Reland "VM: Improve single-target polymorphic calls."

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/bit_vector.h"
 #include "vm/bootstrap.h"
 #include "vm/compiler.h"
 #include "vm/constant_propagator.h"
@@ skipping 115 matching lines @@
 
 
 CheckClassInstr::CheckClassInstr(Value* value,
                                  intptr_t deopt_id,
                                  const ICData& unary_checks,
                                  TokenPosition token_pos)
     : TemplateInstruction(deopt_id),
       unary_checks_(unary_checks),
       cids_(unary_checks.NumberOfChecks()),
       licm_hoisted_(false),
+      is_dense_switch_(IsDenseCidRange(unary_checks)),
       token_pos_(token_pos) {
   ASSERT(unary_checks.IsZoneHandle());
   // Expected useful check data.
   ASSERT(!unary_checks_.IsNull());
   ASSERT(unary_checks_.NumberOfChecks() > 0);
   ASSERT(unary_checks_.NumArgsTested() == 1);
   SetInputAt(0, value);
   // Otherwise use CheckSmiInstr.
   ASSERT((unary_checks_.NumberOfChecks() != 1) ||
          (unary_checks_.GetReceiverClassIdAt(0) != kSmiCid));
@@ skipping 78 matching lines @@
 // we can check against null instance instead.
 bool CheckClassInstr::DeoptIfNotNull() const {
   if (unary_checks().NumberOfChecks() != 1) {
     return false;
   }
   const intptr_t cid = unary_checks().GetCidAt(0);
   return cid == kNullCid;
 }
 
 
-
-bool CheckClassInstr::IsDenseSwitch() const {
-  if (unary_checks().GetReceiverClassIdAt(0) == kSmiCid) return false;
-  if (cids_.length() > 2 &&
-      cids_[cids_.length() - 1] - cids_[0] < kBitsPerWord) {
-    return true;
+bool CheckClassInstr::IsDenseCidRange(const ICData& unary_checks) {
+  ASSERT(unary_checks.NumArgsTested() == 1);
+  // TODO(fschneider): Support smis in dense cid checks.
+  if (unary_checks.GetReceiverClassIdAt(0) == kSmiCid) return false;
+  if (unary_checks.NumberOfChecks() <= 2) return false;
+  intptr_t max = 0;
+  intptr_t min = kIntptrMax;
+  for (intptr_t i = 0; i < unary_checks.NumberOfChecks(); ++i) {
+    intptr_t cid = unary_checks.GetCidAt(i);
+    if (cid < min) min = cid;
+    if (cid > max) max = cid;
   }
-  return false;
+  return (max - min) < kBitsPerWord;
 }
 
 
+bool CheckClassInstr::IsDenseSwitch() const {
+  return is_dense_switch_;
+}
+
+
 intptr_t CheckClassInstr::ComputeCidMask() const {
   ASSERT(IsDenseSwitch());
   intptr_t mask = 0;
   for (intptr_t i = 0; i < cids_.length(); ++i) {
     mask |= static_cast<intptr_t>(1) << (cids_[i] - cids_[0]);
   }
   return mask;
 }
 
 
@@ skipping 3485 matching lines @@
   set_native_c_function(native_function);
   function().SetIsNativeAutoSetupScope(auto_setup_scope);
   Dart_NativeEntryResolver resolver = library.native_entry_resolver();
   bool is_bootstrap_native = Bootstrap::IsBootstapResolver(resolver);
   set_is_bootstrap_native(is_bootstrap_native);
 }
 
 #undef __
 
 }  // namespace dart