[turbofan] Add support for accessing Uint8ClampedArrays.

This adds a new NumberToUint8Clamped simplified operator that does the
round ties to even + clamping necessary to store to Uint8ClampedArrays.

BUG=v8:4470,v8:5267,v8:5615
R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2489563004
Cr-Commit-Position: refs/heads/master@{#40861}

src/compiler/access-info.cc

@@ -25,8 +25,6 @@ bool CanInlineElementAccess(Handle<Map> map) {
   if (map->has_indexed_interceptor()) return false;
   ElementsKind const elements_kind = map->elements_kind();
   if (IsFastElementsKind(elements_kind)) return true;
-  // TODO(bmeurer): Add support for other elements kind.
-  if (elements_kind == UINT8_CLAMPED_ELEMENTS) return false;
   if (IsFixedTypedArrayElementsKind(elements_kind)) return true;
   return false;
 }

src/compiler/effect-control-linearizer.cc

@@ -780,6 +780,9 @@ bool EffectControlLinearizer::TryWireInStateEffect(Node* node,
     case IrOpcode::kFloat64RoundTruncate:
       state = LowerFloat64RoundTruncate(node, *effect, *control);
       break;
+    case IrOpcode::kFloat64RoundTiesEven:
+      state = LowerFloat64RoundTiesEven(node, *effect, *control);
+      break;
     default:
       return false;
   }
@@ -3375,20 +3378,19 @@ EffectControlLinearizer::LowerFloat64RoundUp(Node* node, Node* effect,
 }
 
 EffectControlLinearizer::ValueEffectControl
-EffectControlLinearizer::LowerFloat64RoundDown(Node* node, Node* effect,
+EffectControlLinearizer::BuildFloat64RoundDown(Node* value, Node* effect,
                                                Node* control) {
-  // Nothing to be done if a fast hardware instruction is available.
   if (machine()->Float64RoundDown().IsSupported()) {
-    return ValueEffectControl(node, effect, control);
-  }
-
+    value = graph()->NewNode(machine()->Float64RoundDown().op(), value);
+  } else {
     Node* const one = jsgraph()->Float64Constant(1.0);
     Node* const zero = jsgraph()->Float64Constant(0.0);
     Node* const minus_one = jsgraph()->Float64Constant(-1.0);
     Node* const minus_zero = jsgraph()->Float64Constant(-0.0);
     Node* const two_52 = jsgraph()->Float64Constant(4503599627370496.0E0);
-  Node* const minus_two_52 = jsgraph()->Float64Constant(-4503599627370496.0E0);
-  Node* const input = node->InputAt(0);
+    Node* const minus_two_52 =
+        jsgraph()->Float64Constant(-4503599627370496.0E0);
+    Node* const input = value;
 
     // General case for floor.
     //
@@ -3415,7 +3417,8 @@ EffectControlLinearizer::LowerFloat64RoundDown(Node* node, Node* effect,
     //         else
     //           -0 - temp2
     //
-  // Note: We do not use the Diamond helper class here, because it really hurts
+    // Note: We do not use the Diamond helper class here, because it really
+    // hurts
     // readability with nested diamonds.
 
     Node* check0 = graph()->NewNode(machine()->Float64LessThan(), zero, input);
@@ -3445,7 +3448,8 @@ EffectControlLinearizer::LowerFloat64RoundDown(Node* node, Node* effect,
       }
 
       if_true0 = graph()->NewNode(common()->Merge(2), if_true1, if_false1);
-    vtrue0 = graph()->NewNode(common()->Phi(MachineRepresentation::kFloat64, 2),
+      vtrue0 =
+          graph()->NewNode(common()->Phi(MachineRepresentation::kFloat64, 2),
                            vtrue1, vfalse1, if_true0);
     }
 
@@ -3497,11 +3501,111 @@ EffectControlLinearizer::LowerFloat64RoundDown(Node* node, Node* effect,
                            vtrue1, vfalse1, if_false0);
     }
 
