Improve RangeBoundary::LowerBound/UpperBound.

runtime/vm/intermediate_language.cc

 // Copyright (c) 2012, 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/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 2100 matching lines @@
 RangeBoundary RangeBoundary::FromDefinition(Definition* defn, intptr_t offs) {
   if (defn->IsConstant() && defn->AsConstant()->value().IsSmi()) {
     return FromConstant(Smi::Cast(defn->AsConstant()->value()).Value() + offs);
   }
   return RangeBoundary(kSymbol, reinterpret_cast<intptr_t>(defn), offs);
 }
 
 
 RangeBoundary RangeBoundary::LowerBound() const {
   if (IsConstant()) return *this;
-  if (symbol()->range() == NULL) return MinSmi();
-  return Add(symbol()->range()->min().LowerBound(),
+  return Add(Range::ConstantMin(symbol()->range()),
              RangeBoundary::FromConstant(offset_),
              MinSmi());
 }
 
 
 RangeBoundary RangeBoundary::UpperBound() const {
   if (IsConstant()) return *this;
-  if (symbol()->range() == NULL) return MaxSmi();
-  return Add(symbol()->range()->max().UpperBound(),
+  return Add(Range::ConstantMax(symbol()->range()),
              RangeBoundary::FromConstant(offset_),
              MaxSmi());
 }
 
 
+static Definition* UnwrapConstraint(Definition* defn) {
+  while (defn->IsConstraint()) {
+    defn = defn->AsConstraint()->value()->definition();
+  }
+  return defn;
+}
+
+
 static bool AreEqualDefinitions(Definition* a, Definition* b) {
+  a = UnwrapConstraint(a);
+  b = UnwrapConstraint(b);
   return (a == b) || (!a->AffectedBySideEffect() && a->Equals(b));
 }
 
 
 // Returns true if two range boundaries refer to the same symbol.
 static bool DependOnSameSymbol(const RangeBoundary& a, const RangeBoundary& b) {
   return a.IsSymbol() && b.IsSymbol() &&
       AreEqualDefinitions(a.symbol(), b.symbol());
 }
 
@@ skipping 453 matching lines @@
   } while (CanonicalizeMaxBoundary(&max) || CanonicalizeMinBoundary(&length));
 
   // Failed to prove that maximum is bounded with array length.
   return false;
 }
 
 
 #undef __
 
 }  // namespace dart