Instruction size and growth threshold for inlining.

runtime/vm/flow_graph_inliner.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/flow_graph_inliner.h"
 
 #include "vm/compiler.h"
 #include "vm/flags.h"
 #include "vm/flow_graph.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_optimizer.h"
 #include "vm/il_printer.h"
 #include "vm/intrinsifier.h"
 #include "vm/longjump.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, trace_inlining, false, "Trace inlining");
 DEFINE_FLAG(charp, inlining_filter, NULL, "Inline only in named function");
+DEFINE_FLAG(int, inlining_size_threshold, 250,
+            "Inline only functions with up to threshold instructions");
+DEFINE_FLAG(int, inlining_growth_factor, 3,
+            "Stop inlining when a function grows by the factor");
 DECLARE_FLAG(bool, print_flow_graph);
 DECLARE_FLAG(int, deoptimization_counter_threshold);
 
 #define TRACE_INLINING(statement)                                              \
   do {                                                                         \
     if (FLAG_trace_inlining) statement;                                        \
   } while (false)
 
 
 // Test if a call is recursive by looking in the deoptimization environment.
 static bool IsCallRecursive(const Function& function, Definition* call) {
   Environment* env = call->env();
   while (env != NULL) {
     if (function.raw() == env->function().raw()) return true;
     env = env->outer();
   }
   return false;
 }
 
 
 class CallSiteInliner : public FlowGraphVisitor {
  public:
   explicit CallSiteInliner(FlowGraph* flow_graph)
       : FlowGraphVisitor(flow_graph->postorder()),
         caller_graph_(flow_graph),
         next_ssa_temp_index_(flow_graph->max_virtual_register_number()),
         inlined_(false),
+        initial_size_(flow_graph->InstructionCount()),
+        inlined_size_(0),
         static_calls_(),
         closure_calls_(),
         instance_calls_() { }
 
   void VisitClosureCall(ClosureCallInstr* call) {
     closure_calls_.Add(call);
   }
 
   void VisitPolymorphicInstanceCall(PolymorphicInstanceCallInstr* call) {
     instance_calls_.Add(call);
   }
 
   void VisitStaticCall(StaticCallInstr* call) {
     if (call->function().is_inlinable()) static_calls_.Add(call);
   }
 
   void FindCallSites() {
     VisitBlocks();
   }
 
   void InlineCalls() {
     InlineStaticCalls();
     InlineClosureCalls();
     InlineInstanceCalls();
   }
 
   bool inlined() const { return inlined_; }
 
+  double GrowthFactor() const {
+    return static_cast<double>(inlined_size_) /
+        static_cast<double>(initial_size_);
+  }
+
  private:
   bool TryInlining(const Function& function,
                    GrowableArray<Value*>* arguments,
                    Definition* call) {
     TRACE_INLINING(OS::Print("  => %s\n", function.ToCString()));
 
     // Abort if the inlinable bit on the function is low.
     if (!function.is_inlinable()) {
       TRACE_INLINING(OS::Print("     Bailout: not inlinable\n"));
       return false;
@@ skipping 63 matching lines @@
       optimizer.ApplyICData();
       callee_graph->ComputeUseLists();
 
       if (FLAG_trace_inlining && FLAG_print_flow_graph) {
         OS::Print("Callee graph for inlining %s\n",
                   parsed_function.function().ToFullyQualifiedCString());
         FlowGraphPrinter printer(*callee_graph);
         printer.PrintBlocks();
       }
 
-      // TODO(zerny): If result is more than size threshold then abort.
+      // If result is more than size threshold then abort.
+      // TODO(zerny): Do this after CP and dead code elimination.
+      intptr_t size = callee_graph->InstructionCount();
+      if (size > FLAG_inlining_size_threshold) {
+        function.set_is_inlinable(false);
+        isolate->set_long_jump_base(base);
+        isolate->set_deopt_id(prev_deopt_id);
+        isolate->set_ic_data_array(prev_ic_data.raw());
+        TRACE_INLINING(OS::Print("     Bailout: graph size %"Pd"\n", size));
+        return false;
+      }
+
+      // If the growth factor is more than threshold abort.
+      double growth =
+          static_cast<double>(inlined_size_ + size) /
+          static_cast<double>(initial_size_);
+      if (growth > static_cast<double>(FLAG_inlining_growth_factor)) {
+        function.set_is_inlinable(false);
+        isolate->set_long_jump_base(base);
+        isolate->set_deopt_id(prev_deopt_id);
+        isolate->set_ic_data_array(prev_ic_data.raw());
+        TRACE_INLINING(OS::Print("     Bailout: growth factor %f\n",
+                                 growth));
+        return false;
+      }
 
       // TODO(zerny): If effort is less than threshold then inline recursively.
 
