Improve redundant load elimination

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 34 matching lines @@
     "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(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);
 
 
 // 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 88 matching lines @@
     }
 
     if (optimized) {
       TimerScope timer(FLAG_compiler_stats,
                        &CompilerStats::ssa_timer,
                        isolate);
       // Transform to SSA (virtual register 0 and no inlining arguments).
       flow_graph->ComputeSSA(0, NULL);
     }
 
-    if (FLAG_print_flow_graph) {
+    if (FLAG_print_flow_graph ||
+        (optimized && FLAG_print_flow_graph_optimized)) {
       OS::Print("Before Optimizations\n");
       FlowGraphPrinter printer(*flow_graph);
       printer.PrintBlocks();
     }
 
     if (optimized) {
       TimerScope timer(FLAG_compiler_stats,
                        &CompilerStats::graphoptimizer_timer,
                        isolate);
 
@@ skipping 65 matching lines @@
         // optimistically moves CheckSmi through phis into loop preheaders
         // making some phis smi.
         flow_graph->ComputeUseLists();
         optimizer.InferSmiRanges();
       }
 
       // Perform register allocation on the SSA graph.
       FlowGraphAllocator allocator(*flow_graph);
       allocator.AllocateRegisters();
 
-      if (FLAG_print_flow_graph) {
+      if (FLAG_print_flow_graph || FLAG_print_flow_graph_optimized) {
         OS::Print("After Optimizations:\n");
         FlowGraphPrinter printer(*flow_graph);
         printer.PrintBlocks();
       }
     }
 
     Assembler assembler;
     FlowGraphCompiler graph_compiler(&assembler,
                                      *flow_graph,
                                      optimized);
@@ skipping 376 matching lines @@
     result = 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