X86: Simplify X86ISD::Wrapper operand checks.

[pcc]

Summary

We only ever create TargetConstantPool, TargetJumpTable, TargetExternalSymbol,
TargetGlobalAddress, TargetGlobalTLSAddress, MCSymbol and TargetBlockAddress
nodes as operands of X86ISD::Wrapper nodes, so we can remove one check and
invert the other.

Also update the documentation comment for X86ISD::Wrapper.

[craig.topper]

LGTM

llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp

bool X86DAGToDAGISel::selectMOV64Imm32(SDValue N, SDValue &Imm) {
 
   // In static codegen with small code model, we can get the address of a label
   // into a register with 'movl'. TableGen has already made sure we're looking
   // at a label of some kind.
   assert(N->getOpcode() == X86ISD::Wrapper &&
          "Unexpected node type for MOV32ri64");
   N = N.getOperand(0);
 
-  if (N->getOpcode() != ISD::TargetConstantPool &&
-      N->getOpcode() != ISD::TargetJumpTable &&
-      N->getOpcode() != ISD::TargetGlobalAddress &&
-      N->getOpcode() != ISD::TargetExternalSymbol &&
-      N->getOpcode() != ISD::MCSymbol &&
-      N->getOpcode() != ISD::TargetBlockAddress)
+  // At least GNU as does not accept 'movl' for TPOFF relocations.
+  // FIXME: We could use 'movl' when we know we are targeting MC.
+  if (N->getOpcode() == ISD::TargetGlobalTLSAddress)
     return false;
 
   Imm = N;
   return TM.getCodeModel() == CodeModel::Small;
 }
 
 bool X86DAGToDAGISel::selectLEA64_32Addr(SDValue N, SDValue &Base,
                                          SDValue &Scale, SDValue &Index,
if (auto *CN = dyn_cast<ConstantSDNode>(N)) {
     Op = CurDAG->getTargetConstant(CN->getAPIntValue(), SDLoc(CN),
                                    N.getValueType());
     return true;
   }
 
   if (N.getOpcode() != X86ISD::Wrapper)
     return false;
 
-  unsigned Opc = N.getOperand(0)->getOpcode();
-  if (Opc == ISD::TargetConstantPool || Opc == ISD::TargetJumpTable ||
-      Opc == ISD::TargetExternalSymbol || Opc == ISD::TargetGlobalAddress ||
-      Opc == ISD::TargetGlobalTLSAddress || Opc == ISD::MCSymbol ||
-      Opc == ISD::TargetBlockAddress) {
-    Op = N.getOperand(0);
-    return true;
-  }
 
-  return false;
-}
-
 bool X86DAGToDAGISel::tryFoldLoad(SDNode *P, SDValue N,
                                   SDValue &Base, SDValue &Scale,
                                   SDValue &Index, SDValue &Disp,
                                   SDValue &Segment) {
   if (!ISD::isNON_EXTLoad(N.getNode()) ||
       !IsProfitableToFold(N, P, P) ||
       !IsLegalToFold(N, P, P, OptLevel))
     return false;

llvm/trunk/lib/Target/X86/X86ISelLowering.h

enum NodeType : unsigned {
 
       /// Repeat move, corresponds to X86::REP_MOVSx.
       REP_MOVS,
 
       /// On Darwin, this node represents the result of the popl
       /// at function entry, used for PIC code.
       GlobalBaseReg,
 
-      /// A wrapper node for TargetConstantPool,
-      /// TargetExternalSymbol, and TargetGlobalAddress.
+      /// A wrapper node for TargetConstantPool, TargetJumpTable,
+      /// TargetExternalSymbol, TargetGlobalAddress, TargetGlobalTLSAddress,
+      /// MCSymbol and TargetBlockAddress.
       Wrapper,
 
       /// Special wrapper used under X86-64 PIC mode for RIP
       /// relative displacements.
       WrapperRIP,
 
       /// Copies a 64-bit value from the low word of an XMM vector
       /// to an MMX vector.  If you think this is too close to the previous