Added flag --inline_smi_string_hashcode and --inline_smi_string_hashcode_ratio to decide when/if sh…

runtime/vm/flow_graph_compiler.cc

 // Copyright (c) 2013, 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/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 14 matching lines @@
 #include "vm/raw_object.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 #include "vm/timeline.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, enable_simd_inline, true,
     "Enable inlining of SIMD related method calls.");
+DEFINE_FLAG(bool, inline_smi_string_hashcode, true,
+    "Inline hashcode for Smi and one-byte strings in case of megamorphic call");
+DEFINE_FLAG(int, inline_smi_string_hashcode_ratio, 50,
+    "Minimal hotness (0..100) of one-byte-string before inlining its hashcode");
 DEFINE_FLAG(int, min_optimization_counter_threshold, 5000,
     "The minimum invocation count for a function.");
 DEFINE_FLAG(int, optimization_counter_scale, 2000,
     "The scale of invocation count, by size of the function.");
 DEFINE_FLAG(bool, source_lines, false, "Emit source line as assembly comment.");
 DEFINE_FLAG(bool, trace_inlining_intervals, false,
     "Inlining interval diagnostics");
 DEFINE_FLAG(bool, use_megamorphic_stub, true, "Out of line megamorphic lookup");
 
 DECLARE_FLAG(bool, code_comments);
@@ skipping 105 matching lines @@
     if (it.CurrentLocation().IsInvalid()) {
       MaterializeObjectInstr* mat =
           it.CurrentValue()->definition()->AsMaterializeObject();
       ASSERT(mat != NULL);
       builder->AddMaterialization(mat);
     }
   }
 }
 
 
+bool FlowGraphCompiler::ShouldInlineSmiStringHashCode(const ICData& ic_data) {
+  if (!FLAG_inline_smi_string_hashcode) return false;

[zra, 2016/04/27 16:28:17]

Please add curly braces. Maybe also merge with the if below that also returns
false.

[srdjan, 2016/04/27 18:10:22]

Done.

+  if (ic_data.target_name() != Symbols::hashCode().raw()) return false;
+  // Precompiled code has no ICData, optimistically inline it.
+  if (ic_data.IsNull() || (ic_data.NumberOfChecks() == 0)) return true;

[zra, 2016/04/27 16:28:17]

ditto.

[srdjan, 2016/04/27 18:10:22]

Done.

+  // Check if OneByteString is hot enough.

[zra, 2016/04/27 16:28:17]

Sorry if I'm confused. So Smi hashcode will only be inlined if OneByteString is
hot?

[srdjan, 2016/04/27 18:10:22]

Yes, because Smi test must be done anyway.  Added comment TODO.

Also added 'lost' check that the hottest class is OnebyteString,

+  const ICData& ic_data_sorted =
+      ICData::Handle(ic_data.AsUnaryClassChecksSortedByCount());
+  ASSERT(ic_data_sorted.NumberOfChecks() > 0);
+  const intptr_t total_count = ic_data_sorted.AggregateCount();
+  const intptr_t ratio = ic_data_sorted.GetCountAt(0) * 100 / total_count;

[zra, 2016/04/27 16:28:17]

Maybe add parens around the multiply.

[srdjan, 2016/04/27 18:10:22]

Done.

+  return ratio > FLAG_inline_smi_string_hashcode_ratio;
+}
+
+
 FlowGraphCompiler::FlowGraphCompiler(
     Assembler* assembler,
     FlowGraph* flow_graph,
     const ParsedFunction& parsed_function,
     bool is_optimizing,
     const GrowableArray<const Function*>& inline_id_to_function,
     const GrowableArray<TokenPosition>& inline_id_to_token_pos,
     const GrowableArray<intptr_t>& caller_inline_id)
       : thread_(Thread::Current()),
         zone_(Thread::Current()->zone()),
@@ skipping 1796 matching lines @@
 
 
 void FlowGraphCompiler::FrameStateClear() {
   ASSERT(!is_optimizing());
   frame_state_.TruncateTo(0);
 }
 #endif  // defined(DEBUG) && !defined(TARGET_ARCH_DBC)
 
 
 }  // namespace dart