Simplify some code related to x64 calling convention.

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1626 matching lines @@
       __ movq(kScratchRegister, stamp_operand);
       __ cmpq(kScratchRegister, FieldOperand(object,
                                              JSDate::kCacheStampOffset));
       __ j(not_equal, &runtime, Label::kNear);
       __ movq(result, FieldOperand(object, JSDate::kValueOffset +
                                            kPointerSize * index->value()));
       __ jmp(&done);
     }
     __ bind(&runtime);
     __ PrepareCallCFunction(2);
-#ifdef _WIN64
-  __ movq(rcx, object);
-  __ movq(rdx, index, RelocInfo::NONE64);
-#else
-  __ movq(rdi, object);
-  __ movq(rsi, index, RelocInfo::NONE64);
-#endif
+    __ movq(arg_reg_1, object);
+    __ movq(arg_reg_2, index, RelocInfo::NONE64);
     __ CallCFunction(ExternalReference::get_date_field_function(isolate()), 2);
     __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
     __ bind(&done);
   }
 }
 
 
 void LCodeGen::DoSeqStringSetChar(LSeqStringSetChar* instr) {
   SeqStringSetCharGenerator::Generate(masm(),
                                       instr->encoding(),
@@ skipping 1975 matching lines @@
   __ sqrtsd(input_reg, input_reg);
   __ bind(&done);
 }
 
 
 void LCodeGen::DoPower(LPower* instr) {
   Representation exponent_type = instr->hydrogen()->right()->representation();
   // Having marked this as a call, we can use any registers.
   // Just make sure that the input/output registers are the expected ones.
 
-  // Choose register conforming to calling convention (when bailing out).
-#ifdef _WIN64
   Register exponent = rdx;
-#else
-  Register exponent = rdi;
-#endif
   ASSERT(!instr->right()->IsRegister() ||
          ToRegister(instr->right()).is(exponent));
   ASSERT(!instr->right()->IsDoubleRegister() ||
          ToDoubleRegister(instr->right()).is(xmm1));
   ASSERT(ToDoubleRegister(instr->left()).is(xmm2));
   ASSERT(ToDoubleRegister(instr->result()).is(xmm3));
 
   if (exponent_type.IsTagged()) {
     Label no_deopt;
     __ JumpIfSmi(exponent, &no_deopt);
@@ skipping 2022 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64