[llvm] r324567 - [DAGCombiner] Don't create truncate nodes in (aext (zextload x)) -> (zextload x) and similar folds. NFCI

[Craig Topper via llvm-commits]

Author: ctopper
Date: Wed Feb  7 22:04:18 2018
New Revision: 324567

URL: http://llvm.org/viewvc/llvm-project?rev=324567&view=rev
Log:
[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.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=324567&r1=324566&r2=324567&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Feb  7 22:04:18 2018
@@ -7592,10 +7592,7 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SD
                                        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(SD
                                        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(SDN
   // 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(SDN
                                        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!
     }
   }