[turbofan] Enable tail calls for %_CallFunction.

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 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/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/scopes.h"
@@ skipping 520 matching lines @@
     }                                                            \
   } while (false)
 
 
 void CodeGenerator::AssembleDeconstructActivationRecord() {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   int stack_slots = frame()->GetSpillSlotCount();
   if (descriptor->IsJSFunctionCall() || stack_slots > 0) {
     __ movq(rsp, rbp);
     __ popq(rbp);
-    int32_t bytes_to_pop =
-        descriptor->IsJSFunctionCall()
-            ? static_cast<int32_t>(descriptor->JSParameterCount() *
-                                   kPointerSize)
-            : 0;
-    __ popq(Operand(rsp, bytes_to_pop));
-    __ addq(rsp, Immediate(bytes_to_pop));
   }
 }
 
 
 // Assembles an instruction after register allocation, producing machine code.
 void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
   X64OperandConverter i(this, instr);
 
   switch (ArchOpcodeField::decode(instr->opcode())) {
     case kArchCallCodeObject: {
@@ skipping 1013 matching lines @@
   } else if (descriptor->IsJSFunctionCall() || needs_frame_) {
     // Canonicalize JSFunction return sites for now.
     if (return_label_.is_bound()) {
       __ jmp(&return_label_);
     } else {
       __ bind(&return_label_);
       __ movq(rsp, rbp);  // Move stack pointer back to frame pointer.
       __ popq(rbp);       // Pop caller's frame pointer.
       int pop_count = descriptor->IsJSFunctionCall()
                           ? static_cast<int>(descriptor->JSParameterCount())
-                          : 0;
-      __ Ret(pop_count * kPointerSize, rbx);
+                          : (info()->IsStub()
+                                 ? info()->code_stub()->GetStackParameterCount()
+                                 : 0);
+      if (pop_count == 0) {
+        __ Ret();
+      } else {
+        __ Ret(pop_count * kPointerSize, rbx);
+      }
     }
   } else {
-    __ ret(0);
+    __ Ret();
   }
 }
 
 
 void CodeGenerator::AssembleMove(InstructionOperand* source,
                                  InstructionOperand* destination) {
   X64OperandConverter g(this, NULL);
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister()) {
@@ skipping 178 matching lines @@
       __ Nop(padding_size);
     }
   }
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8