Optimize function at its entry instead of at exit.

runtime/vm/code_generator.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/code_generator.h"
 
 #include "vm/assembler_macros.h"
 #include "vm/ast.h"
 #include "vm/bigint_operations.h"
 #include "vm/code_patcher.h"
@@ skipping 1321 matching lines @@
       ic_data.raw(),
       function.usage_counter(),
       ic_data.NumberOfChecks(),
       ic_data.is_closure_call() ? "closure" : "",
       function.ToFullyQualifiedCString());
 }
 
 
 // This is called from function that needs to be optimized.
 // The requesting function can be already optimized (reoptimization).
+// Returns the Code object where to continue execution.
 DEFINE_RUNTIME_ENTRY(OptimizeInvokedFunction, 1) {
   ASSERT(arguments.ArgCount() ==
          kOptimizeInvokedFunctionRuntimeEntry.argument_count());
   const intptr_t kLowInvocationCount = -100000000;
   const Function& function = Function::CheckedHandle(arguments.ArgAt(0));
+  ASSERT(!function.IsNull());
   if (isolate->debugger()->HasBreakpoint(function)) {
     // We cannot set breakpoints in optimized code, so do not optimize
     // the function.
     function.set_usage_counter(0);
+    arguments.SetReturn(Code::Handle(function.CurrentCode()));
     return;
   }
   if (function.deoptimization_counter() >=
       FLAG_deoptimization_counter_threshold) {
     if (FLAG_trace_failed_optimization_attempts) {
       PrintCaller("Too Many Deoptimizations");
     }
     // TODO(srdjan): Investigate excessive deoptimization.
     function.set_usage_counter(kLowInvocationCount);
+    arguments.SetReturn(Code::Handle(function.CurrentCode()));
     return;
   }
   if ((FLAG_optimization_filter != NULL) &&
       (strstr(function.ToFullyQualifiedCString(),
               FLAG_optimization_filter) == NULL)) {
     function.set_usage_counter(kLowInvocationCount);
+    arguments.SetReturn(Code::Handle(function.CurrentCode()));
     return;
   }
   if (function.is_optimizable()) {
     const Error& error =
         Error::Handle(Compiler::CompileOptimizedFunction(function));
     if (!error.IsNull()) {
       Exceptions::PropagateError(error);
     }
     const Code& optimized_code = Code::Handle(function.CurrentCode());
     ASSERT(!optimized_code.IsNull());
     // Set usage counter for reoptimization.
     function.set_usage_counter(
         function.usage_counter() - FLAG_reoptimization_counter_threshold);
   } else {
     if (FLAG_trace_failed_optimization_attempts) {
       PrintCaller("Not Optimizable");
     }
     // TODO(5442338): Abort as this should not happen.
     function.set_usage_counter(kLowInvocationCount);
   }
+  arguments.SetReturn(Code::Handle(function.CurrentCode()));
 }
 
 
 // The caller must be a static call in a Dart frame, or an entry frame.
 // Patch static call to point to valid code's entry point.
 DEFINE_RUNTIME_ENTRY(FixCallersTarget, 0) {
   ASSERT(arguments.ArgCount() ==
       kFixCallersTargetRuntimeEntry.argument_count());
 
   StackFrameIterator iterator(StackFrameIterator::kDontValidateFrames);
@@ skipping 392 matching lines @@
     return;
   }
   HeapTrace* heap_trace = Isolate::Current()->heap()->trace();
   heap_trace->TraceStoreIntoObject(RawObject::ToAddr(object),
                                    field_addr,
                                    RawObject::ToAddr(value));
 }
 END_LEAF_RUNTIME_ENTRY
 
 }  // namespace dart