[DAGCombiner] Don't create truncate nodes in (aext (zextload x)) -> (zextload x) and similar folds. NFCI

The truncate is being used to replace other users of of the load, but we checked that the load only has one use so there are no other uses to replace.

llvm-svn: 324567

1 files changed, 5 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 13f662145cf..b6efa91bae4 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7592,10 +7592,7 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
                                        LN0->getBasePtr(), MemVT,
                                        LN0->getMemOperand());
       CombineTo(N, ExtLoad);
-      CombineTo(N0.getNode(),
-                DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
-                            N0.getValueType(), ExtLoad),
-                ExtLoad.getValue(1));
+      DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
       return SDValue(N, 0);   // Return N so it doesn't get rechecked!
     }
   }
@@ -7964,10 +7961,7 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
                                        LN0->getBasePtr(), MemVT,
                                        LN0->getMemOperand());
       CombineTo(N, ExtLoad);
-      CombineTo(N0.getNode(),
-                DAG.getNode(ISD::TRUNCATE, SDLoc(N0), N0.getValueType(),
-                            ExtLoad),
-                ExtLoad.getValue(1));
+      DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
       return SDValue(N, 0);   // Return N so it doesn't get rechecked!
     }
   }
@@ -8134,9 +8128,8 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
   // fold (aext (zextload x)) -> (aext (truncate (zextload x)))
   // fold (aext (sextload x)) -> (aext (truncate (sextload x)))
   // fold (aext ( extload x)) -> (aext (truncate (extload  x)))
-  if (N0.getOpcode() == ISD::LOAD &&
-      !ISD::isNON_EXTLoad(N0.getNode()) && ISD::isUNINDEXEDLoad(N0.getNode()) &&
-      N0.hasOneUse()) {
+  if (N0.getOpcode() == ISD::LOAD && !ISD::isNON_EXTLoad(N0.getNode()) &&
+      ISD::isUNINDEXEDLoad(N0.getNode()) && N0.hasOneUse()) {
     LoadSDNode *LN0 = cast<LoadSDNode>(N0);
     ISD::LoadExtType ExtType = LN0->getExtensionType();
     EVT MemVT = LN0->getMemoryVT();
@@ -8145,10 +8138,7 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
                                        VT, LN0->getChain(), LN0->getBasePtr(),
                                        MemVT, LN0->getMemOperand());
       CombineTo(N, ExtLoad);
-      CombineTo(N0.getNode(),
-                DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
-                            N0.getValueType(), ExtLoad),
-                ExtLoad.getValue(1));
+      DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
       return SDValue(N, 0);   // Return N so it doesn't get rechecked!
     }
   }