[turbofan] Use the typer to statically detect Smis.

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/968773004

Cr-Commit-Position: refs/heads/master@{#26939}

src/compiler/change-lowering.cc

@@ -165,7 +165,7 @@ Reduction ChangeLowering::ChangeInt32ToTagged(Node* value, Node* control) {
         machine()->Word64Shl(),
         graph()->NewNode(machine()->ChangeInt32ToInt64(), value),
         SmiShiftBitsConstant()));
-  } else if (NodeProperties::GetBounds(value).upper->Is(Type::Signed31())) {
+  } else if (NodeProperties::GetBounds(value).upper->Is(Type::SignedSmall())) {
     return Replace(
         graph()->NewNode(machine()->WordShl(), value, SmiShiftBitsConstant()));
   }

src/compiler/simplified-lowering.cc

@@ -1140,12 +1140,13 @@ Node* SimplifiedLowering::OffsetMinusTagConstant(int32_t offset) {
 }
 
 
-WriteBarrierKind SimplifiedLowering::ComputeWriteBarrierKind(
-    BaseTaggedness base_is_tagged, MachineType representation, Node* value) {
-  // TODO(turbofan): skip write barriers for Smis, etc.
-  if (machine()->Is64() && value->opcode() == IrOpcode::kChangeInt32ToTagged) {
-    // TODO(bmeurer): Remove this hack once we have a way to represent "sminess"
-    // of values, either in types or representations.
+namespace {
+
+WriteBarrierKind ComputeWriteBarrierKind(BaseTaggedness base_is_tagged,
+                                         MachineType representation,
+                                         Type* type) {
+  if (type->Is(Type::TaggedSigned())) {
+    // Write barriers are only for writes of heap objects.
     return kNoWriteBarrier;
   }
   if (base_is_tagged == kTaggedBase &&
@@ -1156,6 +1157,8 @@ WriteBarrierKind SimplifiedLowering::ComputeWriteBarrierKind(
   return kNoWriteBarrier;
 }
 
+}  // namespace
+
 
 void SimplifiedLowering::DoLoadField(Node* node) {
   const FieldAccess& access = FieldAccessOf(node->op());
@@ -1167,8 +1170,9 @@ void SimplifiedLowering::DoLoadField(Node* node) {
 
 void SimplifiedLowering::DoStoreField(Node* node) {
   const FieldAccess& access = FieldAccessOf(node->op());
-  WriteBarrierKind kind = ComputeWriteBarrierKind(
-      access.base_is_tagged, access.machine_type, node->InputAt(1));
+  Type* type = NodeProperties::GetBounds(node->InputAt(1)).upper;
+  WriteBarrierKind kind =
+      ComputeWriteBarrierKind(access.base_is_tagged, access.machine_type, type);
   node->set_op(
       machine()->Store(StoreRepresentation(access.machine_type, kind)));
   Node* offset = jsgraph()->IntPtrConstant(access.offset - access.tag());
@@ -1273,10 +1277,11 @@ void SimplifiedLowering::DoLoadElement(Node* node) {
 
 void SimplifiedLowering::DoStoreElement(Node* node) {
   const ElementAccess& access = ElementAccessOf(node->op());
-  node->set_op(machine()->Store(StoreRepresentation(
-      access.machine_type,
-      ComputeWriteBarrierKind(access.base_is_tagged, access.machine_type,
-                              node->InputAt(2)))));
+  Type* type = NodeProperties::GetBounds(node->InputAt(2)).upper;
+  node->set_op(machine()->Store(
+      StoreRepresentation(access.machine_type,
+                          ComputeWriteBarrierKind(access.base_is_tagged,
+                                                  access.machine_type, type))));
   node->ReplaceInput(1, ComputeIndex(access, node->InputAt(1)));
 }
 

src/compiler/simplified-lowering.h

@@ -57,9 +57,6 @@ class SimplifiedLowering FINAL {
   Node* IsTagged(Node* node);
   Node* Untag(Node* node);
   Node* OffsetMinusTagConstant(int32_t offset);
-  WriteBarrierKind ComputeWriteBarrierKind(BaseTaggedness base_is_tagged,
-                                           MachineType representation,
-                                           Node* value);
   Node* ComputeIndex(const ElementAccess& access, Node* const key);
   Node* StringComparison(Node* node, bool requires_ordering);
   Node* Int32Div(Node* const node);

src/compiler/typer.cc

@@ -1616,16 +1616,15 @@ Bounds Typer::Visitor::TypeStringAdd(Node* node) {
 }
 
 
-static Type* ChangeRepresentation(Type* type, Type* rep, Zone* zone) {
-  // TODO(neis): Enable when expressible.
-  /*
-  return Type::Union(
-      Type::Intersect(type, Type::Semantic(), zone),
-      Type::Intersect(rep, Type::Representation(), zone), zone);
-  */
-  return type;
+namespace {
+
+Type* ChangeRepresentation(Type* type, Type* rep, Zone* zone) {
+  return Type::Union(Type::Semantic(type, zone),
+                     Type::Representation(rep, zone), zone);
 }
 
