -> (smaller load x)
- if (ISD::isNON_EXTLoad(N0.Val) && N0.hasOneUse()) {
+ if (ISD::isNON_EXTLoad(N0.Val) && N0.hasOneUse() &&
+ // Do not allow folding to i1 here. i1 is implicitly stored in memory in
+ // zero extended form: by shrinking the load, we lose track of the fact
+ // that it is already zero extended.
+ // FIXME: This should be reevaluated.
+ VT != MVT::i1) {
assert(MVT::getSizeInBits(N0.getValueType()) > MVT::getSizeInBits(VT) &&
"Cannot truncate to larger type!");
LoadSDNode *LN0 = cast<LoadSDNode>(N0);