Reapply "Fix misoptimization of 'is' test""

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 2718 matching lines @@
     const Object& constant_value = value()->BoundConstant();
     if (constant_value.IsSmi() &&
         cids_.Contains(Smi::Cast(constant_value).Value())) {
       return NULL;
     }
   }
   return this;
 }
 
 
+TestCidsInstr::TestCidsInstr(TokenPosition token_pos,
+                             Token::Kind kind,
+                             Value* value,
+                             const ZoneGrowableArray<intptr_t>& cid_results,
+                             intptr_t deopt_id)
+    : TemplateComparison(token_pos, kind, deopt_id),
+      cid_results_(cid_results),
+      licm_hoisted_(false) {
+  ASSERT((kind == Token::kIS) || (kind == Token::kISNOT));
+  SetInputAt(0, value);
+  set_operation_cid(kObjectCid);
+#ifdef DEBUG
+  ASSERT(cid_results[0] == kSmiCid);
+  if (deopt_id == Thread::kNoDeoptId) {
+    // The entry for Smi can be special, but all other entries have
+    // to match in the no-deopt case.
+    for (intptr_t i = 4; i < cid_results.length(); i += 2) {
+      ASSERT(cid_results[i + 1] == cid_results[3]);
+    }
+  }
+#endif
+}
+
+
 Definition* TestCidsInstr::Canonicalize(FlowGraph* flow_graph) {
   CompileType* in_type = left()->Type();
   intptr_t cid = in_type->ToCid();
   if (cid == kDynamicCid) return this;
 
   const ZoneGrowableArray<intptr_t>& data = cid_results();
   const intptr_t true_result = (kind() == Token::kIS) ? 1 : 0;
   for (intptr_t i = 0; i < data.length(); i += 2) {
     if (data[i] == cid) {
       return (data[i + 1] == true_result)
                  ? flow_graph->GetConstant(Bool::True())
                  : flow_graph->GetConstant(Bool::False());
     }
   }
 
-  // TODO(sra): Handle misses if the instruction is not deoptimizing.
+  if (!CanDeoptimize()) {
+    return (data[data.length() - 1] == true_result)
+               ? flow_graph->GetConstant(Bool::False())
+               : flow_graph->GetConstant(Bool::True());
+  }
+
   // TODO(sra): Handle nullable input, possibly canonicalizing to a compare
   // against `null`.
   return this;
 }
 
 
 Instruction* GuardFieldClassInstr::Canonicalize(FlowGraph* flow_graph) {
   if (field().guarded_cid() == kDynamicCid) {
     return NULL;  // Nothing to guard.
   }
@@ skipping 1088 matching lines @@
   return new TestCidsInstr(token_pos(), kind(), new_left, cid_results(),
                            deopt_id());
 }
 
 
 bool TestCidsInstr::AttributesEqual(Instruction* other) const {
   TestCidsInstr* other_instr = other->AsTestCids();
   if (!ComparisonInstr::AttributesEqual(other)) {
     return false;
   }
+  if (CanDeoptimize() != other->CanDeoptimize()) {

[Vyacheslav Egorov (Google), 2017/05/30 10:54:20]

I don't think CanDeoptimize() should be compared here, it does not matter if
they match as long as they compare the same thing they can be used
interchangeably.

+    return false;
+  }
   if (cid_results().length() != other_instr->cid_results().length()) {
     return false;
   }
   for (intptr_t i = 0; i < cid_results().length(); i++) {
     if (cid_results()[i] != other_instr->cid_results()[i]) {
       return false;
     }
   }
   return true;
 }
@@ skipping 458 matching lines @@
                      "native function '%s' (%" Pd " arguments) cannot be found",
                      native_name().ToCString(), function().NumParameters());
   }
   set_is_auto_scope(auto_setup_scope);
   set_native_c_function(native_function);
 }
 
 #undef __
 
 }  // namespace dart