Canonicalize TestCidsInstr

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index c68f277692311605272ee04f5a0cced09fcf3624..5cd9aa82fbdc0161103c19e84e7edfd6dc308474 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -2586,6 +2586,37 @@ Instruction* CheckClassIdInstr::Canonicalize(FlowGraph* flow_graph) {
 }
 
 
+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.