[interpreter] Add support for scalable operands.

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index a7bce4083b90c8ed2915d926be4401851258f72d..44342376e57e436b3767331ecc77df1b201091d2 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -222,6 +222,10 @@ BreakLocation::BytecodeArrayIterator::GetDebugBreakType() {
   BytecodeArray* bytecode_array = debug_info_->original_bytecode_array();
   interpreter::Bytecode bytecode =
       interpreter::Bytecodes::FromByte(bytecode_array->get(code_offset()));
+  if (interpreter::Bytecodes::GetPrefixBytecodeScale(bytecode) > 1) {

[rmcilroy, 2016/03/10 16:45:37]

Could you pull out the logic for getting the current bytecode and operand scale
to a helper function and use that throughout.

[oth, 2016/03/11 16:26:12]

Done.

+    bytecode = interpreter::Bytecodes::FromByte(
+        bytecode_array->get(code_offset() + 1));
+  }
 
   if (bytecode == interpreter::Bytecode::kDebugger) {
     return DEBUGGER_STATEMENT;
@@ -421,9 +425,17 @@ void BreakLocation::SetDebugBreak() {
     BytecodeArray* bytecode_array = abstract_code()->GetBytecodeArray();
     interpreter::Bytecode bytecode =
         interpreter::Bytecodes::FromByte(bytecode_array->get(code_offset()));
+    int prefix_offset = 0;
+    int operand_scale =
+        interpreter::Bytecodes::GetPrefixBytecodeScale(bytecode);
+    if (operand_scale > 1) {
+      prefix_offset = 1;
+      bytecode = interpreter::Bytecodes::FromByte(
+          bytecode_array->get(code_offset() + prefix_offset));
+    }
     interpreter::Bytecode debugbreak =
-        interpreter::Bytecodes::GetDebugBreak(bytecode);
-    bytecode_array->set(code_offset(),
+        interpreter::Bytecodes::GetDebugBreak(bytecode, operand_scale);
+    bytecode_array->set(code_offset() + prefix_offset,
                         interpreter::Bytecodes::ToByte(debugbreak));
   }
   DCHECK(IsDebugBreak());
@@ -443,7 +455,11 @@ void BreakLocation::ClearDebugBreak() {
   } else {
     BytecodeArray* bytecode_array = abstract_code()->GetBytecodeArray();
     BytecodeArray* original = debug_info_->original_bytecode_array();
-    bytecode_array->set(code_offset(), original->get(code_offset()));
+    int operand_scale = interpreter::Bytecodes::GetPrefixBytecodeScale(
+        interpreter::Bytecodes::FromByte(original->get(code_offset())));
+    int prefix_offset = operand_scale > 1 ? 1 : 0;
+    bytecode_array->set(code_offset() + prefix_offset,
+                        original->get(code_offset() + prefix_offset));
   }
   DCHECK(!IsDebugBreak());
 }
@@ -461,6 +477,10 @@ bool BreakLocation::IsDebugBreak() const {
     BytecodeArray* bytecode_array = abstract_code()->GetBytecodeArray();
     interpreter::Bytecode bytecode =
         interpreter::Bytecodes::FromByte(bytecode_array->get(code_offset()));
+    if (interpreter::Bytecodes::GetPrefixBytecodeScale(bytecode) > 1) {
+      bytecode = interpreter::Bytecodes::FromByte(
+          bytecode_array->get(code_offset()) + 1);
+    }
     return interpreter::Bytecodes::IsDebugBreak(bytecode);
   }
 }
@@ -1593,7 +1613,13 @@ Object* Debug::SetAfterBreakTarget(JavaScriptFrame* frame) {
     int bytecode_offset = interpreted_frame->GetBytecodeOffset();
     interpreter::Bytecode bytecode =
         interpreter::Bytecodes::FromByte(bytecode_array->get(bytecode_offset));
-    return isolate_->interpreter()->GetBytecodeHandler(bytecode);
+    int operand_scale =
+        interpreter::Bytecodes::GetPrefixBytecodeScale(bytecode);
+    if (operand_scale > 1) {
+      interpreter::Bytecodes::FromByte(
+          bytecode_array->get(bytecode_offset + 1));
+    }
+    return isolate_->interpreter()->GetBytecodeHandler(bytecode, operand_scale);
   } else {
     after_break_target_ = NULL;
     if (!LiveEdit::SetAfterBreakTarget(this)) {