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

src/mips/builtins-mips.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_MIPS
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 836 matching lines @@
   // 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);
 
   __ Push(ra, fp, cp, a1);
   __ Addu(fp, sp, Operand(StandardFrameConstants::kFixedFrameSizeFromFp));
 
   // Get the bytecode array from the function object and load the pointer to the
   // first entry into kInterpreterBytecodeRegister.
   __ lw(a0, FieldMemOperand(a1, JSFunction::kSharedFunctionInfoOffset));
+  Label load_debug_bytecode_array, bytecode_array_loaded;
+  Register debug_info = kInterpreterBytecodeArrayRegister;
+  DCHECK(!debug_info.is(a0));
+  __ lw(debug_info, FieldMemOperand(a0, SharedFunctionInfo::kDebugInfoOffset));
+  __ Branch(&load_debug_bytecode_array, ne, debug_info,
+            Operand(DebugInfo::uninitialized()));
   __ lw(kInterpreterBytecodeArrayRegister,
         FieldMemOperand(a0, SharedFunctionInfo::kFunctionDataOffset));
+  __ bind(&bytecode_array_loaded);
 
   if (FLAG_debug_code) {
     // Check function data field is actually a BytecodeArray object.
     __ SmiTst(kInterpreterBytecodeArrayRegister, t0);
     __ Assert(ne, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry, t0,
               Operand(zero_reg));
     __ GetObjectType(kInterpreterBytecodeArrayRegister, t0, t0);
     __ Assert(eq, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry, t0,
               Operand(BYTECODE_ARRAY_TYPE));
   }
@@ skipping 51 matching lines @@
   __ lbu(a0, MemOperand(a0));
   __ Lsa(at, kInterpreterDispatchTableRegister, a0, kPointerSizeLog2);
   __ lw(at, MemOperand(at));
   // TODO(rmcilroy): Make dispatch table point to code entrys to avoid untagging
   // and header removal.
   __ Addu(at, at, Operand(Code::kHeaderSize - kHeapObjectTag));
   __ Call(at);
 
   // Even though the first bytecode handler was called, we will never return.
   __ Abort(kUnexpectedReturnFromBytecodeHandler);
+
+  // Load debug copy of the bytecode array.
+  __ bind(&load_debug_bytecode_array);
+  __ lw(kInterpreterBytecodeArrayRegister,
+        FieldMemOperand(debug_info, DebugInfo::kAbstractCodeIndex));
+  __ Branch(&bytecode_array_loaded);
 }
 
 
 void Builtins::Generate_InterpreterExitTrampoline(MacroAssembler* masm) {
   // TODO(rmcilroy): List of things not currently dealt with here but done in
   // fullcodegen's EmitReturnSequence.
   //  - Supporting FLAG_trace for Runtime::TraceExit.
   //  - Support profiler (specifically decrementing profiling_counter
   //    appropriately and calling out to HandleInterrupts if necessary).
 
@@ skipping 1701 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS