Implement tracking and optimizations of packed arrays

src/elements-kind.h

Index: src/elements-kind.h
diff --git a/src/elements-kind.h b/src/elements-kind.h
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+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_ELEMENTS_KIND_H_
+#define V8_ELEMENTS_KIND_H_
+
+#include "v8checks.h"
+
+namespace v8 {
+namespace internal {
+
+enum ElementsKind {
+  // The "fast" kind for elements that only contain SMI values. Must be first
+  // to make it possible to efficiently check maps for this kind.
+  FAST_SMI_ELEMENTS,
+  FAST_HOLEY_SMI_ELEMENTS,
+
+  // The "fast" kind for tagged values. Must be second to make it possible to
+  // efficiently check maps for this and the FAST_SMI_ONLY_ELEMENTS kind
+  // together at once.
+  FAST_ELEMENTS,
+  FAST_HOLEY_ELEMENTS,
+
+  // The "fast" kind for unwrapped, non-tagged double values.
+  FAST_DOUBLE_ELEMENTS,
+  FAST_HOLEY_DOUBLE_ELEMENTS,
+
+  // The "slow" kind.
+  DICTIONARY_ELEMENTS,
+  NON_STRICT_ARGUMENTS_ELEMENTS,
+  // The "fast" kind for external arrays
+  EXTERNAL_BYTE_ELEMENTS,
+  EXTERNAL_UNSIGNED_BYTE_ELEMENTS,
+  EXTERNAL_SHORT_ELEMENTS,
+  EXTERNAL_UNSIGNED_SHORT_ELEMENTS,
+  EXTERNAL_INT_ELEMENTS,
+  EXTERNAL_UNSIGNED_INT_ELEMENTS,
+  EXTERNAL_FLOAT_ELEMENTS,
+  EXTERNAL_DOUBLE_ELEMENTS,
+  EXTERNAL_PIXEL_ELEMENTS,
+
+  // Derived constants from ElementsKind
+  FIRST_ELEMENTS_KIND = FAST_SMI_ELEMENTS,
+  LAST_ELEMENTS_KIND = EXTERNAL_PIXEL_ELEMENTS,
+  FIRST_FAST_ELEMENTS_KIND = FAST_SMI_ELEMENTS,
+  LAST_FAST_ELEMENTS_KIND = FAST_HOLEY_DOUBLE_ELEMENTS,
+  FIRST_EXTERNAL_ARRAY_ELEMENTS_KIND = EXTERNAL_BYTE_ELEMENTS,
+  LAST_EXTERNAL_ARRAY_ELEMENTS_KIND = EXTERNAL_PIXEL_ELEMENTS,
+  TERMINAL_FAST_ELEMENTS_KIND = FAST_HOLEY_ELEMENTS
+};
+
+const int kElementsKindCount = LAST_ELEMENTS_KIND - FIRST_ELEMENTS_KIND + 1;
+const int kFastElementsKindCount = LAST_FAST_ELEMENTS_KIND -
+    FIRST_FAST_ELEMENTS_KIND + 1;
+
+void PrintElementsKind(FILE* out, ElementsKind kind);
+
+ElementsKind GetInitialFastElementsKind();
+
+ElementsKind GetFastElementsKindFromSequenceIndex(int sequence_index);
+
+int GetSequenceIndexFromFastElementsKind(ElementsKind elements_kind);
+
+
+inline bool IsFastElementsKind(ElementsKind kind) {
+  ASSERT(FIRST_FAST_ELEMENTS_KIND == 0);
+  return kind <= FAST_HOLEY_DOUBLE_ELEMENTS;
+}
+
+
+inline bool IsFastDoubleElementsKind(ElementsKind kind) {
+  return kind == FAST_DOUBLE_ELEMENTS ||
+      kind == FAST_HOLEY_DOUBLE_ELEMENTS;
+}
+
+
+inline bool IsFastSmiOrObjectElementsKind(ElementsKind kind) {
+  return kind == FAST_SMI_ELEMENTS ||
+      kind == FAST_HOLEY_SMI_ELEMENTS ||
+      kind == FAST_ELEMENTS ||
+      kind == FAST_HOLEY_ELEMENTS;
+}
+
+
