[DAGCombiner] Avoid creating truncate nodes in (zext (and (load)))->(and (zextload)) fold until we know for sure we're going to need it. NFCI

The truncate is only needed if the load has additional users. It used to get passed to extendSetCCUses so was created early, but that's no longer the case.

llvm-svn: 324562

1 files changed, 25 insertions, 22 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 64112e23c05..13f662145cf 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7560,16 +7560,17 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
       SDValue ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, DL, VT, LN0->getChain(),
                                        LN0->getBasePtr(), N0.getValueType(),
                                        LN0->getMemOperand());
-      SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
-                                  N0.getValueType(), ExtLoad);
       ExtendSetCCUses(SetCCs, N0, ExtLoad, DL, ISD::SIGN_EXTEND);
       // If the load value is used only by N, replace it via CombineTo N.
       bool NoReplaceTrunc = SDValue(LN0, 0).hasOneUse();
       CombineTo(N, ExtLoad);
-      if (NoReplaceTrunc)
+      if (NoReplaceTrunc) {
         DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
-      else
+      } else {
+        SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
+                                    N0.getValueType(), ExtLoad);
         CombineTo(LN0, Trunc, ExtLoad.getValue(1));
+      }
       return SDValue(N, 0);
     }
   }
@@ -7624,9 +7625,6 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
         Mask = Mask.sext(VT.getSizeInBits());
         SDValue And = DAG.getNode(N0.getOpcode(), DL, VT,
                                   ExtLoad, DAG.getConstant(Mask, DL, VT));
-        SDValue Trunc = DAG.getNode(ISD::TRUNCATE,
-                                    SDLoc(N0.getOperand(0)),
-                                    N0.getOperand(0).getValueType(), ExtLoad);
         ExtendSetCCUses(SetCCs, N0, ExtLoad, DL, ISD::SIGN_EXTEND);
         bool NoReplaceTruncAnd = !N0.hasOneUse();
         bool NoReplaceTrunc = SDValue(LN00, 0).hasOneUse();
@@ -7637,10 +7635,13 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
               DAG.getNode(ISD::TRUNCATE, DL, N0.getValueType(), And);
           CombineTo(N0.getNode(), TruncAnd);
         }
-        if (NoReplaceTrunc)
+        if (NoReplaceTrunc) {
           DAG.ReplaceAllUsesOfValueWith(SDValue(LN00, 1), ExtLoad.getValue(1));
-        else
+        } else {
+          SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(LN00),
+                                      LN00->getValueType(0), ExtLoad);
           CombineTo(LN00, Trunc, ExtLoad.getValue(1));
+        }
         return SDValue(N,0); // Return N so it doesn't get rechecked!
       }
     }
@@ -7871,16 +7872,17 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
                                        LN0->getBasePtr(), N0.getValueType(),
                                        LN0->getMemOperand());
 
-      SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
-                                  N0.getValueType(), ExtLoad);
       ExtendSetCCUses(SetCCs, N0, ExtLoad, SDLoc(N), ISD::ZERO_EXTEND);
       // If the load value is used only by N, replace it via CombineTo N.
       bool NoReplaceTrunc = SDValue(LN0, 0).hasOneUse();
       CombineTo(N, ExtLoad);
-      if (NoReplaceTrunc)
+      if (NoReplaceTrunc) {
         DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
-      else
+      } else {
+        SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
+                                    N0.getValueType(), ExtLoad);
         CombineTo(LN0, Trunc, ExtLoad.getValue(1));
+      }
       return SDValue(N, 0); // Return N so it doesn't get rechecked!
     }
   }
@@ -7927,9 +7929,6 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
         SDLoc DL(N);
         SDValue And = DAG.getNode(N0.getOpcode(), DL, VT,
                                   ExtLoad, DAG.getConstant(Mask, DL, VT));
-        SDValue Trunc = DAG.getNode(ISD::TRUNCATE,
-                                    SDLoc(N0.getOperand(0)),
-                                    N0.getOperand(0).getValueType(), ExtLoad);
         ExtendSetCCUses(SetCCs, N0, ExtLoad, DL, ISD::ZERO_EXTEND);
         bool NoReplaceTruncAnd = !N0.hasOneUse();
         bool NoReplaceTrunc = SDValue(LN00, 0).hasOneUse();
@@ -7940,10 +7939,13 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
               DAG.getNode(ISD::TRUNCATE, DL, N0.getValueType(), And);
           CombineTo(N0.getNode(), TruncAnd);
         }
-        if (NoReplaceTrunc)
+        if (NoReplaceTrunc) {
           DAG.ReplaceAllUsesOfValueWith(SDValue(LN00, 1), ExtLoad.getValue(1));
-        else
+        } else {
+          SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(LN00),
+                                      LN00->getValueType(0), ExtLoad);
           CombineTo(LN00, Trunc, ExtLoad.getValue(1));
+        }
         return SDValue(N,0); // Return N so it doesn't get rechecked!
       }
     }
@@ -8113,17 +8115,18 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
                                        LN0->getChain(),
                                        LN0->getBasePtr(), N0.getValueType(),
                                        LN0->getMemOperand());
-      SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
-                                  N0.getValueType(), ExtLoad);
       ExtendSetCCUses(SetCCs, N0, ExtLoad, SDLoc(N),
                       ISD::ANY_EXTEND);
       // If the load value is used only by N, replace it via CombineTo N.
       bool NoReplaceTrunc = N0.hasOneUse();
       CombineTo(N, ExtLoad);
-      if (NoReplaceTrunc)
+      if (NoReplaceTrunc) {
         DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
-      else
+      } else {
+        SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
+                                    N0.getValueType(), ExtLoad);
         CombineTo(LN0, Trunc, ExtLoad.getValue(1));
+      }
       return SDValue(N, 0); // Return N so it doesn't get rechecked!
     }
   }