[llvm] r337589 - [X86] Remove what appear to be unnecessary uses of DCI.CombineTo

[Craig Topper via llvm-commits]

Author: ctopper
Date: Fri Jul 20 10:57:42 2018
New Revision: 337589

URL: http://llvm.org/viewvc/llvm-project?rev=337589&view=rev
Log:
[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

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=337589&r1=337588&r2=337589&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Fri Jul 20 10:57:42 2018
@@ -30830,7 +30830,7 @@ static SDValue combineTargetShuffle(SDVa
 
   // 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,
     // 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
   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(SDN
     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(SDNod
   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, Sel
     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, S
     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();