Increase deoptimization counter threshold to 16, cleanups.

runtime/vm/compiler.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/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/code_generator.h"
@@ skipping 26 matching lines @@
 DEFINE_FLAG(bool, disassemble_optimized, false, "Disassemble optimized code.");
 DEFINE_FLAG(bool, trace_bailout, false, "Print bailout from ssa compiler.");
 DEFINE_FLAG(bool, trace_compiler, false, "Trace compiler operations.");
 DEFINE_FLAG(bool, constant_propagation, true,
     "Do conditional constant propagation/unreachable code elimination.");
 DEFINE_FLAG(bool, common_subexpression_elimination, true,
     "Do common subexpression elimination.");
 DEFINE_FLAG(bool, loop_invariant_code_motion, true,
     "Do loop invariant code motion.");
 DEFINE_FLAG(bool, propagate_types, true, "Do static type propagation.");
-DEFINE_FLAG(int, deoptimization_counter_threshold, 5,
-    "How many times we allow deoptimization before we disallow"
-    " certain optimizations");
+DEFINE_FLAG(int, deoptimization_counter_threshold, 16,
+    "How many times we allow deoptimization before we disallow optimization.");
 DEFINE_FLAG(bool, use_inlining, true, "Enable call-site inlining");
 DEFINE_FLAG(bool, range_analysis, true, "Enable range analysis");
 DEFINE_FLAG(bool, verify_compiler, false,
     "Enable compiler verification assertions");
 DECLARE_FLAG(bool, print_flow_graph);
 DECLARE_FLAG(bool, print_flow_graph_optimized);
+DECLARE_FLAG(bool, trace_failed_optimization_attempts);
 
 
 // Compile a function. Should call only if the function has not been compiled.
 //   Arg0: function object.
 DEFINE_RUNTIME_ENTRY(CompileFunction, 1) {
   ASSERT(arguments.ArgCount() == kCompileFunctionRuntimeEntry.argument_count());
   const Function& function = Function::CheckedHandle(arguments.ArgAt(0));
   ASSERT(!function.HasCode());
   const Error& error = Error::Handle(Compiler::CompileFunction(function));
   if (!error.IsNull()) {
@@ skipping 409 matching lines @@
       parsed_function->AllocateVariables();
     }
 
     const bool success =
         CompileParsedFunctionHelper(*parsed_function, optimized);
     if (optimized && !success) {
       // Optimizer bailed out. Disable optimizations and to never try again.
       if (FLAG_trace_compiler) {
         OS::Print("--> disabling optimizations for '%s'\n",
                   function.ToFullyQualifiedCString());
+      } else if (FLAG_trace_failed_optimization_attempts) {
+        OS::Print("Cannot optimize: %s\n", function.ToFullyQualifiedCString());
       }
       function.set_is_optimizable(false);
       isolate->set_long_jump_base(base);
       return Error::null();
     }
 
     ASSERT(success);
     per_compile_timer.Stop();
 
     if (FLAG_trace_compiler) {
@@ skipping 141 matching lines @@
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     isolate->set_long_jump_base(base);
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart