[WIP][turbofan] Instruction scheduler for Turbofan.

src/compiler/ppc/instruction-scheduler-ppc.cc

+// Copyright 2015 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/compiler/instruction-scheduler.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+

[Jarin, 2015/12/02 08:27:49]

I am wondering whether it would not be better if we had something like

bool InstructionScheduler::SchedulerSupported() { return false; }

and then query this method in the instruction selector (in addition to checking
the flag). That way, when we flip the flag to enable scheduling, it will not
blow up on the architectures that do not support scheduling.

What do you think?

+int InstructionScheduler::GetTargetInstructionFlags(
+    const Instruction* instr) const {
+  UNIMPLEMENTED();
+}
+
+
+int InstructionScheduler::GetInstructionLatency(const Instruction* instr) {
+  UNIMPLEMENTED();
+}
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8