       // Plug result in the caller graph.
       caller_graph_->InlineCall(call, callee_graph);
       next_ssa_temp_index_ = caller_graph_->max_virtual_register_number();
 
       // Remove push arguments of the call.
       for (intptr_t i = 0; i < call->ArgumentCount(); ++i) {
         PushArgumentInstr* push = call->ArgumentAt(i);
@@ skipping 17 matching lines @@
       callee_graph->graph_entry()->constant_null()->ReplaceUsesWith(
           caller_graph_->graph_entry()->constant_null());
 
       TRACE_INLINING(OS::Print("     Success\n"));
 
       // Check that inlining maintains use lists.
       DEBUG_ASSERT(caller_graph_->ValidateUseLists());
 
       // Build succeeded so we restore the bailout jump.
       inlined_ = true;
+      inlined_size_ += size;
       isolate->set_long_jump_base(base);
       isolate->set_deopt_id(prev_deopt_id);
       isolate->set_ic_data_array(prev_ic_data.raw());
       return true;
     } else {
       Error& error = Error::Handle();
       error = isolate->object_store()->sticky_error();
       isolate->object_store()->clear_sticky_error();
       isolate->set_long_jump_base(base);
       isolate->set_deopt_id(prev_deopt_id);
@@ skipping 38 matching lines @@
   }
 
   void InlineInstanceCalls() {
     TRACE_INLINING(OS::Print("  Polymorphic Instance Calls (%d)\n",
                              instance_calls_.length()));
     for (intptr_t i = 0; i < instance_calls_.length(); ++i) {
       PolymorphicInstanceCallInstr* instr = instance_calls_[i];
       const ICData& ic_data = instr->ic_data();
       const Function& target = Function::ZoneHandle(ic_data.GetTargetAt(0));
       if (instr->with_checks()) {
-        TRACE_INLINING(OS::Print("    Bailout: %"Pd" checks target '%s'\n",
+        TRACE_INLINING(OS::Print("     Bailout: %"Pd" checks target '%s'\n",
                                  ic_data.NumberOfChecks(),
                                  target.ToCString()));
         continue;
       }
       GrowableArray<Value*> arguments(instr->ArgumentCount());
       for (int i = 0; i < instr->ArgumentCount(); ++i) {
         arguments.Add(instr->ArgumentAt(i)->value());
       }
       TryInlining(target, &arguments, instr);
     }
   }
 
   FlowGraph* caller_graph_;
   intptr_t next_ssa_temp_index_;
   bool inlined_;
+  intptr_t initial_size_;
+  intptr_t inlined_size_;
 
   GrowableArray<StaticCallInstr*> static_calls_;
   GrowableArray<ClosureCallInstr*> closure_calls_;
   GrowableArray<PolymorphicInstanceCallInstr*> instance_calls_;
 };
 
 
 void FlowGraphInliner::Inline() {
   if ((FLAG_inlining_filter != NULL) &&
       (strstr(flow_graph_->
@@ skipping 11 matching lines @@
               parsed_function().function().ToFullyQualifiedCString());
     FlowGraphPrinter printer(*flow_graph_);
     printer.PrintBlocks();
   }
 
   CallSiteInliner inliner(flow_graph_);
   inliner.FindCallSites();
   inliner.InlineCalls();
 
   if (inliner.inlined()) {
-    if (FLAG_trace_inlining && FLAG_print_flow_graph) {
-      OS::Print("After Inlining of %s\n", flow_graph_->
-                parsed_function().function().ToFullyQualifiedCString());
-      FlowGraphPrinter printer(*flow_graph_);
-      printer.PrintBlocks();
+    if (FLAG_trace_inlining) {
+      OS::Print("Inlining growth factor: %f\n", inliner.GrowthFactor());
+      if (FLAG_print_flow_graph) {
+        OS::Print("After Inlining of %s\n", flow_graph_->
+                  parsed_function().function().ToFullyQualifiedCString());
+        FlowGraphPrinter printer(*flow_graph_);
+        printer.PrintBlocks();
+      }
     }
   }
 }
 
 }  // namespace dart