[turbofan] Add DebugBreak machine operator and support

src/compiler/opcodes.h

 // Copyright 2013 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.
 
 #ifndef V8_COMPILER_OPCODES_H_
 #define V8_COMPILER_OPCODES_H_
 
 #include <iosfwd>
 
 // Opcodes for control operators.
 #define CONTROL_OP_LIST(V) \
   V(Start)                 \
   V(Loop)                  \
   V(Branch)                \
   V(Switch)                \
   V(IfTrue)                \
   V(IfFalse)               \
   V(IfSuccess)             \
   V(IfException)           \
   V(IfValue)               \
   V(IfDefault)             \
   V(Merge)                 \
+  V(DebugBreak)            \

[Michael Starzinger, 2016/05/19 08:42:11]

As discussed offline: Could this be turned into a machine operator instead of a
control operator? Otherwise we need to handle it in all control flow analysis
phases (e.g. scheduler and friends).

[danno, 2016/05/19 08:46:48]

Done.

   V(Deoptimize)            \
   V(DeoptimizeIf)          \
   V(DeoptimizeUnless)      \
   V(Return)                \
   V(TailCall)              \
   V(Terminate)             \
   V(OsrNormalEntry)        \
   V(OsrLoopEntry)          \
   V(Throw)                 \
   V(End)
@@ skipping 590 matching lines @@
   }
 };
 
 std::ostream& operator<<(std::ostream&, IrOpcode::Value);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_OPCODES_H_