VM: Reduce the number of edge counters in generated code.

runtime/vm/intermediate_language_ia32.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_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
+#include "vm/flow_graph.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/locations.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 
 #define __ compiler->assembler()->
 
@@ skipping 5970 matching lines @@
 void GraphEntryInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   if (!compiler->CanFallThroughTo(normal_entry())) {
     __ jmp(compiler->GetJumpLabel(normal_entry()));
   }
 }
 
 
 void TargetEntryInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   __ Bind(compiler->GetJumpLabel(this));
   if (!compiler->is_optimizing()) {
-    if (FLAG_emit_edge_counters) {
+    if (FLAG_emit_edge_counters &&
+        (!last_instruction()->IsGoto() ||
+         (this == compiler->flow_graph().graph_entry()->normal_entry()))) {

[srdjan, 2014/06/06 14:59:51]

How about factoring this test into TargetInstr::NeedsEdgeCounter().

[Florian Schneider, 2014/06/10 08:56:39]

Moved to FlowGraphCompiler::NeedEdgeCounter(TargetEntryInstr* block).

       compiler->EmitEdgeCounter();
     }
     // The deoptimization descriptor points after the edge counter code for
     // uniformity with ARM and MIPS, where we can reuse pattern matching
     // code that matches backwards from the end of the pattern.
     compiler->AddCurrentDescriptor(PcDescriptors::kDeopt,
                                    deopt_id_,
                                    Scanner::kNoSourcePos);
   }
   if (HasParallelMove()) {
@@ skipping 279 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(ArgumentCount());  // Discard arguments.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_IA32