-  Node* merge0 = graph()->NewNode(common()->Merge(2), if_true0, if_false0);
-  Node* value =
+    control = graph()->NewNode(common()->Merge(2), if_true0, if_false0);
+    value = graph()->NewNode(common()->Phi(MachineRepresentation::kFloat64, 2),
+                             vtrue0, vfalse0, control);
+  }
+  return ValueEffectControl(value, effect, control);
+}
+
+EffectControlLinearizer::ValueEffectControl
+EffectControlLinearizer::LowerFloat64RoundDown(Node* node, Node* effect,
+                                               Node* control) {
+  // Nothing to be done if a fast hardware instruction is available.
+  if (machine()->Float64RoundDown().IsSupported()) {
+    return ValueEffectControl(node, effect, control);
+  }
+
+  Node* const input = node->InputAt(0);
+  return BuildFloat64RoundDown(input, effect, control);
+}
+
+EffectControlLinearizer::ValueEffectControl
+EffectControlLinearizer::LowerFloat64RoundTiesEven(Node* node, Node* effect,
+                                                   Node* control) {
+  // Nothing to be done if a fast hardware instruction is available.
+  if (machine()->Float64RoundTiesEven().IsSupported()) {
+    return ValueEffectControl(node, effect, control);
+  }
+
+  Node* const one = jsgraph()->Float64Constant(1.0);
+  Node* const two = jsgraph()->Float64Constant(2.0);
+  Node* const half = jsgraph()->Float64Constant(0.5);
+  Node* const zero = jsgraph()->Float64Constant(0.0);
+  Node* const input = node->InputAt(0);
+
+  // Generate case for round ties to even:
+  //
+  //   let value = floor(input) in
+  //   let temp1 = input - value in
+  //   if temp1 < 0.5 then
+  //     value
+  //   else if 0.5 < temp1 then
+  //     value + 1.0
+  //   else
+  //     let temp2 = value % 2.0 in
+  //     if temp2 == 0.0 then
+  //       value
+  //     else
+  //       value + 1.0
+  //
+  // Note: We do not use the Diamond helper class here, because it really hurts
+  // readability with nested diamonds.
+
+  ValueEffectControl continuation =
+      BuildFloat64RoundDown(input, effect, control);
+  Node* value = continuation.value;
+  effect = continuation.effect;
+  control = continuation.control;
+
+  Node* temp1 = graph()->NewNode(machine()->Float64Sub(), input, value);
+
+  Node* check0 = graph()->NewNode(machine()->Float64LessThan(), temp1, half);
+  Node* branch0 = graph()->NewNode(common()->Branch(), check0, control);
+
+  Node* if_true0 = graph()->NewNode(common()->IfTrue(), branch0);
+  Node* vtrue0 = value;
+
+  Node* if_false0 = graph()->NewNode(common()->IfFalse(), branch0);
+  Node* vfalse0;
+  {
+    Node* check1 = graph()->NewNode(machine()->Float64LessThan(), half, temp1);
+    Node* branch1 = graph()->NewNode(common()->Branch(), check1, if_false0);
+
+    Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
+    Node* vtrue1 = graph()->NewNode(machine()->Float64Add(), value, one);
+
+    Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
+    Node* vfalse1;
+    {
+      Node* temp2 = graph()->NewNode(machine()->Float64Mod(), value, two);
+
+      Node* check2 = graph()->NewNode(machine()->Float64Equal(), temp2, zero);
+      Node* branch2 = graph()->NewNode(common()->Branch(), check2, if_false1);
+
+      Node* if_true2 = graph()->NewNode(common()->IfTrue(), branch2);
+      Node* vtrue2 = value;
+
+      Node* if_false2 = graph()->NewNode(common()->IfFalse(), branch2);
+      Node* vfalse2 = graph()->NewNode(machine()->Float64Add(), value, one);
+
+      if_false1 = graph()->NewNode(common()->Merge(2), if_true2, if_false2);
+      vfalse1 =
           graph()->NewNode(common()->Phi(MachineRepresentation::kFloat64, 2),
-                       vtrue0, vfalse0, merge0);
-  return ValueEffectControl(value, effect, merge0);
+                           vtrue2, vfalse2, if_false1);
+    }
+
+    if_false0 = graph()->NewNode(common()->Merge(2), if_true1, if_false1);
+    vfalse0 =
+        graph()->NewNode(common()->Phi(MachineRepresentation::kFloat64, 2),
+                         vtrue1, vfalse1, if_false0);
+  }
+
+  control = graph()->NewNode(common()->Merge(2), if_true0, if_false0);
+  value = graph()->NewNode(common()->Phi(MachineRepresentation::kFloat64, 2),
+                           vtrue0, vfalse0, control);
+
+  return ValueEffectControl(value, effect, control);
 }
 
