Fold (zext (load x) to (zextload x).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24702 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 7adfecb..acd80cf 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1552,7 +1552,7 @@
TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, N0.getValueType())))
return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0),
DAG.getValueType(N0.getValueType()));
- // fold (sext (load x)) -> (sextload x)
+ // fold (sext (load x)) -> (sext (truncate (sextload x)))
if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse()) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2),
@@ -1576,6 +1576,23 @@
// fold (zext (zext x)) -> (zext x)
if (N0.getOpcode() == ISD::ZERO_EXTEND)
return DAG.getNode(ISD::ZERO_EXTEND, VT, N0.getOperand(0));
+ // fold (zext (zextload x)) -> (zextload x)
+ if (N0.getOpcode() == ISD::ZEXTLOAD && VT == N0.getValueType())
+ return N0;
+ // fold (zext (truncate x)) -> (zextinreg x) iff x size == zext size.
+ if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT&&
+ !AfterLegalize)
+ return DAG.getZeroExtendInReg(N0.getOperand(0), VT);
+ // fold (zext (load x)) -> (zext (truncate (zextload x)))
+ if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse()) {
+ SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, N0.getOperand(0),
+ N0.getOperand(1), N0.getOperand(2),
+ N0.getValueType());
+ WorkList.push_back(N);
+ CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad),
+ ExtLoad.getValue(1));
+ return SDOperand();
+ }
return SDOperand();
}