Support immediate operands for array bounds checks.

runtime/vm/intermediate_language_ia32.cc

Index: runtime/vm/intermediate_language_ia32.cc
===================================================================
--- runtime/vm/intermediate_language_ia32.cc	(revision 11804)
+++ runtime/vm/intermediate_language_ia32.cc	(working copy)
@@ -2225,7 +2225,17 @@
 
 
 LocationSummary* CheckArrayBoundComp::MakeLocationSummary() const {
-  return LocationSummary::Make(2,
+  const intptr_t kNumInputs = 2;
+  ConstantComp* constant_index = index()->definition()->AsConstant();
+  if (constant_index != NULL) {
+  const intptr_t kNumTemps = 0;
+    LocationSummary* locs =
+        new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
+    locs->set_in(0, Location::RequiresRegister());
+    locs->set_in(1, Location::Constant(constant_index->value()));

[Vyacheslav Egorov (Google), 2012/09/04 14:38:41]

I recommend creating a helper RegisterOrConstant that returns either
RequiresRegister() location or Constant location.

+    return locs;
+  }
+  return LocationSummary::Make(kNumInputs,
                                Location::NoLocation(),
                                LocationSummary::kNoCall);
 }
@@ -2233,24 +2243,31 @@
 
 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:
-      __ cmpl(index, FieldAddress(receiver, Array::length_offset()));
-      break;
-    case kGrowableObjectArrayCid:
-      __ cmpl(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 int32_t imm =
+        reinterpret_cast<int32_t>(constant.raw());
+    __ cmpl(FieldAddress(receiver, length_offset), Immediate(imm));
+    __ j(BELOW_EQUAL, deopt);
+  } else {
+    Register index = locs()->in(1).reg();
+    __ cmpl(index, FieldAddress(receiver, length_offset));
+    __ j(ABOVE_EQUAL, deopt);
   }
-  __ j(ABOVE_EQUAL, deopt);
 }