[turbofan] LiveRange splintering optimizations.

Related to 1318893002 - another source of regressions in
benchmarks sensitive to compile time is the splintering
logic. This change addresses some, but not all, of that. In
particular, there are still some places (figuring out if a
range has a hole right where a deferred set of blocks is)
that need another look.

BUG=chromium:1318893002
LOG=n

Review URL: https://codereview.chromium.org/1319843002

Cr-Commit-Position: refs/heads/master@{#30425}

src/compiler/live-range-separator.cc

@@ -118,7 +118,8 @@ void SplinterRangesInDeferredBlocks(RegisterAllocationData *data) {
     if (!block->IsDeferred()) continue;
 
     RpoNumber last_deferred = block->last_deferred();
-    i = last_deferred.ToInt();
+    // last_deferred + 1 is not deferred, so no point in visiting it.
+    i = last_deferred.ToInt() + 1;
 
     LifetimePosition first_cut = LifetimePosition::GapFromInstructionIndex(
         block->first_instruction_index());
@@ -126,7 +127,7 @@ void SplinterRangesInDeferredBlocks(RegisterAllocationData *data) {
     LifetimePosition last_cut = LifetimePosition::GapFromInstructionIndex(
         static_cast<int>(code->instructions().size()));
 
-    const BitVector *in_set = in_sets[i];
+    const BitVector *in_set = in_sets[block->rpo_number().ToInt()];
     InstructionBlock *last = code->InstructionBlockAt(last_deferred);
     const BitVector *out_set = LiveRangeBuilder::ComputeLiveOut(last, data);
     last_cut = LifetimePosition::GapFromInstructionIndex(

src/compiler/register-allocator.cc

@@ -1201,13 +1201,14 @@ RegisterAllocationData::RegisterAllocationData(
       config_(config),
       phi_map_(allocation_zone()),
       live_in_sets_(code->InstructionBlockCount(), nullptr, allocation_zone()),
+      live_out_sets_(code->InstructionBlockCount(), nullptr, allocation_zone()),
       live_ranges_(code->VirtualRegisterCount() * 2, nullptr,
                    allocation_zone()),
       fixed_live_ranges_(this->config()->num_general_registers(), nullptr,
                          allocation_zone()),
       fixed_double_live_ranges_(this->config()->num_double_registers(), nullptr,
                                 allocation_zone()),
-      spill_ranges_(allocation_zone()),
+      spill_ranges_(code->VirtualRegisterCount(), nullptr, allocation_zone()),
       delayed_references_(allocation_zone()),
       assigned_registers_(nullptr),
       assigned_double_registers_(nullptr),
@@ -1334,7 +1335,11 @@ SpillRange* RegisterAllocationData::AssignSpillRangeToLiveRange(
   }
   range->set_spill_type(TopLevelLiveRange::SpillType::kSpillRange);
 
-  spill_ranges().insert(spill_range);
+  int spill_range_index =
+      range->IsSplinter() ? range->splintered_from()->vreg() : range->vreg();
+
+  spill_ranges()[spill_range_index] = spill_range;
+
   return spill_range;
 }
 
@@ -1683,28 +1688,33 @@ LiveRangeBuilder::LiveRangeBuilder(RegisterAllocationData* data,
 
