[llvm] r261020 - [X86] Extract ANDNP combine. NFC.

[Ahmed Bougacha via llvm-commits]

Author: ab
Date: Tue Feb 16 16:13:49 2016
New Revision: 261020

URL: http://llvm.org/viewvc/llvm-project?rev=261020&view=rev
Log:
[X86] Extract ANDNP combine. NFC.

This makes it IMO more readable and reduces indentation.

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=261020&r1=261019&r2=261020&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Tue Feb 16 16:13:49 2016
@@ -26087,34 +26087,47 @@ static SDValue CMPEQCombine(SDNode *N, S
   return SDValue();
 }
 
-/// CanFoldXORWithAllOnes - Test whether the XOR operand is a AllOnes vector
-/// so it can be folded inside ANDNP.
-static bool CanFoldXORWithAllOnes(const SDNode *N) {
+// Try to fold: (and (xor X, -1), Y) -> (andnp X, Y).
+static SDValue combineANDXORWithAllOnesIntoANDNP(SDNode *N, SelectionDAG &DAG) {
+  assert(N->getOpcode() == ISD::AND);
+
   EVT VT = N->getValueType(0);
+  SDValue N0 = N->getOperand(0);
+  SDValue N1 = N->getOperand(1);
+  SDLoc DL(N);
 
-  // Match direct AllOnes for 128 and 256-bit vectors
-  if (ISD::isBuildVectorAllOnes(N))
-    return true;
-
-  // Look through a bit convert.
-  if (N->getOpcode() == ISD::BITCAST)
-    N = N->getOperand(0).getNode();
-
-  // Sometimes the operand may come from a insert_subvector building a 256-bit
-  // allones vector
-  if (VT.is256BitVector() &&
-      N->getOpcode() == ISD::INSERT_SUBVECTOR) {
-    SDValue V1 = N->getOperand(0);
-    SDValue V2 = N->getOperand(1);
-
-    if (V1.getOpcode() == ISD::INSERT_SUBVECTOR &&
-        V1.getOperand(0).getOpcode() == ISD::UNDEF &&
-        ISD::isBuildVectorAllOnes(V1.getOperand(1).getNode()) &&
-        ISD::isBuildVectorAllOnes(V2.getNode()))
-      return true;
-  }
+  if (VT != MVT::v2i64 && VT != MVT::v4i64)
+    return SDValue();
 
-  return false;
+  // Canonicalize XOR to the left.
+  if (N1.getOpcode() == ISD::XOR)
+    std::swap(N0, N1);
+
+  if (N0.getOpcode() != ISD::XOR)
+    return SDValue();
+
+  SDValue N00 = N0->getOperand(0);
+  SDValue N01 = N0->getOperand(1);
+
+  // Look through a bitcast.
+  if (N01->getOpcode() == ISD::BITCAST)
+    N01 = N01->getOperand(0);
+
+  // Either match a direct AllOnes for 128 and 256-bit vectors, or an
+  // insert_subvector building a 256-bit AllOnes vector.
+  if (!ISD::isBuildVectorAllOnes(N01.getNode())) {
+    if (!VT.is256BitVector() || N01->getOpcode() != ISD::INSERT_SUBVECTOR)
+      return SDValue();
+
+    SDValue V1 = N01->getOperand(0);
+    SDValue V2 = N01->getOperand(1);
+    if (V1.getOpcode() != ISD::INSERT_SUBVECTOR ||
+        V1.getOperand(0).getOpcode() != ISD::UNDEF ||
+        !ISD::isBuildVectorAllOnes(V1.getOperand(1).getNode()) ||
+        !ISD::isBuildVectorAllOnes(V2.getNode()))
+      return SDValue();
+  }
+  return DAG.getNode(X86ISD::ANDNP, DL, VT, N00, N1);
 }
 
