Pattern match on generated code to find edge counters.

runtime/vm/intermediate_language_arm.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_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 4426 matching lines @@
 void GraphEntryInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   if (!compiler->CanFallThroughTo(normal_entry())) {
     __ b(compiler->GetJumpLabel(normal_entry()));
   }
 }
 
 
 void TargetEntryInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   __ Bind(compiler->GetJumpLabel(this));
   if (!compiler->is_optimizing()) {
-    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)));
     __ Comment("Edge counter");
     __ LoadObject(R0, counter);
     __ ldr(IP, FieldAddress(R0, Array::element_offset(0)));
     __ adds(IP, IP, ShifterOperand(Smi::RawValue(1)));
     __ LoadImmediate(IP, Smi::RawValue(Smi::kMaxValue), VS);  // If overflow.
     __ str(IP, FieldAddress(R0, Array::element_offset(0)));
+    // On ARM 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);
   }
   if (HasParallelMove()) {
     compiler->parallel_move_resolver()->EmitNativeCode(parallel_move());
   }
 }
 
 
 LocationSummary* GotoInstr::MakeLocationSummary() const {
   return new LocationSummary(0, 0, LocationSummary::kNoCall);
 }
 
 
 void GotoInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  if (!compiler->is_optimizing()) {
+    // Add an edge counter.
+    const Array& counter = Array::ZoneHandle(Array::New(1, Heap::kOld));
+    counter.SetAt(0, Smi::Handle(Smi::New(0)));
+    __ Comment("Edge counter");
+    __ LoadObject(R0, counter);
+    __ ldr(IP, FieldAddress(R0, Array::element_offset(0)));
+    __ adds(IP, IP, ShifterOperand(Smi::RawValue(1)));
+    __ LoadImmediate(IP, Smi::RawValue(Smi::kMaxValue), VS);  // If overflow.
+    __ str(IP, FieldAddress(R0, Array::element_offset(0)));
+    // Add a deoptimization descriptor for deoptimizing instructions that
+    // may be inserted before this instruction.  On ARM 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.
+  }
   if (HasParallelMove()) {
     compiler->parallel_move_resolver()->EmitNativeCode(parallel_move());
   }
 
   // We can fall through if the successor is the next block in the list.
   // Otherwise, we need a jump.
   if (!compiler->CanFallThroughTo(successor())) {
     __ b(compiler->GetJumpLabel(successor()));
   }
 }
@@ skipping 196 matching lines @@
   compiler->GenerateCall(token_pos(),
                          &label,
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM