VM: Store edge counters in one per-function array.

runtime/vm/flow_graph_compiler_arm64.cc

Index: runtime/vm/flow_graph_compiler_arm64.cc
diff --git a/runtime/vm/flow_graph_compiler_arm64.cc b/runtime/vm/flow_graph_compiler_arm64.cc
index 57c9fd643a9d88c5807ad93135ef027c26029bc7..01d9561ac15be0ae7fe56e3cbf83c034e4dd61db 100644
--- a/runtime/vm/flow_graph_compiler_arm64.cc
+++ b/runtime/vm/flow_graph_compiler_arm64.cc
@@ -1178,20 +1178,19 @@ void FlowGraphCompiler::GenerateRuntimeCall(intptr_t token_pos,
 }
 
 
-void FlowGraphCompiler::EmitEdgeCounter() {
+void FlowGraphCompiler::EmitEdgeCounter(intptr_t edge_id) {
   // We do not check for overflow when incrementing the edge counter.  The
   // function should normally be optimized long before the counter can
   // overflow; and though we do not reset the counters when we optimize or
   // deoptimize, there is a bound on the number of
   // optimization/deoptimization cycles we will attempt.
+  ASSERT(!edge_counters_array_.IsNull());
   ASSERT(assembler_->constant_pool_allowed());
-  const Array& counter = Array::ZoneHandle(zone(), Array::New(1, Heap::kOld));
-  counter.SetAt(0, Smi::Handle(zone(), Smi::New(0)));
   __ Comment("Edge counter");
-  __ LoadUniqueObject(R0, counter);
-  __ LoadFieldFromOffset(TMP, R0, Array::element_offset(0));
+  __ LoadObject(R0, edge_counters_array_);
+  __ LoadFieldFromOffset(TMP, R0, Array::element_offset(edge_id));
   __ add(TMP, TMP, Operand(Smi::RawValue(1)));
-  __ StoreFieldToOffset(TMP, R0, Array::element_offset(0));
+  __ StoreFieldToOffset(TMP, R0, Array::element_offset(edge_id));
 }