[turbofan] Add CalleeSavedFPRegisters to CallDescriptor.

src/compiler/arm64/linkage-arm64.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/assembler.h"
 #include "src/code-stubs.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/linkage-impl.h"
 #include "src/zone.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 struct Arm64LinkageHelperTraits {
   static Register ReturnValueReg() { return x0; }
   static Register ReturnValue2Reg() { return x1; }
   static Register JSCallFunctionReg() { return x1; }
   static Register ContextReg() { return cp; }
   static Register RuntimeCallFunctionReg() { return x1; }
   static Register RuntimeCallArgCountReg() { return x0; }
   static RegList CCalleeSaveRegisters() {
     // TODO(dcarney): correct callee saved registers.
     return 0;
   }
+  static RegList CCalleeSaveFPURegisters() {
+    // TODO(palfia): finish.
+    return 0;

[paul.l..., 2015/06/15 23:05:17]

arm64 has CPURegList::GetCallerSaved() & CPURegList::GetCallerSavedFP, and they
also have MacroAssembler::PushCPURegList(). You'll want to be careful that
whatever methods you use for save/restore are no slower than the stp/ldp
(register pair) operations that they use in the existing TF code.

[akos.palfi.imgtec, 2015/06/22 17:33:20]

OK, I'm generating the same stp/ldp code.

+  }
   static Register CRegisterParameter(int i) {
     static Register register_parameters[] = {x0, x1, x2, x3, x4, x5, x6, x7};
     return register_parameters[i];
   }
   static int CRegisterParametersLength() { return 8; }
 };
 
 
 typedef LinkageHelper<Arm64LinkageHelperTraits> LH;
 
@@ skipping 23 matching lines @@
 
 
 CallDescriptor* Linkage::GetSimplifiedCDescriptor(Zone* zone,
                                                   const MachineSignature* sig) {
   return LH::GetSimplifiedCDescriptor(zone, sig);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8