PPC: [crankshaft] Support ES6 tail call elimination.

src/ppc/macro-assembler-ppc.h

Index: src/ppc/macro-assembler-ppc.h
diff --git a/src/ppc/macro-assembler-ppc.h b/src/ppc/macro-assembler-ppc.h
index d9dbd568273f6abca6f7c76e48d5897af5f076eb..8cd9cf8c205755a55e2c0f9e5ccfbe074a398fa1 100644
--- a/src/ppc/macro-assembler-ppc.h
+++ b/src/ppc/macro-assembler-ppc.h
@@ -156,12 +156,6 @@ class MacroAssembler : public Assembler {
 
   void Call(Label* target);
 
-  // Emit call to the code we are currently generating.
-  void CallSelf() {
-    Handle<Code> self(reinterpret_cast<Code**>(CodeObject().location()));
-    Call(self, RelocInfo::CODE_TARGET);
-  }
-
   // Register move. May do nothing if the registers are identical.
   void Move(Register dst, Smi* smi) { LoadSmiLiteral(dst, smi); }
   void Move(Register dst, Handle<Object> value);
@@ -564,6 +558,15 @@ class MacroAssembler : public Assembler {
   // ---------------------------------------------------------------------------
   // JavaScript invokes
 
+  // Removes current frame and its arguments from the stack preserving
+  // the arguments and a return address pushed to the stack for the next call.
+  // Both |callee_args_count| and |caller_args_count_reg| do not include
+  // receiver. |callee_args_count| is not modified, |caller_args_count_reg|
+  // is trashed.
+  void PrepareForTailCall(const ParameterCount& callee_args_count,
+                          Register caller_args_count_reg, Register scratch0,
+                          Register scratch1);
+
   // Invoke the JavaScript function code by either calling or jumping.
   void InvokeFunctionCode(Register function, Register new_target,
                           const ParameterCount& expected,