Reland: Introducing the LLVM greedy register allocator.

src/compiler/pipeline.cc

Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index c165fbdb6e9d62fd395867081a982f6618e64cb0..30b9fe3512238dc2408fe0d583023f05fba82db4 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -244,8 +244,13 @@ class PipelineData {
     DCHECK(!register_allocator_);
     DCHECK(!frame_);
     frame_ = new (instruction_zone()) Frame();
-    register_allocator_ = new (instruction_zone())
-        RegisterAllocator(config, local_zone, frame(), sequence(), debug_name);
+    if (FLAG_turbo_greedy_regalloc) {
+      register_allocator_ = new (instruction_zone())
+          GreedyAllocator(config, local_zone, frame(), sequence(), debug_name);
+    } else {
+      register_allocator_ = new (instruction_zone()) LinearScanAllocator(
+          config, local_zone, frame(), sequence(), debug_name);
+    }
   }
 
  private: