0a5bffe24d
This simplifies the mark getter enough to generate a branch-free check on many architectures (e.g. using cmov on x64 or csel on ARM). As a drive-by, we can now make the mark access const. Review-Url: https://codereview.chromium.org/2583043004 Cr-Commit-Position: refs/heads/master@{#41833}
80 lines
2.2 KiB
C++
80 lines
2.2 KiB
C++
// Copyright 2015 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_COMPILER_NODE_MARKER_H_
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#define V8_COMPILER_NODE_MARKER_H_
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#include "src/compiler/node.h"
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namespace v8 {
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namespace internal {
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namespace compiler {
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// Forward declarations.
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class Graph;
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// Base class for templatized NodeMarkers.
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class NodeMarkerBase {
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public:
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NodeMarkerBase(Graph* graph, uint32_t num_states);
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V8_INLINE Mark Get(const Node* node) {
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Mark mark = node->mark();
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if (mark < mark_min_) {
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return 0;
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}
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DCHECK_LT(mark, mark_max_);
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return mark - mark_min_;
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}
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V8_INLINE void Set(Node* node, Mark mark) {
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DCHECK_LT(mark, mark_max_ - mark_min_);
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DCHECK_LT(node->mark(), mark_max_);
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node->set_mark(mark + mark_min_);
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}
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private:
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Mark const mark_min_;
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Mark const mark_max_;
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DISALLOW_COPY_AND_ASSIGN(NodeMarkerBase);
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};
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// A NodeMarker assigns a local "state" to every node of a graph in constant
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// memory. Only one NodeMarker per graph is valid at a given time, that is,
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// after you create a NodeMarker you should no longer use NodeMarkers that
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// were created earlier. Internally, the local state is stored in the Node
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// structure.
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//
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// When you initialize a NodeMarker, all the local states are conceptually
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// set to State(0) in constant time.
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//
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// In its current implementation, in debug mode NodeMarker will try to
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// (efficiently) detect invalid use of an older NodeMarker. Namely, if you set a
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// node with a NodeMarker, and then get or set that node with an older
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// NodeMarker you will get a crash.
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//
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// GraphReducer uses a NodeMarker, so individual Reducers cannot use a
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// NodeMarker.
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template <typename State>
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class NodeMarker : public NodeMarkerBase {
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public:
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V8_INLINE NodeMarker(Graph* graph, uint32_t num_states)
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: NodeMarkerBase(graph, num_states) {}
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V8_INLINE State Get(const Node* node) {
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return static_cast<State>(NodeMarkerBase::Get(node));
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}
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V8_INLINE void Set(Node* node, State state) {
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NodeMarkerBase::Set(node, static_cast<Mark>(state));
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}
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};
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} // namespace compiler
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} // namespace internal
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} // namespace v8
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#endif // V8_COMPILER_NODE_MARKER_H_
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