[crankshaft] Support inlining of function calls in tail position (in ES6 sense).

src/crankshaft/lithium.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.
 
 #include "src/crankshaft/lithium.h"
 
 #include "src/ast/scopes.h"
 
 #if V8_TARGET_ARCH_IA32
 #include "src/crankshaft/ia32/lithium-ia32.h"  // NOLINT
@@ skipping 509 matching lines @@
 LEnvironment* LChunkBuilderBase::CreateEnvironment(
     HEnvironment* hydrogen_env, int* argument_index_accumulator,
     ZoneList<HValue*>* objects_to_materialize) {
   if (hydrogen_env == NULL) return NULL;
 
   LEnvironment* outer =
       CreateEnvironment(hydrogen_env->outer(), argument_index_accumulator,
                         objects_to_materialize);
   BailoutId ast_id = hydrogen_env->ast_id();
   DCHECK(!ast_id.IsNone() ||
          hydrogen_env->frame_type() != JS_FUNCTION);

[Michael Starzinger, 2016/03/21 14:06:50]

nit: I think this DCHECK can be made stronger ...

DCHECK(!ast_id.IsNone() ||
       (hydrogen_env->frame_type() != JS_FUNCTION &&
        hydrogen_env->frame_type() != TAIL_CALLER_FUNCTION));

[Igor Sheludko, 2016/03/22 14:08:37]

Done.

 
+  if (hydrogen_env->frame_type() == TAIL_CALLER_FUNCTION) {
+    return new (zone())
+        LEnvironment(hydrogen_env->closure(), hydrogen_env->frame_type(),
+                     ast_id, 0, 0, 0, outer, hydrogen_env->entry(), zone());
+  }
+
   int omitted_count = (hydrogen_env->frame_type() == JS_FUNCTION)
                           ? 0
                           : hydrogen_env->specials_count();
 
   int value_count = hydrogen_env->length() - omitted_count;
   LEnvironment* result =
       new(zone()) LEnvironment(hydrogen_env->closure(),
                                hydrogen_env->frame_type(),
                                ast_id,
                                hydrogen_env->parameter_count(),
@@ skipping 115 matching lines @@
 
 LPhase::~LPhase() {
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceLithium(name(), chunk_);
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8