[turbofan] Introduce TruncateTaggedToBit operator for ToBoolean truncation.

src/compiler/representation-change.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/representation-change.h"
 
 #include <sstream>
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 632 matching lines @@
   return jsgraph()->graph()->NewNode(op, node);
 }
 
 
 Node* RepresentationChanger::GetBitRepresentationFor(
     Node* node, MachineRepresentation output_rep, Type* output_type) {
   // Eagerly fold representation changes for constants.
   switch (node->opcode()) {
     case IrOpcode::kHeapConstant: {
       Handle<HeapObject> value = OpParameter<Handle<HeapObject>>(node);
-      DCHECK(value.is_identical_to(factory()->true_value()) ||
-             value.is_identical_to(factory()->false_value()));
-      return jsgraph()->Int32Constant(
-          value.is_identical_to(factory()->true_value()) ? 1 : 0);
+      return jsgraph()->Int32Constant(value->BooleanValue() ? 1 : 0);
     }
     default:
       break;
   }
   // Select the correct X -> Bit operator.
   const Operator* op;
   if (Type::Semantic(output_type, jsgraph()->zone())->Is(Type::None())) {
     // This is an impossible value; it should not be used at runtime.
     // We just provide a dummy value here.
     return jsgraph()->Int32Constant(0);
   } else if (output_rep == MachineRepresentation::kTagged ||
-             output_rep == MachineRepresentation::kTaggedSigned ||
              output_rep == MachineRepresentation::kTaggedPointer) {
-    op = simplified()->ChangeTaggedToBit();
+    if (output_type->Is(Type::BooleanOrNullOrUndefined())) {
+      // true is the only trueish Oddball.
+      op = simplified()->ChangeTaggedToBit();
+    } else {
+      op = simplified()->TruncateTaggedToBit();
+    }
+  } else if (output_rep == MachineRepresentation::kTaggedSigned) {
+    node = jsgraph()->graph()->NewNode(machine()->WordEqual(), node,
+                                       jsgraph()->ZeroConstant());
+    return jsgraph()->graph()->NewNode(machine()->Word32Equal(), node,
+                                       jsgraph()->Int32Constant(0));
+  } else if (IsWord(output_rep)) {
+    node = jsgraph()->graph()->NewNode(machine()->Word32Equal(), node,
+                                       jsgraph()->Int32Constant(0));
+    return jsgraph()->graph()->NewNode(machine()->Word32Equal(), node,
+                                       jsgraph()->Int32Constant(0));
+  } else if (output_rep == MachineRepresentation::kFloat32) {
+    node = jsgraph()->graph()->NewNode(machine()->Float32Abs(), node);
+    return jsgraph()->graph()->NewNode(machine()->Float32LessThan(),
+                                       jsgraph()->Float32Constant(0.0), node);
+  } else if (output_rep == MachineRepresentation::kFloat64) {
+    node = jsgraph()->graph()->NewNode(machine()->Float64Abs(), node);
+    return jsgraph()->graph()->NewNode(machine()->Float64LessThan(),
+                                       jsgraph()->Float64Constant(0.0), node);
   } else {
     return TypeError(node, output_rep, output_type,
                      MachineRepresentation::kBit);
   }
   return jsgraph()->graph()->NewNode(op, node);
 }
 
 Node* RepresentationChanger::GetWord64RepresentationFor(
     Node* node, MachineRepresentation output_rep, Type* output_type) {
   if (Type::Semantic(output_type, jsgraph()->zone())->Is(Type::None())) {
@@ skipping 251 matching lines @@
 }
 
 Node* RepresentationChanger::InsertChangeTaggedToFloat64(Node* node) {
   return jsgraph()->graph()->NewNode(simplified()->ChangeTaggedToFloat64(),
                                      node);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8