Detect simple tail calls

src/compiler/linkage.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/code-stubs.h"
 #include "src/compiler.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/node.h"
 #include "src/compiler/pipeline.h"
 #include "src/scopes.h"
@@ skipping 16 matching lines @@
       break;
   }
   return os;
 }
 
 
 std::ostream& operator<<(std::ostream& os, const CallDescriptor& d) {
   // TODO(svenpanne) Output properties etc. and be less cryptic.
   return os << d.kind() << ":" << d.debug_name() << ":r" << d.ReturnCount()
             << "j" << d.JSParameterCount() << "i" << d.InputCount() << "f"
-            << d.FrameStateCount();
+            << d.FrameStateCount() << "t" << d.SupportsTailCalls();
 }
 
 
+bool CallDescriptor::HasSameReturnLocationsAs(
+    const CallDescriptor* other) const {
+  if (ReturnCount() != other->ReturnCount()) return false;
+  for (size_t i = 0; i < ReturnCount(); ++i) {
+    if (GetReturnLocation(i) != other->GetReturnLocation(i)) return false;
+  }
+  return true;
+}
+
+
 CallDescriptor* Linkage::ComputeIncoming(Zone* zone, CompilationInfo* info) {
   if (info->code_stub() != NULL) {
     // Use the code stub interface descriptor.
     CallInterfaceDescriptor descriptor =
         info->code_stub()->GetCallInterfaceDescriptor();
     return GetStubCallDescriptor(info->isolate(), zone, descriptor, 0,
                                  CallDescriptor::kNoFlags,
                                  Operator::kNoProperties);
   }
   if (info->function() != NULL) {
@@ skipping 83 matching lines @@
 
   // Most inlined runtime functions (except the ones listed above) can be called
   // without a FrameState or will be lowered by JSIntrinsicLowering internally.
   const Runtime::Function* const f = Runtime::FunctionForId(function);
   if (f->intrinsic_type == Runtime::IntrinsicType::INLINE) return false;
 
   return true;
 }
 
 
+bool CallDescriptor::UsesOnlyRegisters() const {
+  for (size_t i = 0; i < InputCount(); ++i) {
+    if (!GetInputLocation(i).is_register()) return false;
+  }
+  for (size_t i = 0; i < ReturnCount(); ++i) {
+    if (!GetReturnLocation(i).is_register()) return false;
+  }
+  return true;
+}
+
+
 //==============================================================================
 // Provide unimplemented methods on unsupported architectures, to at least link.
 //==============================================================================
 #if !V8_TURBOFAN_BACKEND
 CallDescriptor* Linkage::GetJSCallDescriptor(Zone* zone, bool is_osr,
                                              int parameter_count,
                                              CallDescriptor::Flags flags) {
   UNIMPLEMENTED();
   return NULL;
 }
@@ skipping 24 matching lines @@
 
 CallDescriptor* Linkage::GetSimplifiedCDescriptor(Zone* zone,
                                                   const MachineSignature* sig) {
   UNIMPLEMENTED();
   return NULL;
 }
 #endif  // !V8_TURBOFAN_BACKEND
 }
 }
 }  // namespace v8::internal::compiler