[X86] Remove what appear to be unnecessary uses of DCI.CombineTo

CombineTo is most useful when you need to replace multiple results, avoid the worklist management, or you need to something else after the combine, etc. Otherwise you should be able to just return the new node and let DAGCombiner go through its usual worklist code.

All of the places changed in this patch look to be standard cases where we should be able to use the more stand behavior of just returning the new node.

Differential Revision: https://reviews.llvm.org/D49569

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337589 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 9543b6429a4d0f444d3f679cd2d4f45a36f121f5..ad571cd8f4a4920e31ec7d9f343d1b4c08690e2c 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -30830,7 +30830,7 @@ static SDValue combineTargetShuffle(SDValue N, SelectionDAG &DAG,
 
   // Nuke no-op shuffles that show up after combining.
   if (isNoopShuffleMask(Mask))
-    return DCI.CombineTo(N.getNode(), N.getOperand(0), /*AddTo*/ true);
+    return N.getOperand(0);
 
   // Look for simplifications involving one or two shuffle instructions.
   SDValue V = N.getOperand(0);
@@ -31286,9 +31286,8 @@ static SDValue combineShuffle(SDNode *N, SelectionDAG &DAG,
     // a particular chain.
     if (SDValue Res = combineX86ShufflesRecursively(
             {Op}, 0, Op, {0}, {}, /*Depth*/ 1,
-            /*HasVarMask*/ false, DAG, Subtarget)) {
-      return DCI.CombineTo(N, Res);
-    }
+            /*HasVarMask*/ false, DAG, Subtarget))
+      return Res;
   }
 
   return SDValue();
@@ -34259,9 +34258,8 @@ static SDValue combineVectorPack(SDNode *N, SelectionDAG &DAG,
   SDValue Op(N, 0);
   if (SDValue Res =
           combineX86ShufflesRecursively({Op}, 0, Op, {0}, {}, /*Depth*/ 1,
-                                        /*HasVarMask*/ false, DAG, Subtarget)) {
-    return DCI.CombineTo(N, Res);
-  }
+                                        /*HasVarMask*/ false, DAG, Subtarget))
+    return Res;
 
   return SDValue();
 }
@@ -34320,9 +34318,8 @@ static SDValue combineVectorShiftImm(SDNode *N, SelectionDAG &DAG,
     SDValue Op(N, 0);
     if (SDValue Res = combineX86ShufflesRecursively(
             {Op}, 0, Op, {0}, {}, /*Depth*/ 1,
-            /*HasVarMask*/ false, DAG, Subtarget)) {
-      return DCI.CombineTo(N, Res);
-    }
+            /*HasVarMask*/ false, DAG, Subtarget))
+      return Res;
   }
 
   // Constant Folding.
@@ -34360,9 +34357,8 @@ static SDValue combineVectorInsert(SDNode *N, SelectionDAG &DAG,
   SDValue Op(N, 0);
   if (SDValue Res =
           combineX86ShufflesRecursively({Op}, 0, Op, {0}, {}, /*Depth*/ 1,
-                                        /*HasVarMask*/ false, DAG, Subtarget)) {
-    return DCI.CombineTo(N, Res);
-  }
+                                        /*HasVarMask*/ false, DAG, Subtarget))
+    return Res;
 
   return SDValue();
 }
@@ -34816,9 +34812,8 @@ static SDValue combineAnd(SDNode *N, SelectionDAG &DAG,
     SDValue Op(N, 0);
     if (SDValue Res = combineX86ShufflesRecursively(
             {Op}, 0, Op, {0}, {}, /*Depth*/ 1,
-            /*HasVarMask*/ false, DAG, Subtarget)) {
-      return DCI.CombineTo(N, Res);
-    }
+            /*HasVarMask*/ false, DAG, Subtarget))
+      return Res;
   }
 
   // Attempt to combine a scalar bitmask AND with an extracted shuffle.
@@ -37226,9 +37221,8 @@ static SDValue combineAndnp(SDNode *N, SelectionDAG &DAG,
     SDValue Op(N, 0);
     if (SDValue Res = combineX86ShufflesRecursively(
             {Op}, 0, Op, {0}, {}, /*Depth*/ 1,
-            /*HasVarMask*/ false, DAG, Subtarget)) {
-      return DCI.CombineTo(N, Res);
-    }
+            /*HasVarMask*/ false, DAG, Subtarget))
+      return Res;
   }
 
   return SDValue();