[mips] Fix fcopysign for MIPS-IV and add the test.

[dsanders]

Summary

This was another incorrect use of hasMips64() vs isGP64bit().

Depends on D3344

[vmedic]

LGTM

lib/Target/Mips/MipsISelLowering.cpp

static SDValue lowerFCOPYSIGN64(SDValue Op, SelectionDAG &DAG,
   SDValue SllY = DAG.getNode(ISD::SHL, DL, TyX, SrlY,
                              DAG.getConstant(WidthX - 1, MVT::i32));
   SDValue Or = DAG.getNode(ISD::OR, DL, TyX, SrlX, SllY);
   return DAG.getNode(ISD::BITCAST, DL, Op.getOperand(0).getValueType(), Or);
 }
 
 SDValue
 MipsTargetLowering::lowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) const {
-  if (Subtarget->hasMips64())
+  if (Subtarget->isGP64bit())
     return lowerFCOPYSIGN64(Op, DAG, Subtarget->hasExtractInsert());
 
   return lowerFCOPYSIGN32(Op, DAG, Subtarget->hasExtractInsert());
 }
 
 SDValue MipsTargetLowering::
 lowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const {
   // check the depth

test/CodeGen/Mips/fcopysign-f32-f64.ll

+; RUN: llc  < %s -march=mips64el -mcpu=mips4 -mattr=n64 | FileCheck %s -check-prefix=64
 ; RUN: llc  < %s -march=mips64el -mcpu=mips64 -mattr=n64 | FileCheck %s -check-prefix=64
 ; RUN: llc  < %s -march=mips64el -mcpu=mips64r2 -mattr=n64 | FileCheck %s -check-prefix=64R2
 
 declare double @copysign(double, double) nounwind readnone
 
 declare float @copysignf(float, float) nounwind readnone
 
 define float @func2(float %d, double %f) nounwind readnone {

test/CodeGen/Mips/fcopysign.ll

 ; RUN: llc  < %s -march=mipsel -mcpu=mips32 | FileCheck %s -check-prefix=32
 ; RUN: llc  < %s -march=mipsel -mcpu=mips32r2 | FileCheck %s -check-prefix=32R2
+; RUN: llc  < %s -march=mips64el -mcpu=mips4 -mattr=n64 | FileCheck %s -check-prefix=64
 ; RUN: llc  < %s -march=mips64el -mcpu=mips64 -mattr=n64 | FileCheck %s -check-prefix=64
 ; RUN: llc  < %s -march=mips64el -mcpu=mips64r2 -mattr=n64 | FileCheck %s -check-prefix=64R2
 
 define double @func0(double %d0, double %d1) nounwind readnone {
 entry:
 ;
 ; 32: lui  $[[MSK1:[0-9]+]], 32768
 ; 32: and  $[[AND1:[0-9]+]], ${{[0-9]+}}, $[[MSK1]]