Introduce Diamond, a helper for building diamond-shaped control patterns.

tools/gyp/v8.gyp

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 393 matching lines @@
         '../../src/compiler/code-generator-impl.h',
         '../../src/compiler/code-generator.cc',
         '../../src/compiler/code-generator.h',
         '../../src/compiler/common-node-cache.h',
         '../../src/compiler/common-operator.cc',
         '../../src/compiler/common-operator.h',
         '../../src/compiler/control-builders.cc',
         '../../src/compiler/control-builders.h',
         '../../src/compiler/control-reducer.cc',
         '../../src/compiler/control-reducer.h',
+        '../../src/compiler/diamond.h',
         '../../src/compiler/frame.h',
         '../../src/compiler/gap-resolver.cc',
         '../../src/compiler/gap-resolver.h',
         '../../src/compiler/generic-algorithm-inl.h',
         '../../src/compiler/generic-algorithm.h',
         '../../src/compiler/generic-graph.h',
         '../../src/compiler/generic-node-inl.h',
         '../../src/compiler/generic-node.h',
         '../../src/compiler/graph-builder.cc',
         '../../src/compiler/graph-builder.h',
@@ skipping 1307 matching lines @@
         }],
         ['v8_compress_startup_data=="bz2"', {
           'libraries': [
             '-lbz2',
           ]
         }],
       ],
     },
   ],
 }