[turbofan] Improve branch folding over phis and ranges.

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/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::_;
 using testing::AllOf;
 using testing::Capture;
 using testing::CaptureEq;
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-class ControlReducerTest : public GraphTest {
+class ControlReducerTest : public TypedGraphTest {
+ public:
+  ControlReducerTest()
+      : TypedGraphTest(1),
+        machine_(zone()),
+        javascript_(zone()),
+        jsgraph_(isolate(), graph(), common(), &javascript_, &machine_) {}
+
  protected:
+  MachineOperatorBuilder machine_;
+  JSOperatorBuilder javascript_;
+  JSGraph jsgraph_;
+
   void ReduceGraph() {
-    JSOperatorBuilder javascript(zone());
-    MachineOperatorBuilder machine(zone());
-    JSGraph jsgraph(isolate(), graph(), common(), &javascript, &machine);
-    ControlReducer::ReduceGraph(zone(), &jsgraph, common());
+    if (FLAG_trace_turbo_graph) {
+      OFStream os(stdout);
+      os << "-- Graph before control reduction" << std::endl;
+      os << AsRPO(*graph());
+    }
+    ControlReducer::ReduceGraph(zone(), jsgraph(), common());
+    if (FLAG_trace_turbo_graph) {
+      OFStream os(stdout);
+      os << "-- Graph after control reduction" << std::endl;
+      os << AsRPO(*graph());
+    }
   }
+
+  JSGraph* jsgraph() { return &jsgraph_; }
 };
 
 
 TEST_F(ControlReducerTest, NonTerminatingLoop) {
   Node* loop = graph()->NewNode(common()->Loop(2), graph()->start());
   loop->AppendInput(graph()->zone(), loop);
   ReduceGraph();
   Capture<Node*> branch;
   EXPECT_THAT(
       graph()->end(),
@@ skipping 71 matching lines @@
       graph()->end(),
       IsEnd(IsReturn(
           IsUndefinedConstant(), graph()->start(),
           IsIfFalse(AllOf(
               CaptureEq(&branch),
               IsBranch(IsAlways(),
                        AllOf(loop, IsLoop(graph()->start(),
                                           IsIfTrue(CaptureEq(&branch))))))))));
 }
 
