Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 1 | // Copyright 2015 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/coalesced-live-ranges.h" |
| 6 | #include "src/compiler/greedy-allocator.h" |
| 7 | #include "src/compiler/register-allocator.h" |
| 8 | |
| 9 | namespace v8 { |
| 10 | namespace internal { |
| 11 | namespace compiler { |
| 12 | |
| 13 | |
| 14 | LiveRangeConflictIterator::LiveRangeConflictIterator(const LiveRange* range, |
| 15 | IntervalStore* storage) |
| 16 | : query_(range->first_interval()), |
| 17 | pos_(storage->end()), |
| 18 | intervals_(storage) { |
| 19 | MovePosAndQueryToFirstConflict(); |
| 20 | } |
| 21 | |
| 22 | |
| 23 | LiveRange* LiveRangeConflictIterator::Current() const { |
| 24 | if (IsFinished()) return nullptr; |
| 25 | return pos_->range_; |
| 26 | } |
| 27 | |
| 28 | |
| 29 | void LiveRangeConflictIterator::MovePosToFirstConflictForQuery() { |
| 30 | DCHECK_NOT_NULL(query_); |
| 31 | auto end = intervals_->end(); |
| 32 | LifetimePosition q_start = query_->start(); |
| 33 | LifetimePosition q_end = query_->end(); |
| 34 | |
| 35 | if (intervals_->empty() || intervals_->rbegin()->end_ <= q_start || |
| 36 | intervals_->begin()->start_ >= q_end) { |
| 37 | pos_ = end; |
| 38 | return; |
| 39 | } |
| 40 | |
| 41 | pos_ = intervals_->upper_bound(AsAllocatedInterval(q_start)); |
| 42 | // pos is either at the end (no start strictly greater than q_start) or |
| 43 | // at some position with the aforementioned property. In either case, the |
| 44 | // allocated interval before this one may intersect our query: |
| 45 | // either because, although it starts before this query's start, it ends |
| 46 | // after; or because it starts exactly at the query start. So unless we're |
| 47 | // right at the beginning of the storage - meaning the first allocated |
| 48 | // interval is also starting after this query's start - see what's behind. |
| 49 | if (pos_ != intervals_->begin()) { |
| 50 | --pos_; |
| 51 | if (!QueryIntersectsAllocatedInterval()) { |
| 52 | // The interval behind wasn't intersecting, so move back. |
| 53 | ++pos_; |
| 54 | } |
| 55 | } |
| 56 | if (pos_ == end || !QueryIntersectsAllocatedInterval()) { |
| 57 | pos_ = end; |
| 58 | } |
| 59 | } |
| 60 | |
| 61 | |
| 62 | void LiveRangeConflictIterator::MovePosAndQueryToFirstConflict() { |
| 63 | auto end = intervals_->end(); |
| 64 | for (; query_ != nullptr; query_ = query_->next()) { |
| 65 | MovePosToFirstConflictForQuery(); |
| 66 | if (pos_ != end) { |
| 67 | DCHECK(QueryIntersectsAllocatedInterval()); |
| 68 | return; |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | Invalidate(); |
| 73 | } |
| 74 | |
| 75 | |
| 76 | void LiveRangeConflictIterator::IncrementPosAndSkipOverRepetitions() { |
| 77 | auto end = intervals_->end(); |
| 78 | DCHECK(pos_ != end); |
| 79 | LiveRange* current_conflict = Current(); |
| 80 | while (pos_ != end && pos_->range_ == current_conflict) { |
| 81 | ++pos_; |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | |
| 86 | LiveRange* LiveRangeConflictIterator::InternalGetNext(bool clean_behind) { |
| 87 | if (IsFinished()) return nullptr; |
| 88 | |
| 89 | LiveRange* to_clear = Current(); |
| 90 | IncrementPosAndSkipOverRepetitions(); |
| 91 | // At this point, pos_ is either at the end, or on an interval that doesn't |
| 92 | // correspond to the same range as to_clear. This interval may not even be |
| 93 | // a conflict. |
| 94 | if (clean_behind) { |
| 95 | // Since we parked pos_ on an iterator that won't be affected by removal, |
| 96 | // we can safely delete to_clear's intervals. |
| 97 | for (auto interval = to_clear->first_interval(); interval != nullptr; |
| 98 | interval = interval->next()) { |
| 99 | AllocatedInterval erase_key(interval->start(), interval->end(), nullptr); |
| 100 | intervals_->erase(erase_key); |
| 101 | } |
| 102 | } |
| 103 | // We may have parked pos_ at the end, or on a non-conflict. In that case, |
| 104 | // move to the next query and reinitialize pos and query. This may invalidate |
| 105 | // the iterator, if no more conflicts are available. |
| 106 | if (!QueryIntersectsAllocatedInterval()) { |
| 107 | query_ = query_->next(); |
| 108 | MovePosAndQueryToFirstConflict(); |
| 109 | } |
| 110 | return Current(); |
| 111 | } |
| 112 | |
| 113 | |
| 114 | LiveRangeConflictIterator CoalescedLiveRanges::GetConflicts( |
| 115 | const LiveRange* range) { |
| 116 | return LiveRangeConflictIterator(range, &intervals()); |
| 117 | } |
| 118 | |
| 119 | |
| 120 | void CoalescedLiveRanges::AllocateRange(LiveRange* range) { |
| 121 | for (auto interval = range->first_interval(); interval != nullptr; |
| 122 | interval = interval->next()) { |
| 123 | AllocatedInterval to_insert(interval->start(), interval->end(), range); |
| 124 | intervals().insert(to_insert); |
| 125 | } |
| 126 | } |
| 127 | |
| 128 | |
| 129 | bool CoalescedLiveRanges::VerifyAllocationsAreValidForTesting() const { |
| 130 | LifetimePosition last_end = LifetimePosition::GapFromInstructionIndex(0); |
| 131 | for (auto i : intervals_) { |
| 132 | if (i.start_ < last_end) { |
| 133 | return false; |
| 134 | } |
| 135 | last_end = i.end_; |
| 136 | } |
| 137 | return true; |
| 138 | } |
| 139 | |
| 140 | |
| 141 | } // namespace compiler |
| 142 | } // namespace internal |
| 143 | } // namespace v8 |