Revert "Lift the spill at each irreducible loop block restriction."

This reverts commit 79e9f43951c3cfa9ab3b0fea93e5bfdfa7aa5950.

Change-Id: I0670618b4076e06bd3f6bf8c385abfd1b651393c

1 files changed, 6 insertions, 31 deletions

diff --git a/compiler/optimizing/register_allocator.cc b/compiler/optimizing/register_allocator.cc
index 44fb8de97e..d77639d608 100644
--- a/compiler/optimizing/register_allocator.cc
+++ b/compiler/optimizing/register_allocator.cc
@@ -179,7 +179,7 @@ void RegisterAllocator::AllocateRegistersInternal() {
     }
 
     if (block->IsCatchBlock() ||
-        (block->IsLoopHeader() && block->GetLoopInformation()->IsIrreducible())) {
+        (block->GetLoopInformation() != nullptr && block->GetLoopInformation()->IsIrreducible())) {
       // By blocking all registers at the top of each catch block or irreducible loop, we force
       // intervals belonging to the live-in set of the catch/header block to be spilled.
       // TODO(ngeoffray): Phis in this block could be allocated in register.
@@ -1749,10 +1749,8 @@ void RegisterAllocator::ConnectSplitSiblings(LiveInterval* interval,
   }
 
   // Find the intervals that cover `from` and `to`.
-  size_t destination_position = to->GetLifetimeStart();
-  size_t source_position = from->GetLifetimeEnd() - 1;
-  LiveInterval* destination = interval->GetSiblingAt(destination_position);
-  LiveInterval* source = interval->GetSiblingAt(source_position);
+  LiveInterval* destination = interval->GetSiblingAt(to->GetLifetimeStart());
+  LiveInterval* source = interval->GetSiblingAt(from->GetLifetimeEnd() - 1);
 
   if (destination == source) {
     // Interval was not split.
@@ -1777,41 +1775,18 @@ void RegisterAllocator::ConnectSplitSiblings(LiveInterval* interval,
     return;
   }
 
-  Location location_source;
-  // `GetSiblingAt` returns the interval whose start and end cover `position`,
-  // but does not check whether the interval is inactive at that position.
-  // The only situation where the interval is inactive at that position is in the
-  // presence of irreducible loops for constants and ArtMethod.
-  if (codegen_->GetGraph()->HasIrreducibleLoops() &&
-      (source == nullptr || !source->CoversSlow(source_position))) {
-    DCHECK(IsMaterializableEntryBlockInstructionOfGraphWithIrreducibleLoop(defined_by));
-    if (defined_by->IsConstant()) {
-      location_source = defined_by->GetLocations()->Out();
-    } else {
-      DCHECK(defined_by->IsCurrentMethod());
-      location_source = parent->NeedsTwoSpillSlots()
-          ? Location::DoubleStackSlot(parent->GetSpillSlot())
-          : Location::StackSlot(parent->GetSpillSlot());
-    }
-  } else {
-    DCHECK(source != nullptr);
-    DCHECK(source->CoversSlow(source_position));
-    DCHECK(destination->CoversSlow(destination_position));
-    location_source = source->ToLocation();
-  }
-
   // If `from` has only one successor, we can put the moves at the exit of it. Otherwise
   // we need to put the moves at the entry of `to`.
   if (from->GetNormalSuccessors().size() == 1) {
     InsertParallelMoveAtExitOf(from,
                                defined_by,
-                               location_source,
+                               source->ToLocation(),
                                destination->ToLocation());
   } else {
     DCHECK_EQ(to->GetPredecessors().size(), 1u);
     InsertParallelMoveAtEntryOf(to,
                                 defined_by,
-                                location_source,
+                                source->ToLocation(),
                                 destination->ToLocation());
   }
 }
@@ -1915,7 +1890,7 @@ void RegisterAllocator::Resolve() {
   for (HLinearOrderIterator it(*codegen_->GetGraph()); !it.Done(); it.Advance()) {
     HBasicBlock* block = it.Current();
     if (block->IsCatchBlock() ||
-        (block->IsLoopHeader() && block->GetLoopInformation()->IsIrreducible())) {
+        (block->GetLoopInformation() != nullptr && block->GetLoopInformation()->IsIrreducible())) {
       // Instructions live at the top of catch blocks or irreducible loop header
       // were forced to spill.
       if (kIsDebugBuild) {