+
+TEST_F(ControlReducerTest, PhiAsInputToBranch_true) {
+  Node* p0 = Parameter(0);
+  Node* branch1 = graph()->NewNode(common()->Branch(), p0, graph()->start());
+  Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
+  Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
+  Node* merge1 = graph()->NewNode(common()->Merge(2), if_true1, if_false1);
+  Node* phi1 = graph()->NewNode(common()->Phi(kMachInt32, 2),
+                                jsgraph()->Int32Constant(1),
+                                jsgraph()->Int32Constant(2), merge1);
+
+  Node* branch2 = graph()->NewNode(common()->Branch(), phi1, merge1);
+  Node* if_true2 = graph()->NewNode(common()->IfTrue(), branch2);
+  Node* if_false2 = graph()->NewNode(common()->IfFalse(), branch2);
+  Node* merge2 = graph()->NewNode(common()->Merge(2), if_true2, if_false2);
+  Node* result = graph()->NewNode(common()->Phi(kMachInt32, 2),
+                                  jsgraph()->Int32Constant(11),
+                                  jsgraph()->Int32Constant(22), merge2);
+
+  Node* ret =
+      graph()->NewNode(common()->Return(), result, graph()->start(), merge2);
+  graph()->end()->ReplaceInput(0, ret);
+
+  ReduceGraph();
+
+  // First diamond is not reduced.
+  EXPECT_THAT(merge1, IsMerge(IsIfTrue(branch1), IsIfFalse(branch1)));
+
+  // Second diamond should be folded away.
+  EXPECT_THAT(graph()->end(),
+              IsEnd(IsReturn(IsInt32Constant(11), graph()->start(), merge1)));
+}
+
+
+TEST_F(ControlReducerTest, PhiAsInputToBranch_false) {
+  Node* p0 = Parameter(0);
+  Node* branch1 = graph()->NewNode(common()->Branch(), p0, graph()->start());
+  Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
+  Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
+  Node* merge1 = graph()->NewNode(common()->Merge(2), if_true1, if_false1);
+  Node* phi1 = graph()->NewNode(common()->Phi(kMachInt32, 2),
+                                jsgraph()->Int32Constant(0),
+                                jsgraph()->BooleanConstant(false), merge1);
+
+  Node* branch2 = graph()->NewNode(common()->Branch(), phi1, merge1);
+  Node* if_true2 = graph()->NewNode(common()->IfTrue(), branch2);
+  Node* if_false2 = graph()->NewNode(common()->IfFalse(), branch2);
+  Node* merge2 = graph()->NewNode(common()->Merge(2), if_true2, if_false2);
+  Node* result = graph()->NewNode(common()->Phi(kMachInt32, 2),
+                                  jsgraph()->Int32Constant(11),
+                                  jsgraph()->Int32Constant(22), merge2);
+
+  Node* ret =
+      graph()->NewNode(common()->Return(), result, graph()->start(), merge2);
+  graph()->end()->ReplaceInput(0, ret);
+
+  ReduceGraph();
+
+  // First diamond is not reduced.
+  EXPECT_THAT(merge1, IsMerge(IsIfTrue(branch1), IsIfFalse(branch1)));
+
+  // Second diamond should be folded away.
+  EXPECT_THAT(graph()->end(),
+              IsEnd(IsReturn(IsInt32Constant(22), graph()->start(), merge1)));
+}
+
+
+TEST_F(ControlReducerTest, PhiAsInputToBranch_unknown_true) {
+  Node* p0 = Parameter(0);
+  Node* phi0 = graph()->NewNode(common()->Phi(kMachInt32, 2), p0,
+                                jsgraph()->Int32Constant(1), graph()->start());
+  Node* branch1 = graph()->NewNode(common()->Branch(), phi0, graph()->start());
+  Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
+  Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
+  Node* merge1 = graph()->NewNode(common()->Merge(2), if_true1, if_false1);
+  Node* phi1 = graph()->NewNode(common()->Phi(kMachInt32, 2),
+                                jsgraph()->Int32Constant(111),
+                                jsgraph()->Int32Constant(222), merge1);
+
+  Node* ret =
+      graph()->NewNode(common()->Return(), phi1, graph()->start(), merge1);
+  graph()->end()->ReplaceInput(0, ret);
+
+  ReduceGraph();
+
+  // Branch should not be folded.
+  EXPECT_THAT(phi1,
+              IsPhi(kMachInt32, IsInt32Constant(111), IsInt32Constant(222),
+                    IsMerge(IsIfTrue(branch1), IsIfFalse(branch1))));
+  EXPECT_THAT(graph()->end(), IsEnd(IsReturn(phi1, graph()->start(), merge1)));
+}
+
+
+TEST_F(ControlReducerTest, RangeAsInputToBranch_true1) {
+  Node* p0 = Parameter(Type::Range(1, 2, zone()), 0);
+  Node* branch1 = graph()->NewNode(common()->Branch(), p0, graph()->start());
+  Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
+  Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
+  Node* merge1 = graph()->NewNode(common()->Merge(1), if_true1, if_false1);
+  Node* result = graph()->NewNode(common()->Phi(kMachInt32, 2),
+                                  jsgraph()->Int32Constant(11),
+                                  jsgraph()->Int32Constant(44), merge1);
+
+  Node* ret =
+      graph()->NewNode(common()->Return(), result, graph()->start(), merge1);
+  graph()->end()->ReplaceInput(0, ret);
+
+  ReduceGraph();
+
+  // Diamond should be folded away.
+  EXPECT_THAT(
+      graph()->end(),
+      IsEnd(IsReturn(IsInt32Constant(11), graph()->start(), graph()->start())));
+}
+
+
+TEST_F(ControlReducerTest, RangeAsInputToBranch_true2) {
+  Node* p0 = Parameter(Type::Range(-2, -1, zone()), 0);
+  Node* branch1 = graph()->NewNode(common()->Branch(), p0, graph()->start());
+  Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
+  Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
+  Node* merge1 = graph()->NewNode(common()->Merge(1), if_true1, if_false1);
+  Node* result = graph()->NewNode(common()->Phi(kMachInt32, 2),
+                                  jsgraph()->Int32Constant(11),
+                                  jsgraph()->Int32Constant(44), merge1);
+
+  Node* ret =
+      graph()->NewNode(common()->Return(), result, graph()->start(), merge1);
+  graph()->end()->ReplaceInput(0, ret);
+
+  ReduceGraph();
+
+  // Diamond should be folded away.
+  EXPECT_THAT(
+      graph()->end(),
+      IsEnd(IsReturn(IsInt32Constant(11), graph()->start(), graph()->start())));
+}
+
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8