Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 1 | // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include "src/compiler/value-numbering-reducer.h" |
| 6 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 7 | #include <cstring> |
| 8 | |
| 9 | #include "src/base/functional.h" |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 10 | #include "src/compiler/node.h" |
| 11 | |
| 12 | namespace v8 { |
| 13 | namespace internal { |
| 14 | namespace compiler { |
| 15 | |
| 16 | namespace { |
| 17 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 18 | size_t HashCode(Node* node) { |
| 19 | size_t h = base::hash_combine(node->op()->HashCode(), node->InputCount()); |
| 20 | for (int j = 0; j < node->InputCount(); ++j) { |
| 21 | h = base::hash_combine(h, node->InputAt(j)->id()); |
| 22 | } |
| 23 | return h; |
| 24 | } |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 25 | |
| 26 | |
| 27 | bool Equals(Node* a, Node* b) { |
| 28 | DCHECK_NOT_NULL(a); |
| 29 | DCHECK_NOT_NULL(b); |
| 30 | DCHECK_NOT_NULL(a->op()); |
| 31 | DCHECK_NOT_NULL(b->op()); |
| 32 | if (!a->op()->Equals(b->op())) return false; |
| 33 | if (a->InputCount() != b->InputCount()) return false; |
| 34 | for (int j = 0; j < a->InputCount(); ++j) { |
| 35 | DCHECK_NOT_NULL(a->InputAt(j)); |
| 36 | DCHECK_NOT_NULL(b->InputAt(j)); |
| 37 | if (a->InputAt(j)->id() != b->InputAt(j)->id()) return false; |
| 38 | } |
| 39 | return true; |
| 40 | } |
| 41 | |
| 42 | } // namespace |
| 43 | |
| 44 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 45 | ValueNumberingReducer::ValueNumberingReducer(Zone* zone) |
| 46 | : entries_(nullptr), capacity_(0), size_(0), zone_(zone) {} |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 47 | |
| 48 | |
| 49 | ValueNumberingReducer::~ValueNumberingReducer() {} |
| 50 | |
| 51 | |
| 52 | Reduction ValueNumberingReducer::Reduce(Node* node) { |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 53 | if (!node->op()->HasProperty(Operator::kIdempotent)) return NoChange(); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 54 | |
| 55 | const size_t hash = HashCode(node); |
| 56 | if (!entries_) { |
| 57 | DCHECK(size_ == 0); |
| 58 | DCHECK(capacity_ == 0); |
| 59 | // Allocate the initial entries and insert the first entry. |
| 60 | capacity_ = kInitialCapacity; |
| 61 | entries_ = zone()->NewArray<Node*>(kInitialCapacity); |
| 62 | memset(entries_, 0, sizeof(*entries_) * kInitialCapacity); |
| 63 | entries_[hash & (kInitialCapacity - 1)] = node; |
| 64 | size_ = 1; |
| 65 | return NoChange(); |
| 66 | } |
| 67 | |
| 68 | DCHECK(size_ < capacity_); |
| 69 | DCHECK(size_ * kCapacityToSizeRatio < capacity_); |
| 70 | |
| 71 | const size_t mask = capacity_ - 1; |
| 72 | size_t dead = capacity_; |
| 73 | |
| 74 | for (size_t i = hash & mask;; i = (i + 1) & mask) { |
| 75 | Node* entry = entries_[i]; |
| 76 | if (!entry) { |
| 77 | if (dead != capacity_) { |
| 78 | // Reuse dead entry that we discovered on the way. |
| 79 | entries_[dead] = node; |
| 80 | } else { |
| 81 | // Have to insert a new entry. |
| 82 | entries_[i] = node; |
| 83 | size_++; |
| 84 | |
| 85 | // Resize to keep load factor below 1/kCapacityToSizeRatio. |
| 86 | if (size_ * kCapacityToSizeRatio >= capacity_) Grow(); |
| 87 | } |
| 88 | DCHECK(size_ * kCapacityToSizeRatio < capacity_); |
| 89 | return NoChange(); |
| 90 | } |
| 91 | |
| 92 | if (entry == node) { |
| 93 | // We need to check for a certain class of collisions here. Imagine the |
| 94 | // following scenario: |
| 95 | // |
| 96 | // 1. We insert node1 with op1 and certain inputs at index i. |
| 97 | // 2. We insert node2 with op2 and certain inputs at index i+1. |
| 98 | // 3. Some other reducer changes node1 to op2 and the inputs from node2. |
| 99 | // |
| 100 | // Now we are called again to reduce node1, and we would return NoChange |
| 101 | // in this case because we find node1 first, but what we should actually |
| 102 | // do is return Replace(node2) instead. |
| 103 | for (size_t j = (i + 1) & mask;; j = (j + 1) & mask) { |
| 104 | Node* entry = entries_[j]; |
| 105 | if (!entry) { |
| 106 | // No collision, {node} is fine. |
| 107 | return NoChange(); |
| 108 | } |
| 109 | if (entry->IsDead()) { |
| 110 | continue; |
| 111 | } |
| 112 | if (Equals(entry, node)) { |
| 113 | // Overwrite the colliding entry with the actual entry. |
| 114 | entries_[i] = entry; |
| 115 | return Replace(entry); |
| 116 | } |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | // Skip dead entries, but remember their indices so we can reuse them. |
| 121 | if (entry->IsDead()) { |
| 122 | dead = i; |
| 123 | continue; |
| 124 | } |
| 125 | if (Equals(entry, node)) { |
| 126 | return Replace(entry); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 127 | } |
| 128 | } |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 129 | } |
| 130 | |
| 131 | |
| 132 | void ValueNumberingReducer::Grow() { |
| 133 | // Allocate a new block of entries kCapacityToSizeRatio times the previous |
| 134 | // capacity. |
| 135 | Node** const old_entries = entries_; |
| 136 | size_t const old_capacity = capacity_; |
| 137 | capacity_ *= kCapacityToSizeRatio; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 138 | entries_ = zone()->NewArray<Node*>(capacity_); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 139 | memset(entries_, 0, sizeof(*entries_) * capacity_); |
| 140 | size_ = 0; |
| 141 | size_t const mask = capacity_ - 1; |
| 142 | |
| 143 | // Insert the old entries into the new block (skipping dead nodes). |
| 144 | for (size_t i = 0; i < old_capacity; ++i) { |
| 145 | Node* const old_entry = old_entries[i]; |
| 146 | if (!old_entry || old_entry->IsDead()) continue; |
| 147 | for (size_t j = HashCode(old_entry) & mask;; j = (j + 1) & mask) { |
| 148 | Node* const entry = entries_[j]; |
| 149 | if (entry == old_entry) { |
| 150 | // Skip duplicate of the old entry. |
| 151 | break; |
| 152 | } |
| 153 | if (!entry) { |
| 154 | entries_[j] = old_entry; |
| 155 | size_++; |
| 156 | break; |
| 157 | } |
| 158 | } |
| 159 | } |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 160 | } |
| 161 | |
| 162 | } // namespace compiler |
| 163 | } // namespace internal |
| 164 | } // namespace v8 |