reduce indentation and improve comments, no functionality change.

llvm-svn: 122389

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -4242,7 +4242,6 @@ SDValue DAGCombiner::ReduceLoadWidth(SDNode *N) {
       // of the extended byte.  This is not worth optimizing for.
       if (ShAmt >= VT.getSizeInBits())
         return SDValue();
-
     }
   }
 
@@ -4250,20 +4249,26 @@ SDValue DAGCombiner::ReduceLoadWidth(SDNode *N) {
   // we can fold the truncate through the shift.
   unsigned ShLeftAmt = 0;
   if (ShAmt == 0 && N0.getOpcode() == ISD::SHL && N0.hasOneUse() &&
-      ExtVT == VT &&
-      TLI.isNarrowingProfitable(N0.getValueType(), VT)) {
+      ExtVT == VT && TLI.isNarrowingProfitable(N0.getValueType(), VT)) {
     if (ConstantSDNode *N01 = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
       ShLeftAmt = N01->getZExtValue();
       N0 = N0.getOperand(0);
     }
   }
   
+  // If we haven't found a load, we can't narrow it.  Don't transform one with
+  // multiple uses, this would require adding a new load.
+  if (!isa<LoadSDNode>(N0) || !N0.hasOneUse() ||
+      // Don't change the width of a volatile load.
+      cast<LoadSDNode>(N0)->isVolatile())
+    return SDValue();
+
   // Do not generate loads of non-round integer types since these can
   // be expensive (and would be wrong if the type is not byte sized).
-  if (isa<LoadSDNode>(N0) && N0.hasOneUse() && ExtVT.isRound() &&
-      cast<LoadSDNode>(N0)->getMemoryVT().getSizeInBits() >= EVTBits &&
-      // Do not change the width of a volatile load.
-      !cast<LoadSDNode>(N0)->isVolatile()) {
+  if (!ExtVT.isRound() ||
+      cast<LoadSDNode>(N0)->getMemoryVT().getSizeInBits() < EVTBits)
+    return SDValue();
+  
   LoadSDNode *LN0 = cast<LoadSDNode>(N0);
   EVT PtrType = N0.getOperand(1).getValueType();
 
@@ -4310,9 +4315,6 @@ SDValue DAGCombiner::ReduceLoadWidth(SDNode *N) {
   return Result;
 }
 
-  return SDValue();
-}
-
 SDValue DAGCombiner::visitSIGN_EXTEND_INREG(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);