[interpreter, debugger] support debug breaks via bytecode array copy

src/arm/builtins-arm.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_ARM
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 843 matching lines @@
   // Open a frame scope to indicate that there is a frame on the stack.  The
   // MANUAL indicates that the scope shouldn't actually generate code to set up
   // the frame (that is done below).
   FrameScope frame_scope(masm, StackFrame::MANUAL);
   __ PushFixedFrame(r1);
   __ add(fp, sp, Operand(StandardFrameConstants::kFixedFrameSizeFromFp));
 
   // Get the bytecode array from the function object and load the pointer to the
   // first entry into kInterpreterBytecodeRegister.
   __ ldr(r0, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
+  Register debug_info = kInterpreterBytecodeArrayRegister;
+  DCHECK(!debug_info.is(r0));
+  __ ldr(debug_info, FieldMemOperand(r0, SharedFunctionInfo::kDebugInfoOffset));
+  __ cmp(debug_info, Operand(DebugInfo::uninitialized()));
+  // Load original bytecode array or the debug copy.
   __ ldr(kInterpreterBytecodeArrayRegister,
-         FieldMemOperand(r0, SharedFunctionInfo::kFunctionDataOffset));
+         FieldMemOperand(r0, SharedFunctionInfo::kFunctionDataOffset), eq);
+  __ ldr(kInterpreterBytecodeArrayRegister,
+         FieldMemOperand(debug_info, DebugInfo::kAbstractCodeIndex), ne);
 
   if (FLAG_debug_code) {
     // Check function data field is actually a BytecodeArray object.
     __ SmiTst(kInterpreterBytecodeArrayRegister);
     __ Assert(ne, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
     __ CompareObjectType(kInterpreterBytecodeArrayRegister, r0, no_reg,
                          BYTECODE_ARRAY_TYPE);
     __ Assert(eq, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
   }
 
@@ skipping 1682 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM