Profiler experiments: interrupt check at function exit

src/ia32/full-codegen-ia32.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 314 matching lines @@
 
 void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt,
                                        Label* back_edge_target) {
   Comment cmnt(masm_, "[ Stack check");
   Label ok;
 
   if (FLAG_count_based_interrupts) {
     int weight = 1;
     if (FLAG_weighted_back_edges) {
       ASSERT(back_edge_target->is_bound());
-      int distance = masm_->pc_offset() - back_edge_target->pos();
+      int distance = masm_->SizeOfCodeGeneratedSince(back_edge_target);
       weight = Min(127, Max(1, distance / 100));
     }
     __ sub(Operand::Cell(profiling_counter_), Immediate(Smi::FromInt(weight)));
     __ j(positive, &ok, Label::kNear);
     InterruptStub stub;
     __ CallStub(&stub);
   } else {
     // Count based interrupts happen often enough when they are enabled
     // that the additional stack checks are not necessary (they would
     // only check for interrupts).
@@ skipping 36 matching lines @@
   Comment cmnt(masm_, "[ Return sequence");
   if (return_label_.is_bound()) {
     __ jmp(&return_label_);
   } else {
     // Common return label
     __ bind(&return_label_);
     if (FLAG_trace) {
       __ push(eax);
       __ CallRuntime(Runtime::kTraceExit, 1);
     }
+    if (FLAG_interrupt_at_exit) {
+      // Pretend that the exit is a backwards jump to the entry.
+      int weight = 1;
+      if (FLAG_weighted_back_edges) {
+        int distance = masm_->pc_offset();
+        weight = Min(127, Max(1, distance / 100));
+      }
+      __ sub(Operand::Cell(profiling_counter_),
+             Immediate(Smi::FromInt(weight)));
+      Label ok;
+      __ j(positive, &ok, Label::kNear);
+      __ push(eax);
+      InterruptStub stub;
+      __ CallStub(&stub);
+      __ pop(eax);
+      // Reset the countdown.
+      __ mov(Operand::Cell(profiling_counter_),
+             Immediate(Smi::FromInt(FLAG_interrupt_budget)));
+      __ bind(&ok);
+    }
 #ifdef DEBUG
     // Add a label for checking the size of the code used for returning.
     Label check_exit_codesize;
     masm_->bind(&check_exit_codesize);
 #endif
     SetSourcePosition(function()->end_position() - 1);
     __ RecordJSReturn();
     // Do not use the leave instruction here because it is too short to
     // patch with the code required by the debugger.
     __ mov(esp, ebp);
@@ skipping 4035 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32