 EffectControlLinearizer::ValueEffectControl

src/compiler/effect-control-linearizer.h

@@ -182,6 +182,8 @@ class V8_EXPORT_PRIVATE EffectControlLinearizer {
                                          Node* control);
   ValueEffectControl LowerFloat64RoundDown(Node* node, Node* effect,
                                            Node* control);
+  ValueEffectControl LowerFloat64RoundTiesEven(Node* node, Node* effect,
+                                               Node* control);
   ValueEffectControl LowerFloat64RoundTruncate(Node* node, Node* effect,
                                                Node* control);
 
@@ -193,6 +195,8 @@ class V8_EXPORT_PRIVATE EffectControlLinearizer {
   ValueEffectControl BuildCheckedHeapNumberOrOddballToFloat64(
       CheckTaggedInputMode mode, Node* value, Node* frame_state, Node* effect,
       Node* control);
+  ValueEffectControl BuildFloat64RoundDown(Node* value, Node* effect,
+                                           Node* control);
   ValueEffectControl LowerStringComparison(Callable const& callable, Node* node,
                                            Node* effect, Node* control);
 

src/compiler/js-native-context-specialization.cc

@@ -1200,6 +1200,14 @@ JSNativeContextSpecialization::BuildElementAccess(
         value = effect = graph()->NewNode(simplified()->CheckNumber(), value,
                                           effect, control);
 
+        // Introduce the appropriate truncation for {value}. Currently we
+        // only need to do this for ClamedUint8Array {receiver}s, as the
+        // other truncations are implicit in the StoreTypedElement, but we
+        // might want to change that at some point.
+        if (external_array_type == kExternalUint8ClampedArray) {
+          value = graph()->NewNode(simplified()->NumberToUint8Clamped(), value);
+        }
+
         // Check if we can skip the out-of-bounds store.
         if (store_mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS) {
           Node* check =

src/compiler/opcodes.h

@@ -281,6 +281,7 @@
   V(NumberToBoolean)                   \
   V(NumberToInt32)                     \
   V(NumberToUint32)                    \
+  V(NumberToUint8Clamped)              \
   V(NumberSilenceNaN)
 
 #define SIMPLIFIED_OTHER_OP_LIST(V) \

src/compiler/operation-typer.cc

@@ -490,6 +490,13 @@ Type* OperationTyper::NumberToUint32(Type* type) {
   return Type::Unsigned32();
 }
 
