[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

[Chris Lattner]

Changes in directory llvm/lib/CodeGen/SelectionDAG:

DAGCombiner.cpp updated: 1.254 -> 1.255
---
Log message:

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.


---
Diffs of the changes:  (+6 -1)

 DAGCombiner.cpp |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletion(-)


Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.254 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.255
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.254	Mon Nov 20 12:05:46 2006
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp	Sun Nov 26 22:40:53 2006
@@ -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);