[turbofan] Greedy allocator refactoring.

src/compiler/coalesced-live-ranges.cc

+// 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/compiler/coalesced-live-ranges.h"
+#include "src/compiler/greedy-allocator.h"
+#include "src/compiler/register-allocator.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+#define TRACE(...)                             \
+  do {                                         \
+    if (FLAG_trace_alloc) PrintF(__VA_ARGS__); \
+  } while (false)
+
+
+const float CoalescedLiveRanges::kAllocatedRangeMultiplier = 10.0;
+
+void CoalescedLiveRanges::AllocateRange(LiveRange* range) {
+  UpdateWeightAtAllocation(range);
+  for (auto interval = range->first_interval(); interval != nullptr;
+       interval = interval->next()) {
+    storage().insert({interval->start(), interval->end(), range});
+  }
+}
+
+
+void CoalescedLiveRanges::Remove(LiveRange* range) {
+  for (auto interval = range->first_interval(); interval != nullptr;
+       interval = interval->next()) {
+    storage().erase({interval->start(), interval->end(), nullptr});
+  }
+  range->UnsetAssignedRegister();
+}
+
+
+float CoalescedLiveRanges::GetMaximumConflictingWeight(
+    const LiveRange* range) const {
+  float ret = LiveRange::kInvalidWeight;
+  auto end = storage().end();
+  for (auto query = range->first_interval(); query != nullptr;
+       query = query->next()) {
+    auto conflict = GetFirstConflict(query);
+
+    if (conflict == end) continue;
+    for (; QueryIntersectsAllocatedInterval(query, conflict); ++conflict) {
+      // It is possible we'll visit the same range multiple times, because
+      // successive (not necessarily consecutive) intervals belong to the same
+      // range, or because different intervals of the query range have the same
+      // range as conflict.
+      DCHECK_NE(conflict->range->weight(), LiveRange::kInvalidWeight);
+      ret = Max(ret, conflict->range->weight());
+      if (ret == LiveRange::kMaxWeight) break;
+    }
+  }
+  return ret;
+}
+
+
+void CoalescedLiveRanges::EvictAndRescheduleConflicts(
+    LiveRange* range, AllocationScheduler* scheduler) {
+  auto end = storage().end();
+
+  for (auto query = range->first_interval(); query != nullptr;
+       query = query->next()) {
+    auto conflict = GetFirstConflict(query);
+    if (conflict == end) continue;
+    while (QueryIntersectsAllocatedInterval(query, conflict)) {
+      LiveRange* range_to_evict = conflict->range;
+      // Bypass successive intervals belonging to the same range, because we're
+      // about to remove this range, and we don't want the storage iterator to
+      // become invalid.
+      while (conflict != end && conflict->range == range_to_evict) {
+        ++conflict;
+      }
+
+      DCHECK(range_to_evict->HasRegisterAssigned());
+      CHECK(!range_to_evict->IsFixed());
+      Remove(range_to_evict);
+      UpdateWeightAtEviction(range_to_evict);
+      TRACE("Evicted range %d.\n", range_to_evict->id());
+      scheduler->Schedule(range_to_evict);
+    }
+  }
+}
+
+
+bool CoalescedLiveRanges::VerifyAllocationsAreValid() const {
+  LifetimePosition last_end = LifetimePosition::GapFromInstructionIndex(0);
+  for (auto i : storage_) {
+    if (i.start < last_end) {
+      return false;
+    }
+    last_end = i.end;
+  }
+  return true;
+}
+
+
+void CoalescedLiveRanges::UpdateWeightAtAllocation(LiveRange* range) {
+  DCHECK_NE(range->weight(), LiveRange::kInvalidWeight);
+  range->set_weight(range->weight() * kAllocatedRangeMultiplier);
+}
+
+
+void CoalescedLiveRanges::UpdateWeightAtEviction(LiveRange* range) {
+  DCHECK_NE(range->weight(), LiveRange::kInvalidWeight);
+  range->set_weight(range->weight() / kAllocatedRangeMultiplier);
+}
+
+
+CoalescedLiveRanges::interval_iterator CoalescedLiveRanges::GetFirstConflict(
+    const UseInterval* query) const {
+  DCHECK(query != nullptr);
+  auto end = storage().end();
+  LifetimePosition q_start = query->start();
+  LifetimePosition q_end = query->end();
+
+  if (storage().empty() || storage().rbegin()->end <= q_start ||
+      storage().begin()->start >= q_end) {
+    return end;
+  }
+
+  auto ret = storage().upper_bound(AsAllocatedInterval(q_start));
+  // ret is either at the end (no start strictly greater than q_start) or
+  // at some position with the aforementioned property. In either case, the
+  // allocated interval before this one may intersect our query:
+  // either because, although it starts before this query's start, it ends
+  // after; or because it starts exactly at the query start. So unless we're
+  // right at the beginning of the storage - meaning the first allocated
+  // interval is also starting after this query's start - see what's behind.
+  if (ret != storage().begin()) {
+    --ret;
+    if (!QueryIntersectsAllocatedInterval(query, ret)) {
+      // The interval behind wasn't intersecting, so move back.
+      ++ret;
+    }
+  }
+  if (ret != end && QueryIntersectsAllocatedInterval(query, ret)) return ret;
+  return end;
+}
+
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8