 BitVector* LiveRangeBuilder::ComputeLiveOut(const InstructionBlock* block,
                                             RegisterAllocationData* data) {
-  // Compute live out for the given block, except not including backward
-  // successor edges.
-  Zone* zone = data->allocation_zone();
-  const InstructionSequence* code = data->code();
-
-  auto live_out = new (zone) BitVector(code->VirtualRegisterCount(), zone);
-
-  // Process all successor blocks.
-  for (auto succ : block->successors()) {
-    // Add values live on entry to the successor.
-    if (succ <= block->rpo_number()) continue;
-    auto live_in = data->live_in_sets()[succ.ToSize()];
-    if (live_in != nullptr) live_out->Union(*live_in);
-
-    // All phi input operands corresponding to this successor edge are live
-    // out from this block.
-    auto successor = code->InstructionBlockAt(succ);
-    size_t index = successor->PredecessorIndexOf(block->rpo_number());
-    DCHECK(index < successor->PredecessorCount());
-    for (auto phi : successor->phis()) {
-      live_out->Add(phi->operands()[index]);
+  size_t block_index = block->rpo_number().ToSize();
+  BitVector* live_out = data->live_out_sets()[block_index];
+  if (live_out == nullptr) {
+    // Compute live out for the given block, except not including backward
+    // successor edges.
+    Zone* zone = data->allocation_zone();
+    const InstructionSequence* code = data->code();
+
+    live_out = new (zone) BitVector(code->VirtualRegisterCount(), zone);
+
+    // Process all successor blocks.
+    for (const RpoNumber& succ : block->successors()) {
+      // Add values live on entry to the successor.
+      if (succ <= block->rpo_number()) continue;
+      BitVector* live_in = data->live_in_sets()[succ.ToSize()];
+      if (live_in != nullptr) live_out->Union(*live_in);
+
+      // All phi input operands corresponding to this successor edge are live
+      // out from this block.
+      auto successor = code->InstructionBlockAt(succ);
+      size_t index = successor->PredecessorIndexOf(block->rpo_number());
+      DCHECK(index < successor->PredecessorCount());
+      for (PhiInstruction* phi : successor->phis()) {
+        live_out->Add(phi->operands()[index]);
+      }
     }
+    data->live_out_sets()[block_index] = live_out;
   }
   return live_out;
 }
@@ -2829,23 +2839,22 @@ OperandAssigner::OperandAssigner(RegisterAllocationData* data) : data_(data) {}
 
 
 void OperandAssigner::AssignSpillSlots() {
-  ZoneSet<SpillRange*>& spill_ranges = data()->spill_ranges();
+  ZoneVector<SpillRange*>& spill_ranges = data()->spill_ranges();
   // Merge disjoint spill ranges
-  for (auto i = spill_ranges.begin(), end = spill_ranges.end(); i != end; ++i) {
-    SpillRange* range = *i;
+  for (size_t i = 0; i < spill_ranges.size(); ++i) {
+    SpillRange* range = spill_ranges[i];
+    if (range == nullptr) continue;
     if (range->IsEmpty()) continue;
-    auto j = i;
-    j++;
-    for (; j != end; ++j) {
-      SpillRange* other = *j;
-      if (!other->IsEmpty()) {
+    for (size_t j = i + 1; j < spill_ranges.size(); ++j) {
+      SpillRange* other = spill_ranges[j];
+      if (other != nullptr && !other->IsEmpty()) {
         range->TryMerge(other);
       }
     }
   }
   // Allocate slots for the merged spill ranges.
-  for (auto range : spill_ranges) {
-    if (range->IsEmpty()) continue;
+  for (SpillRange* range : spill_ranges) {
+    if (range == nullptr || range->IsEmpty()) continue;
     // Allocate a new operand referring to the spill slot.
     int byte_width = range->ByteWidth();
     int index = data()->frame()->AllocateSpillSlot(byte_width);

src/compiler/register-allocator.h

@@ -683,7 +683,8 @@ class RegisterAllocationData final : public ZoneObject {
     return fixed_double_live_ranges_;
   }
   ZoneVector<BitVector*>& live_in_sets() { return live_in_sets_; }
-  ZoneSet<SpillRange*>& spill_ranges() { return spill_ranges_; }
+  ZoneVector<BitVector*>& live_out_sets() { return live_out_sets_; }
+  ZoneVector<SpillRange*>& spill_ranges() { return spill_ranges_; }
   DelayedReferences& delayed_references() { return delayed_references_; }
   InstructionSequence* code() const { return code_; }
   // This zone is for datastructures only needed during register allocation
@@ -741,10 +742,11 @@ class RegisterAllocationData final : public ZoneObject {
   const RegisterConfiguration* const config_;
   PhiMap phi_map_;
   ZoneVector<BitVector*> live_in_sets_;
+  ZoneVector<BitVector*> live_out_sets_;
   ZoneVector<TopLevelLiveRange*> live_ranges_;
   ZoneVector<TopLevelLiveRange*> fixed_live_ranges_;
   ZoneVector<TopLevelLiveRange*> fixed_double_live_ranges_;
-  ZoneSet<SpillRange*> spill_ranges_;
+  ZoneVector<SpillRange*> spill_ranges_;
   DelayedReferences delayed_references_;
   BitVector* assigned_registers_;
   BitVector* assigned_double_registers_;