Support immediate operands for array bounds checks.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 11818)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -2241,32 +2241,43 @@
 
 
 LocationSummary* CheckArrayBoundComp::MakeLocationSummary() const {
-  return LocationSummary::Make(2,
-                               Location::NoLocation(),
-                               LocationSummary::kNoCall);
+  const intptr_t kNumInputs = 2;
+  const intptr_t kNumTemps = 0;
+  LocationSummary* locs =
+      new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
+  locs->set_in(0, Location::RequiresRegister());
+  locs->set_in(1, Location::RegisterOrConstant(index()));
+  return locs;
 }
 
 
 void CheckArrayBoundComp::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register receiver = locs()->in(0).reg();
-  Register index = locs()->in(1).reg();
 
   const DeoptReasonId deopt_reason =
       (array_type() == kGrowableObjectArrayCid) ?
       kDeoptLoadIndexedGrowableArray : kDeoptLoadIndexedFixedArray;
   Label* deopt = compiler->AddDeoptStub(deopt_id(),
                                         deopt_reason);
-  switch (array_type()) {
-    case kArrayCid:
-    case kImmutableArrayCid:
-      __ cmpq(index, FieldAddress(receiver, Array::length_offset()));
-      break;
-    case kGrowableObjectArrayCid:
-      __ cmpq(index,
-              FieldAddress(receiver, GrowableObjectArray::length_offset()));
-      break;
+  ASSERT(array_type() == kArrayCid ||
+         array_type() == kImmutableArrayCid ||
+         array_type() == kGrowableObjectArrayCid);
+  intptr_t length_offset = (array_type() == kGrowableObjectArrayCid)
+      ? GrowableObjectArray::length_offset()
+      : Array::length_offset();
+
+  if (locs()->in(1).IsConstant()) {
+    const Object& constant = locs()->in(1).constant();
+    ASSERT(constant.IsSmi());
+    const int64_t imm =
+        reinterpret_cast<int64_t>(constant.raw());
+    __ cmpq(FieldAddress(receiver, length_offset), Immediate(imm));
+    __ j(BELOW_EQUAL, deopt);
+  } else {
+    Register index = locs()->in(1).reg();
+    __ cmpq(index, FieldAddress(receiver, length_offset));
+    __ j(ABOVE_EQUAL, deopt);
   }
-  __ j(ABOVE_EQUAL, deopt);
 }