Do not eagerly update allow_osr_at_loop_nesting_level.

src/runtime-profiler.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.
 
 #include "src/v8.h"
 
 #include "src/runtime-profiler.h"
 
 #include "src/assembler.h"
 #include "src/bootstrapper.h"
@@ skipping 92 matching lines @@
     }
     ASSERT(!function->IsInOptimizationQueue());
     function->MarkForConcurrentOptimization();
   } else {
     // The next call to the function will trigger optimization.
     function->MarkForOptimization();
   }
 }
 
 
-void RuntimeProfiler::AttemptOnStackReplacement(JSFunction* function) {
+void RuntimeProfiler::AttemptOnStackReplacement(JSFunction* function,
+                                                int loop_nesting_levels) {
+  SharedFunctionInfo* shared = function->shared();
   // See AlwaysFullCompiler (in compiler.cc) comment on why we need
   // Debug::has_break_points().
   if (!FLAG_use_osr ||
       isolate_->DebuggerHasBreakPoints() ||
       function->IsBuiltin()) {
     return;
   }
 
-  SharedFunctionInfo* shared = function->shared();
+

[Jakob Kummerow, 2014/06/23 15:29:23]

nit: don't need this empty line (why did it move anyway?).

   // If the code is not optimizable, don't try OSR.
   if (!shared->code()->optimizable()) return;
 
   // We are not prepared to do OSR for a function that already has an
   // allocated arguments object.  The optimized code would bypass it for
   // arguments accesses, which is unsound.  Don't try OSR.
   if (shared->uses_arguments()) return;
 
   // We're using on-stack replacement: patch the unoptimized code so that
   // any back edge in any unoptimized frame will trigger on-stack
   // replacement for that frame.
   if (FLAG_trace_osr) {
     PrintF("[OSR - patching back edges in ");
     function->PrintName();
     PrintF("]\n");
   }
 
-  BackEdgeTable::Patch(isolate_, shared->code());
+  for (int i = 0; i < loop_nesting_levels; i++) {
+    BackEdgeTable::Patch(isolate_, shared->code());
+  }
 }
 
 
 void RuntimeProfiler::OptimizeNow() {
   HandleScope scope(isolate_);
 
   if (isolate_->DebuggerHasBreakPoints()) return;
 
   DisallowHeapAllocation no_gc;
 
@@ skipping 17 matching lines @@
       SharedFunctionInfo* shared_function_info = functions[i]->shared();
       int ticks = shared_function_info->profiler_ticks();
       if (ticks < Smi::kMaxValue) {
         shared_function_info->set_profiler_ticks(ticks + 1);
       }
     }
 
     if (shared_code->kind() != Code::FUNCTION) continue;
     if (function->IsInOptimizationQueue()) continue;
 
-    if (FLAG_always_osr &&
-        shared_code->allow_osr_at_loop_nesting_level() == 0) {
-      // Testing mode: always try an OSR compile for every function.
-      for (int i = 0; i < Code::kMaxLoopNestingMarker; i++) {
-        // TODO(titzer): fix AttemptOnStackReplacement to avoid this dumb loop.
-        shared_code->set_allow_osr_at_loop_nesting_level(i);
-        AttemptOnStackReplacement(function);
-      }
+    if (FLAG_always_osr) {
+      AttemptOnStackReplacement(function, Code::kMaxLoopNestingMarker);
       // Fall through and do a normal optimized compile as well.
     } else if (!frame->is_optimized() &&
         (function->IsMarkedForOptimization() ||
          function->IsMarkedForConcurrentOptimization() ||
          function->IsOptimized())) {
       // Attempt OSR if we are still running unoptimized code even though the
       // the function has long been marked or even already been optimized.
       int ticks = shared_code->profiler_ticks();
       int allowance = kOSRCodeSizeAllowanceBase +
                       ticks * kOSRCodeSizeAllowancePerTick;
       if (shared_code->CodeSize() > allowance) {
         if (ticks < 255) shared_code->set_profiler_ticks(ticks + 1);
       } else {
-        int nesting = shared_code->allow_osr_at_loop_nesting_level();
-        if (nesting < Code::kMaxLoopNestingMarker) {
-          int new_nesting = nesting + 1;
-          shared_code->set_allow_osr_at_loop_nesting_level(new_nesting);
-          AttemptOnStackReplacement(function);
-        }
+        AttemptOnStackReplacement(function);
       }
       continue;
     }
 
     // Only record top-level code on top of the execution stack and
     // avoid optimizing excessively large scripts since top-level code
     // will be executed only once.
     const int kMaxToplevelSourceSize = 10 * 1024;
     if (shared->is_toplevel() &&
         (frame_count > 1 || shared->SourceSize() > kMaxToplevelSourceSize)) {
@@ skipping 44 matching lines @@
       Optimize(function, "small function");
     } else {
       shared_code->set_profiler_ticks(ticks + 1);
     }
   }
   any_ic_changed_ = false;
 }
 
 
 } }  // namespace v8::internal