+Type* OperationTyper::NumberToUint8Clamped(Type* type) {
+  DCHECK(type->Is(Type::Number()));
+
+  if (type->Is(cache_.kUint8)) return type;
+  return cache_.kUint8;
+}
+
 Type* OperationTyper::NumberSilenceNaN(Type* type) {
   DCHECK(type->Is(Type::Number()));
   // TODO(jarin): This is a terrible hack; we definitely need a dedicated type

src/compiler/simplified-lowering.cc

@@ -2111,6 +2111,31 @@ class RepresentationSelector {
         if (lower()) DeferReplacement(node, node->InputAt(0));
         return;
       }
+      case IrOpcode::kNumberToUint8Clamped: {
+        Type* const input_type = TypeOf(node->InputAt(0));
+        if (input_type->Is(type_cache_.kUint8OrMinusZeroOrNaN)) {
+          VisitUnop(node, UseInfo::TruncatingWord32(),
+                    MachineRepresentation::kWord32);
+          if (lower()) DeferReplacement(node, node->InputAt(0));
+        } else if (input_type->Is(Type::Unsigned32OrMinusZeroOrNaN())) {
+          VisitUnop(node, UseInfo::TruncatingWord32(),
+                    MachineRepresentation::kWord32);
+          if (lower()) lowering->DoUnsigned32ToUint8Clamped(node);
+        } else if (input_type->Is(Type::Signed32OrMinusZeroOrNaN())) {
+          VisitUnop(node, UseInfo::TruncatingWord32(),
+                    MachineRepresentation::kWord32);
+          if (lower()) lowering->DoSigned32ToUint8Clamped(node);
+        } else if (input_type->Is(type_cache_.kIntegerOrMinusZeroOrNaN)) {
+          VisitUnop(node, UseInfo::TruncatingFloat64(),
+                    MachineRepresentation::kFloat64);
+          if (lower()) lowering->DoIntegerToUint8Clamped(node);
+        } else {
+          VisitUnop(node, UseInfo::TruncatingFloat64(),
+                    MachineRepresentation::kFloat64);
+          if (lower()) lowering->DoNumberToUint8Clamped(node);
+        }
+        return;
+      }
       case IrOpcode::kReferenceEqual: {
         VisitBinop(node, UseInfo::AnyTagged(), MachineRepresentation::kBit);
         if (lower()) {
@@ -3294,6 +3319,71 @@ void SimplifiedLowering::DoNumberToBit(Node* node) {
   NodeProperties::ChangeOp(node, machine()->Float64LessThan());
 }
 
+void SimplifiedLowering::DoIntegerToUint8Clamped(Node* node) {
+  Node* const input = node->InputAt(0);
+  Node* const min = jsgraph()->Float64Constant(0.0);
+  Node* const max = jsgraph()->Float64Constant(255.0);
+
+  node->ReplaceInput(
+      0, graph()->NewNode(machine()->Float64LessThan(), min, input));
+  node->AppendInput(
+      graph()->zone(),
+      graph()->NewNode(
+          common()->Select(MachineRepresentation::kFloat64),
+          graph()->NewNode(machine()->Float64LessThan(), input, max), input,
+          max));
+  node->AppendInput(graph()->zone(), min);
+  NodeProperties::ChangeOp(node,
+                           common()->Select(MachineRepresentation::kFloat64));
+}
+
+void SimplifiedLowering::DoNumberToUint8Clamped(Node* node) {
+  Node* const input = node->InputAt(0);
+  Node* const min = jsgraph()->Float64Constant(0.0);
+  Node* const max = jsgraph()->Float64Constant(255.0);
+
+  node->ReplaceInput(
+      0, graph()->NewNode(
+             common()->Select(MachineRepresentation::kFloat64),
+             graph()->NewNode(machine()->Float64LessThan(), min, input),
+             graph()->NewNode(
+                 common()->Select(MachineRepresentation::kFloat64),
+                 graph()->NewNode(machine()->Float64LessThan(), input, max),
+                 input, max),
+             min));
+  NodeProperties::ChangeOp(node,
+                           machine()->Float64RoundTiesEven().placeholder());
+}
+
+void SimplifiedLowering::DoSigned32ToUint8Clamped(Node* node) {
+  Node* const input = node->InputAt(0);
+  Node* const min = jsgraph()->Int32Constant(0);
+  Node* const max = jsgraph()->Int32Constant(255);
+
+  node->ReplaceInput(
+      0, graph()->NewNode(machine()->Int32LessThanOrEqual(), input, max));
+  node->AppendInput(
+      graph()->zone(),
+      graph()->NewNode(common()->Select(MachineRepresentation::kWord32),
+                       graph()->NewNode(machine()->Int32LessThan(), input, min),
+                       min, input));
+  node->AppendInput(graph()->zone(), max);
+  NodeProperties::ChangeOp(node,
+                           common()->Select(MachineRepresentation::kWord32));
+}
+
+void SimplifiedLowering::DoUnsigned32ToUint8Clamped(Node* node) {
+  Node* const input = node->InputAt(0);
+  Node* const max = jsgraph()->Uint32Constant(255u);
+
+  node->ReplaceInput(
+      0, graph()->NewNode(machine()->Uint32LessThanOrEqual(), input, max));
+  node->AppendInput(graph()->zone(), input);
+  node->AppendInput(graph()->zone(), max);
+  NodeProperties::ChangeOp(node,
+                           common()->Select(MachineRepresentation::kWord32));
+}
+
 Node* SimplifiedLowering::ToNumberCode() {
   if (!to_number_code_.is_set()) {
     Callable callable = CodeFactory::ToNumber(isolate());

