[Interpreter] Add support for jumps using constants with wide operands.

src/interpreter/constant-array-builder.cc

Index: src/interpreter/constant-array-builder.cc
diff --git a/src/interpreter/constant-array-builder.cc b/src/interpreter/constant-array-builder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6ba00ba3e04e8355f925c7a7c17bf015d43214da
--- /dev/null
+++ b/src/interpreter/constant-array-builder.cc
@@ -0,0 +1,197 @@
+// 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/interpreter/constant-array-builder.h"
+
+#include "src/isolate.h"
+#include "src/objects-inl.h"
+
+namespace v8 {
+namespace internal {
+namespace interpreter {
+
+ConstantArrayBuilder::ConstantArraySlice::ConstantArraySlice(Zone* zone,
+                                                             size_t start_index,
+                                                             size_t capacity)
+    : start_index_(start_index),
+      capacity_(capacity),
+      reserved_(0),
+      constants_(zone) {}
+
+
+size_t ConstantArrayBuilder::ConstantArraySlice::reserved() const {
+  return reserved_;
+}
+
+
+size_t ConstantArrayBuilder::ConstantArraySlice::size() const {
+  return constants_.size();
+}
+
+
+size_t ConstantArrayBuilder::ConstantArraySlice::available() const {
+  return capacity() - reserved_ - constants_.size();
+}
+
+
+size_t ConstantArrayBuilder::ConstantArraySlice::start_index() const {
+  return start_index_;
+}
+
+
+size_t ConstantArrayBuilder::ConstantArraySlice::capacity() const {
+  return capacity_;
+}
+
+
+void ConstantArrayBuilder::ConstantArraySlice::Reserve() {
+  DCHECK_GT(available(), 0u);
+  reserved_++;
+  DCHECK_LE(reserved_, capacity() - constants_.size());
+}
+
+
+void ConstantArrayBuilder::ConstantArraySlice::Unreserve() {
+  DCHECK_GT(reserved_, 0u);
+  reserved_--;
+}
+
+
+size_t ConstantArrayBuilder::ConstantArraySlice::Allocate(
+    Handle<Object> object) {
+  DCHECK_GT(available(), 0u);
+  size_t index = constants_.size();
+  DCHECK_LT(index, capacity());
+  constants_.push_back(object);
+  return index + start_index();
+}
+
+
+Handle<Object> ConstantArrayBuilder::ConstantArraySlice::At(
+    size_t index) const {
+  return constants_[index - start_index()];
+}
+
+
+STATIC_CONST_MEMBER_DEFINITION const size_t ConstantArrayBuilder::kMaxCapacity;
+STATIC_CONST_MEMBER_DEFINITION const size_t ConstantArrayBuilder::kLowCapacity;
+
+
+ConstantArrayBuilder::ConstantArrayBuilder(Isolate* isolate, Zone* zone)
+    : isolate_(isolate),
+      idx8_slice_(zone, 0, kLowCapacity),
+      idx16_slice_(zone, kLowCapacity, kHighCapacity),
+      constants_map_(isolate->heap(), zone) {
+  STATIC_ASSERT(kMaxCapacity == static_cast<size_t>(kMaxUInt16 + 1));
+  DCHECK_EQ(idx8_slice_.start_index(), 0u);
+  DCHECK_EQ(idx8_slice_.capacity(), kLowCapacity);
+  DCHECK_EQ(idx16_slice_.start_index(), kLowCapacity);
+  DCHECK_EQ(idx16_slice_.capacity(), kMaxCapacity - kLowCapacity);
+}
+
+
+size_t ConstantArrayBuilder::size() const {
+  if (idx16_slice_.size() > 0) {
+    return idx16_slice_.start_index() + idx16_slice_.size();
+  } else {
+    return idx8_slice_.size();
+  }
+}
+
+
+Handle<Object> ConstantArrayBuilder::At(size_t index) const {
+  if (index >= idx16_slice_.start_index()) {
+    return idx16_slice_.At(index);
+  } else if (index < idx8_slice_.size()) {
+    return idx8_slice_.At(index);
+  } else {
+    return isolate_->factory()->the_hole_value();
+  }
+}
+
+
+Handle<FixedArray> ConstantArrayBuilder::ToFixedArray(Factory* factory) const {
+  Handle<FixedArray> fixed_array =
+      factory->NewFixedArray(static_cast<int>(size()), PretenureFlag::TENURED);
+  for (int i = 0; i < fixed_array->length(); i++) {
+    fixed_array->set(i, *At(static_cast<size_t>(i)));
+  }
+  return fixed_array;
+}
+
+
+size_t ConstantArrayBuilder::Insert(Handle<Object> object) {
+  index_t* entry = constants_map_.Find(object);
+  return (entry == nullptr) ? AllocateEntry(object) : *entry;
+}
+
+
+ConstantArrayBuilder::index_t ConstantArrayBuilder::AllocateEntry(
+    Handle<Object> object) {
+  DCHECK(!object->IsOddball());
+  size_t index;
+  index_t* entry = constants_map_.Get(object);
+  if (idx8_slice_.available() > 0) {
+    index = idx8_slice_.Allocate(object);
+    DCHECK_LT(index, idx8_slice_.capacity());
+  } else {

[rmcilroy, 2016/01/05 13:46:10]

We should probably add a (non-debug) CHECK that there is capacity in the
idx16_slice to ensure we crash rather than causing a buffer overrun.

[oth, 2016/01/05 18:31:59]

Done.

+    index = idx16_slice_.Allocate(object);
+    DCHECK_LT(index, idx8_slice_.capacity() + idx16_slice_.capacity());
+  }
+  *entry = static_cast<index_t>(index);
+  return *entry;
+}
+
+
+OperandSize ConstantArrayBuilder::CreateReservedEntry() {
+  if (idx8_slice_.available() > 0) {
+    idx8_slice_.Reserve();
+    return OperandSize::kByte;
+  } else {

[rmcilroy, 2016/01/05 13:46:10]

Also a CHECK here (or an else if idx8_slice_.available() > 0) { ... } else {
UNREACHABLE(); }?

[oth, 2016/01/05 18:31:59]

Done.

+    idx16_slice_.Reserve();
+    return OperandSize::kShort;
+  }
+}
+
+
+size_t ConstantArrayBuilder::CommitReservedEntry(OperandSize operand_size,
+                                                 Handle<Object> object) {
+  DiscardReservedEntry(operand_size);
+  size_t index;
+  index_t* entry = constants_map_.Find(object);
+  if (nullptr == entry) {
+    index = AllocateEntry(object);
+  } else {
+    if (operand_size == OperandSize::kByte &&
+        *entry >= idx8_slice_.capacity()) {
+      // The object is already in the constant array, but has an index
+      // outside the range of an idx8 operand so we need to create a
+      // duplicate entry in the idx8 operand range to satisfy the
+      // commitment.
+      *entry = static_cast<index_t>(idx8_slice_.Allocate(object));
+    }
+    index = *entry;
+  }
+  DCHECK(operand_size == OperandSize::kShort || index < idx8_slice_.capacity());
+  DCHECK_LT(index, kMaxCapacity);
+  return index;
+}
+
+
+void ConstantArrayBuilder::DiscardReservedEntry(OperandSize operand_size) {
+  switch (operand_size) {
+    case OperandSize::kByte:
+      idx8_slice_.Unreserve();
+      return;
+    case OperandSize::kShort:
+      idx16_slice_.Unreserve();
+      return;
+    default:
+      UNREACHABLE();
+  }
+}
+
+}  // namespace interpreter
+}  // namespace internal
+}  // namespace v8