Canonicalize TestCidsInstr

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 2568 matching lines @@
     const Object& constant_value = value()->BoundConstant();
     if (constant_value.IsSmi() &&
         Smi::Cast(constant_value).Value() == cid_) {
       return NULL;
     }
   }
   return this;
 }
 
 
+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();
+  intptr_t result = -1;
+  for (intptr_t i = 0; i < data.length(); i += 2) {
+    if (data[i] == cid) {
+      result = data[i + 1];
+      break;

[Florian Schneider, 2016/04/18 14:57:28]

Maybe something like:

const intptr_t true_result = (kind() == Token::kIS) ? 1 : 0;
return (data[i + 1] == true_result)
    ? flow_graph->GetConstant(Bool::True())
    : flow_graph->GetConstant(Bool::False());

to avoid the three if-statements below?

[sra1, 2016/04/19 03:19:18]

Done.

+    }
+  }
+  if (result >= 0) {
+    if (kind() != Token::kIS) {
+      result = !result;

[Ivan Posva, 2016/04/18 04:37:46]

intptr_t is not a boolean.

[sra1, 2016/04/19 03:19:18]

Done.

+    }
+    if (result) {

[Ivan Posva, 2016/04/18 04:37:46]

ditto.

[sra1, 2016/04/19 03:19:18]

Done.

+      return flow_graph->GetConstant(Bool::True());
+    } else {

[Florian Schneider, 2016/04/18 14:57:28]

Please check that we have test coverage for the cases in our test suite. I often
just add temporary UNREACHABLE() statements into each case and run the tests,
removing each one after being hit.

+      return flow_graph->GetConstant(Bool::False());
+    }
+  }
+
+  // TODO(sra): Handle misses if the instruction is not deoptimizing.
+  // TODO(sra): Handle nullable input, possible canonicalizing to a compare
+  // against `null`.

[Florian Schneider, 2016/04/18 14:59:41]

Add a TODO to add support in the constant propagator as well
(ConstantPropagator::VisitTestCids)

[sra1, 2016/04/19 03:19:18]

Done.

+  return this;
+}
+
+
 Instruction* GuardFieldClassInstr::Canonicalize(FlowGraph* flow_graph) {
   if (field().guarded_cid() == kDynamicCid) {
     return NULL;  // Nothing to guard.
   }
 
   if (field().is_nullable() && value()->Type()->IsNull()) {
     return NULL;
   }
 
   const intptr_t cid = field().is_nullable() ? value()->Type()->ToNullableCid()
@@ skipping 1154 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