+inline bool IsFastSmiElementsKind(ElementsKind kind) {
+  return kind == FAST_SMI_ELEMENTS ||
+      kind == FAST_HOLEY_SMI_ELEMENTS;
+}
+
+
+inline bool IsFastObjectElementsKind(ElementsKind kind) {
+  return kind == FAST_ELEMENTS ||
+      kind == FAST_HOLEY_ELEMENTS;
+}
+
+
+inline bool IsFastHoleyElementsKind(ElementsKind kind) {
+  return kind == FAST_HOLEY_SMI_ELEMENTS ||
+      kind == FAST_HOLEY_DOUBLE_ELEMENTS ||
+      kind == FAST_HOLEY_ELEMENTS;
+}
+
+
+inline bool IsHoleyElementsKind(ElementsKind kind) {
+  return IsFastHoleyElementsKind(kind) ||
+      kind == DICTIONARY_ELEMENTS;
+}
+
+
+inline bool IsFastPackedElementsKind(ElementsKind kind) {
+  return kind == FAST_SMI_ELEMENTS ||
+      kind == FAST_DOUBLE_ELEMENTS ||
+      kind == FAST_ELEMENTS;
+}
+
+
+inline ElementsKind GetPackedElementsKind(ElementsKind holey_kind) {
+  if (holey_kind == FAST_HOLEY_SMI_ELEMENTS) {
+    return FAST_SMI_ELEMENTS;
+  }
+  if (holey_kind == FAST_HOLEY_DOUBLE_ELEMENTS) {
+    return FAST_DOUBLE_ELEMENTS;
+  }
+  if (holey_kind == FAST_HOLEY_ELEMENTS) {
+    return FAST_ELEMENTS;
+  }
+  return holey_kind;
+}
+
+
+inline ElementsKind GetHoleyElementsKind(ElementsKind packed_kind) {
+  if (packed_kind == FAST_SMI_ELEMENTS) {
+    return FAST_HOLEY_SMI_ELEMENTS;
+  }
+  if (packed_kind == FAST_DOUBLE_ELEMENTS) {
+    return FAST_HOLEY_DOUBLE_ELEMENTS;
+  }
+  if (packed_kind == FAST_ELEMENTS) {
+    return FAST_HOLEY_ELEMENTS;
+  }
+  return packed_kind;
+}
+
+
+inline ElementsKind FastSmiToObjectElementsKind(ElementsKind from_kind) {
+  ASSERT(IsFastSmiElementsKind(from_kind));
+  return (from_kind == FAST_SMI_ELEMENTS)
+      ? FAST_ELEMENTS
+      : FAST_HOLEY_ELEMENTS;
+}
+
+
+inline bool IsSimpleMapChangeTransition(ElementsKind from_kind,
+                                        ElementsKind to_kind) {
+  return (GetHoleyElementsKind(from_kind) == to_kind) ||
+      (IsFastSmiElementsKind(from_kind) &&
+       IsFastObjectElementsKind(to_kind));
+}
+
+
+bool IsMoreGeneralElementsKindTransition(ElementsKind from_kind,
+                                         ElementsKind to_kind);
+
+
+inline bool IsTransitionableFastElementsKind(ElementsKind from_kind) {
+  return IsFastElementsKind(from_kind) &&
+      from_kind != TERMINAL_FAST_ELEMENTS_KIND;
+}
+
+
+ElementsKind GetNextMoreGeneralFastElementsKind(ElementsKind elements_kind,
+                                                bool allow_only_packed);
+
+
+inline bool CanTransitionToMoreGeneralFastElementsKind(
+    ElementsKind elements_kind,
+    bool allow_only_packed) {
+  return elements_kind != TERMINAL_FAST_ELEMENTS_KIND &&
+      (!allow_only_packed || elements_kind != FAST_ELEMENTS);
+}
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_ELEMENTS_KIND_H_