X87: [turbofan] Add basic support for calling to (a subset of) C functions.

src/compiler/x87/linkage-x87.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 X87LinkageHelperTraits {
   static Register ReturnValueReg() { return eax; }
   static Register ReturnValue2Reg() { return edx; }
   static Register JSCallFunctionReg() { return edi; }
   static Register ContextReg() { return esi; }
   static Register RuntimeCallFunctionReg() { return ebx; }
   static Register RuntimeCallArgCountReg() { return eax; }
   static RegList CCalleeSaveRegisters() {
     return esi.bit() | edi.bit() | ebx.bit();
   }
   static Register CRegisterParameter(int i) { return no_reg; }
   static int CRegisterParametersLength() { return 0; }
+  static int CStackBackingStoreLength() { return 0; }
 };
 
 typedef LinkageHelper<X87LinkageHelperTraits> LH;
 
 CallDescriptor* Linkage::GetJSCallDescriptor(Zone* zone, bool is_osr,
                                              int parameter_count,
                                              CallDescriptor::Flags flags) {
   return LH::GetJSCallDescriptor(zone, is_osr, parameter_count, flags);
 }
 
@@ skipping 17 matching lines @@
 
 
 CallDescriptor* Linkage::GetSimplifiedCDescriptor(Zone* zone,
                                                   const MachineSignature* sig) {
   return LH::GetSimplifiedCDescriptor(zone, sig);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8