Fix scheduler for floating non-naked non-empty loops.

R=jarin@chromium.org
TEST=cctest/test-scheduler/NestedFloatingDiamondWithLoop

Review URL: https://codereview.chromium.org/709753002

Cr-Commit-Position: refs/heads/master@{#25283}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25283 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/scheduler.cc

@@ -295,6 +295,9 @@ class CFGBuilder {
   }
 
  private:
+  // TODO(mstarzinger): Only for Scheduler::FuseFloatingControl.
+  friend class Scheduler;
+
   void FixNode(BasicBlock* block, Node* node) {
     schedule_->AddNode(block, node);
     scheduler_->UpdatePlacement(node, Scheduler::kFixed);
@@ -1158,7 +1161,6 @@ class ScheduleEarlyNodeVisitor {
 
     // Fixed nodes already know their schedule early position.
     if (scheduler_->GetPlacement(node) == Scheduler::kFixed) {
-      DCHECK_EQ(schedule_->start(), data->minimum_block_);
       data->minimum_block_ = schedule_->block(node);
       Trace("Fixing #%d:%s minimum_block = B%d, dominator_depth = %d\n",
             node->id(), node->op()->mnemonic(),
@@ -1450,6 +1452,29 @@ void Scheduler::FuseFloatingControl(BasicBlock* block, Node* node) {
   }
   GenerateImmediateDominatorTree();
 
+  // Iterate on phase 4: Schedule nodes early.
+  // TODO(mstarzinger): The following loop gathering the propagation roots is a
+  // temporary solution and should be merged into the rest of the scheduler as
+  // soon as the approach settled for all floating loops.
+  NodeVector propagation_roots(cfg_builder.control_);
+  for (Node* node : cfg_builder.control_) {
+    for (Node* use : node->uses()) {
+      if (use->opcode() == IrOpcode::kPhi ||
+          use->opcode() == IrOpcode::kEffectPhi) {
+        propagation_roots.push_back(use);
+      }
+    }
+  }
+  if (FLAG_trace_turbo_scheduler) {
+    Trace("propagation roots: ");
+    for (Node* node : propagation_roots) {
+      Trace("#%d:%s ", node->id(), node->op()->mnemonic());
+    }
+    Trace("\n");
+  }
+  ScheduleEarlyNodeVisitor schedule_early_visitor(zone_, this);
+  schedule_early_visitor.Run(&propagation_roots);
+
   // Move previously planned nodes.
   // TODO(mstarzinger): Improve that by supporting bulk moves.
   scheduled_nodes_.resize(schedule_->BasicBlockCount(), NodeVector(zone_));

test/cctest/compiler/test-scheduler.cc

@@ -1825,10 +1825,8 @@ TEST(NestedFloatingDiamondWithLoop) {
   Node* loop = graph.NewNode(common.Loop(2), f, start);
   Node* ind = graph.NewNode(common.Phi(kMachAnyTagged, 2), p0, p0, loop);
 
-  // TODO(mstarzinger): Make scheduler deal with non-empty loops here.
-  // Node* add = graph.NewNode(&kIntAdd, ind, fv);
-
-  Node* br1 = graph.NewNode(common.Branch(), ind, loop);
+  Node* add = graph.NewNode(&kIntAdd, ind, fv);
+  Node* br1 = graph.NewNode(common.Branch(), add, loop);
   Node* t1 = graph.NewNode(common.IfTrue(), br1);
   Node* f1 = graph.NewNode(common.IfFalse(), br1);
 
@@ -1843,7 +1841,7 @@ TEST(NestedFloatingDiamondWithLoop) {
 
   graph.SetEnd(end);
 
-  ComputeAndVerifySchedule(19, &graph);
+  ComputeAndVerifySchedule(20, &graph);
 }