Look for SSE and instructions of this form: (and x, (build_vector c1,c2,c3,c4)).

If there exists a use of a build_vector that's the bitwise complement of the mask,
then transform the node to
(and (xor x, (build_vector -1,-1,-1,-1)), (build_vector ~c1,~c2,~c3,~c4)).

Since this transformation is only useful when 1) the given build_vector will
become a load from constpool, and 2) (and (xor x -1), y) matches to a single
instruction, I decided this is appropriate as a x86 specific transformation.
rdar://7323335


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96389 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 50 insertions, 1 deletions

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 9974d8c997..4c40fe1803 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -990,6 +990,7 @@ X86TargetLowering::X86TargetLowering(X86TargetMachine &TM)
   setTargetDAGCombine(ISD::VECTOR_SHUFFLE);
   setTargetDAGCombine(ISD::BUILD_VECTOR);
   setTargetDAGCombine(ISD::SELECT);
+  setTargetDAGCombine(ISD::AND);
   setTargetDAGCombine(ISD::SHL);
   setTargetDAGCombine(ISD::SRA);
   setTargetDAGCombine(ISD::SRL);
@@ -9157,6 +9158,53 @@ static SDValue PerformCMOVCombine(SDNode *N, SelectionDAG &DAG,
   return SDValue();
 }
 
+/// PerformANDCombine - Look for SSE and instructions of this form:
+/// (and x, (build_vector c1,c2,c3,c4)). If there exists a use of a build_vector
+/// that's the bitwise complement of the mask, then transform the node to
+/// (and (xor x, (build_vector -1,-1,-1,-1)), (build_vector ~c1,~c2,~c3,~c4)).
+static SDValue PerformANDCombine(SDNode *N, SelectionDAG &DAG,
+                                 TargetLowering::DAGCombinerInfo &DCI) {
+  EVT VT = N->getValueType(0);
+  if (!VT.isVector() || !VT.isInteger())
+    return SDValue();
+
+  SDValue N0 = N->getOperand(0);
+  SDValue N1 = N->getOperand(1);
+  if (N0.getOpcode() == ISD::XOR || !N1.hasOneUse())
+    return SDValue();
+
+  if (N1.getOpcode() == ISD::BUILD_VECTOR) {
+    unsigned NumElts = VT.getVectorNumElements();
+    EVT EltVT = VT.getVectorElementType();
+    SmallVector<SDValue, 8> Mask;
+    Mask.reserve(NumElts);
+    for (unsigned i = 0; i != NumElts; ++i) {
+      SDValue Arg = N1.getOperand(i);
+      if (Arg.getOpcode() == ISD::UNDEF) {
+        Mask.push_back(Arg);
+        continue;
+      }
+      ConstantSDNode *C = dyn_cast<ConstantSDNode>(Arg);
+      if (!C) return SDValue();
+      Mask.push_back(DAG.getConstant(~C->getAPIntValue(), EltVT));
+    }
+    N1 = DAG.getNode(ISD::BUILD_VECTOR, N1.getDebugLoc(), VT,
+                     &Mask[0], NumElts);
+    if (!N1.use_empty()) {
+      unsigned Bits = EltVT.getSizeInBits();
+      Mask.clear();
+      for (unsigned i = 0; i != NumElts; ++i)
+        Mask.push_back(DAG.getConstant(APInt::getAllOnesValue(Bits), EltVT));
+      SDValue NewMask = DAG.getNode(ISD::BUILD_VECTOR, N->getDebugLoc(),
+                                    VT, &Mask[0], NumElts);
+      return DAG.getNode(ISD::AND, N->getDebugLoc(), VT,
+                         DAG.getNode(ISD::XOR, N->getDebugLoc(), VT,
+                                     N0, NewMask), N1);
+    }
+  }
+
+  return SDValue();
+}
 
 /// PerformMulCombine - Optimize a single multiply with constant into two
 /// in order to implement it with two cheaper instructions, e.g.
@@ -9305,7 +9353,7 @@ static SDValue PerformShiftCombine(SDNode* N, SelectionDAG &DAG,
       }
     } else if (InVec.getOpcode() == ISD::INSERT_VECTOR_ELT) {
        if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(InVec.getOperand(2))) {
-         unsigned SplatIdx = cast<ShuffleVectorSDNode>(ShAmtOp)->getSplatIndex();
+         unsigned SplatIdx= cast<ShuffleVectorSDNode>(ShAmtOp)->getSplatIndex();
          if (C->getZExtValue() == SplatIdx)
            BaseShAmt = InVec.getOperand(1);
        }
@@ -9690,6 +9738,7 @@ SDValue X86TargetLowering::PerformDAGCombine(SDNode *N,
   case ISD::VECTOR_SHUFFLE: return PerformShuffleCombine(N, DAG, *this);
   case ISD::SELECT:         return PerformSELECTCombine(N, DAG, Subtarget);
   case X86ISD::CMOV:        return PerformCMOVCombine(N, DAG, DCI);
+  case ISD::AND:            return PerformANDCombine(N, DAG, DCI);
   case ISD::MUL:            return PerformMulCombine(N, DAG, DCI);
   case ISD::SHL:
   case ISD::SRA: