[es6] Further fixing of tail Calls.

src/full-codegen/x64/full-codegen-x64.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 371 matching lines @@
   }
   __ bind(&ok);
 
   PrepareForBailoutForId(stmt->EntryId(), NO_REGISTERS);
   // Record a mapping of the OSR id to this PC.  This is used if the OSR
   // entry becomes the target of a bailout.  We don't expect it to be, but
   // we want it to work if it is.
   PrepareForBailoutForId(stmt->OsrEntryId(), NO_REGISTERS);
 }
 
+void FullCodeGenerator::EmitProfilingCounterHandlingForReturnSequence(
+    bool is_tail_call) {
+  // Pretend that the exit is a backwards jump to the entry.
+  int weight = 1;
+  if (info_->ShouldSelfOptimize()) {
+    weight = FLAG_interrupt_budget / FLAG_self_opt_count;
+  } else {
+    int distance = masm_->pc_offset();
+    weight = Min(kMaxBackEdgeWeight, Max(1, distance / kCodeSizeMultiplier));
+  }
+  EmitProfilingCounterDecrement(weight);
+  Label ok;
+  __ j(positive, &ok, Label::kNear);
+  // Don't need to save result register if we are going to do a tail call.
+  if (!is_tail_call) {
+    __ Push(rax);
+  }
+  __ call(isolate()->builtins()->InterruptCheck(), RelocInfo::CODE_TARGET);
+  if (!is_tail_call) {
+    __ Pop(rax);
+  }
+  EmitProfilingCounterReset();
+  __ bind(&ok);
+}
 
 void FullCodeGenerator::EmitReturnSequence() {
   Comment cmnt(masm_, "[ Return sequence");
   if (return_label_.is_bound()) {
     __ jmp(&return_label_);
   } else {
     __ bind(&return_label_);
     if (FLAG_trace) {
       __ Push(rax);
       __ CallRuntime(Runtime::kTraceExit);
     }
-    // Pretend that the exit is a backwards jump to the entry.
-    int weight = 1;
-    if (info_->ShouldSelfOptimize()) {
-      weight = FLAG_interrupt_budget / FLAG_self_opt_count;
-    } else {
-      int distance = masm_->pc_offset();
-      weight = Min(kMaxBackEdgeWeight,
-                   Max(1, distance / kCodeSizeMultiplier));
-    }
-    EmitProfilingCounterDecrement(weight);
-    Label ok;
-    __ j(positive, &ok, Label::kNear);
-    __ Push(rax);
-    __ call(isolate()->builtins()->InterruptCheck(),
-            RelocInfo::CODE_TARGET);
-    __ Pop(rax);
-    EmitProfilingCounterReset();
-    __ bind(&ok);
+    EmitProfilingCounterHandlingForReturnSequence(false);
 
     SetReturnPosition(literal());
     __ leave();
 
     int arg_count = info_->scope()->num_parameters() + 1;
     int arguments_bytes = arg_count * kPointerSize;
     __ Ret(arguments_bytes, rcx);
   }
 }
 
@@ skipping 2188 matching lines @@
 void FullCodeGenerator::EmitCall(Call* expr, ConvertReceiverMode mode) {
   // Load the arguments.
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
     VisitForStackValue(args->at(i));
   }
 
   PrepareForBailoutForId(expr->CallId(), NO_REGISTERS);
   SetCallPosition(expr);
+  if (expr->tail_call_mode() == TailCallMode::kAllow) {
+    if (FLAG_trace) {
+      __ CallRuntime(Runtime::kTraceTailCall);
+    }
+    // Update profiling counters before the tail call since we will
+    // not return to this function.
+    EmitProfilingCounterHandlingForReturnSequence(true);
+  }
   Handle<Code> ic =
       CodeFactory::CallIC(isolate(), arg_count, mode, expr->tail_call_mode())
           .code();
   __ Move(rdx, SmiFromSlot(expr->CallFeedbackICSlot()));
   __ movp(rdi, Operand(rsp, (arg_count + 1) * kPointerSize));
   // Don't assign a type feedback id to the IC, since type feedback is provided
   // by the vector above.
   CallIC(ic);
 
   RecordJSReturnSite(expr);
@@ skipping 1953 matching lines @@
   DCHECK_EQ(isolate->builtins()->OsrAfterStackCheck()->entry(),
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64