src/compiler/simplified-lowering.h

@@ -44,6 +44,10 @@ class SimplifiedLowering final {
   void DoIntegral32ToBit(Node* node);
   void DoOrderedNumberToBit(Node* node);
   void DoNumberToBit(Node* node);
+  void DoIntegerToUint8Clamped(Node* node);
+  void DoNumberToUint8Clamped(Node* node);
+  void DoSigned32ToUint8Clamped(Node* node);
+  void DoUnsigned32ToUint8Clamped(Node* node);
 
  private:
   JSGraph* const jsgraph_;

src/compiler/simplified-operator.cc

@@ -393,6 +393,7 @@ UnicodeEncoding UnicodeEncodingOf(const Operator* op) {
   V(NumberToBoolean, Operator::kNoProperties, 1, 0)              \
   V(NumberToInt32, Operator::kNoProperties, 1, 0)                \
   V(NumberToUint32, Operator::kNoProperties, 1, 0)               \
+  V(NumberToUint8Clamped, Operator::kNoProperties, 1, 0)         \
   V(NumberSilenceNaN, Operator::kNoProperties, 1, 0)             \
   V(StringCharCodeAt, Operator::kNoProperties, 2, 1)             \
   V(StringFromCharCode, Operator::kNoProperties, 1, 0)           \

src/compiler/simplified-operator.h

@@ -269,6 +269,7 @@ class V8_EXPORT_PRIVATE SimplifiedOperatorBuilder final
   const Operator* NumberToBoolean();
   const Operator* NumberToInt32();
   const Operator* NumberToUint32();
+  const Operator* NumberToUint8Clamped();
 
   const Operator* NumberSilenceNaN();
 

src/compiler/type-cache.h

@@ -26,6 +26,8 @@ class TypeCache final {
   Type* const kInt8 = CreateRange<int8_t>();
   Type* const kUint8 = CreateRange<uint8_t>();
   Type* const kUint8Clamped = kUint8;
+  Type* const kUint8OrMinusZeroOrNaN =
+      Type::Union(kUint8, Type::MinusZeroOrNaN(), zone());
   Type* const kInt16 = CreateRange<int16_t>();
   Type* const kUint16 = CreateRange<uint16_t>();
   Type* const kInt32 = Type::Signed32();

src/compiler/typed-optimization.cc

@@ -87,6 +87,8 @@ Reduction TypedOptimization::Reduce(Node* node) {
     case IrOpcode::kNumberRound:
     case IrOpcode::kNumberTrunc:
       return ReduceNumberRoundop(node);
+    case IrOpcode::kNumberToUint8Clamped:
+      return ReduceNumberToUint8Clamped(node);
     case IrOpcode::kPhi:
       return ReducePhi(node);
     case IrOpcode::kSelect:
@@ -192,6 +194,15 @@ Reduction TypedOptimization::ReduceNumberRoundop(Node* node) {
   return NoChange();
 }
 
