[Interpreter] Enable tracing of bytecode handler dispatches.

src/interpreter/interpreter-assembler.cc

 // Copyright 2015 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.
 
 #include "src/interpreter/interpreter-assembler.h"
 
+#include <limits>
 #include <ostream>
 
 #include "src/code-factory.h"
 #include "src/frames.h"
 #include "src/interface-descriptors.h"
 #include "src/interpreter/bytecodes.h"
 #include "src/interpreter/interpreter.h"
 #include "src/machine-type.h"
 #include "src/macro-assembler.h"
 #include "src/zone.h"
@@ skipping 514 matching lines @@
   DispatchTo(Advance(Bytecodes::Size(bytecode_, operand_scale_)));
 }
 
 void InterpreterAssembler::DispatchTo(Node* new_bytecode_offset) {
   Node* target_bytecode = Load(
       MachineType::Uint8(), BytecodeArrayTaggedPointer(), new_bytecode_offset);
   if (kPointerSize == 8) {
     target_bytecode = ChangeUint32ToUint64(target_bytecode);
   }
 
+  if (FLAG_trace_ignition_dispatches) {
+    TraceBytecodeDispatch(target_bytecode);
+  }
+
   // TODO(rmcilroy): Create a code target dispatch table to avoid conversion
   // from code object on every dispatch.
   Node* target_code_object =
       Load(MachineType::Pointer(), DispatchTableRawPointer(),
            WordShl(target_bytecode, IntPtrConstant(kPointerSizeLog2)));
 
   DispatchToBytecodeHandler(target_code_object, new_bytecode_offset);
 }
 
 void InterpreterAssembler::DispatchToBytecodeHandler(Node* handler,
@@ skipping 16 matching lines @@
   //
   //   Indices 0-255 correspond to bytecodes with operand_scale == 0
   //   Indices 256-511 correspond to bytecodes with operand_scale == 1
   //   Indices 512-767 correspond to bytecodes with operand_scale == 2
   Node* next_bytecode_offset = Advance(1);
   Node* next_bytecode = Load(MachineType::Uint8(), BytecodeArrayTaggedPointer(),
                              next_bytecode_offset);
   if (kPointerSize == 8) {
     next_bytecode = ChangeUint32ToUint64(next_bytecode);
   }
+
+  if (FLAG_trace_ignition_dispatches) {
+    TraceBytecodeDispatch(next_bytecode);
+  }
+
   Node* base_index;
   switch (operand_scale) {
     case OperandScale::kDouble:
       base_index = IntPtrConstant(1 << kBitsPerByte);
       break;
     case OperandScale::kQuadruple:
       base_index = IntPtrConstant(2 << kBitsPerByte);
       break;
     default:
       UNREACHABLE();
@@ skipping 63 matching lines @@
   Bind(&match);
   Goto(&end);
   Bind(&end);
 }
 
 void InterpreterAssembler::TraceBytecode(Runtime::FunctionId function_id) {
   CallRuntime(function_id, GetContext(), BytecodeArrayTaggedPointer(),
               SmiTag(BytecodeOffset()), GetAccumulator());
 }
 
+void InterpreterAssembler::TraceBytecodeDispatch(Node* target_bytecode) {
+  Node* counters_table = ExternalConstant(
+      ExternalReference::interpreter_dispatch_counters(isolate()));
+  Node* source_bytecode_table_index = IntPtrConstant(
+      static_cast<int>(bytecode_) * (static_cast<int>(Bytecode::kLast) + 1));
+
+  Node* counter_offset =
+      WordShl(IntPtrAdd(source_bytecode_table_index, target_bytecode),
+              IntPtrConstant(kPointerSizeLog2));
+  Node* old_counter =
+      Load(MachineType::IntPtr(), counters_table, counter_offset);
+
+  CodeStubAssembler::Label counter_ok(this);
+  CodeStubAssembler::Label counter_saturated(this);
+  CodeStubAssembler::Label end(this);
+
+  Node* counter_reached_max = WordEqual(
+      old_counter, IntPtrConstant(std::numeric_limits<uintptr_t>::max()));
+  Branch(counter_reached_max, &counter_saturated, &counter_ok);
+  Bind(&counter_ok);
+  Node* new_counter = IntPtrAdd(old_counter, IntPtrConstant(1));
+  StoreNoWriteBarrier(MachineType::PointerRepresentation(), counters_table,
+                      counter_offset, new_counter);
+  Goto(&end);
+  Bind(&counter_saturated);
+  Goto(&end);
+  Bind(&end);
+}
+
 // static
 bool InterpreterAssembler::TargetSupportsUnalignedAccess() {
 #if V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
   return false;
 #elif V8_TARGET_ARCH_ARM || V8_TARGET_ARCH_ARM64 || V8_TARGET_ARCH_PPC
   return CpuFeatures::IsSupported(UNALIGNED_ACCESSES);
 #elif V8_TARGET_ARCH_IA32 || V8_TARGET_ARCH_X64 || V8_TARGET_ARCH_X87 || \
     V8_TARGET_ARCH_S390
   return true;
 #else
 #error "Unknown Architecture"
 #endif
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8