Teach DAG combine to handle vector logical operations with vectors of all 1s or all 0s. These cases can show up when vectors are split for legalizing. Fix some tests that were dependent on these cases not being combined.

llvm-svn: 169684

1 files changed, 30 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 6cd07c2c729..4a17dc0d2c3 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2427,6 +2427,18 @@ SDValue DAGCombiner::visitAND(SDNode *N) {
   if (VT.isVector()) {
     SDValue FoldedVOp = SimplifyVBinOp(N);
     if (FoldedVOp.getNode()) return FoldedVOp;
+
+    // fold (and x, 0) -> 0, vector edition
+    if (ISD::isBuildVectorAllZeros(N0.getNode()))
+      return N0;
+    if (ISD::isBuildVectorAllZeros(N1.getNode()))
+      return N1;
+
+    // fold (and x, -1) -> x, vector edition
+    if (ISD::isBuildVectorAllOnes(N0.getNode()))
+      return N1;
+    if (ISD::isBuildVectorAllOnes(N1.getNode()))
+      return N0;
   }
 
   // fold (and x, undef) -> 0
@@ -3025,6 +3037,18 @@ SDValue DAGCombiner::visitOR(SDNode *N) {
   if (VT.isVector()) {
     SDValue FoldedVOp = SimplifyVBinOp(N);
     if (FoldedVOp.getNode()) return FoldedVOp;
+
+    // fold (or x, 0) -> x, vector edition
+    if (ISD::isBuildVectorAllZeros(N0.getNode()))
+      return N1;
+    if (ISD::isBuildVectorAllZeros(N1.getNode()))
+      return N0;
+
+    // fold (or x, -1) -> -1, vector edition
+    if (ISD::isBuildVectorAllOnes(N0.getNode()))
+      return N0;
+    if (ISD::isBuildVectorAllOnes(N1.getNode()))
+      return N1;
   }
 
   // fold (or x, undef) -> -1
@@ -3334,6 +3358,12 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
   if (VT.isVector()) {
     SDValue FoldedVOp = SimplifyVBinOp(N);
     if (FoldedVOp.getNode()) return FoldedVOp;
+
+    // fold (xor x, 0) -> x, vector edition
+    if (ISD::isBuildVectorAllZeros(N0.getNode()))
+      return N1;
+    if (ISD::isBuildVectorAllZeros(N1.getNode()))
+      return N0;
   }
 
   // fold (xor undef, undef) -> 0. This is a common idiom (misuse).