+}  // namespace
+
 
 Bounds Typer::Visitor::TypeChangeTaggedToInt32(Node* node) {
   Bounds arg = Operand(node, 0);
@@ -1657,9 +1656,12 @@ Bounds Typer::Visitor::TypeChangeTaggedToFloat64(Node* node) {
 Bounds Typer::Visitor::TypeChangeInt32ToTagged(Node* node) {
   Bounds arg = Operand(node, 0);
   // TODO(neis): DCHECK(arg.upper->Is(Type::Signed32()));
-  return Bounds(
-      ChangeRepresentation(arg.lower, Type::Tagged(), zone()),
-      ChangeRepresentation(arg.upper, Type::Tagged(), zone()));
+  Type* lower_rep = arg.lower->Is(Type::SignedSmall()) ? Type::TaggedSigned()
+                                                       : Type::Tagged();
+  Type* upper_rep = arg.upper->Is(Type::SignedSmall()) ? Type::TaggedSigned()
+                                                       : Type::Tagged();
+  return Bounds(ChangeRepresentation(arg.lower, lower_rep, zone()),
+                ChangeRepresentation(arg.upper, upper_rep, zone()));
 }
 
 

test/cctest/compiler/test-simplified-lowering.cc

@@ -1441,6 +1441,7 @@ TEST(LowerLoadField_to_load) {
 
 
 TEST(LowerStoreField_to_store) {
+  {
     TestingGraph t(Type::Any(), Type::Signed32());
 
     for (size_t i = 0; i < arraysize(kMachineReps); i++) {
@@ -1463,17 +1464,18 @@ TEST(LowerStoreField_to_store) {
       }
       CHECK_EQ(kMachineReps[i], rep.machine_type());
     }
-
-  if (t.machine()->Is64()) {
+  }
+  {
+    TestingGraph t(Type::Any(),
+                   Type::Intersect(Type::SignedSmall(), Type::TaggedSigned()));
     FieldAccess access = {kTaggedBase, FixedArrayBase::kHeaderSize,
                           Handle<Name>::null(), Type::Any(), kMachAnyTagged};
-    Node* val = t.graph()->NewNode(t.simplified()->ChangeInt32ToTagged(), t.p0);
     Node* store = t.graph()->NewNode(t.simplified()->StoreField(access), t.p0,
-                                     val, t.start, t.start);
+                                     t.p1, t.start, t.start);
     t.Effect(store);
     t.Lower();
     CHECK_EQ(IrOpcode::kStore, store->opcode());
-    CHECK_EQ(val, store->InputAt(2));
+    CHECK_EQ(t.p1, store->InputAt(2));
     StoreRepresentation rep = OpParameter<StoreRepresentation>(store);
     CHECK_EQ(kNoWriteBarrier, rep.write_barrier_kind());
   }
@@ -1503,6 +1505,7 @@ TEST(LowerLoadElement_to_load) {
 
 
 TEST(LowerStoreElement_to_store) {
+  {
     TestingGraph t(Type::Any(), Type::Signed32());
 
     for (size_t i = 0; i < arraysize(kMachineReps); i++) {
@@ -1510,8 +1513,8 @@ TEST(LowerStoreElement_to_store) {
                               Type::Any(), kMachineReps[i]};
 
       Node* val = t.ExampleWithOutput(kMachineReps[i]);
-    Node* store = t.graph()->NewNode(t.simplified()->StoreElement(access), t.p0,
-                                     t.p1, val, t.start, t.start);
+      Node* store = t.graph()->NewNode(t.simplified()->StoreElement(access),
+                                       t.p0, t.p1, val, t.start, t.start);
       t.Effect(store);
       t.Lower();
       CHECK_EQ(IrOpcode::kStore, store->opcode());
@@ -1524,6 +1527,21 @@ TEST(LowerStoreElement_to_store) {
       }
       CHECK_EQ(kMachineReps[i], rep.machine_type());
     }
+  }
+  {
+    TestingGraph t(Type::Any(), Type::Signed32(),
+                   Type::Intersect(Type::SignedSmall(), Type::TaggedSigned()));
+    ElementAccess access = {kTaggedBase, FixedArrayBase::kHeaderSize,
+                            Type::Any(), kMachAnyTagged};
+    Node* store = t.graph()->NewNode(t.simplified()->StoreElement(access), t.p0,
+                                     t.p1, t.p2, t.start, t.start);
+    t.Effect(store);
+    t.Lower();
+    CHECK_EQ(IrOpcode::kStore, store->opcode());
+    CHECK_EQ(t.p2, store->InputAt(2));
+    StoreRepresentation rep = OpParameter<StoreRepresentation>(store);
+    CHECK_EQ(kNoWriteBarrier, rep.write_barrier_kind());
+  }
 }
 
 

test/unittests/compiler/change-lowering-unittest.cc

@@ -181,7 +181,7 @@ class ChangeLowering32Test : public ChangeLoweringTest {
 TARGET_TEST_F(ChangeLowering32Test, ChangeInt32ToTagged) {
   Node* val = Parameter(0);
   Node* node = graph()->NewNode(simplified()->ChangeInt32ToTagged(), val);
-  NodeProperties::SetBounds(val, Bounds(Type::None(), Type::Signed32()));
+  NodeProperties::SetBounds(val, Bounds(Type::None(), Type::Integral32()));
   Reduction reduction = Reduce(node);
   ASSERT_TRUE(reduction.Changed());
 
@@ -209,7 +209,7 @@ TARGET_TEST_F(ChangeLowering32Test, ChangeInt32ToTagged) {
 TARGET_TEST_F(ChangeLowering32Test, ChangeInt32ToTaggedSmall) {
   Node* val = Parameter(0);
   Node* node = graph()->NewNode(simplified()->ChangeInt32ToTagged(), val);
-  NodeProperties::SetBounds(val, Bounds(Type::None(), Type::Signed31()));
+  NodeProperties::SetBounds(val, Bounds(Type::None(), Type::SignedSmall()));
   Reduction reduction = Reduce(node);
   ASSERT_TRUE(reduction.Changed());