Add the PPC fcpsgn instruction

Modern PPC cores support a floating-point copysign instruction, and we can use
this to lower the FCOPYSIGN node (which is created from calls to the libm
copysign function). A couple of extra patterns are necessary because the
operand types of FCOPYSIGN need not agree.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188653 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCSubtarget.cpp

@@ -74,6 +74,7 @@ void PPCSubtarget::initializeEnvironment() {
   Use64BitRegs = false;
   HasAltivec = false;
   HasQPX = false;
+  HasFCPSGN = false;
   HasFSQRT = false;
   HasFRE = false;
   HasFRES = false;