[PowerPC] Eliminate integer compare instructions - vol. 3

Adds handling for i32 SETNE comparison (both sign and zero extended).

Differential Revision: https://reviews.llvm.org/D33718

llvm-svn: 304901

1 files changed, 35 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index d51f2698c7e..afd2e87078a 100644
--- a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -2824,6 +2824,20 @@ SDValue PPCDAGToDAGISel::get32BitZExtCompare(SDValue LHS, SDValue RHS,
     return SDValue(CurDAG->getMachineNode(PPC::RLWINM, dl, MVT::i32,
                                           ShiftOps), 0);
   }
+  case ISD::SETNE: {
+    // (zext (setcc %a, %b, setne)) -> (xor (lshr (cntlzw (xor %a, %b)), 5), 1)
+    // (zext (setcc %a, 0, setne))  -> (xor (lshr (cntlzw %a), 5), 1)
+    SDValue Xor = IsRHSZero ? LHS :
+      SDValue(CurDAG->getMachineNode(PPC::XOR, dl, MVT::i32, LHS, RHS), 0);
+    SDValue Clz =
+      SDValue(CurDAG->getMachineNode(PPC::CNTLZW, dl, MVT::i32, Xor), 0);
+    SDValue ShiftOps[] = { Clz, getI32Imm(27, dl), getI32Imm(5, dl),
+      getI32Imm(31, dl) };
+    SDValue Shift =
+      SDValue(CurDAG->getMachineNode(PPC::RLWINM, dl, MVT::i32, ShiftOps), 0);
+    return SDValue(CurDAG->getMachineNode(PPC::XORI, dl, MVT::i32, Shift,
+                                          getI32Imm(1, dl)), 0);
+  }
   }
 }
 
@@ -2850,6 +2864,27 @@ SDValue PPCDAGToDAGISel::get32BitSExtCompare(SDValue LHS, SDValue RHS,
     return SDValue(CurDAG->getMachineNode(PPC::SRADI_32, dl, MVT::i32, Sldi,
                                           getI32Imm(63, dl)), 0);
   }
+  case ISD::SETNE: {
+    // Bitwise xor the operands, count leading zeros, shift right by 5 bits and
+    // flip the bit, finally take 2's complement.
+    // (sext (setcc %a, %b, setne)) ->
+    //   (neg (xor (lshr (ctlz (xor %a, %b)), 5), 1))
+    // Same as above, but the first xor is not needed.
+    // (sext (setcc %a, 0, setne)) ->
+    //   (neg (xor (lshr (ctlz %a), 5), 1))
+    SDValue Xor = IsRHSZero ? LHS :
+      SDValue(CurDAG->getMachineNode(PPC::XOR, dl, MVT::i32, LHS, RHS), 0);
+    SDValue Clz =
+      SDValue(CurDAG->getMachineNode(PPC::CNTLZW, dl, MVT::i32, Xor), 0);
+    SDValue ShiftOps[] =
+      { Clz, getI32Imm(27, dl), getI32Imm(5, dl), getI32Imm(31, dl) };
+    SDValue Shift =
+      SDValue(CurDAG->getMachineNode(PPC::RLWINM, dl, MVT::i32, ShiftOps), 0);
+    SDValue Xori =
+      SDValue(CurDAG->getMachineNode(PPC::XORI, dl, MVT::i32, Shift,
+                                     getI32Imm(1, dl)), 0);
+    return SDValue(CurDAG->getMachineNode(PPC::NEG, dl, MVT::i32, Xori), 0);
+  }
   }
 }