Pattern match on generated code to find edge counters.

runtime/vm/intermediate_language_mips.cc

Index: runtime/vm/intermediate_language_mips.cc
diff --git a/runtime/vm/intermediate_language_mips.cc b/runtime/vm/intermediate_language_mips.cc
index a1d5b188cc92b3fbf160f3efae9974d4b1db8c92..c84eb19041083017fabe1b0c916673b46f517bc7 100644
--- a/runtime/vm/intermediate_language_mips.cc
+++ b/runtime/vm/intermediate_language_mips.cc
@@ -3838,22 +3838,13 @@ void GraphEntryInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 void TargetEntryInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   __ Bind(compiler->GetJumpLabel(this));
   if (!compiler->is_optimizing()) {
+    compiler->EmitEdgeCounter();
+    // On MIPS the deoptimization descriptor points after the edge counter
+    // code so that we can reuse the same pattern matching code as at call
+    // sites, which matches backwards from the end of the pattern.
     compiler->AddCurrentDescriptor(PcDescriptors::kDeopt,
                                    deopt_id_,
                                    Scanner::kDummyTokenIndex);
-    // Add an edge counter.
-    const Array& counter = Array::ZoneHandle(Array::New(1, Heap::kOld));
-    counter.SetAt(0, Smi::Handle(Smi::New(0)));
-    Label done;
-    __ Comment("Edge counter");
-    __ LoadObject(T0, counter);
-    __ lw(T1, FieldAddress(T0, Array::element_offset(0)));
-    __ AddImmediateDetectOverflow(T1, T1, Smi::RawValue(1), CMPRES, T2);
-    __ bgez(CMPRES, &done);
-    __ delay_slot()->sw(T1, FieldAddress(T0, Array::element_offset(0)));
-    __ LoadImmediate(TMP1, Smi::RawValue(Smi::kMaxValue));
-    __ sw(TMP1, FieldAddress(T0, Array::element_offset(0)));  // If overflow.
-    __ Bind(&done);
   }
   if (HasParallelMove()) {
     compiler->parallel_move_resolver()->EmitNativeCode(parallel_move());
@@ -3868,6 +3859,17 @@ LocationSummary* GotoInstr::MakeLocationSummary() const {
 
 void GotoInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   __ TraceSimMsg("GotoInstr");
+  if (!compiler->is_optimizing()) {
+    compiler->EmitEdgeCounter();
+    // Add a deoptimization descriptor for deoptimizing instructions that
+    // may be inserted before this instruction.  On MIPS this descriptor
+    // points after the edge counter code so that we can reuse the same
+    // pattern matching code as at call sites, which matches backwards from
+    // the end of the pattern.
+    compiler->AddCurrentDescriptor(PcDescriptors::kDeopt,
+                                   GetDeoptId(),
+                                   0);  // No token position.

[Florian Schneider, 2013/10/01 10:10:02]

Use Scanner::kDummyTokenIndex?

+  }
   if (HasParallelMove()) {
     compiler->parallel_move_resolver()->EmitNativeCode(parallel_move());
   }