DBC: Eager deoptimization and CheckSmi instruction.

runtime/vm/intermediate_language_dbc.cc

Index: runtime/vm/intermediate_language_dbc.cc
diff --git a/runtime/vm/intermediate_language_dbc.cc b/runtime/vm/intermediate_language_dbc.cc
index 4af998e6a78edb5d9df89bc7aea2ed1ca7584bb1..3212027d030f8a4a4bbf909f87f62c99854f4596 100644
--- a/runtime/vm/intermediate_language_dbc.cc
+++ b/runtime/vm/intermediate_language_dbc.cc
@@ -108,10 +108,9 @@ DECLARE_FLAG(int, optimization_counter_threshold);
   M(UnboxInteger32)                                                            \
   M(CheckedSmiOp)                                                              \
   M(CheckArrayBound)                                                           \
-  M(CheckSmi)                                                                  \
+  M(BinarySmiOp)                                                               \
   M(CheckClassId)                                                              \
   M(CheckClass)                                                                \
-  M(BinarySmiOp)                                                               \
   M(TestSmi)                                                                   \
   M(RelationalOp)                                                              \
   M(EqualityCompare)                                                           \
@@ -850,8 +849,12 @@ Representation LoadIndexedInstr::representation() const {
 Representation StoreIndexedInstr::RequiredInputRepresentation(
     intptr_t idx) const {
   // Array can be a Dart object or a pointer to external data.
-  if (idx == 0)  return kNoRepresentation;  // Flexible input representation.
-  if (idx == 1) return kTagged;  // Index is a smi.
+  if (idx == 0) {
+    return kNoRepresentation;  // Flexible input representation.
+  }
+  if (idx == 1) {
+    return kTagged;  // Index is a smi.
+  }
   ASSERT(idx == 2);
   switch (class_id_) {
     case kArrayCid:
@@ -903,6 +906,17 @@ void Environment::DropArguments(intptr_t argc) {
 }
 
 
+EMIT_NATIVE_CODE(CheckSmi, 1) {
+  Label* deopt = compiler->AddDeoptStub(deopt_id(),
+                                        ICData::kDeoptCheckSmi,
+                                        licm_hoisted_ ? ICData::kHoisted : 0);
+  __ Push(locs()->in(0).reg());

[zra, 2016/06/07 22:31:28]

Thoughts about adding an instruction for this that just checks the tag?

[Vyacheslav Egorov (Google), 2016/06/08 11:58:53]

Yes, I think this should be just a special bytecode instruction.

[zra, 2016/06/08 17:46:30]

Done.

+  __ LoadClassIdTOS();
+  __ PushConstant(Smi::Handle(Smi::New(kSmiCid)));
+  __ IfNeStrictTOS();
+  __ Jump(deopt);

[Vyacheslav Egorov (Google), 2016/06/08 11:58:53]

__ Jump(deopt) could just be __ Deopt(...)

[zra, 2016/06/08 17:46:30]

Done.

+}
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC