[turbofan] Match selects in control reducer (configurable).

test/unittests/compiler/control-reducer-unittest.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/control-reducer.h"
+#include "src/compiler/diamond.h"
 #include "src/compiler/graph-visualizer.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node.h"
 #include "test/unittests/compiler/graph-unittest.h"
 #include "test/unittests/compiler/node-test-utils.h"
 #include "testing/gmock-support.h"
 
 using testing::_;
@@ skipping 11 matching lines @@
       : TypedGraphTest(1),
         machine_(zone()),
         javascript_(zone()),
         jsgraph_(isolate(), graph(), common(), &javascript_, &machine_) {}
 
  protected:
   MachineOperatorBuilder machine_;
   JSOperatorBuilder javascript_;
   JSGraph jsgraph_;
 
-  void ReduceGraph() {
+  void ReduceGraph(int max_phis_for_select = 0) {
     if (FLAG_trace_turbo_graph) {
       OFStream os(stdout);
       os << "-- Graph before control reduction" << std::endl;
       os << AsRPO(*graph());
     }
-    ControlReducer::ReduceGraph(zone(), jsgraph(), common());
+    ControlReducer::ReduceGraph(zone(), jsgraph(), common(),
+                                max_phis_for_select);
     if (FLAG_trace_turbo_graph) {
       OFStream os(stdout);
       os << "-- Graph after control reduction" << std::endl;
       os << AsRPO(*graph());
     }
   }
 
   JSGraph* jsgraph() { return &jsgraph_; }
 };
 
@@ skipping 218 matching lines @@
 
   ReduceGraph();
 
   // Diamond should be folded away.
   EXPECT_THAT(
       graph()->end(),
       IsEnd(IsReturn(IsInt32Constant(11), graph()->start(), graph()->start())));
 }
 
 
+TEST_F(ControlReducerTest, SelectPhi) {
+  Node* p0 = Parameter(0);
+  const MachineType kType = kMachInt32;
+  Diamond d(graph(), common(), p0);
+  Node* phi =
+      d.Phi(kType, jsgraph()->Int32Constant(1), jsgraph()->Int32Constant(2));
+
+  Node* ret =
+      graph()->NewNode(common()->Return(), phi, graph()->start(), d.merge);
+  graph()->end()->ReplaceInput(0, ret);
+
+  ReduceGraph(1);
+
+  // Phi should be replaced with a select.
+  EXPECT_THAT(graph()->end(),
+              IsEnd(IsReturn(
+                  IsSelect(kType, p0, IsInt32Constant(1), IsInt32Constant(2)),
+                  graph()->start(), graph()->start())));
+}
+
+
+TEST_F(ControlReducerTest, SelectPhis_fail) {
+  Node* p0 = Parameter(0);
+  const MachineType kType = kMachInt32;
+  Diamond d(graph(), common(), p0);
+  Node* phi =
+      d.Phi(kType, jsgraph()->Int32Constant(1), jsgraph()->Int32Constant(2));
+  Node* phi2 =
+      d.Phi(kType, jsgraph()->Int32Constant(11), jsgraph()->Int32Constant(22));
+  USE(phi2);
+  Node* ret =
+      graph()->NewNode(common()->Return(), phi, graph()->start(), d.merge);
+  graph()->end()->ReplaceInput(0, ret);
+
+  ReduceGraph(1);
+
+  // Diamond should not be replaced with a select (too many phis).
+  EXPECT_THAT(ret, IsReturn(phi, graph()->start(), d.merge));
+  EXPECT_THAT(graph()->end(), IsEnd(ret));
+}
+
+
+TEST_F(ControlReducerTest, SelectTwoPhis) {
+  Node* p0 = Parameter(0);
+  const MachineType kType = kMachInt32;
+  Diamond d(graph(), common(), p0);
+  Node* phi1 =
+      d.Phi(kType, jsgraph()->Int32Constant(1), jsgraph()->Int32Constant(2));
+  Node* phi2 =
+      d.Phi(kType, jsgraph()->Int32Constant(2), jsgraph()->Int32Constant(3));
+  MachineOperatorBuilder machine(zone());
+  Node* add = graph()->NewNode(machine.Int32Add(), phi1, phi2);
+  Node* ret =
+      graph()->NewNode(common()->Return(), add, graph()->start(), d.merge);
+  graph()->end()->ReplaceInput(0, ret);
+
+  ReduceGraph(2);
+
+  // Phis should be replaced with two selects.
+  EXPECT_THAT(
+      ret,
+      IsReturn(IsInt32Add(
+                   IsSelect(kType, p0, IsInt32Constant(1), IsInt32Constant(2)),
+                   IsSelect(kType, p0, IsInt32Constant(2), IsInt32Constant(3))),
+               graph()->start(), graph()->start()));
+  EXPECT_THAT(graph()->end(), IsEnd(ret));
+}
+
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8