Merge (x & y) == 0 pattern to emit a single test instruction.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
diff --git a/runtime/vm/intermediate_language_x64.cc b/runtime/vm/intermediate_language_x64.cc
index 3a7a6e1e82a2df1241185aa42824ca76f92afd12..bfc2c42f3770c1422867d0053259d1f17d8774de 100644
--- a/runtime/vm/intermediate_language_x64.cc
+++ b/runtime/vm/intermediate_language_x64.cc
@@ -165,8 +165,7 @@ bool IfThenElseInstr::Supports(ComparisonInstr* comparison,
                                Value* v2) {
   if (!(comparison->IsStrictCompare() &&
         !comparison->AsStrictCompare()->needs_number_check()) &&
-      !(comparison->IsEqualityCompare() &&
-        (comparison->AsEqualityCompare()->receiver_class_id() == kSmiCid))) {
+      !comparison->IsSmiEquality()) {
     return false;
   }
 
@@ -918,6 +917,41 @@ void EqualityCompareInstr::EmitBranchCode(FlowGraphCompiler* compiler,
 }
 
 
+LocationSummary* TestSmiInstr::MakeLocationSummary() const {
+  const intptr_t kNumInputs = 2;
+  const intptr_t kNumTemps = 0;
+  LocationSummary* locs =
+      new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
+  locs->set_in(0, Location::RequiresRegister());
+  // Only one input can be a constant operand. The case of two constant
+  // operands should be handled by constant propagation.
+  locs->set_in(1, Location::RegisterOrConstant(right()));
+  return locs;
+}
+
+
+void TestSmiInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  // Never emitted outside of the BranchInstr.
+  UNREACHABLE();
+}
+
+
+void TestSmiInstr::EmitBranchCode(FlowGraphCompiler* compiler,
+                                  BranchInstr* branch) {
+  Condition branch_condition = (kind() == Token::kNE) ? NOT_ZERO : ZERO;
+  Location right = locs()->in(1);
+  if (right.IsConstant()) {
+    ASSERT(right.constant().IsSmi());
+    const int64_t imm =
+        reinterpret_cast<int64_t>(right.constant().raw());
+    __ testq(locs()->in(0).reg(), Immediate(imm));
+  } else {
+    __ testq(locs()->in(0).reg(), right.reg());
+  }
+  branch->EmitBranchOnCondition(compiler, branch_condition);
+}
+
+
 LocationSummary* RelationalOpInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps = 0;