Add a HBreak instruction for debugging

src/arm/lithium-codegen-arm.cc

 // 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 2180 matching lines @@
     __ b(NegateCondition(cc), chunk_->GetAssemblyLabel(right_block));
   } else if (right_block == next_block) {
     __ b(cc, chunk_->GetAssemblyLabel(left_block));
   } else {
     __ b(cc, chunk_->GetAssemblyLabel(left_block));
     __ b(chunk_->GetAssemblyLabel(right_block));
   }
 }
 
 
+void LCodeGen::DoDebugBreak(LDebugBreak* instr) {
+  __ stop("LBreak");
+}
+
+
 void LCodeGen::DoBranch(LBranch* instr) {
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
   Representation r = instr->hydrogen()->value()->representation();
   if (r.IsInteger32()) {
     Register reg = ToRegister(instr->value());
     __ cmp(reg, Operand::Zero());
     EmitBranch(true_block, false_block, ne);
   } else if (r.IsDouble()) {
@@ skipping 3694 matching lines @@
   __ sub(scratch, result, Operand(index, LSL, kPointerSizeLog2 - kSmiTagSize));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal