Detect simple tail calls

src/compiler/linkage-impl.h

 // 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.
 
 #ifndef V8_COMPILER_LINKAGE_IMPL_H_
 #define V8_COMPILER_LINKAGE_IMPL_H_
 
 #include "src/code-stubs.h"
 #include "src/compiler/osr.h"
 
@@ skipping 197 matching lines @@
       if (i < LinkageTraits::CRegisterParametersLength()) {
         locations.AddParam(regloc(LinkageTraits::CRegisterParameter(i)));
       } else {
         locations.AddParam(stackloc(-1 - i));
       }
     }
 
     // The target for C calls is always an address (i.e. machine pointer).
     MachineType target_type = kMachPtr;
     LinkageLocation target_loc = LinkageLocation::AnyRegister();
-    return new (zone) CallDescriptor(  // --
-        CallDescriptor::kCallAddress,  // kind
-        target_type,                   // target MachineType
-        target_loc,                    // target location
-        msig,                          // machine_sig
-        locations.Build(),             // location_sig
-        0,                             // js_parameter_count
-        Operator::kNoProperties,       // properties
-        LinkageTraits::CCalleeSaveRegisters(), CallDescriptor::kNoFlags,
+    return new (zone) CallDescriptor(           // --
+        CallDescriptor::kCallAddress,           // kind
+        target_type,                            // target MachineType
+        target_loc,                             // target location
+        msig,                                   // machine_sig
+        locations.Build(),                      // location_sig
+        0,                                      // js_parameter_count
+        Operator::kNoProperties,                // properties
+        LinkageTraits::CCalleeSaveRegisters(),  // callee-saved registers
+        CallDescriptor::kNoFlags,               // flags
         "c-call");
   }
 
   static LinkageLocation regloc(Register reg) {
     return LinkageLocation(Register::ToAllocationIndex(reg));
   }
 
   static LinkageLocation stackloc(int i) {
     DCHECK_LT(i, 0);
     return LinkageLocation(i);
@@ skipping 46 matching lines @@
     int parameter_index = 1 + index;  // skip index 0, which is the target.
     return incoming_->GetInputLocation(parameter_index);
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_LINKAGE_IMPL_H_