+Reduction TypedOptimization::ReduceNumberToUint8Clamped(Node* node) {
+  Node* const input = NodeProperties::GetValueInput(node, 0);
+  Type* const input_type = NodeProperties::GetType(input);
+  if (input_type->Is(type_cache_.kUint8)) {
+    return Replace(input);
+  }
+  return NoChange();
+}
+
 Reduction TypedOptimization::ReducePhi(Node* node) {
   // Try to narrow the type of the Phi {node}, which might be more precise now
   // after lowering based on types, i.e. a SpeculativeNumberAdd has a more

src/compiler/typed-optimization.h

@@ -47,6 +47,7 @@ class V8_EXPORT_PRIVATE TypedOptimization final
   Reduction ReduceCheckString(Node* node);
   Reduction ReduceLoadField(Node* node);
   Reduction ReduceNumberRoundop(Node* node);
+  Reduction ReduceNumberToUint8Clamped(Node* node);
   Reduction ReducePhi(Node* node);
   Reduction ReduceSelect(Node* node);
 

src/compiler/verifier.cc

@@ -826,6 +826,7 @@ void Verifier::Visitor::Check(Node* node) {
       CheckTypeIs(node, Type::Signed32());
       break;
     case IrOpcode::kNumberToUint32:
+    case IrOpcode::kNumberToUint8Clamped:
       // Number -> Unsigned32
       CheckValueInputIs(node, 0, Type::Number());
       CheckTypeIs(node, Type::Unsigned32());

test/mjsunit/compiler/uint8-clamped-array.js

@@ -0,0 +1,73 @@
+// Copyright 2016 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.
+
+// Flags: --allow-natives-syntax
+
+(function() {
+  function foo(a, v) {
+    a[0] = v & 0xff;
+  }
+
+  var a = new Uint8ClampedArray(4);
+  foo(a, 1);
+  foo(a, 2);
+  %OptimizeFunctionOnNextCall(foo);
+  foo(a, 256);
+  assertOptimized(foo);
+  assertEquals(0, a[0]);
+})();
+
+(function() {
+  function foo(a, v) {
+    a[0] = v >>> 0;
+  }
+
+  var a = new Uint8ClampedArray(4);
+  foo(a, 1);
+  foo(a, 2);
+  %OptimizeFunctionOnNextCall(foo);
+  foo(a, 256);
+  assertOptimized(foo);
+  assertEquals(255, a[0]);
+})();
+
+(function() {
+  function foo(a, v) {
+    a[0] = v | 0;
+  }
+
+  var a = new Uint8ClampedArray(4);
+  foo(a, 1);
+  foo(a, 2);
+  %OptimizeFunctionOnNextCall(foo);
+  foo(a, 256);
+  assertOptimized(foo);
+  assertEquals(255, a[0]);
+  foo(a, -1);
+  assertOptimized(foo);
+  assertEquals(0, a[0]);
+})();
+
+(function() {
+  function foo(a, v) {
+    a[0] = v;
+  }
+
+  var a = new Uint8ClampedArray(4);
+  foo(a, 1);
+  foo(a, 2);
+  %OptimizeFunctionOnNextCall(foo);
+  foo(a, Infinity);
+  assertOptimized(foo);
+  assertEquals(255, a[0]);
+  foo(a, -Infinity);
+  assertOptimized(foo);
+  assertEquals(0, a[0]);
+  foo(a, 0.5);
+  assertOptimized(foo);
+  assertEquals(0, a[0]);
+  foo(a, 1.5);
+  assertOptimized(foo);
+  assertEquals(2, a[0]);
+})();