 // On AVX/AVX2 the type v8i1 is legalized to v8i16, which is an XMM sized
@@ -26340,6 +26353,9 @@ static SDValue PerformAndCombine(SDNode
   if (SDValue FPLogic = convertIntLogicToFPLogic(N, DAG, Subtarget))
     return FPLogic;
 
+  if (SDValue R = combineANDXORWithAllOnesIntoANDNP(N, DAG))
+    return R;
+
   EVT VT = N->getValueType(0);
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
@@ -26347,47 +26363,27 @@ static SDValue PerformAndCombine(SDNode
 
   // Create BEXTR instructions
   // BEXTR is ((X >> imm) & (2**size-1))
-  if (VT == MVT::i32 || VT == MVT::i64) {
-    // Check for BEXTR.
-    if ((Subtarget.hasBMI() || Subtarget.hasTBM()) &&
-        (N0.getOpcode() == ISD::SRA || N0.getOpcode() == ISD::SRL)) {
-      ConstantSDNode *MaskNode = dyn_cast<ConstantSDNode>(N1);
-      ConstantSDNode *ShiftNode = dyn_cast<ConstantSDNode>(N0.getOperand(1));
-      if (MaskNode && ShiftNode) {
-        uint64_t Mask = MaskNode->getZExtValue();
-        uint64_t Shift = ShiftNode->getZExtValue();
-        if (isMask_64(Mask)) {
-          uint64_t MaskSize = countPopulation(Mask);
-          if (Shift + MaskSize <= VT.getSizeInBits())
-            return DAG.getNode(X86ISD::BEXTR, DL, VT, N0.getOperand(0),
-                               DAG.getConstant(Shift | (MaskSize << 8), DL,
-                                               VT));
-        }
-      }
-    } // BEXTR
-
+  if (VT != MVT::i32 && VT != MVT::i64)
     return SDValue();
-  }
 
-  // Want to form ANDNP nodes:
-  // 1) In the hopes of then easily combining them with OR and AND nodes
-  //    to form PBLEND/PSIGN.
-  // 2) To match ANDN packed intrinsics
-  if (VT != MVT::v2i64 && VT != MVT::v4i64)
+  if (!Subtarget.hasBMI() && !Subtarget.hasTBM())
+    return SDValue();
+  if (N0.getOpcode() != ISD::SRA && N0.getOpcode() != ISD::SRL)
     return SDValue();
 
-  // Check LHS for vnot
-  if (N0.getOpcode() == ISD::XOR &&
-      //ISD::isBuildVectorAllOnes(N0.getOperand(1).getNode()))
-      CanFoldXORWithAllOnes(N0.getOperand(1).getNode()))
-    return DAG.getNode(X86ISD::ANDNP, DL, VT, N0.getOperand(0), N1);
-
-  // Check RHS for vnot
-  if (N1.getOpcode() == ISD::XOR &&
-      //ISD::isBuildVectorAllOnes(N1.getOperand(1).getNode()))
-      CanFoldXORWithAllOnes(N1.getOperand(1).getNode()))
-    return DAG.getNode(X86ISD::ANDNP, DL, VT, N1.getOperand(0), N0);
-
+  ConstantSDNode *MaskNode = dyn_cast<ConstantSDNode>(N1);
+  ConstantSDNode *ShiftNode = dyn_cast<ConstantSDNode>(N0.getOperand(1));
+  if (MaskNode && ShiftNode) {
+    uint64_t Mask = MaskNode->getZExtValue();
+    uint64_t Shift = ShiftNode->getZExtValue();
+    if (isMask_64(Mask)) {
+      uint64_t MaskSize = countPopulation(Mask);
+      if (Shift + MaskSize <= VT.getSizeInBits())
+        return DAG.getNode(X86ISD::BEXTR, DL, VT, N0.getOperand(0),
+                           DAG.getConstant(Shift | (MaskSize << 8), DL,
+                                           VT));
+    }
+  }
   return SDValue();
 }