[crankshaft] Added checks to tail call instructions that we don't have to restore caller doubles.

src/crankshaft/ppc/lithium-codegen-ppc.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/crankshaft/ppc/lithium-codegen-ppc.h"
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/crankshaft/hydrogen-osr.h"
@@ skipping 3333 matching lines @@
   __ ShiftLeftImm(r0, length, Operand(kPointerSizeLog2));
   __ LoadPX(scratch, MemOperand(elements, r0));
   __ push(scratch);
   __ addi(length, length, Operand(-1));
   __ bdnz(&loop);
 
   __ bind(&invoke);
 
   InvokeFlag flag = CALL_FUNCTION;
   if (instr->hydrogen()->tail_call_mode() == TailCallMode::kAllow) {
+    DCHECK(!info()->saves_caller_doubles());
     // TODO(ishell): drop current frame before pushing arguments to the stack.
     flag = JUMP_FUNCTION;
     ParameterCount actual(r3);
     // It is safe to use r6, r7 and r8 as scratch registers here given that
     // 1) we are not going to return to caller function anyway,
     // 2) r6 (new.target) will be initialized below.
     PrepareForTailCall(actual, r6, r7, r8);
   }
 
   DCHECK(instr->HasPointerMap());
@@ skipping 470 matching lines @@
 
 void LCodeGen::DoInvokeFunction(LInvokeFunction* instr) {
   HInvokeFunction* hinstr = instr->hydrogen();
   DCHECK(ToRegister(instr->context()).is(cp));
   DCHECK(ToRegister(instr->function()).is(r4));
   DCHECK(instr->HasPointerMap());
 
   bool is_tail_call = hinstr->tail_call_mode() == TailCallMode::kAllow;
 
   if (is_tail_call) {
+    DCHECK(!info()->saves_caller_doubles());
     ParameterCount actual(instr->arity());
     // It is safe to use r6, r7 and r8 as scratch registers here given that
     // 1) we are not going to return to caller function anyway,
     // 2) r6 (new.target) will be initialized below.
     PrepareForTailCall(actual, r6, r7, r8);
   }
 
   Handle<JSFunction> known_function = hinstr->known_function();
   if (known_function.is_null()) {
     LPointerMap* pointers = instr->pointer_map();
@@ skipping 1906 matching lines @@
 
 void LCodeGen::DoStoreFrameContext(LStoreFrameContext* instr) {
   Register context = ToRegister(instr->context());
   __ StoreP(context, MemOperand(fp, StandardFrameConstants::kContextOffset));
 }
 
 
 #undef __
 }  // namespace internal
 }  // namespace v8