Optimize identical-comparisons based on propagated type information.

runtime/vm/intermediate_language.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/intermediate_language.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
@@ skipping 1510 matching lines @@
   if (defn->IsComparison() &&
       (value()->Type()->ToCid() == kBoolCid) &&
       defn->HasOnlyUse(value())) {
     defn->AsComparison()->NegateComparison();
     return defn;
   }
   return this;
 }
 
 
+static bool MayBeBoxableNumber(intptr_t cid) {
+  return (cid == kDynamicCid) ||
+         (cid == kMintCid) ||
+         (cid == kBigintCid) ||
+         (cid == kDoubleCid);
+}
+
+
+static bool MaybeNumber(CompileType* type) {
+  ASSERT(Type::Handle(Type::Number()).IsMoreSpecificThan(
+         Type::Handle(Type::Number()), NULL));
+  return type->ToAbstractType()->IsDynamicType()
+      || type->IsMoreSpecificThan(Type::Handle(Type::Number()));
+}
+
+
 // Returns a replacement for a strict comparison and signals if the result has
 // to be negated.
 static Definition* CanonicalizeStrictCompare(StrictCompareInstr* compare,
                                              bool* negated) {
+  // Use propagated cid and type information to eliminate number checks.
+  // If one of the inputs is not a boxable number (Mint, Double, Bigint), or
+  // is not a subtype of num, no need for number checks.
+  if (compare->needs_number_check()) {
+    if (!MayBeBoxableNumber(compare->left()->Type()->ToCid()) ||
+        !MayBeBoxableNumber(compare->right()->Type()->ToCid()))  {
+      compare->set_needs_number_check(false);
+    } else if (!MaybeNumber(compare->left()->Type()) ||
+               !MaybeNumber(compare->right()->Type())) {
+      compare->set_needs_number_check(false);
+    }
+  }
+
   *negated = false;
   Object& constant = Object::Handle();
   Value* other = NULL;
   if (compare->right()->BindsToConstant()) {
     constant = compare->right()->BoundConstant().raw();
     other = compare->left();
   } else if (compare->left()->BindsToConstant()) {
     constant = compare->left()->BoundConstant().raw();
     other = compare->right();
   } else {
@@ skipping 1226 matching lines @@
       return kCosRuntimeEntry;
     default:
       UNREACHABLE();
   }
   return kSinRuntimeEntry;
 }
 
 #undef __
 
 }  // namespace dart